The Nigerian Niger Delta crude oil, which is the mainstay of Nigerian economy, exhibits waxiness, with deposits in the range of 30-45 % (Adewusi 1997; Fasesan and Adewumi, 2003; Taiwo et al., 2009 and Oladiipo et al., 2009). In fact, pipelines have been known to wax up beyond recovery in Nigeria. Production tubing has also been known to wax up, necessitating frequent wax cutting, using scrapers conveyed by wireline, which is an expensive practice. Billions of dollars has been lost to its prevention and remediation (Oladiipo et. al., 2009). The resultant effect on the petroleum industries include among others, reduced or deferred production, well shut-in, pipeline replacements and/or abandonment. For efficient operation of a pipeline system, steady and continuous flow

entire coastline of Nigeria (Fawehinmi, 2007).

Fig. 1.2. Niger Delta region, Nigeria.

to the refineries is threatened.

without any interruption is desirable (Chang et al., 1999). The difficulties in pipeline transportation are due to this complex nature of crude oil, which cause a variety of difficulties during the production, separation, transportation and refining of oil (Al-Besharah et al., 1987). For example, formation of asphaltic sludge after shutting in a production well temporarily and after stimulation treatment by acid has resulted in partial or complete plugging of the well (Ayala et al., 2007and Escobedo et al., 1997). Relative amount and molecular distribution of wax, resin and asphaltene as well as thermal and shear history of high pour point waxy crude sample directly affects the rheological properties of crude oil (Ajienka and Ikoku, 1997).

Phase changes in petroleum fluids during production, transportation and processing, constitute a challenging and an industrially important phenomenon. Polydisperse nature of hydrocarbons and other organic molecules in petroleum fluids accounts for the complexity of their phase behavior (Mansoori, 2009), which could be reversible or irreversible (Abedi et al., 1998). Generally, heavy fractions have little or no effect on the liquid-vapour phase behaviour of the majority of petroleum fluids. Their main contribution is in solid separation from petroleum fluids, due to changes in the composition, temperature and pressure (Mansoori, 2009; Escobedo and Mansoori, 2010). The main components of the heavy fraction, which participate in the solid phase formation include asphaltenes, diamondoids, petroleum resins and wax. Petroleum wax consist mainly saturated paraffin hydrocarbons with number of carbon atoms in the range of 18–36. Wax may also contain small amounts of naphthenic hydrocarbons with their number of carbon atoms in the range of 30–60. Wax usually exists in intermediate crudes, heavy oils, tar sands and oil shales. The distribution of n-alkanes as a function of the number of carbon-atom in a paraffin wax sample is given in figure 1.3 below.

Fig. 1.3. Carbon number distribution of paraffin wax.

Crude Oil Transportation: Nigerian Niger Delta Waxy Crude 139

The pipeline transportation system simulated for crude oil experimental measurement comprises the experimental pipe system, the circulating water system and crude oil

P P

P

**JT**

**V**

**JT**

**V**

The experimental pipe system and water circulation system are arranged in shell and tube mode. The water jacket around the reservoir tank can control the oil temperature in the pipe system while water circulation system controls the wall temperature of the test section. The internal diameter of pipe at both the test and reference section is 20.47 mm with the total

V- Valves; P – Pressure gauge; FM – Flow Meter; PM – Pump; WIN & WOUT - Heating/cooling Water IN and OUT; JT- jacketed Tank

**FM**

**WIN**

**PM**

The differential pressure of the test section and the reference section were measured during the wax transportation experiment. The wall temperature of the test section was varied and the differential pressure measured. The data collected were used to calculate the extent of the wax deposition and to elucidate on the mechanism of deposition. Carbon number distribution of paraffin wax determined by gas chromatography technique using the IP 372/

Effectiveness of some flow improvers for the waxy crude oils was determined through the pour point test (using Herzog MC 850 pour point test equipment) according to the ASTM-97 and kinematic viscosity by the IP 71 procedures. The dynamic inhibitive strength of these modifiers was equally experimented using the simulated crude oil pipeline transportation.

**2.4 Pipeline crude oil transportation simulation**

**WOU**

Fig. 2.1. Simulated pipeline transportation system.

**2.5 Evaluation tests of flow improvers**

**2.4.1 Wax deposition in simulated transportation flow line**

length of 2.75 m.

85 methods.

reservoir system (Fig. 2.1.).

**V**

Phase equilibrium deal with the various situations in which two or more phases (or state of aggregation) coexist in thermodynamic equilibrium with each other. Reservoir oil contains paraffin wax in solution. The average temperature of the oil in production well is somewhat higher than the atmospheric temperature. When a waxy crude oil is cooled, the heavier paraffinic constituents begin to separate as solid crystals once the solubility limit is exceeded (Karan et al., 2000). Thermodynamically, the solid-liquid phase boundary temperature, that is the maximum temperature at which the solid and liquid phases co-exist in equilibrium at a fixed pressure, is the wax appearance temperature (WAT). This depends on wax concentration, the crystallization habit of wax, and the shear stability of different wax structures (Holder and Winkler, 1965; Hussain et al., 1999).

This contribution therefore present the various phase-transitions, which may occur in petroleum fluids, and a unified perspective of their phase behaviors. Experimental determination of the rheological properties and the characteristics of the crude oil were carried out and the data tested on different established rheological models for ease of simulating the flow behavior of the crude oil. The wax deposition tendencies of crude oil in the pipelines and its influences on the transportation capacity were determined. The various methods of mitigating flow assurance problems and wax deposition inhibition highlighted towards adequate crude oil production.

#### **2. Experimental methods**

#### **2.1 Materials**

All crude oil samples used in this study were from Niger Delta Oil field in Nigeria, having density and API gravity in the range of 847 - 869 kg/m3 and 24.4 – 36.5 o at 15 oC, respectively. For physical properties measurements, the crude samples were shaken vigorously for one hour to homogenize and presents good representation of samples. Standard methods were employed in determination of the physical properties.

#### **2.2 Rheological properties measurements**

The rheological behavior of the crude oil samples were studied using Haake Rheo Stress model RS100 rheometer having several operating test modes. The test sample charged into the rheometer cup was allowed to equilibrate at a particular temperature. The unit was set to desired shear rates and operated at 10 revolution per minute, then the temperature of the test, the shear rate and the shear stress were recorded. The procedure was repeated at various other set temperatures and shear rates. The resulting sample deformation was detected using digital encoder with high impulse resolution. Thus, it allows measurements of small yield values, strains, or shear rates. The rheometer is equipped with a cone and plate sensor.

#### **2.3 Determination of the wax content**

Wax content was determined by precipitation method (Coto et al., 2008). It involves samples dissolution in n-pentane, precipitation with acetone:n-pentane mixture in ratio 3:1 and separating by filtration in Buchner funnel using glass microfiber Whatman filter N934.

#### **2.4 Pipeline crude oil transportation simulation**

138 Crude Oil Exploration in the World

Phase equilibrium deal with the various situations in which two or more phases (or state of aggregation) coexist in thermodynamic equilibrium with each other. Reservoir oil contains paraffin wax in solution. The average temperature of the oil in production well is somewhat higher than the atmospheric temperature. When a waxy crude oil is cooled, the heavier paraffinic constituents begin to separate as solid crystals once the solubility limit is exceeded (Karan et al., 2000). Thermodynamically, the solid-liquid phase boundary temperature, that is the maximum temperature at which the solid and liquid phases co-exist in equilibrium at a fixed pressure, is the wax appearance temperature (WAT). This depends on wax concentration, the crystallization habit of wax, and the shear stability of different wax

This contribution therefore present the various phase-transitions, which may occur in petroleum fluids, and a unified perspective of their phase behaviors. Experimental determination of the rheological properties and the characteristics of the crude oil were carried out and the data tested on different established rheological models for ease of simulating the flow behavior of the crude oil. The wax deposition tendencies of crude oil in the pipelines and its influences on the transportation capacity were determined. The various methods of mitigating flow assurance problems and wax deposition inhibition highlighted

All crude oil samples used in this study were from Niger Delta Oil field in Nigeria, having density and API gravity in the range of 847 - 869 kg/m3 and 24.4 – 36.5 o at 15 oC, respectively. For physical properties measurements, the crude samples were shaken vigorously for one hour to homogenize and presents good representation of samples.

The rheological behavior of the crude oil samples were studied using Haake Rheo Stress model RS100 rheometer having several operating test modes. The test sample charged into the rheometer cup was allowed to equilibrate at a particular temperature. The unit was set to desired shear rates and operated at 10 revolution per minute, then the temperature of the test, the shear rate and the shear stress were recorded. The procedure was repeated at various other set temperatures and shear rates. The resulting sample deformation was detected using digital encoder with high impulse resolution. Thus, it allows measurements of small yield values, strains, or shear rates. The rheometer is equipped with a cone and

Wax content was determined by precipitation method (Coto et al., 2008). It involves samples dissolution in n-pentane, precipitation with acetone:n-pentane mixture in ratio 3:1 and separating by filtration in Buchner funnel using glass microfiber Whatman filter N934.

Standard methods were employed in determination of the physical properties.

structures (Holder and Winkler, 1965; Hussain et al., 1999).

towards adequate crude oil production.

**2.2 Rheological properties measurements**

**2.3 Determination of the wax content**

**2. Experimental methods**

**2.1 Materials**

plate sensor.

The pipeline transportation system simulated for crude oil experimental measurement comprises the experimental pipe system, the circulating water system and crude oil reservoir system (Fig. 2.1.).

V- Valves; P – Pressure gauge; FM – Flow Meter; PM – Pump; WIN & WOUT - Heating/cooling Water IN and OUT; JT- jacketed Tank

Fig. 2.1. Simulated pipeline transportation system.

The experimental pipe system and water circulation system are arranged in shell and tube mode. The water jacket around the reservoir tank can control the oil temperature in the pipe system while water circulation system controls the wall temperature of the test section. The internal diameter of pipe at both the test and reference section is 20.47 mm with the total length of 2.75 m.

#### **2.4.1 Wax deposition in simulated transportation flow line**

The differential pressure of the test section and the reference section were measured during the wax transportation experiment. The wall temperature of the test section was varied and the differential pressure measured. The data collected were used to calculate the extent of the wax deposition and to elucidate on the mechanism of deposition. Carbon number distribution of paraffin wax determined by gas chromatography technique using the IP 372/ 85 methods.

#### **2.5 Evaluation tests of flow improvers**

Effectiveness of some flow improvers for the waxy crude oils was determined through the pour point test (using Herzog MC 850 pour point test equipment) according to the ASTM-97 and kinematic viscosity by the IP 71 procedures. The dynamic inhibitive strength of these modifiers was equally experimented using the simulated crude oil pipeline transportation.

Crude Oil Transportation: Nigerian Niger Delta Waxy Crude 141

Sample Bingham Plastic Casson Power Law

Table 3.1. Rheological Parameters and Correlation Coefficients of Models.

behavior, which is time dependent non-Newtonian fluid.

**3.2 Temperature effect**

τo μP R2 τo μ R2 m n R2

I 139.4 0.487 0.983 113.0 0.387 0.898 66.09 0.259 0.766 II 184.9 0.505 0.991 149.8 0.385 0.944 91.20 0.240 0.836 III 244.0 0.779 0.992 197.4 0.485 0.919 501.19 0.253 0.800

According to Bogne and Doughty (1966), the rheological characteristics of materials form a continuous spectrum of behavior, ranging from the perfectly elastic Hookean solid at one extreme, to that of purely viscous Newtonian fluid at the other. Between these idealized extremes is the behavior of real materials that include, among others, non-Hookean solids, non-Newtonian fluids, and viscoelastic substances. The waxy crude oil generally belongs to the non-Newtonian fluids while the Nigerian Niger delta waxy crude showed plastic

Temperature has a strong effect on viscosity and viscous behavior. This effect provides the ow behavior curve in terms of the viscosity-shear rate or viscosity-shear stress relationships. Fig. 3.2 shows the effect of temperature on shear stress-shear rate behavior over the temperature range of 25 – 55 oC experimented. The crude oil shows non-Newtonian shear thinning (viscosity reduction) behavior over the range of shear rates studied. By definition, yield stress, τo, is the limiting stress below which a sample behaves as a solid. At low stress, the elastic deformation takes place, which disappears when the applied stress is released (Guozhong and Gang , 2010 ). Chang et al., (1998) described the

Fig. 3.1. Rheogram of the waxy crude samples.

#### **3. Results and discussions**

#### **3.1 Rheological behaviour and modelling**

Rheology is the science of the deformation of matter. It involves the study of the change in form and flow of matter in term of elasticity, viscosity and plasticity under applied stresses or strains. The rheological behavior of waxy oil is crucial in the design of pipeline, flow handling equipment and processing purposes in the oil industry. The study of the rheological characteristics of crude oil is significant to lowering the energy consumption and ensuring safety and cost effectiveness in pipeline transportation of waxy crudes. Figure 3.1 shows a typical rheogram in terms of shear stress and shear rate. Shear stress increases asymptotically and significantly with shear rate. Several researchers have investigated models to describe the rheological properties of waxy oils (Davenport and Somper, 1971; Matveenko et al., 1995 and Remizov et al., 2000). Generally the behaviour can be broadly grouped into two; Newtonian and non-Newtonian fluids. Whereas the Newtonian fluids exhibit a linear relationship between shear stress and shear rate, the non-Newtonian fluids do not. The non-Newtonian fluids have yield stress, which is the upper limit of stress before flow occurs. At this point, the range of reversible elastic deformation ends and range of irreversible deformation or visco-elastic viscous flow occur (Chang et al., 2000). The existence of yield stress behavior depends upon the degree on interlocking structure developed by waxing and fragility of the network (Philip et al., 2011).

Modeling analysis carried out by fitting the rheological data to three models are reported in Table 3.1. The models include

Bingham plastic,

$$
\mathfrak{tr} = \mathfrak{x}\_{\alpha} + \mathfrak{m}\_{\mathrm{P}} \mathfrak{y} \tag{3.1}
$$

Casson,

$$
\pi^{1/2} = \mathfrak{r}\_o + \mathfrak{u}\gamma^{1/2} \tag{3.2}
$$

and Power law,

$$
\pi = \mathbf{m} \gamma^{\mathbf{n}} \tag{3.3}
$$

where γ is the applied shear rate (s-1) and τ is the corresponding shear stress in Pa, m and n are consistency index in Pa s and ow behavior index, the τo and μ are the apparent yield stress in Pa and the apparent viscosity in Pa s. Bingham model predicted very adequately the flow behavior of the crude oil over the tested range of shear rates. This observation suggests Nigerian Niger Delta waxy crude oil exhibits plastic behavior. Table 3.1 reports the highest regression correlation coefficient, R2, of 0.992 for the Bingham model. This is similar to an earlier work on waxy crudes from this area (Taiwo et al., 2009), with good prediction of the yield stress within percentage deviation of 2.88 ± 0.15.

