respectively, as their electrolyte. The electrolyte is filled in a metal vessel, which acts as the cathode. The carbon materials function both as fuel and the anode and are dipped into the electrolyte. Solid oxide DCFC resembles the other two DCFCs except using an oxygen ion (O2�) conducting ceramic electrolyte. The most commonly used electrolyte is Y2O3 stabilized zirconia due to high ionic conductivity, better stability, chemical and thermal compatibility, mechanical robustness, easy fabrication, and low cost [45–47]. Solid oxide DCFC though favorable for its simple design, but it has the limitation of low output [48]. This low output is explicitly due to the limited reaction zone at the carbon fuel and the electrolyte interface.

A DCFC consumes solid carbon and oxygen to produce electrical energy through electrochemical anodic and cathodic reactions [49, 50]. The overall reaction involved in DCFC is the simple combination of carbon and oxygen to form carbon dioxide. Electrooxidation of carbon occurs at the anode, whereas electroreduction of oxygen occurs at the cathode [40, 49, 50]. Working of different types of DCFC is shown in **Figure 2**.

**Reaction at the anode (oxidation of carbon).**

$$\text{C} + \left(\text{electrolyte}\right) \text{4OH}^- \rightarrow \text{CO}\_2 + 2\text{H}\_2\text{O} + 4\text{e}^-. \tag{3}$$

$$\text{C} + \text{(electrolyte)} \; 2\text{CO} \\ \text{3}^{2-} \rightarrow \text{3CO}\_2 + 4\text{e}^-. \tag{4}$$

**Overall anodic reaction.**

$$\text{C} + 2\text{O}^{2-} \rightarrow \text{CO}\_2 + 4\text{e}^-.\tag{5}$$

**Reaction at the cathode(reduction of oxygen).**

$$\text{O}\_2 + 2\text{H}\_2\text{O} + 4\text{e}^- \rightarrow 4\text{OH}^-.\tag{6}$$

$$\text{2CO}\_2 + \text{O}\_2 + 4\text{e}^- \rightarrow 2\text{CO}\_3\text{}^{2-}.\tag{7}$$

$$\text{O}\_2 + 4\text{e}^- \rightarrow 2\text{O}^{2-}.\tag{8}$$

If DCFC is supposed to operate at a high temperature (above 700°C), carbon electrooxidation is overlooked by the reverse Boudouard reaction (electrooxidation of CO). So direct electrooxidation of solid carbon is overlooked by direct electrooxidation of CO, termed as CO shuttling mechanism [51] which leads to low carbon fuel utilization [52].

$$\text{C} + \text{CO}\_2 \leftrightarrow \text{2CO}.\tag{9}$$

Being reverse Boudouard reaction is endothermic, decreasing the working temperature of DCFC will enhance the CO reduction in the anode exhaust, thereby increase carbon fuel usage [49, 53]. DCFC attracts the scholarly attraction owing to its low-maintenance cost, simple cell structure, and rich availability of carbon feedstocks, i.e., biomass. List of biochar derived from biomass which finds its utility in various types of DCFC is given in **Table 3**.

*Prospects of Biochar as a Renewable Resource for Electricity DOI: http://dx.doi.org/10.5772/intechopen.108161*

**Figure 2.**

*Working of different types of DCFC.*

#### **Table 3.**

*List of Biochar served as fuel in DCFC.*

#### **4. Challenges and future perspective**

To understand the mechanism behind the electrochemical reaction kinetics and carbon oxidation at the anode/electrolyte interface is still a challenge for us. In addition to that, metallic components in the biochar inhibit the electrochemical performance of the fuel cell. Determining the amount of ash accumulation is also a key factor and should be researched into as well to determine the lifetime of DCFC. Technological expertise in the cell design along with the clear understanding of kinetics will solve the issues in near future.

#### **5. Conclusion**

Biochar an inexhaustive renewable resource solves many environmental issues arised in recent decades, viz., pollution, remediation in soil, and water. Research studies in recent years advocate the multifarious utility of biochar as fuel in DCFC and as electrodes, separator, and catalyst for ORR in MFC. Moreover, biochar-based MFCs remove hazardous chemicals from wastewater, DCFC utilizes carbon from zero-cost sources as fuel along with the generation of electricity.

### **Author details**

Ariharaputhiran Anitha\* and Nagarajan Ramila Devi Department of Chemistry, V.V. Vanniaperumal College for Women, Virudhunagar, India

\*Address all correspondence to<EMAIL_ADDRESS>
© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Prospects of Biochar as a Renewable Resource for Electricity DOI: http://dx.doi.org/10.5772/intechopen.108161*

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#### **Chapter 10**

## Biochar Synergistic New Ammonia Capture of CO2 and High-Value Utilization of Intermediate Products

*Yu Zhang, Yalong Zhang, Dongdong Feng, Jiabo Wu, Jianmin Gao, Qian Du and Yudong Huang*

#### **Abstract**

In the face of global warming and the urgent need for CO2 reduction, carbon capture, utilization, and storage, technology plays an important role. Based on the traditional liquid-phase and solid-phase CO2 capture technologies, the liquid-phase ammonia and biochar CO2 capture technologies are reviewed with emphasis. A multiphase carbon capture technology that uses biochar to enhance the mass transfercrystallization process of the new ammonia CO2 capture technology is proposed. High CO2 capture efficiency, limited ammonia escape, and low system energy consumption can be achieved through the orderly construction of three-dimensional graded pore channels and the directional functionalization of biochar. The intermediate products of CO2 captured by the ammonia process and the special agricultural waste rice husk components were considered. The use of rice husk-based biochar for CO2 