Rheology is the science of the deformation of matter. It involves the study of the change in form and flow of matter in term of elasticity, viscosity and plasticity under applied stresses or strains. The rheological behavior of waxy oil is crucial in the design of pipeline, flow handling equipment and processing purposes in the oil industry. The study of the rheological characteristics of crude oil is significant to lowering the energy consumption and ensuring safety and cost effectiveness in pipeline transportation of waxy crudes. Figure 3.1 shows a typical rheogram in terms of shear stress and shear rate. Shear stress increases asymptotically and significantly with shear rate. Several researchers have investigated models to describe the rheological properties of waxy oils (Davenport and Somper, 1971; Matveenko et al., 1995 and Remizov et al., 2000). Generally the behaviour can be broadly grouped into two; Newtonian and non-Newtonian fluids. Whereas the Newtonian fluids exhibit a linear relationship between shear stress and shear rate, the non-Newtonian fluids do not. The non-Newtonian fluids have yield stress, which is the upper limit of stress before flow occurs. At this point, the range of reversible elastic deformation ends and range of irreversible deformation or visco-elastic viscous flow occur (Chang et al., 2000). The existence of yield stress behavior depends upon the degree on interlocking structure developed by waxing and fragility of the network (Philip et al.,

Modeling analysis carried out by fitting the rheological data to three models are reported in

1/2 1/2

where γ is the applied shear rate (s-1) and τ is the corresponding shear stress in Pa, m and n are consistency index in Pa s and ow behavior index, the τo and μ are the apparent yield stress in Pa and the apparent viscosity in Pa s. Bingham model predicted very adequately the flow behavior of the crude oil over the tested range of shear rates. This observation suggests Nigerian Niger Delta waxy crude oil exhibits plastic behavior. Table 3.1 reports the highest regression correlation coefficient, R2, of 0.992 for the Bingham model. This is similar to an earlier work on waxy crudes from this area (Taiwo et al., 2009), with good prediction of the yield stress within percentage deviation

o P (3.1)

o (3.2)

n m (3.3)

**3. Results and discussions**

2011).

Casson,

Table 3.1. The models include

Bingham plastic,

and Power law,

of 2.88 ± 0.15.

**3.1 Rheological behaviour and modelling**

Fig. 3.1. Rheogram of the waxy crude samples.

Table 3.1. Rheological Parameters and Correlation Coefficients of Models.

According to Bogne and Doughty (1966), the rheological characteristics of materials form a continuous spectrum of behavior, ranging from the perfectly elastic Hookean solid at one extreme, to that of purely viscous Newtonian fluid at the other. Between these idealized extremes is the behavior of real materials that include, among others, non-Hookean solids, non-Newtonian fluids, and viscoelastic substances. The waxy crude oil generally belongs to the non-Newtonian fluids while the Nigerian Niger delta waxy crude showed plastic behavior, which is time dependent non-Newtonian fluid.

#### **3.2 Temperature effect**

Temperature has a strong effect on viscosity and viscous behavior. This effect provides the ow behavior curve in terms of the viscosity-shear rate or viscosity-shear stress relationships. Fig. 3.2 shows the effect of temperature on shear stress-shear rate behavior over the temperature range of 25 – 55 oC experimented. The crude oil shows non-Newtonian shear thinning (viscosity reduction) behavior over the range of shear rates studied. By definition, yield stress, τo, is the limiting stress below which a sample behaves as a solid. At low stress, the elastic deformation takes place, which disappears when the applied stress is released (Guozhong and Gang , 2010 ). Chang et al., (1998) described the

Crude Oil Transportation: Nigerian Niger Delta Waxy Crude 143

Viscosity differences are relatively larger at low shear rates than at high shear rates. At high temperature, wax in the crude oil could not agglomerate and form aggregates, and hence reducing the oil viscosity. At high shear rate, (≥ 100 s-1), an almost constant viscosity was observed with increasing share rate. This could result from effective dispersion of wax agglomerates in the continuous phase originally immobilized within the agglomerate, after

The observed variation with temperature is attributable to the strong effect of temperature on the viscosity of wax and asphaltene components in crude oil. At high temperature, the ordered structure of these chemical components are destroyed, and hence reducing the oil viscosity (Khan, 1996). As the shear rate increases, the chain type molecules disentangled, stretched, and reoriented parallel to the driving force, and hence reduced the heavy crude

Fig. 3.4 shows the wax deposited as a function of temperature for the three Nigerian crude oils samples. Sample II has the highest percentage wax content of 33.5% with wax appearance temperature (WAT) of 43.5 oC while for sample I the wax content is 10.5 % with

being completely broken down into the basic particles.

oil viscosity (Ghannam and Esmail,1998, 2006).

Fig. 3.4. Wax precpitation as a function of temperature.

**3.3 Wax deposition characteristics**

WAT of 35 oC.

Fig. 3.2. Shear stress as a function of shear rate with varying temperature (Sample I).

yielding behavior of a waxy crude oil as having three distinct characteristics—an elastic response, a creep and a fracture. The shear stress at the point of fracture is the value of practical importance and is usually taken as the yield stress. Above the yield stress point, the applied stress leads to unlimited deformation which causes the sample to start flow (Ghannam and Esmail, 2005). The yield point, which is required to start the flow, decreases with temperature from 150 Nm-2 at room temperature of 25 oC to 104 Nm-2 at the temperature of 55 oC. Similar trend ensued for the other samples. At a higher cooling rate, the rate of wax precipitation is higher. Hence, a higher stress is necessary either to aggregate the crystals, or to breakdown the structure.

In addition, the apparent viscosity decreases considerably with increasing temperature (Fig 3.3).

Fig. 3.3. Effect of temperature on viscosity of the crude.

Fig. 3.2. Shear stress as a function of shear rate with varying temperature (Sample I).

the crystals, or to breakdown the structure.

Fig. 3.3. Effect of temperature on viscosity of the crude.

3.3).

yielding behavior of a waxy crude oil as having three distinct characteristics—an elastic response, a creep and a fracture. The shear stress at the point of fracture is the value of practical importance and is usually taken as the yield stress. Above the yield stress point, the applied stress leads to unlimited deformation which causes the sample to start flow (Ghannam and Esmail, 2005). The yield point, which is required to start the flow, decreases with temperature from 150 Nm-2 at room temperature of 25 oC to 104 Nm-2 at the temperature of 55 oC. Similar trend ensued for the other samples. At a higher cooling rate, the rate of wax precipitation is higher. Hence, a higher stress is necessary either to aggregate

In addition, the apparent viscosity decreases considerably with increasing temperature (Fig

Viscosity differences are relatively larger at low shear rates than at high shear rates. At high temperature, wax in the crude oil could not agglomerate and form aggregates, and hence reducing the oil viscosity. At high shear rate, (≥ 100 s-1), an almost constant viscosity was observed with increasing share rate. This could result from effective dispersion of wax agglomerates in the continuous phase originally immobilized within the agglomerate, after being completely broken down into the basic particles.

The observed variation with temperature is attributable to the strong effect of temperature on the viscosity of wax and asphaltene components in crude oil. At high temperature, the ordered structure of these chemical components are destroyed, and hence reducing the oil viscosity (Khan, 1996). As the shear rate increases, the chain type molecules disentangled, stretched, and reoriented parallel to the driving force, and hence reduced the heavy crude oil viscosity (Ghannam and Esmail,1998, 2006).

#### **3.3 Wax deposition characteristics**

Fig. 3.4 shows the wax deposited as a function of temperature for the three Nigerian crude oils samples. Sample II has the highest percentage wax content of 33.5% with wax appearance temperature (WAT) of 43.5 oC while for sample I the wax content is 10.5 % with WAT of 35 oC.

Fig. 3.4. Wax precpitation as a function of temperature.

Crude Oil Transportation: Nigerian Niger Delta Waxy Crude 145

The average wax deposition rates reported in Fig. 3.6 were at temperature differences of 3 °C, 5 °C and 8 °C respectively, at 30 h deposition time. Generally, gradual increase in deposition rate with increasing temperature difference was observed. However, at zero °C temperature difference, experimental results showed that no deposition occur because there is no driving force for lateral diffusion of the wax molecules. When the oil temperature is 50 °C, the average wax deposition rate was zero at temperature difference of 3 °C, corresponding to the wall temperature of 47 °C, which is slightly above the WAT of the crude sample. Under this condition, the paraffin molecule super saturation concentration is very low, thus, its wax deposition power tend to zero. However, at 5 °C temperature difference, the deposition rate was 0.025 mm/d. This observation was due to lateral diffusion of the wax in crude oil. When temperature difference increased to 8 °C, the rate increased to 0.10 mm/d. It reflects wall temperature of 42 °C which is lower than the WAT

of the crude oil sample.

Fig. 3.6. Variation of deposition rate with temperature difference.

At the oil temperature of 45 °C, the average wax deposition rate increases with the fall in the wall temperature. When the temperature difference between the oil and the wall is 8 ° C (the wall temperature is 37 °C), the average wax deposition rate is 0.12 mm/d and higher than that experienced for 50 oC oil temperature. For the oil temperature of 40 °C, deposition rate is generally higher than other temperature conditions. However, at higher temperature

The wax appearance temperature (WAT) and the pour point temperature (PPT) are good pointers to the temperature regime, in which a waxy crude oil is expected to start to show non-Newtonian behavior. Their determination is an important step in the study of rheological behavior of such systems. In fact, WAT is probably the most important flow assurance measurement for waxy crudes. Pour point represents the lowest temperature at which the crude oil can be stored or handled without congealing in the tanks or pipelines. Usually, it is 10-20 oC lower than the cloud point (Ajienka, 1983). The pour point of samples experimented were in the range of 18 and 32 oC. As the fluid cools below WAT, crystal size tends to increase and crystal aggregation is usual, particularly under quiescent and low shear condition, such that the solid-like behavior of the waxy suspension increases. At some point between the WAT and pour point, a transition can be determined depending on wax development and is thus strongly affected by thermal and shear conditions. This is considered an indication of initial development of interlocking network (Lopes-da-Silva and Coutinho, 2004).

#### **3.4 Wax deposition rate in flow system**

As trot to understanding the deposition pattern and hence the flow assurance of the oil samples, simulated transportation flow pipe described in section 2.4 was developed. It is a modification to earlier work (Taiwo et al., 2009), with consideration for the idea of Guozhong and Gang (2010). As expected, the wax deposit thickness showed inverse proportionality with wall temperature and direct relation with temperature difference between the oil and pipe wall (Fig 3.5). In addition, a monotonic increase with time was observed. The low thickness observed at 42 oC wall temperature is significant of closeness to the WAT of oil sample which is 43.5 oC. In addition, the average wax deposition rate (mm/d) increases with increased difference in temperature as shown in Fig. 3.6.

Fig. 3.5. Wax deposit thickness variation with time as a function of wall temperature.

The wax appearance temperature (WAT) and the pour point temperature (PPT) are good pointers to the temperature regime, in which a waxy crude oil is expected to start to show non-Newtonian behavior. Their determination is an important step in the study of rheological behavior of such systems. In fact, WAT is probably the most important flow assurance measurement for waxy crudes. Pour point represents the lowest temperature at which the crude oil can be stored or handled without congealing in the tanks or pipelines. Usually, it is 10-20 oC lower than the cloud point (Ajienka, 1983). The pour point of samples experimented were in the range of 18 and 32 oC. As the fluid cools below WAT, crystal size tends to increase and crystal aggregation is usual, particularly under quiescent and low shear condition, such that the solid-like behavior of the waxy suspension increases. At some point between the WAT and pour point, a transition can be determined depending on wax development and is thus strongly affected by thermal and shear conditions. This is considered an indication of initial development of interlocking network (Lopes-da-Silva and

As trot to understanding the deposition pattern and hence the flow assurance of the oil samples, simulated transportation flow pipe described in section 2.4 was developed. It is a modification to earlier work (Taiwo et al., 2009), with consideration for the idea of Guozhong and Gang (2010). As expected, the wax deposit thickness showed inverse proportionality with wall temperature and direct relation with temperature difference between the oil and pipe wall (Fig 3.5). In addition, a monotonic increase with time was observed. The low thickness observed at 42 oC wall temperature is significant of closeness to the WAT of oil sample which is 43.5 oC. In addition, the average wax deposition rate

(mm/d) increases with increased difference in temperature as shown in Fig. 3.6.

Fig. 3.5. Wax deposit thickness variation with time as a function of wall temperature.

Coutinho, 2004).

**3.4 Wax deposition rate in flow system**

The average wax deposition rates reported in Fig. 3.6 were at temperature differences of 3 °C, 5 °C and 8 °C respectively, at 30 h deposition time. Generally, gradual increase in deposition rate with increasing temperature difference was observed. However, at zero °C temperature difference, experimental results showed that no deposition occur because there is no driving force for lateral diffusion of the wax molecules. When the oil temperature is 50 °C, the average wax deposition rate was zero at temperature difference of 3 °C, corresponding to the wall temperature of 47 °C, which is slightly above the WAT of the crude sample. Under this condition, the paraffin molecule super saturation concentration is very low, thus, its wax deposition power tend to zero. However, at 5 °C temperature difference, the deposition rate was 0.025 mm/d. This observation was due to lateral diffusion of the wax in crude oil. When temperature difference increased to 8 °C, the rate increased to 0.10 mm/d. It reflects wall temperature of 42 °C which is lower than the WAT of the crude oil sample.

Fig. 3.6. Variation of deposition rate with temperature difference.

At the oil temperature of 45 °C, the average wax deposition rate increases with the fall in the wall temperature. When the temperature difference between the oil and the wall is 8 ° C (the wall temperature is 37 °C), the average wax deposition rate is 0.12 mm/d and higher than that experienced for 50 oC oil temperature. For the oil temperature of 40 °C, deposition rate is generally higher than other temperature conditions. However, at higher temperature

Crude Oil Transportation: Nigerian Niger Delta Waxy Crude 147

additive co-crystallize with the wax and the polar end groups disrupts the orthorhombic

Trichloroethylene, xylene and tri ethanolamine actively decreased the pour point of the samples and their wax deposition potentials on doping. The oxygen containing groups in the doping agents take the role of inhibiting the growth of waxes and poisoning them by adsorptive surface poisoning mechanism. The PPDs on adsorption on the surface of the wax renders its nuclei inactive for further growth. The waxes then occur in small sized particles distributed within the crude oil samples, thus cannot form net-like structure

Bello et. al., 2005 Taiwo et al 2009

No additive 0.05 36 0.25 28 0.28 33 0.335 36

Ketone 0.037 22 0.15 22 0.185 18 0.188 25

Amine - - 0.085 18 0.106 23 0.107 16 Xylene 0.013 17 0.115 17 0.143 17 0.154 18

hexanone 0.028 18 - - - - - -

Ethylene 0.009 16 - - - - - -

Wax deposition (g/g)

> Pour point (oC)

EB FL BL EL

Wax deposition (g/g)

I II III

Pour point (oC)

Wax deposition (g/g)

Wax deposition (g/g)

No additive 0.105 18 0.305 32 0.150 27 Methyl Ethyl Ketone 0.069 14 0.164 23.5 0.084 21.5 Tri Ethanol Amine 0.040 12 0.092 17 0.053 18.5 Xylene 0.054 11.5 0.130 18 0.067 17.5 Cyclo-hexanone 0.052 12.5 0.182 22 0.076 18 Tri Chloro Ethylene 0.048 11 0.171 19.5 0.062 17

Pour point (oC)

Wax deposition (g/g)

Pour point (oC)

Pour point (oC)

Pour point (oC)

crystal structure into a compact pyramidal form (Hemant et al., 2008).

required for solidification and deposition.

Wax deposition (g/g)

Adewusi, 1998

Pour point (oF)

Table 3.2 Evaluation of various solvents for flow improver.

Wax deposition (g/g)

Table 3.3 Screening of common solvents for flow improver.

Pour Point Depressant

Methyl Ethyl

Tri Ethanol

Cyclo-

Tri Chloro

Pour Point Depressant

difference, the deposition rate almost assumed same value. This may be due to wax content in the crude.

The theory of the molecular diffusion suggests gradual wax deposition in the pipe as the wall temperature decreases. However, at low wall temperature of the test section, the differential pressure of the test section increased sharply. This rapid increase of the differential pressure should therefore not be the resultant effect of the wax deposition, since a gradual increase in wax deposition was observed (Figs. 3.4 and 3.5). A fast increase of the oil viscosity near the wall could have resulted from the drop in wall temperature, thereby distorting the ow regime in the test section due to the radial differential temperature; this makes the differential pressure of the test section increase suddenly. Mansoori, (2009) attributes this observation to phase transition which influence the Gibbs energy of the system hence sudden change in pressure drop.

#### **3.5 Doping of waxy crude**

Wax build-up in tubing and flow lines is a typical flow assurance problem. This makes transportation of such waxy crudes un-economically feasible. To improve mobility of the oils, viscosity reduction is imminent. This can be done by heating, blending of the oils with lighter oils or other solvents having pour-point depressing effect (Hemant et al., 2008). In addition there are applications of microwaves, ultrasound irradiation, magnetic fields, lining and coating pipelines with fiber-reinforced plastics to reduce the wettability of paraffin with the wall of the pipe, and covering the inner wall surfaces with polypropylene (Hemant et al., 2008). Pipeline heating is usually deployed for small distances (with insulation) and moving the oil as quickly as possible. This passive insulation becomes in effective when longer pipe length oil transport is required. High backpressure will set in requiring expensive booster pumps. Electrically heated subsea pipeline is considered an alternative (Langner and Brass, 2001). Even then, the complexity of the pipeline design required and need to heat whole pipe length makes the configuration costly to deploy and operate (Martinez-Paloua et al., 2011). Doping with solvent, which keeps the wax in solution, is therefore essential in ensuring oil mobility. Based on evaluation of preliminary studies (Adewusi, 1998; Fasesan and Adewumi, 2003; Bello et al., 2005a, 2005b, 2006 and Taiwo et al., 2009), xylene based pour point depression solvents were considered. Table 3.2 reports some solvents for improving the transportation of Niger Delta waxy crudes. Xylene (X) and tri chloro ethylene (TCE) are good pour point depressant based on the work of Adewusi (1998) and Bello et al., (2005a), while Taiwo et al., (2009) showed tri ethanol amine (TEA) to be very good wax deposition inhibitor (Table 3.2). These three solvents further confirm their wax inhibition strength from the report of the present experimentation (Table 3.3). Xylene reduced the pour point from 32 oC to 18 oC for sample II that has the highest wax content of 30.5 percent, while TCE and TEA reduced it to 19.5 and 17 oC, respectively. Pour point depressants (PPDs) accomplish this task by modifying the size and shape of wax crystals and inhibit the formation of large wax crystal lattices (Wang et al., 2003). Generally, the PPDs create barrier to the formation of the interlocking crystal wax network (Wang et al. 1999). As a result, the altered shape and smaller size of the wax crystals reduce the formation of the interlocking networks and reduces the pour point (Hemant et al., 2008) by preventing wax agglomeration (Hafiz and Khidr, 2007). In some cases pendant chains in the

difference, the deposition rate almost assumed same value. This may be due to wax content

The theory of the molecular diffusion suggests gradual wax deposition in the pipe as the wall temperature decreases. However, at low wall temperature of the test section, the differential pressure of the test section increased sharply. This rapid increase of the differential pressure should therefore not be the resultant effect of the wax deposition, since a gradual increase in wax deposition was observed (Figs. 3.4 and 3.5). A fast increase of the oil viscosity near the wall could have resulted from the drop in wall temperature, thereby distorting the ow regime in the test section due to the radial differential temperature; this makes the differential pressure of the test section increase suddenly. Mansoori, (2009) attributes this observation to phase transition which influence the Gibbs energy of the

Wax build-up in tubing and flow lines is a typical flow assurance problem. This makes transportation of such waxy crudes un-economically feasible. To improve mobility of the oils, viscosity reduction is imminent. This can be done by heating, blending of the oils with lighter oils or other solvents having pour-point depressing effect (Hemant et al., 2008). In addition there are applications of microwaves, ultrasound irradiation, magnetic fields, lining and coating pipelines with fiber-reinforced plastics to reduce the wettability of paraffin with the wall of the pipe, and covering the inner wall surfaces with polypropylene (Hemant et al., 2008). Pipeline heating is usually deployed for small distances (with insulation) and moving the oil as quickly as possible. This passive insulation becomes in effective when longer pipe length oil transport is required. High backpressure will set in requiring expensive booster pumps. Electrically heated subsea pipeline is considered an alternative (Langner and Brass, 2001). Even then, the complexity of the pipeline design required and need to heat whole pipe length makes the configuration costly to deploy and operate (Martinez-Paloua et al., 2011). Doping with solvent, which keeps the wax in solution, is therefore essential in ensuring oil mobility. Based on evaluation of preliminary studies (Adewusi, 1998; Fasesan and Adewumi, 2003; Bello et al., 2005a, 2005b, 2006 and Taiwo et al., 2009), xylene based pour point depression solvents were considered. Table 3.2 reports some solvents for improving the transportation of Niger Delta waxy crudes. Xylene (X) and tri chloro ethylene (TCE) are good pour point depressant based on the work of Adewusi (1998) and Bello et al., (2005a), while Taiwo et al., (2009) showed tri ethanol amine (TEA) to be very good wax deposition inhibitor (Table 3.2). These three solvents further confirm their wax inhibition strength from the report of the present experimentation (Table 3.3). Xylene reduced the pour point from 32 oC to 18 oC for sample II that has the highest wax content of 30.5 percent, while TCE and TEA reduced it to 19.5 and 17 oC, respectively. Pour point depressants (PPDs) accomplish this task by modifying the size and shape of wax crystals and inhibit the formation of large wax crystal lattices (Wang et al., 2003). Generally, the PPDs create barrier to the formation of the interlocking crystal wax network (Wang et al. 1999). As a result, the altered shape and smaller size of the wax crystals reduce the formation of the interlocking networks and reduces the pour point (Hemant et al., 2008) by preventing wax agglomeration (Hafiz and Khidr, 2007). In some cases pendant chains in the

in the crude.

system hence sudden change in pressure drop.

**3.5 Doping of waxy crude**

additive co-crystallize with the wax and the polar end groups disrupts the orthorhombic crystal structure into a compact pyramidal form (Hemant et al., 2008).

Trichloroethylene, xylene and tri ethanolamine actively decreased the pour point of the samples and their wax deposition potentials on doping. The oxygen containing groups in the doping agents take the role of inhibiting the growth of waxes and poisoning them by adsorptive surface poisoning mechanism. The PPDs on adsorption on the surface of the wax renders its nuclei inactive for further growth. The waxes then occur in small sized particles distributed within the crude oil samples, thus cannot form net-like structure required for solidification and deposition.

Table 3.2 Evaluation of various solvents for flow improver.

Table 3.3 Screening of common solvents for flow improver.

Crude Oil Transportation: Nigerian Niger Delta Waxy Crude 149

The dynamic inhibitive strength of the flow improvers tested by applying the doping agents into the crude samples in the reservoir tanks of the simulated pipeline transportation set-up, showed a marked reduction relative to that obtained for undoped samples. This showed that the PPD apart from lowering the pour point of the waxy crude caused reduction in pressure build-up by keeping the wax particles in solution and hence reduced viscosity of crude samples. Wax deposition was not feasible in the test pipe surfaces even at 8 oC temperature difference between the oil temperature and the wall temperature. The moderately higher-pressure drop with TCEX over the TEAX modified crude samples further confirms the strength of TEAX in wax crystal modification (Fig 3.10). Plate 3.1 showed the wax dispersed in crude oil sample upon modification. This evidently supports the view of Azevedo and Teixeira (2003) that shear dispersion play significant role in wax

deposit removal thus affecting the rate of wax accumulation.

Fig. 3.8. Pour point depression test for sample II at varying test temperature.

It is suggested that the reduction of the measured viscosity is due to the interactions between the hydroxyl functions or the delocalized unpaired electron over the π-orbital especially in the phenyl group of PPD and some functionalities of the wax (Gateau et al., 2004). This could have premised the performance of TEAX and TCEX. With 0.1 volume fraction of TEA or TCE in TEAX or TCEX binary, the shear thinning behavior is enhanced, and the viscosity as well as the pour point decreases as the temperature increases (Figs 3.7 and 3.8). TEAX improved the rheological characteristic behavior better than TCEX. The reduction of viscosity on the addition of the solvents is due to the dissolution of paraffin wax, the effect xylene on the effectiveness of these dopants is significant and play a major role in reducing the viscosity. This observation gave credence to the report of Chanda et al., (1998).

Fig. 3.7. Viscosity variation for doped sample II with temperature.

#### **3.6 Hydrocarbon distribution in the crude oil wax**

The crude oil samples wax had similar hydrocarbon distributions. The carbon number distribution of the paraffin wax is shown in Fig. 3.9. Samples I and III had very identical carbon number distribution, and all samples showed the same peak carbon number. This ranged between C31 and C33 indicative of paraffinic wax, although tailing to C38 an occurrence of naphthenic crude.

It is suggested that the reduction of the measured viscosity is due to the interactions between the hydroxyl functions or the delocalized unpaired electron over the π-orbital especially in the phenyl group of PPD and some functionalities of the wax (Gateau et al., 2004). This could have premised the performance of TEAX and TCEX. With 0.1 volume fraction of TEA or TCE in TEAX or TCEX binary, the shear thinning behavior is enhanced, and the viscosity as well as the pour point decreases as the temperature increases (Figs 3.7 and 3.8). TEAX improved the rheological characteristic behavior better than TCEX. The reduction of viscosity on the addition of the solvents is due to the dissolution of paraffin wax, the effect xylene on the effectiveness of these dopants is significant and play a major role in reducing the viscosity. This observation gave credence to the report of Chanda et al.,

Fig. 3.7. Viscosity variation for doped sample II with temperature.

The crude oil samples wax had similar hydrocarbon distributions. The carbon number distribution of the paraffin wax is shown in Fig. 3.9. Samples I and III had very identical carbon number distribution, and all samples showed the same peak carbon number. This ranged between C31 and C33 indicative of paraffinic wax, although tailing to C38 an

**3.6 Hydrocarbon distribution in the crude oil wax**

occurrence of naphthenic crude.

(1998).

The dynamic inhibitive strength of the flow improvers tested by applying the doping agents into the crude samples in the reservoir tanks of the simulated pipeline transportation set-up, showed a marked reduction relative to that obtained for undoped samples. This showed that the PPD apart from lowering the pour point of the waxy crude caused reduction in pressure build-up by keeping the wax particles in solution and hence reduced viscosity of crude samples. Wax deposition was not feasible in the test pipe surfaces even at 8 oC temperature difference between the oil temperature and the wall temperature. The moderately higher-pressure drop with TCEX over the TEAX modified crude samples further confirms the strength of TEAX in wax crystal modification (Fig 3.10). Plate 3.1 showed the wax dispersed in crude oil sample upon modification. This evidently supports the view of Azevedo and Teixeira (2003) that shear dispersion play significant role in wax deposit removal thus affecting the rate of wax accumulation.

Fig. 3.8. Pour point depression test for sample II at varying test temperature.

Crude Oil Transportation: Nigerian Niger Delta Waxy Crude 151

A B

A study of transportation of waxy Nigerian Niger Delta crude oil using flow improver was performed. This study has been able to highlight the significance of TEA in improving the flow of this crude oil by significantly lowering the pour point and wax deposition potentials of the crude sample. The crude oil had been established to show plastic behaviour with Bingham non-newtonian model adequately predicts its rheological behaviour with occurrence of yield stress. The simulated pipeline transportation system for experimentation revealed mass diffusion mechanism for transport and deposition of waxes on the tube wall. The characteristics and behaviour of solvent modified crude oils should help in addressing

The authors appreciate the technical staff of Chemical Engineering Department, Obafemi Awolowo University, Ile-Ife, Nigeria for the fabrication works, Department of Petroleum Engineering, University of Ibadan, Nigeria for making their facility available for this study, and the Department of Petroleum Resources (DPR), Nigeria, for assistance during the

Abedi, S.J., Seyfaie, S. and Shaw, J.M. (1998). Unusual retrograde condensation and

Adewusi V. A. (1998). An improved inhibition of paraffin deposition from waxy crudes.

Adewusi, V. A. (1997). Prediction of wax deposition potential of hydrocarbon systems for

asphaltene precipitation in a model heavy oil system, *Journal of Petroleum Science*

Plate 3.1. Micrograph of crude sample at X 500 magnification (A: undoped B: doped)

cost-effective solution to flow assurance problems in the industry.

*and Technology.* 16 (3/4), 209–226.

*Petroleum Science and Technology* 16(9 & 10), 953 - 970

viscosity-pressure correlations. *Fuel* 76:1079–1083.

**4. Conclusion**

**5. Acknowledgment**

sample collection.

**6. References**

Fig. 3.9. Hydrocarbon distribution in wax samples.

Fig. 3.10. Variation of pressure drop with time for doped and undoped sample in dynamic test.

Plate 3.1. Micrograph of crude sample at X 500 magnification (A: undoped B: doped)

### **4. Conclusion**

150 Crude Oil Exploration in the World

Fig. 3.10. Variation of pressure drop with time for doped and undoped sample in dynamic

Fig. 3.9. Hydrocarbon distribution in wax samples.

test.

A study of transportation of waxy Nigerian Niger Delta crude oil using flow improver was performed. This study has been able to highlight the significance of TEA in improving the flow of this crude oil by significantly lowering the pour point and wax deposition potentials of the crude sample. The crude oil had been established to show plastic behaviour with Bingham non-newtonian model adequately predicts its rheological behaviour with occurrence of yield stress. The simulated pipeline transportation system for experimentation revealed mass diffusion mechanism for transport and deposition of waxes on the tube wall. The characteristics and behaviour of solvent modified crude oils should help in addressing cost-effective solution to flow assurance problems in the industry.

#### **5. Acknowledgment**

The authors appreciate the technical staff of Chemical Engineering Department, Obafemi Awolowo University, Ile-Ife, Nigeria for the fabrication works, Department of Petroleum Engineering, University of Ibadan, Nigeria for making their facility available for this study, and the Department of Petroleum Resources (DPR), Nigeria, for assistance during the sample collection.

#### **6. References**

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implication in production operation, Ph. D Dissertation, University of Port

**9**

*Assam, India*

Prahash Chandra Sarma *Cotton College, Guwahati,*

**Degradation of Petroleum Fractions in Soil Under Natural Environment: A Gravimetric**

The modern civilization depends on exploration, distribution and use of petroleum and thousands of products derived from it. The environment all throughout the world has been very badly damaged due to these chemicals. While pollution of the atmosphere has been caused almost totally by burning of the petroleum products, the leaks, spillages and accidental fallout of petroleum products and the crude petroleum itself have greatly affected land and water resources. The oil field areas always receive a large amount of effluents rich in crude oil and land degradation is a common phenomenon. While using different fractions of petroleum (gasoline, kerosene, diesel etc.) spills and leakages cannot be avoided and in industrial areas, garages and other places, a large amount of it flows to the nearby areas. All types of oil have amazing spreading power and once a leak occurs, the oil may spread horizontally as well as vertically depending upon soil conditions, moisture, temperature etc. The lighter fraction being volatile are easily removed by evaporation and other physical processes, but the heavy components such as aromatics – simple and polycyclic, Hopanes etc. remain in the soil for a very long time unless biodegraded by soil micro organisms. The detection of presence of some carcinogenic hydrocarbons viz. PAH has made the situation a matter of serious concern. In most cases; the pollutant oil exerts its detrimental effects before it degrades into harmless and simple compounds. Hence a study on the type of degradation mechanism, the measures which can expedite the process of bioremediation and how the soil parameters are influenced by oil pollutants and their degradation is demanded by situation. The present investigation intends to gains some true knowledge on the matter

Human race is dependent on a number of gifts of the nature. One such gift of nature is the Soil resource. It has been defined as the thin layer of the earth's crust in which biological activities take place. The beneficial activities of soil are multidimensional. Animal life is absolutely dependent on plant kingdom for food. Plants absorb nutrients from soil and convert it into a form acceptable to animal kingdom. Thus it is one of the best supporters of

**1. Introduction**

based on experimental findings.

**2. Soil is a depleting natural resource**

**and Gas Chromatographic Analysis**

Condensates. *33rd Annual SPE International Technical Conference and Exhibition in Abuja, Nigeria,* August 3-5, 2009. SPE 128600

### **Degradation of Petroleum Fractions in Soil Under Natural Environment: A Gravimetric and Gas Chromatographic Analysis**

Prahash Chandra Sarma *Cotton College, Guwahati, Assam, India*

#### **1. Introduction**

154 Crude Oil Exploration in the World

Philip, D. A.; Forsdyke, I. N.; McCracken I. R. and Ravenscroft P. D. (2011) Novel approach

Remizov S. V., Kirsanov E. A. Matveenko N. V. (2000), Colloids and Surfaces A.

Taiwo, E. A., Fasesan, S. O. and Akinyemi, O. P.(2009) Rheology of Doped Nigerian Niger-Delta Waxy Crude Oil. *Petroleum Science and Technology*, 27(13),1381 — 1393 Wang J., Brower K. And Buckley J. (1999) Advances in observation of asphaltene

Wang, K. S.; Wu, C. H.; Creek, J. L.; Shuler P. J. and Tang Y. (2003). Evaluation of effects of

*Abuja, Nigeria,* August 3-5, 2009. SPE 128600

16-19, 1999. SPE Paper 50745

369-379

*Journal of Petroleum Science and Engineering* 77(3-4), 286-304

Physicochemical and Engineering Aspects 175, 271-275

Condensates. *33rd Annual SPE International Technical Conference and Exhibition in*

to waxy crude restart: Part 2: An investigation of flow events following shut down.

destabilisation. *Proceeding of SPE on Oil field Chemistry,* Houston, Texas. February,

selected wax inhibitors on paraffin deposition. *Petroleum Science and Technology*. 21,

The modern civilization depends on exploration, distribution and use of petroleum and thousands of products derived from it. The environment all throughout the world has been very badly damaged due to these chemicals. While pollution of the atmosphere has been caused almost totally by burning of the petroleum products, the leaks, spillages and accidental fallout of petroleum products and the crude petroleum itself have greatly affected land and water resources. The oil field areas always receive a large amount of effluents rich in crude oil and land degradation is a common phenomenon. While using different fractions of petroleum (gasoline, kerosene, diesel etc.) spills and leakages cannot be avoided and in industrial areas, garages and other places, a large amount of it flows to the nearby areas. All types of oil have amazing spreading power and once a leak occurs, the oil may spread horizontally as well as vertically depending upon soil conditions, moisture, temperature etc. The lighter fraction being volatile are easily removed by evaporation and other physical processes, but the heavy components such as aromatics – simple and polycyclic, Hopanes etc. remain in the soil for a very long time unless biodegraded by soil micro organisms. The detection of presence of some carcinogenic hydrocarbons viz. PAH has made the situation a matter of serious concern. In most cases; the pollutant oil exerts its detrimental effects before it degrades into harmless and simple compounds. Hence a study on the type of degradation mechanism, the measures which can expedite the process of bioremediation and how the soil parameters are influenced by oil pollutants and their degradation is demanded by situation. The present investigation intends to gains some true knowledge on the matter based on experimental findings.

#### **2. Soil is a depleting natural resource**

Human race is dependent on a number of gifts of the nature. One such gift of nature is the Soil resource. It has been defined as the thin layer of the earth's crust in which biological activities take place. The beneficial activities of soil are multidimensional. Animal life is absolutely dependent on plant kingdom for food. Plants absorb nutrients from soil and convert it into a form acceptable to animal kingdom. Thus it is one of the best supporters of

Degradation of Petroleum Fractions in Soil

operation is an important activity.

**4. Methodology**

Sample No.

Set-1

Set-2

Set-3

Mass of Crude Oil

Under Natural Environment: A Gravimetric and Gas Chromatographic Analysis 157

Biphenyls negatively impact fossil fuel degradation ( Hoeppel et.al, 1995).Out of several methods to expedite the process of degradation of Petroleum Hydrocarbons and to rehabilitate an oil inundated soil such as Bioremediation, Polyencapsulation, Vapour Transport, Land Farming, Alcohol Flooding etc. Bioremediation is considered effective and environmentally benign. Before taking up remediation measures emergency clean up

Soil sample having no history of oil pollution were taken, polluted by known quantity of oil using emulsifier- some with nutrients, some with oxidising agents and some without any additive and the stated experiment was done by placing indoor in polyethene bags and maintaining the conditions necessary for microbial activities (Table-1). Series with B, C, D and E are similar to series A except that the oil is replaced by Kerosene oil, Diesel oil, Lubricating oil and Residual oil respectively. Gravimetric determination was done by withdrawing 20 g polluted soil sample from each bag and by recovering the oil by soxhlet extraction method using Petroleum ether as solvent after definite time interval. Gas Liquid Chromatography (GLC/GC) is the method of choice for rapidly and accurately analysing the volatile substances. It is also applicable to non volatile ones due to availability of higher column temperatures. Different compounds maintain similar sequence in the chromatogram

analyzed under same system of column and identical conditions.

Mass of Soil

Total mass

**-** g g g g ppm mL mL

1A0 0 0 3000 3000 0 2 0 1A1 3 0 2997 3000 1000 2 0 1A2 15 0 2985 3000 5000 2 0 1A3 30 0 2970 3000 10000 2 0 1A4 45 0 2955 3000 15000 2 0 1A5 60 0 2940 3000 20000 2 0

2A0 0 10 2990 3000 0 2 0 2A1 3 10 2987 3000 1000 2 0 2A2 15 10 2975 3000 5000 2 0 2A3 30 10 2960 3000 10000 2 0 2A4 45 10 2945 3000 15000 2 0 2A5 60 10 2930 3000 20000 2 0

3A0 0 0 3000 3000 0 2 10 3A1 3 0 2997 3000 1000 2 10 3A2 15 0 2985 3000 5000 2 10 3A3 30 0 2970 3000 10000 2 10 3A4 45 0 2955 3000 15000 2 10 3A5 60 0 2940 3000 20000 2 10

Table 1. Sample Numbers and their Contents possessing Crude Oil.

Concentration of Crude Oil

Volume of Emulsifier

Volume of H2O2 added

Mass of Nutrient

life. Soil is made of weathered rock material and organic matter. Weathering, the physical and chemical breakdown of rocks is the first step in the soil forming process. The process of soil formation is a very long and slow geological process. The process is cyclic, because the rocks are changed to unconsolidated particles, which may be eventually be cemented together by other chemical and physical mechanisms to yield new rocks. The slowness of this soil producing process indicates that soil is a depleting natural resource when subjected to erosion, loss of fertility or pollution. Soil fertility, the ability of the soil to supply the plants with their essential nutrient elements, directly determines what crops can be grown on a soil and the nutritional value of these crops for man and animals.

#### **3. Land degradation due to hydrocarbon pollutants**

By virtue of the properties such as a portable, dense energy source and as the base of many industrial chemicals; Petroleum is one of the world's most important commodities. Today about 90% of fuel needs are met by oil. The presence of the oil industry has significant environmental impacts. Accidents and routine activities such as seismic exploration, drilling, and generation of polluting wastes affect the society. Oil extraction is often environmentally damaging. Leaks, spillages and accidental fallouts of petroleum and its various fractions are of frequent occurrence. Offshore exploration and extraction of oil disturbs the surrounding marine environment. Crude oil and refined fuel spills from tanker, underground pipelines, and ship accidents and have damaged soil resource, ecosystem in many parts of the world.

Land degradation due to this is a common phenomenon in the modern world. Since the early part of the twentieth century, the damaging effect of the hydrocarbons from oil has been known. Many workers reported the damaging effect of petroleum and its various fractions on soil and water resources (Young, 1935). It was reported that crude oil can sterilise soils and prevent crop growth for various period of time. The duration of the damaging effect depends largely on the degree and depth to which the soil is saturated with the oil. The damage that the oil does is due mostly to the prevention of the plant from obtaining sufficient moisture and from ramifying its roots very little is due to toxicity, as such (Plice, 1948).

Out of various processes of disappearance of oils from polluted soil, microbial degradation of pollutants is one of the most important ones (Davies & Westlaki, 1979). Crude petroleum and its fractions are converted into soil organic matter by bacteria and fungi. During the conversion, the organisms, which are free lives, fix fairly large amount of atmosphere nitrogen in the soil. Later this nitrogen becomes available for plant growth and the organic matter improves soil physical conditions. Based on general principle of hydrocarbon degradation, a programme of rehabilitation such as liming, fertiliser addition, and frequent tilling is considered to be broadly applicable for all types of mineral oils and experiments showed that these are really effective measures (Dibble & Bartha, 1979). Dry micro organisms contain approximately 14% N, 3% P and 1% S in the form of proteins, nucleic acids, polysaccharides and low molecular weight compounds. On the other hand, Petroleum products are composed of hydrogen and sulphur and essentially no phosphorous in their environment in order to grow on hydrocarbons as their carbon and energy sources (Rosenberg, 1993). This application of nutrients especially that of Phosphorous seems to be an effective means of rehabilitation and experiment showed that this is really so (Reynolds & Walworth, 2000). On the contrary, studies showed that the presence of Polychlorinated Biphenyls negatively impact fossil fuel degradation ( Hoeppel et.al, 1995).Out of several methods to expedite the process of degradation of Petroleum Hydrocarbons and to rehabilitate an oil inundated soil such as Bioremediation, Polyencapsulation, Vapour Transport, Land Farming, Alcohol Flooding etc. Bioremediation is considered effective and environmentally benign. Before taking up remediation measures emergency clean up operation is an important activity.

#### **4. Methodology**

156 Crude Oil Exploration in the World

life. Soil is made of weathered rock material and organic matter. Weathering, the physical and chemical breakdown of rocks is the first step in the soil forming process. The process of soil formation is a very long and slow geological process. The process is cyclic, because the rocks are changed to unconsolidated particles, which may be eventually be cemented together by other chemical and physical mechanisms to yield new rocks. The slowness of this soil producing process indicates that soil is a depleting natural resource when subjected to erosion, loss of fertility or pollution. Soil fertility, the ability of the soil to supply the plants with their essential nutrient elements, directly determines what crops can be grown

By virtue of the properties such as a portable, dense energy source and as the base of many industrial chemicals; Petroleum is one of the world's most important commodities. Today about 90% of fuel needs are met by oil. The presence of the oil industry has significant environmental impacts. Accidents and routine activities such as seismic exploration, drilling, and generation of polluting wastes affect the society. Oil extraction is often environmentally damaging. Leaks, spillages and accidental fallouts of petroleum and its various fractions are of frequent occurrence. Offshore exploration and extraction of oil disturbs the surrounding marine environment. Crude oil and refined fuel spills from tanker, underground pipelines, and ship accidents and have damaged soil resource, ecosystem in

Land degradation due to this is a common phenomenon in the modern world. Since the early part of the twentieth century, the damaging effect of the hydrocarbons from oil has been known. Many workers reported the damaging effect of petroleum and its various fractions on soil and water resources (Young, 1935). It was reported that crude oil can sterilise soils and prevent crop growth for various period of time. The duration of the damaging effect depends largely on the degree and depth to which the soil is saturated with the oil. The damage that the oil does is due mostly to the prevention of the plant from obtaining sufficient moisture and

Out of various processes of disappearance of oils from polluted soil, microbial degradation of pollutants is one of the most important ones (Davies & Westlaki, 1979). Crude petroleum and its fractions are converted into soil organic matter by bacteria and fungi. During the conversion, the organisms, which are free lives, fix fairly large amount of atmosphere nitrogen in the soil. Later this nitrogen becomes available for plant growth and the organic matter improves soil physical conditions. Based on general principle of hydrocarbon degradation, a programme of rehabilitation such as liming, fertiliser addition, and frequent tilling is considered to be broadly applicable for all types of mineral oils and experiments showed that these are really effective measures (Dibble & Bartha, 1979). Dry micro organisms contain approximately 14% N, 3% P and 1% S in the form of proteins, nucleic acids, polysaccharides and low molecular weight compounds. On the other hand, Petroleum products are composed of hydrogen and sulphur and essentially no phosphorous in their environment in order to grow on hydrocarbons as their carbon and energy sources (Rosenberg, 1993). This application of nutrients especially that of Phosphorous seems to be an effective means of rehabilitation and experiment showed that this is really so (Reynolds & Walworth, 2000). On the contrary, studies showed that the presence of Polychlorinated

on a soil and the nutritional value of these crops for man and animals.

from ramifying its roots very little is due to toxicity, as such (Plice, 1948).

**3. Land degradation due to hydrocarbon pollutants**

many parts of the world.

Soil sample having no history of oil pollution were taken, polluted by known quantity of oil using emulsifier- some with nutrients, some with oxidising agents and some without any additive and the stated experiment was done by placing indoor in polyethene bags and maintaining the conditions necessary for microbial activities (Table-1). Series with B, C, D and E are similar to series A except that the oil is replaced by Kerosene oil, Diesel oil, Lubricating oil and Residual oil respectively. Gravimetric determination was done by withdrawing 20 g polluted soil sample from each bag and by recovering the oil by soxhlet extraction method using Petroleum ether as solvent after definite time interval. Gas Liquid Chromatography (GLC/GC) is the method of choice for rapidly and accurately analysing the volatile substances. It is also applicable to non volatile ones due to availability of higher column temperatures. Different compounds maintain similar sequence in the chromatogram analyzed under same system of column and identical conditions.

Table 1. Sample Numbers and their Contents possessing Crude Oil.

Degradation of Petroleum Fractions in Soil

growth (Khan & Anjaneyulu, 2005).

At 2nd At 3rd At

4th

Table 4. Average Ambient Temperature during the Period of Experiment.

Temp. At 1st

month

Under Natural Environment: A Gravimetric and Gas Chromatographic Analysis 159

period of the experiment is given (Table 4). The experiment was done during summer in the city of Guwahati, where the average of ambient temperature was 28.24 ± 0.400C in the range of 26.89-29.190C with negligible decreasing trend (correlation coefficient, r = -0.20). These conditions along with other physico-chemical parameters were favourable for microbial

At 5th At 6th Aver-

Many agencies working on Hydrocarbon pollution use GC technique to estimate hydrocarbon pollution. G.C. analysis of the oil recovered from three samples viz. 1A5, 2A5 and 3A5 ( Plate-1) from three sets after two months since placement have shown that number of components become 22, 37 and 39 respectively including solvent (Sarma et al, 2005a). Hydrogen Peroxide decomposes organic compounds from soil. Hence a good number of volatile components under GC conditions have been found in the 3A5 sample. Later these components escape from soil as carbon dioxide and a fraction fixes with soil. In the mass determination of the remaining hydrocarbons, it has been found that degradation in the second set i.e. set having applied NPK is highest. It means that it has already degraded and given away more compounds from the polluted soil sample. It has been seen from the chromatograms that there are no components with retention time in the range of 16.315 -43.247 minutes, 17.682 - 40.729 minutes and 11.589 - 42.677 minutes respectively in1A5, 2A5 and 3A5. A large number of components with minute differences in their retention time are seen in the chromatograms. Table- 5 represents some of such peaks between 1A5 and 2A5. The corresponding peaks in 2A5 appeared with an advance retention time of 0.452 minute in average belonging to the range of 0.571 to 0.392 minute. There are no corresponding peaks in 2A5 for five compounds present in 1A5 (Table-6). Probably these are the compounds degraded completely as a result of profuse microbial activities due to application of nutrients. Table (Table-7) represents the list of peaks which are found in 2A5 but not in 1A5. These are the peaks of compounds formed due to higher microbial activities as a result of application of nutrients. Number of such components are 20 and these compounds occupied a minute area % (average 0.63 %) of the chromatogram in the range

Plate 1. GC Chromatogram of oil recovered after 2 months of placement of sample 3A5.

0C 27.28 29.19 28.65 28.81 28.63 26.89 28.24 ±0.40 -0.20

age

Standard Error Correlation Coefficient

#### **5. Results and discussions**

A few important parameters of the soil such as Texture, pH, Hydraulic Conductivity, Bulk Density, Water Holding Capacity, Soil Organic Carbon, NPK nutrients etc. were determined before the start, in between, and at the end of the experiment(Sing et al, 2000) ( Table-2).

Table 2. Values of Physico-Chemical Parameters of Soil.

Remains of hydrocarbons and their oxygenated derivatives in the above mentioned soil bags were extracted by soxhlet extraction using Petroleum Ether as solvent and gravimetric determination was done (Table-3). It was found that the NPK supplementation is an effective measure of rehabilitation of oil inundated soil. Supply of nutrients to the soil helps micro organisms to grow abundantly, consequently the degradation becomes faster. Hydrogen peroxide decomposes some of the organic matter present in the polluted soil and it also contributes towards the degradation to some extent. It has been found that more than 50% of the applied mass undergoes degradation in average in all the three sets of crude oil experiment during the first two months of placement. The activities of micro organisms are highly dependent on temperature. Ambient temperature was also recorded during the period of the experiment. The monthly average of the ambient temperature during the

Table 3. Balance Amount of Crude Oil Recovered against Months after subtracting the mass found in Controls.

A few important parameters of the soil such as Texture, pH, Hydraulic Conductivity, Bulk Density, Water Holding Capacity, Soil Organic Carbon, NPK nutrients etc. were determined before the start, in between, and at the end of the experiment(Sing et al, 2000) ( Table-2).

Remains of hydrocarbons and their oxygenated derivatives in the above mentioned soil bags were extracted by soxhlet extraction using Petroleum Ether as solvent and gravimetric determination was done (Table-3). It was found that the NPK supplementation is an effective measure of rehabilitation of oil inundated soil. Supply of nutrients to the soil helps micro organisms to grow abundantly, consequently the degradation becomes faster. Hydrogen peroxide decomposes some of the organic matter present in the polluted soil and it also contributes towards the degradation to some extent. It has been found that more than 50% of the applied mass undergoes degradation in average in all the three sets of crude oil experiment during the first two months of placement. The activities of micro organisms are highly dependent on temperature. Ambient temperature was also recorded during the period of the experiment. The monthly average of the ambient temperature during the

Sample Oil Added Amount of Oil Recovered (g) after No. g 1 month 2 month 3 month 4 month 5 month 1A1 3 01.975 01.650 01.111 00.142 00.030 1A2 15 12.797 09.375 07.979 05.634 03.832 1A3 30 17.715 14.200 13.339 10.842 06.327 1A4 45 34.567 20.051 19.018 17.878 10.001 1A5 60 41.400 30.645 23.243 19.835 10.770 2A1 3 01.321 01.200 00.915 00.098 00.022 2A2 15 11.850 08.476 07.700 04.545 02.875 2A3 30 16.715 13.100 11.990 08.895 05.500 2A4 45 31.922 18.025 14.019 13.950 07.290 2A5 60 37.950 27.409 20.890 14.160 09.110 3A1 3 01.613 01.400 00.965 00.110 00.000 3A2 15 12.040 08.734 07.800 05.312 03.005 3A3 30 16.973 13.362 12.319 09.312 05.780 3A4 45 33.727 19.632 16.737 14.499 08.560 3A5 60 38.419 29.319 21.783 15.322 09.234

Table 3. Balance Amount of Crude Oil Recovered against Months after subtracting the mass

Parameter Value Unit Parameter Value Unit Texture Silty clay - pH 6.86 - Bulk Density 1.082 g cm-3 WHC 41.80 %

Electrical Conductivity 0.43 mScm-1 SOC 1.00 % Hydraulic Conductivity 0.073 cm min-1 SOM 1.724 %

Particle Density 2.650 g cm-3 Porosity 59.17 %

**5. Results and discussions**

found in Controls.

Table 2. Values of Physico-Chemical Parameters of Soil.

period of the experiment is given (Table 4). The experiment was done during summer in the city of Guwahati, where the average of ambient temperature was 28.24 ± 0.400C in the range of 26.89-29.190C with negligible decreasing trend (correlation coefficient, r = -0.20). These conditions along with other physico-chemical parameters were favourable for microbial growth (Khan & Anjaneyulu, 2005).

Table 4. Average Ambient Temperature during the Period of Experiment.

Many agencies working on Hydrocarbon pollution use GC technique to estimate hydrocarbon pollution. G.C. analysis of the oil recovered from three samples viz. 1A5, 2A5 and 3A5 ( Plate-1) from three sets after two months since placement have shown that number of components become 22, 37 and 39 respectively including solvent (Sarma et al, 2005a). Hydrogen Peroxide decomposes organic compounds from soil. Hence a good number of volatile components under GC conditions have been found in the 3A5 sample. Later these components escape from soil as carbon dioxide and a fraction fixes with soil. In the mass determination of the remaining hydrocarbons, it has been found that degradation in the second set i.e. set having applied NPK is highest. It means that it has already degraded and given away more compounds from the polluted soil sample. It has been seen from the chromatograms that there are no components with retention time in the range of 16.315 -43.247 minutes, 17.682 - 40.729 minutes and 11.589 - 42.677 minutes respectively in1A5, 2A5 and 3A5. A large number of components with minute differences in their retention time are seen in the chromatograms. Table- 5 represents some of such peaks between 1A5 and 2A5. The corresponding peaks in 2A5 appeared with an advance retention time of 0.452 minute in average belonging to the range of 0.571 to 0.392 minute. There are no corresponding peaks in 2A5 for five compounds present in 1A5 (Table-6). Probably these are the compounds degraded completely as a result of profuse microbial activities due to application of nutrients. Table (Table-7) represents the list of peaks which are found in 2A5 but not in 1A5. These are the peaks of compounds formed due to higher microbial activities as a result of application of nutrients. Number of such components are 20 and these compounds occupied a minute area % (average 0.63 %) of the chromatogram in the range

Plate 1. GC Chromatogram of oil recovered after 2 months of placement of sample 3A5.

Degradation of Petroleum Fractions in Soil

Sl

No

Under Natural Environment: A Gravimetric and Gas Chromatographic Analysis 161

of 0.04 to 2.56%. Table (Table-8) represents 14 peaks due to same compounds between 1A5 and 3A5 with their time of appearance. The corresponding peaks in 3A5 appeared after an average advancement of retention time of 0.589 minute in the range of 0.502 to 0.682 minute. These common components are the examples of some of the compounds which are resistant to degradation during this period. There are no corresponding peaks for eight compounds present in 1A5 (Table-9).These have already disappeared in 3A5. Probably these are the compounds degraded completely as a result of degradation activities due to application of

> Area % Report

1 1 9.053 5.33 8.383 0.68 0.670 2 2 9.355 7.42 8.726 0.52 0.629 3 5 10.992 11.41 10.325 0.46 0.667 4 6 12.271 19.38 11.589 3.68 0.682 5 13 43.247 0.68 42.677 0.22 0.570 6 14 48.772 1.85 48.249 1.15 0.523 7 15 49.805 2.47 49.228 2.97 0.577 8 16 50.389 23.34 49.868 20.99 0.521 9 17 51.724 0.08 51.132 1.19 0.592 10 18 52.736 0.27 52.229 1.50 0.507 11 19 53.152 4.70 52.630 7.23 0.522 12 20 55.236 2.48 54.734 4.93 0.502 13 21 56.304 1.06 55.695 3.11 0.609 14 22 59.828 0.21 59.154 5.48 0.674

Retention Time

Sl. No. 1 2 3 4 5 6 7 8 Peak No 3 4 7 8 9 10 11 12 RT in minute 9.774 10.497 12.810 13.288 14.538 15.286 15.823 16.315 Area % 3.87 2.13 1.27 0.39 6.36 2.11 0.12 3.09

hydrogen peroxide. Table-10 represents the list of peaks which are found in 3A5 but not in 1A5. These are the peaks of compounds formed due to higher microbial activities that occurred on the compounds. Number of such components are 25 and these compounds occupied a minute area (average 1.84%) of the chromatogram in the range of 0.06 to15.19%. GC analysis of the oil, recovered after 1 month and 2 months in the sample 2A3 gave a total of 17 and 24 peaks respectively. There is no peaks during12.217 to 47.277 minutes and during 15.303 to 44.055 minutes in the samples after 1 month and after 2 months respectively. Out of the 17 compounds obtained after I month, it appears that 14 compounds are still present in oil recovered after two months. It means that these components could resist degradation in the second month. These are placed in table (Table-11). These compounds appear 0.232 to 0.387 minute (average 0.275 minute) advance in the sample

Area%

Advance in Retention

Time

Report

Retention Time

Table 8. List of Similar Peaks in GC Analysis Report of 1A5 and 3A5.

Table 9. List of peaks found in 1A5 giving no corresponding peak in 3A5.

as in 1A5 Chromatogram

Table 5. List of Similar Peaks in GC Analysis Report of 1A5 and 2A5.

Table 6. List of peaks found in 1A5 giving no corresponding peak in 2A5.

Table 7. List of peaks found in 2A5 but not in 1A5.

Sl. Serial Number 1A5 2A5 Minute

Area % Report

1 6 12.271 19.38 11.700 45.15 0.571 2 7 12.810 1.27 12.363 3.54 0.447 3 8 13.288 0.39 12.839 1.92 0.449 4 9 14.538 6.36 14.080 12.32 0.458 5 10 15.286 2.11 14.835 6.17 0.451 6 11 15.823 0.12 15.339 2.17 0.484 7 12 16.315 3.09 15.860 5.38 0.455 8 13 43.247 0.68 42.845 0.30 0.402 9 14 48.772 1.85 48.380 0.26 0.392 10 15 49.805 2.47 49.363 0.78 0.442 11 16 50.389 23.34 49.993 5.26 0.396 12 17 51.724 0.08 51.275 0.16 0.449 13 18 52.736 0.27 52.320 1.03 0.416 14 19 53.152 4.70 52.744 1.55 0.408 15 20 55.236 2.48 54.832 0.83 0.404 16 21 56.304 1.06 55.814 0.46 0.490 17 22 59.828 0.21 59.261 0.10 0.567

> Sl No in Chromatogram 1 2 3 4 5 Retention Time in minute 09.053 09.355 09.774 10.497 10.992

> > Sl. No. of peak

1 4 13.220 0.30 11 25 53.630 0.07 2 6 14.513 2.56 12 28 56.367 0.34 3 10 17.682 0.65 13 29 57.210 2.31 4 11 40.729 0.09 14 30 58.320 0.16 5 12 42.359 0.04 15 32 59.782 0.25 6 14 44.121 0.73 16 33 61.080 0.04 7 15 45.072 0.07 17 34 62.848 1.74 8 16 45.714 0.16 18 35 66.697 0.61 9 17 46.270 0.15 19 36 71.440 1.52 10 18 46.840 0.66 20 37 77.554 0.18

Area % 05.33 07.42 03.87 02.13 11.41

Retention Time in minute Area %

Retention Time Area % Report

Advance in Ret. time

Retention Time

Table 5. List of Similar Peaks in GC Analysis Report of 1A5 and 2A5.

Table 6. List of peaks found in 1A5 giving no corresponding peak in 2A5.

Area %

Sl. No.

Retention Time in minute

Table 7. List of peaks found in 2A5 but not in 1A5.

No. As in 1A5

Sl. No. Sl. No.

of peak

Chromatogram

of 0.04 to 2.56%. Table (Table-8) represents 14 peaks due to same compounds between 1A5 and 3A5 with their time of appearance. The corresponding peaks in 3A5 appeared after an average advancement of retention time of 0.589 minute in the range of 0.502 to 0.682 minute. These common components are the examples of some of the compounds which are resistant to degradation during this period. There are no corresponding peaks for eight compounds present in 1A5 (Table-9).These have already disappeared in 3A5. Probably these are the compounds degraded completely as a result of degradation activities due to application of

Table 8. List of Similar Peaks in GC Analysis Report of 1A5 and 3A5.

Table 9. List of peaks found in 1A5 giving no corresponding peak in 3A5.

hydrogen peroxide. Table-10 represents the list of peaks which are found in 3A5 but not in 1A5. These are the peaks of compounds formed due to higher microbial activities that occurred on the compounds. Number of such components are 25 and these compounds occupied a minute area (average 1.84%) of the chromatogram in the range of 0.06 to15.19%.

GC analysis of the oil, recovered after 1 month and 2 months in the sample 2A3 gave a total of 17 and 24 peaks respectively. There is no peaks during12.217 to 47.277 minutes and during 15.303 to 44.055 minutes in the samples after 1 month and after 2 months respectively. Out of the 17 compounds obtained after I month, it appears that 14 compounds are still present in oil recovered after two months. It means that these components could resist degradation in the second month. These are placed in table (Table-11). These compounds appear 0.232 to 0.387 minute (average 0.275 minute) advance in the sample

Degradation of Petroleum Fractions in Soil

Sl. No. Sl. No.

of peak

of 0.05 to 6.33 (Table-14).

Sl No 1 m report Retention

.Time in minute

Under Natural Environment: A Gravimetric and Gas Chromatographic Analysis 163

In the GC analysis of the sample 3A3 after 1 month and after 2 months, it has been seen that there are 11 and 33 components respectively including that for the solvent. There are no peaks appear in between 20.082 to 46.835 and in between 11.662 to 42.728 minutes in the two

1 1 6.823 0.86 6 7 44.055 0.11 2 2 7.256 0.17 7 14 53.817 0.38 3 3 9.225 2.24 8 15 54.476 0.39 4 4 13.335 0.61 9 21 58.546 0.24 5 5 15.303 0.92 10 24 71.991 11.00

Sl. No. Sl. No.

of peak

Retention Time in minute

Area % Advance in RT (minute)

Area %

Area %

Table 12. List of peaks found in the sample 2A3 after 2 months but not in after 1 month.

samples respectively. As many as 8 numbers of peaks of components present after 1 month in 3A3 can be linked to same number of components present in the extract obtained after 2 months. Table (Table-13) represents these peaks. The corresponding peaks appear in the sample after 2 months with an advance retention time average of 0.06 minute in the range of 0.011 to 0.126 minute. Corresponding peaks for the rests three viz. at retention time 20.082, 62.788 and 71.406 minutes are not present in the second month. It implies that these components disappear during the month. The other 25 components which appear in the sample after 2 months are probably due to formation of derivatives as a result of degradation activities. These components have an average area percent of 1.42 in the range

1 1 11.732 36.21 11.662 2.83 0.070 2 3 46.835 1.00 46.709 0.31 0.126 3 4 49.952 2.45 49.912 25.59 0.040 4 5 52.303 5.93 52.275 1.28 0.028 5 6 52.734 1.43 52.681 7.05 0.053 6 7 54.822 0.89 54.777 4.20 0.045 7 8 55.863 3.19 55.760 4.85 0.103 8 9 57.207 16.13 57.196 18.27 0.011

Table 13. List of Similar Peaks in GC analysis report of 3A3 extracted after 1 and 2 months.

The 17 and 11 peaks found respectively in the GC chromatogram of samples 2A3 and 3A3 after 1 month of placement, possess 9 peaks ( Table-15) having a very narrow range of 0.414 to 0.454 minute difference in the retention time except one which appeared at a difference of 0.728 minute. The average difference in retention time is 0.469 minute. It has been seen that larger number of components disappeared from 3A3 at the same time compared to 2A3. Out of 24 and 33 peaks respectively found in the GC chromatogram of samples 2A3 and 3A3 after 2 months 15 similar peaks have been identified and presented in table (Table- 16). Compared to number of peaks found in 2A3, the corresponding peaks in 3A3 appear in

Ret. Time in minute

Area %

Retention Time in minute

obtained after 2 months. This change in retention time is probably due to minor change of experimental conditions during transit. The three components, which appeared at 12.217,

Table 10. List of peaks found in 3A5 but not in 1A5.

Table 11. List of Similar Peaks in GC Analysis Report of 2A3 after 1Month and 2Months.

72.525 and 81.026 minutes with area percent report of 25.47, 1.85 and 1.17 respectively in the sample after 1 month got disappeared in the second month. It has also been seen that another 10 peaks due to 10 new compounds appear in the sample after 2 months (Table- 12). These compounds seem to be the degradation products of various hydrocarbons. These peaks have area percent in the range of 0.11 to 11.00 with an average of 1.69%.

obtained after 2 months. This change in retention time is probably due to minor change of experimental conditions during transit. The three components, which appeared at 12.217,

Area % Sl. No. Sl. No.

1 6 43.743 0.10 14 27 57.153 15.19 2 7 44.919 0.13 15 28 58.234 0.95 3 8 45.577 0.43 16 30 59.705 3.71 4 9 46.125 0.40 17 31 60.961 0.29 5 10 46.702 0.84 18 32 61.788 0.09 6 11 47.778 0.14 19 33 62.792 4.38 7 13 48.620 0.59 20 34 64.446 0.09 8 16 50.340 0.66 21 35 66.609 3.74 9 17 50.776 0.06 22 36 71.413 6.76 10 19 51.836 1.66 23 37 77.370 0.35 11 22 53.537 0.40 24 38 85.062 0.44 12 23 54.169 0.17 25 39 94.824 0.54

13 26 56.245 3.78 -

Time

Table 11. List of Similar Peaks in GC Analysis Report of 2A3 after 1Month and 2Months.

peaks have area percent in the range of 0.11 to 11.00 with an average of 1.69%.

72.525 and 81.026 minutes with area percent report of 25.47, 1.85 and 1.17 respectively in the sample after 1 month got disappeared in the second month. It has also been seen that another 10 peaks due to 10 new compounds appear in the sample after 2 months (Table- 12). These compounds seem to be the degradation products of various hydrocarbons. These

1 1 10.941 0.90 10.686 9.58 0.255 2 3 47.277 0.71 47.001 2.21 0.276 3 4 49.850 0.44 49.571 3.13 0.279 4 5 50.406 9.43 50.159 11.01 0.247 5 6 51.771 0.27 51.465 0.25 0.306 6 7 52.736 7.70 52.496 7.66 0.240 7 8 53.171 3.43 52.928 4.94 0.243 8 9 55.244 1.65 55.012 2.77 0.232 9 10 56.314 4.17 56.037 3.29 0.277 10 11 56.893 0.55 56.594 0.29 0.299 11 12 57.621 18.27 57.365 17.62 0.256 12 13 58.132 3.12 57.860 2.74 0.272 13 14 59.848 0.81 59.561 4.05 0.287 14 15 63.516 20.07 63.129 13.55 0.387

Area % Retention

Time

of peak

RT in minute

Area % Advance

in RT

Area %

Sl. No.

Sl. No. of peak

RT in minute

Table 10. List of peaks found in 3A5 but not in 1A5.

Sl No 1 month report Retention

In the GC analysis of the sample 3A3 after 1 month and after 2 months, it has been seen that there are 11 and 33 components respectively including that for the solvent. There are no peaks appear in between 20.082 to 46.835 and in between 11.662 to 42.728 minutes in the two

Table 12. List of peaks found in the sample 2A3 after 2 months but not in after 1 month.

samples respectively. As many as 8 numbers of peaks of components present after 1 month in 3A3 can be linked to same number of components present in the extract obtained after 2 months. Table (Table-13) represents these peaks. The corresponding peaks appear in the sample after 2 months with an advance retention time average of 0.06 minute in the range of 0.011 to 0.126 minute. Corresponding peaks for the rests three viz. at retention time 20.082, 62.788 and 71.406 minutes are not present in the second month. It implies that these components disappear during the month. The other 25 components which appear in the sample after 2 months are probably due to formation of derivatives as a result of degradation activities. These components have an average area percent of 1.42 in the range of 0.05 to 6.33 (Table-14).

Table 13. List of Similar Peaks in GC analysis report of 3A3 extracted after 1 and 2 months.

The 17 and 11 peaks found respectively in the GC chromatogram of samples 2A3 and 3A3 after 1 month of placement, possess 9 peaks ( Table-15) having a very narrow range of 0.414 to 0.454 minute difference in the retention time except one which appeared at a difference of 0.728 minute. The average difference in retention time is 0.469 minute. It has been seen that larger number of components disappeared from 3A3 at the same time compared to 2A3. Out of 24 and 33 peaks respectively found in the GC chromatogram of samples 2A3 and 3A3 after 2 months 15 similar peaks have been identified and presented in table (Table- 16). Compared to number of peaks found in 2A3, the corresponding peaks in 3A3 appear in

Degradation of Petroleum Fractions in Soil

to be for some degradation products.

Retention Time

. Sl. No.

> As in 2A3

Sl. No

months.

Under Natural Environment: A Gravimetric and Gas Chromatographic Analysis 165

been found in 3B5. Excluding peak at serial number 9, all other similar peaks in the table have higher peak area at 1B5. Besides these, there are about 18 peaks in 3B5 but not in 1B5, out of which the peaks at 2.716 appears to be for the solvent. These 18 peaks (Table-19) seem

> Area % Report

2A3 2A3 3A3 3A3 Minute

Area % Report

Advance in Retention

time

Retention Time (minute)

1 8 47.001 2.21 46.709 0.31 0.292 2 9 49.571 3.13 49.288 5.85 0.283 3 10 50.159 11.01 49.912 25.59 0.247 4 11 51.465 0.25 51.195 1.81 0.270 5 12 52.496 7.66 52.275 1.28 0.221 6 13 52.928 4.94 52.681 7.05 0.247 7 14 53.817 0.38 53.620 0.71 0.197 8 15 54.476 0.39 54.246 0.05 0.230 9 16 55.012 2.77 54.777 4.20 0.235 10 17 56.037 3.29 55.760 4.85 0.277 11 18 56.594 0.27 56.266 3.55 0.328 12 19 57.365 17.62 57.196 18.27 0.169 13 21 58.546 0.24 58.276 1.02 0.270 14 22 59.561 4.05 59.196 6.33 0.365 15 23 63.129 13.55 62.843 1.70 0.286

Table 16. List of Similar Peaks in GC chromatogram of 2A3 and 3A3 extracted after two

Plate 2. GC Chromatogram of Oil recovered after 2 months of placement of the sample 3B5.

advance by a narrow range of 0.169 to 0.365 minutes where the average value obtained is0.261 minute. The components responsible for these peaks are resistant to degradation at least up to two months under the experimental conditions.

Table 14. List of peaks found in the sample 3A3 after 2 months but not in after 1 month.

Table 15. List of Similar Peaks in GC Analysis Report of 2A3and 3A3 after one month.

Gas Chromatographic analysis of recovered oil from kerosene oil polluted soil (B-set) after 2 months of placement showed that number of components at 1B5 and 3B5 ( Plate-2) became 17 and 35 respectively. Gravimetric determination shows that mass of oil recovered in the samples having applied Hydrogen Peroxide is less, whereas number of components in the same is more than that of the sample without Hydrogen Peroxide (Table-17). It indicates that Hydrogen Peroxide removes the pollutants by degrading into smaller compounds. There are no peaks appeared in between the retention time ranges 4.838 to 32.566 minute in1B5 and in the range of 9.611 to 32.669 minute in 3B5. It appears that for every peak in the 1B5 sample, there is a corresponding peak in the 3B5 sample (Table-18) with an average delay of 0.115 minute in the range of 0.095 to 0.190 minute. All peaks present in 1B5 have

advance by a narrow range of 0.169 to 0.365 minutes where the average value obtained is0.261 minute. The components responsible for these peaks are resistant to degradation at

> Sl. No.

1 1 8.258 0.10 14 17 51.891 2.70 2 2 8.807 0.07 15 20 53.620 0.71 3 4 42.728 0.33 16 21 54.246 0.05 4 5 44.020 0.48 17 24 56.266 3.55 5 6 44.956 0.26 18 26 58.276 1.02 6 7 45.629 0.65 19 27 59.196 6.33 7 8 46.177 0.62 20 28 59.742 2.19 8 10 47.826 0.21 21 29 61.125 1.71 9 11 48.299 1.18 22 30 62.843 1.70 10 12 48.682 0.86 23 31 66.631 1.29 11 13 49.288 5.85 24 32 71.433 0.26 12 15 50.393 1.20 25 33 77.479 0.49 13 16 51.195 1.81 - - - -

Sl. No. of peak Retention Time (minute) Area

Area % Advance in

Retention time

%

%

Table 14. List of peaks found in the sample 3A3 after 2 months but not in after 1 month.

Table 15. List of Similar Peaks in GC Analysis Report of 2A3and 3A3 after one month.

Gas Chromatographic analysis of recovered oil from kerosene oil polluted soil (B-set) after 2 months of placement showed that number of components at 1B5 and 3B5 ( Plate-2) became 17 and 35 respectively. Gravimetric determination shows that mass of oil recovered in the samples having applied Hydrogen Peroxide is less, whereas number of components in the same is more than that of the sample without Hydrogen Peroxide (Table-17). It indicates that Hydrogen Peroxide removes the pollutants by degrading into smaller compounds. There are no peaks appeared in between the retention time ranges 4.838 to 32.566 minute in1B5 and in the range of 9.611 to 32.669 minute in 3B5. It appears that for every peak in the 1B5 sample, there is a corresponding peak in the 3B5 sample (Table-18) with an average delay of 0.115 minute in the range of 0.095 to 0.190 minute. All peaks present in 1B5 have

Sl. No. 2A3 report Retention Time Area % Retention

Sl. No. 2A3-1M 3A3-1M Minute

1 2 12.217 25.47 11.772 36.21 0.440 2 3 47.277 0.71 46.835 1.00 0.442 3 5 50.406 9.43 49.952 2.45 0.454 4 7 52.736 7.70 52.303 5.93 0.433 5 8 53.171 3.43 52.734 1.43 0.437 6 9 55.244 1.65 54.822 0.89 0.422 7 10 56.314 0.417 55.863 3.19 0.451 8 12 57.621 18.27 57.207 16.13 0.414 9 15 63.516 20.07 62.788 21.04 0.728

Time(min)

least up to two months under the experimental conditions.

Retention Time (minute) Area

Sl. No.

Sl. No. of peak been found in 3B5. Excluding peak at serial number 9, all other similar peaks in the table have higher peak area at 1B5. Besides these, there are about 18 peaks in 3B5 but not in 1B5, out of which the peaks at 2.716 appears to be for the solvent. These 18 peaks (Table-19) seem to be for some degradation products.

Table 16. List of Similar Peaks in GC chromatogram of 2A3 and 3A3 extracted after two months.

Degradation of Petroleum Fractions in Soil

Under Natural Environment: A Gravimetric and Gas Chromatographic Analysis 167

Against 50 compounds present in 1C3, there are 42 and 27 compounds present in the samples 2C3 and 3C3, where nutrients and Hydrogen Peroxide were applied respectively. It implies that nutrients and Hydrogen Peroxide have a positive role in degradation of higher hydrocarbons into lower ones and subsequent removal of them from soil. A list of similar peaks in GC analysis report of 1C3, 2C3 and 3C3 are given in table (Table-20). It has been seen that the peaks due to same compounds appear in the chromatogram of 2C3 and 3C3 after an average delay in retention time of 0.078 and 0.123 minutes compared to the peaks of 1C3 in a range of 0.018 to 0.194 and 0.087 to 0.232 minutes respectively. This minute difference in retention time is probably due to minor change in experimental conditions during transit. There two peaks in the chromatogram of 2C3 and 3C3 at 54.466 and 54.552 minute with area % 0.53 and 0.22 respectively are probably due to same compound, which is a degradation product. The other two such compounds appear at retention time 61.654 and

71.422 minute in the 2C3 and 3C3 reports are also due to degradation products.

Plate 3. GC Chromatogram of Oil recovered after 3 months of placement of the sample 2C3.

In the GC report of the extracted oil samples from 1C5, 2C5 and 3C5 after three months of placement, number of peaks seen are 21, 34 and 40 respectively. From gravimetric analysis it has been found that extent of degradation in corresponding C5 samples are higher than C3 samples (Table-21). Thus it seems that number of components increases against increase of degradation at a certain stage and then the components gradually disappear. A list of peaks due to same compounds is given in table (Table-22). The peaks at 2C5 appear with a negligible average delay of 0.012 minute in retention time in the range of -0.036 to 0.055. The same for 3C5 peaks is 0.007 minute in the range of -0.070 to 0.034 minute. The existence of

compounds could resist degradation during the initial period of three months. The other compounds present in 2C5 and 3C5 are some of the degradation products. In the same way similar peaks have been found in 1C3 and 1C5, 2C3 and 2C5, and between 3C3 and 3C5.

The chromatograms obtained from the extracts of Lubricating oil polluted samples 1D1, 1D2 and 1D3 (Plate-4) are represented in plates. Number of components which persists degradation and number of components produced as a result of microbial degradation taken together has been found to be 64, 53 and 67 respectively, including solvent peak after lapse of 3 months (Sarma & Bhattacharyya ,2010). From the gravimetric analysis, it appears

these compounds in all the samples indicates that these

Table 17. Amount of Kerosene Oil Degraded against time in Months.

Gas Chromatographic Analysis of the extracted oil after 3 months of mixing in the Diesel oil polluted samples of 1C3, 2C3(Plate-3) and 3C3 gave 50, 42 and 27 peaks respectively ( Sarma ,2010). It has been seen that the peaks at 1C3 starts at retention time 29.592 minute onwards, which for the 2C3 and 3C3 are 31.873 and 40.645 minuterespectively.

Table 18. List of Similar Peaks in GC Analysis Report of 1B5 and 3B5.

Table 19. List of peaks found in the sample 3B5 but not in 1B5.

Gas Chromatographic Analysis of the extracted oil after 3 months of mixing in the Diesel oil polluted samples of 1C3, 2C3(Plate-3) and 3C3 gave 50, 42 and 27 peaks respectively ( Sarma ,2010). It has been seen that the peaks at 1C3 starts at retention time 29.592 minute onwards,

Sl. Sl No 1B5 3B5 Minute

01 01 04.387 01.45 04.567 0.27 0.180 02 02 04.838 19.73 05.028 7.09 0.190 03 03 32.566 01.23 32.669 0.34 0.103 04 04 35.389 02.07 35.490 0.55 0.101 05 05 36.207 05.41 36.309 1.28 0.102 06 06 38.435 00.43 38.541 0.18 0.106 07 07 38.993 03.59 39.096 0.89 0.103 08 08 39.623 10.59 39.726 2.51 0.103 09 09 41.251 00.30 41.360 1.09 0.109 10 10 41.760 09.89 41.867 3.94 0.107 11 11 42.813 11.15 42.923 4.41 0.110 12 12 44.627 01.28 44.743 0.93 0.116 13 13 45.813 07.65 45.921 3.03 0.108 14 14 47.341 04.21 47.446 3.05 0.105 15 15 48.645 04.00 48.748 2.07 0.103 16 16 48.962 15.74 49.073 6.84 0.111 17 17 51.309 01.27 51.404 0.75 0.095

Retention Time (Minute) Area

%

Retention Time in minute

Area %

Delay in Ret. time

Area %

Table 17. Amount of Kerosene Oil Degraded against time in Months.

which for the 2C3 and 3C3 are 31.873 and 40.645 minuterespectively.

Table 18. List of Similar Peaks in GC Analysis Report of 1B5 and 3B5.

Retention Time in minute

Table 19. List of peaks found in the sample 3B5 but not in 1B5.

Area %

Sl. No.

1 1 2.716 57.97 10 20 42.454 0.10 2 4 6.061 0.10 11 22 43.307 0.50 3 5 8.486 0.00 12 23 43.976 0.02 4 6 9.611 0.00 13 29 50.011 0.13 5 8 33.300 0.18 14 31 51.815 0.44 6 9 35.062 0.05 15 32 53.927 0.28 7 12 37.053 0.49 16 33 54.903 0.01 8 13 38.110 0.16 17 34 56.332 0.01 9 17 40.604 0.22 18 35 76.439 0.12

Sl. No. of peak

(Minute)

No. As in 1B5 Chromatogram Retention Time

Sl. No. Sl. No.

of peak

Sample Oil added Amount of degraded oil (g) after Number g 1 month 2 month 3 month 4 month 5 month 1B5 60 21.126 30.355 47.322 53.832 54.753 3B5 60 25.751 32.790 48.048 54.132 55.052 Against 50 compounds present in 1C3, there are 42 and 27 compounds present in the samples 2C3 and 3C3, where nutrients and Hydrogen Peroxide were applied respectively. It implies that nutrients and Hydrogen Peroxide have a positive role in degradation of higher hydrocarbons into lower ones and subsequent removal of them from soil. A list of similar peaks in GC analysis report of 1C3, 2C3 and 3C3 are given in table (Table-20). It has been seen that the peaks due to same compounds appear in the chromatogram of 2C3 and 3C3 after an average delay in retention time of 0.078 and 0.123 minutes compared to the peaks of 1C3 in a range of 0.018 to 0.194 and 0.087 to 0.232 minutes respectively. This minute difference in retention time is probably due to minor change in experimental conditions during transit. There two peaks in the chromatogram of 2C3 and 3C3 at 54.466 and 54.552 minute with area % 0.53 and 0.22 respectively are probably due to same compound, which is a degradation product. The other two such compounds appear at retention time 61.654 and 71.422 minute in the 2C3 and 3C3 reports are also due to degradation products.

Plate 3. GC Chromatogram of Oil recovered after 3 months of placement of the sample 2C3.

In the GC report of the extracted oil samples from 1C5, 2C5 and 3C5 after three months of placement, number of peaks seen are 21, 34 and 40 respectively. From gravimetric analysis it has been found that extent of degradation in corresponding C5 samples are higher than C3 samples (Table-21). Thus it seems that number of components increases against increase of degradation at a certain stage and then the components gradually disappear. A list of peaks due to same compounds is given in table (Table-22). The peaks at 2C5 appear with a negligible average delay of 0.012 minute in retention time in the range of -0.036 to 0.055. The same for 3C5 peaks is 0.007 minute in the range of -0.070 to 0.034 minute. The existence of these compounds in all the samples indicates that these

compounds could resist degradation during the initial period of three months. The other compounds present in 2C5 and 3C5 are some of the degradation products. In the same way similar peaks have been found in 1C3 and 1C5, 2C3 and 2C5, and between 3C3 and 3C5.

The chromatograms obtained from the extracts of Lubricating oil polluted samples 1D1, 1D2 and 1D3 (Plate-4) are represented in plates. Number of components which persists degradation and number of components produced as a result of microbial degradation taken together has been found to be 64, 53 and 67 respectively, including solvent peak after lapse of 3 months (Sarma & Bhattacharyya ,2010). From the gravimetric analysis, it appears

Degradation of Petroleum Fractions in Soil

( as per GC report of 1C5)  -2- 1C5

Retention Time (RT)

Area % of the peak

Under Natural Environment: A Gravimetric and Gas Chromatographic Analysis 169

Table 20. List of Similar Peaks in GC Analysis Report of 1C3, 2C3 and 3C3.

Table 21. Percent of Applied Diesel Oil Degraded against time in Months.

RT Area % of the peak

Table 22. List of Similar peaks in GC Analysis Report of 1C5, 2C5and 3C5.

RT Area % of the peak

1 0.986 0.00 - - - - - **-**  2 35.087 0.77 35.051 0.81 35.017 0.65 -0.036 -0.070 3 37.761 0.83 37.759 0.71 37.753 0.63 -0.002 -0.008 4 38.426 3.84 38.411 3.22 38.395 2.60 -0.015 -0.031 5 40.075 0.36 40.059 1.48 40.034 1.33 -0.016 -0.041 6 40.525 2.94 40.530 2.76 40.526 2.51 0.005 0.001 7 41.595 7.77 41.595 6.44 41.589 5.82 0.000 -0.006 8 43.364 0.72 43.379 1.03 43.381 0.97 0.015 0.017 9 44.581 6.46 44.589 5.64 44.586 5.05 0.008 0.005 10 46.083 2.79 46.106 2.33 46.106 2.30 0.023 0.023 11 47.399 6.71 47.411 6.56 47.415 6.16 0.012 0.016 12 47.699 19.61 47.724 16.63 47.729 16.09 0.025 0.030 13 50.055 7.50 50.073 6.96 50.075 6.44 0.018 0.020 14 50.448 3.35 50.478 2.91 50.479 2.84 0.030 0.031 15 52.578 8.30 52.597 8.43 52.598 8.28 0.019 0.020 16 54.982 6.70 54.995 6.87 54.999 6.67 0.013 0.017 17 57.263 6.27 57.275 6.37 57.280 6.32 0.012 0.017 18 59.730 5.87 59.751 5.53 59.748 5.65 0.021 0.018 19 62.729 5.07 62.755 4.83 62.752 5.13 0.026 0.023 20 66.451 3.95 66.477 4.06 66.479 4.44 0.026 0.028 21 71.096 0.21 71.151 3.02 71.130 3.44 0.055 0.034

of 1C5

Delay in RT of 2C5peaks

compared to peaks

of 1C5

Delay in R T of 3C5peaks

compared to peaks

49 72.360 0.33 - -- - - - 50 76.800 0.08 76.942 1.88 - - 0.142 -

Sample Oil Added Percent of the applied oil Degraded after No. g 1 month 2 months 3 months 4 months 5 months 1C3 30 27.84 43.18 45.20 65.53 67.66 1C5 60 24.25 46.03 56.04 72.43 75.50 2C3 30 33.19 49.88 51.89 69.97 70.98 2C5 60 38.33 53.13 59.03 73.78 77.19 3C3 30 30.91 45.38 47.93 69.09 69.99 3C5 60 36.30 49.52 57.45 73.33 76.45

RT Area % of the

peak

1 29.952 0.03 - -- - - - 2 31.792 0.44 31.873 0.33 - - 0.081 - 3 34.112 0.11 34.195 0.06 - - 0.083 - 4 34.996 0.03 35.042 0.21 - - 0.046 - 5 35.693 0.27 35.776 0.01 - - 0.083 - 6 36.533 0.24 - -- - - - 7 37.100 0.08 37.214 0.02 - - 0.114 - 8 37.662 0.96 37.753 0.41 - - 0.091 - 9 38.287 1.60 38.392 1.32 - - 0.105 - 10 38.806 0.15 - -- - - - 11 39.415 0.39 39.508 0.01 - - 0.093 - 12 39.849 2.57 40.043 0.93 - - 0.194 - 13 40.449 3.17 40.514 2.21 40.645 0.53 0.065 0.131 14 41.504 2.19 41.574 4.41 41.722 0.90 0.070 0.148 15 42.504 1.35 42.576 0.32 - - 0.072 - 16 43.276 2.95 43.368 0.75 43.495 0.05 0.092 0.127 17 43.651 1.73 - -- - - - 18 44.190 1.35 - -- - - - 19 44.513 3.53 44.574 4.03 44.690 2.37 0.061 0.116 20 44.974 0.83 - -- - - - 21 45.364 0.03 - -- - - - 22 46.046 5.28 46.101 5.23 46.195 2.19 0.055 0.094 23 47.365 3.74 47.414 5.96 47.509 5.33 0.049 0.095 24 47.556 22.91 47.634 15.65 47.810 19.82 0.078 0.176 25 48.608 0.51 48.674 0.06 48.786 0.10 0.066 0.112 26 49.142 1.12 49.160 0.81 49.265 0.57 0.018 0.105 27 49.583 0.02 49.649 0.20 - - 0.066 - 28 50.016 3.99 50.073 6.62 50.163 9.04 0.057 0.090 29 50.425 6.06 50.476 3.81 50.563 4.54 0.051 0.087 30 51.141 0.76 51.200 0.44 51.317 0.07 0.059 0.117 31 51.755 0.10 51.779 0.09 51.980 0.23 0.024 0.201 32 52.532 6.49 52.597 8.59 52.687 12.80 0.065 0.090 33 53.474 0.58 53.623 0.54 53.747 0.37 0.149 0.124 34 54.007 0.03 54.136 0.32 54.237 0.04 0.129 0.101 35 54.938 5.55 54.993 7.34 55.087 10.74 0.055 0.094 36 55.954 0.88 56.006 0.68 56.110 0.08 0.052 0.104 37 56.442 0.43 56.476 0.43 56.578 0.03 0.034 0.102 38 56.834 1.97 56.859 1.32 56.972 0.86 0.025 0.113 39 57.213 4.15 57.273 6.59 57.370 9.76 0.060 0.097 40 58.169 0.86 58.229 0.61 58.341 0.06 0.060 0.112 41 58.738 0.10 - -- - - - 42 58.927 0.41 59.042 0.37 - - 0.115 - 43 59.664 3.21 59.735 5.39 59.869 7.94 0.071 0.134 44 60.389 0.04 - -- - - - 45 60.865 0.23 60.930 0.02 - - 0.065 - 46 62.645 2.45 62.735 4.64 62.911 6.41 0.090 0.176 47 66.342 2.18 66.447 3.90 66.679 4.70 0.105 0.232 48 70.973 1.54 71.094 2.92 - - 0.121 -

RT Area % of the peak

Delay in RT of 2C3 compared to 1C3

Delay in R T of 3C3 compared to 1C3

> ( as per GC 1C3)

 -2- 1C3

Retention Time (RT)

Area % of the peak

Table 20. List of Similar Peaks in GC Analysis Report of 1C3, 2C3 and 3C3.

Table 21. Percent of Applied Diesel Oil Degraded against time in Months.

Table 22. List of Similar peaks in GC Analysis Report of 1C5, 2C5and 3C5.

Degradation of Petroleum Fractions in Soil

Under Natural Environment: A Gravimetric and Gas Chromatographic Analysis 171

Table 23. List of Similar Peaks in GC Analysis Report of 1D1, 1D2 and 1D3.

It means that these common compounds are the compounds which are resistant to degradation. The number of such compounds in between 1D1 and 1D2 is 48, between 1D1

Plate 4.  The extent of degradation in presence of hydrogen peroxide is moderate. It seems that hydrogen peroxide increases number of components and later these degradation products disappear from soil. There are some peaks which seem to be due to same compounds (Table-23).

that the extent of degradation is highest in the samples with nutrients. The extent of degradation in presence of hydrogen peroxide is moderate. It seems that hydrogen peroxide increases number of components and later these degradation products disappear from soil.

> -6- 1D3

RT Area % of the peak

1 8.569 0.06 - - 8.340 0.03 - 0.229 2 9.381 2.03 9.706 1.07 9.107 4.32 0.325 0.274 3 11.562 21.09 11.822 18.96 11.316 10.34 0.260 0.246 4 12.595 0.47 - - 12.363 0.43 - 0.232 5 13.203 0.09 - - 12.912 0.55 - 0.291 6 14.122 0.77 14.367 0.37 13.865 0.76 0.245 0.257 7 14.792 0.51 15.026 0.29 14.578 0.47 0.234 0.214 8 15.823 0.23 16.056 0.14 15.535 0.10 0.233 0.288 9 16.167 0.42 16.397 0.27 15.896 0.18 0.230 0.271 10 17.268 0.16 17.541 0.07 16.934 0.67 0.273 0.334 11 18.339 0.18 18.584 0.14 18.052 0.16 0.245 0.287 12 18.714 2.08 18.933 1.54 18.405 3.96 0.219 0.309 13 19.484 7.78 19.689 6.89 19.080 8.69 0.205 0.404 14 19.989 11.70 20.220 11.26 19.667 10.63 0.231 0.322 15 20.761 0.25 - - - - - - 16 21.742 0.65 21.973 0.42 21.440 1.29 0.231 0.302 17 22.356 10.06 22.557 8.57 21.920 12.71 0.201 0.436 18 24.520 0.18 - - 24.165 0.45 - 0.355 19 24.787 0.30 24.985 0.28 24.494 0.66 0.198 0.293 20 27.586 0.28 27.782 0.33 27.260 1.03 0.196 0.326 21 28.222 11.95 28.402 12.15 27.867 8.89 0.180 0.355 22 28.979 0.75 29.143 0.84 28.683 0.75 0.164 0.296 23 29.300 0.68 29.472 0.81 28.996 0.78 0.172 0.304 24 30.794 1.50 30.980 1.14 30.466 3.20 0.186 0.328 25 31.355 1.61 31.609 1.14 30.890 3.71 0.254 0.465 26 34.324 0.29 34.492 0.16 33.982 0.33 0.168 0.342 27 36.155 0.18 36.310 0.12 35.804 0.33 0.155 0.351 28 37.154 0.02 - - 36.700 0.14 - 0.454 29 38.152 1.27 38.311 0.89 37.798 2.15 0.159 0.354 30 39.031 0.06 - - 38.677 0.04 - 0.354 31 40.092 0.11 40.246 0.04 39.770 0.06 0.154 0.322 32 40.681 0.32 40.828 0.13 40.416 0.01 0.147 0.265 33 42.504 0.54 42.645 0.10 42.133 0.41 0.141 0.371 34 42.818 0.35 42.963 0.06 42.799 0.07 0.145 0.019 35 43.996 2.55 44.169 1.07 43.681 1.98 0.173 0.315 36 44.518 1.35 44.668 0.62 44.154 2.03 0.150 0.364

Delay in RT of 1D2 peaks compared to 1D1

Adv in R T of 1D3 peaks compared to peaks of 1D1

There are some peaks which seem to be due to same compounds (Table-23).

RT Area % of the peak

( as per GC report of 1D1)  -2- 1D1

Retention Time (RT)

Area % of the peak

Table 23. List of Similar Peaks in GC Analysis Report of 1D1, 1D2 and 1D3.

It means that these common compounds are the compounds which are resistant to degradation. The number of such compounds in between 1D1 and 1D2 is 48, between 1D1

Plate 4. GC Chromatogram of oil recovered after 3 months of placement of sample 1D3.

Degradation of Petroleum Fractions in Soil

( as per GC report of analysis after 1 month)

 -2- After 1 month

Retention Time (RT)

Area % of the peak

Under Natural Environment: A Gravimetric and Gas Chromatographic Analysis 173

Plate 5. GC Chromatogram of Oil recovered after 2 months of placement of the sample 1E5.

RT Area % of the peak

RT Area % of the peak

Advance in RT of peaks after 2 months compared to peaks after 1 month.

Advance in Retention Time of peaks after 3 months compared to peaks after 1 months.

month

1 09.789 0.70 08.875 0.66 08.619 1.95 0.914 1.170 2 11.995 1.40 11.058 4.21 10.870 2.17 0.937 1.125 3 14.371 0.55 13.409 0.72 13.220 0.55 0.962 1.151 4 19.036 1.45 18.154 1.13 17.819 2.67 0.969 1.304 5 19.728 8.97 18.759 5.48 18.565 11.79 0.969 1.163 6 20.263 19.26 19.212 10.73 18.998 17.44 1.051 1.265 7 22.609 10.82 21.591 7.81 21.390 15.79 1.018 1.219 8 28.498 5.98 27.418 11.07 27.223 17.21 1.080 1.275 9 31.191 1.02 30.128 0.77 29.860 2.48 1.063 1.331 10 32.031 0.12 30.941 0.46 30.548 2.95 1.090 1.483 11 38.424 0.84 37.337 0.65 37.159 1.89 1.087 1.265 12 40.941 0.60 39.910 1.02 39.739 0.10 1.031 1.202 13 43.073 0.32 42.042 1.02 - - 1.031 - 14 44.147 2.36 43.117 3.73 43.058 1.56 1.030 1.089 15 44.768 0.55 43.702 0.78 43.562 1.03 1.066 1.206 16 46.013 0.17 44.935 1.80 44.782 0.08 1.078 1.231 17 47.132 2.25 46.111 4.47 45.936 0.96 1.021 1.196 18 48.652 0.54 47.627 0.94 47.471 0.20 1.025 1.181 19 49.956 2.89 48.942 4.54 48.767 1.49 1.014 1.189 20 50.267 2.10 49.252 2.81 49.078 0.91 1.015 1.189

and 1D3 is 41and among the three is 33 .The common compounds appear with a uniform difference in their retention time. 1D2 peaks appear with an average delay of 0.194 minute in the range of 0.049 to 0.404 minute and 1D3 peaks appear with an average advance retention time of 0.318 in the range of 0.019 to 0.441 minute. The other peaks of 1D2 and 1D3 are probably due to some degradation products. Number of such compounds in 1D2 is 5 and in 1D3 are 26. It indicates that Hydrogen Peroxide decomposes the higher hydrocarbons first and then the degraded components gradually disappear.

G.C. analysis of the recovered oil from residual oil polluted sample 1E5 after 1,2 ( Plate-5) and 3 months gave 37, 65 and 52 peaks due to the undegraded components, derivatives and degradation products respectively. Out of the 37 components obtained after 1 month; 33 and 29 could resist degradation in the second and third months respectively, as revealed from their peaks appeared at a uniformly different retention time( Sarma et al,2004a) (Table-24). The stated 33 peaks appeared at a uniform advance retention time in the range of 0.914 to 1.247 minute with an average of 1.046. The stated 29 peaks appeared at a uniform advance retention time in the range of 0.914 to 1.247 minute with an average of 1.233. The remaining 4 and 4 components appeared in chromatograms obtained after 1 and 2 months respectively seems to be lost from the soil due to microbial activities. The number of peaks appeared in the chromatogram taken after 2 months but not in the previous chromatogram are 32. These peaks, and the corresponding peaks present in the last chromatogram are given in table (Table -25). Here only 17 peaks could resist complete degradation. These 17 peaks appeared at a uniform advance retention time in the range of 0.038 to 0.403 minutes with an average advance retention time of 0.196 minutes. The other 15 components seem to be lost from the soil due to microbial activities during the third month. Out of total 52 peaks appeared in the last chromatogram, only 6 peaks are due to new compounds (Table-26). These are the degradation products of the oil in the third month. Thus it can be concluded that degradation in the initial stage is more vigorous. The process slows down gradually. During degradation the higher compounds produce some fragments or some derivatives as a result of which number of components increases. Later on these compounds gradually disappear.

Table-27 shows number of components detected by GC analysis of a few samples of some of the mineral oils viz. Crude oil, Kerosene oil and Diesel oil–without agents, with nutrients, and with hydrogen peroxide. It appears that Hydrogen Peroxide increases the number of components in the sample and thus degraded the higher compounds. Application of NPK also increases the same, but lesser than Hydrogen Peroxide. For example, in the A5 samples, number of components after 3 months becomes 22 in 1A5 (without agent), 37 in 2A5 (with nutrients) and 39 in 3A5 (with hydrogen peroxide).The following table (Table 28) shows number of components detected by GC analysis of a few samples under identical conditions after one, two and three months. It appears that number of components increases initially and then decreases. It means that higher compounds give some smaller compounds and then escape from soil.

A good number of common components can be identified in the GC chromatogram of different samples (Table-29). These common components appear in the chromatogram after maintaining a uniform difference in their retention time. This difference is probably due to minor difference in the experimental conditions. In between the peaks at serial number 1and 2, the average difference in the retention time is 1.311 minute in the range of 1.304 to 1.316minute. Similarly the average difference in retention time between peaks at serial

and 1D3 is 41and among the three is 33 .The common compounds appear with a uniform difference in their retention time. 1D2 peaks appear with an average delay of 0.194 minute in the range of 0.049 to 0.404 minute and 1D3 peaks appear with an average advance retention time of 0.318 in the range of 0.019 to 0.441 minute. The other peaks of 1D2 and 1D3 are probably due to some degradation products. Number of such compounds in 1D2 is 5 and in 1D3 are 26. It indicates that Hydrogen Peroxide decomposes the higher hydrocarbons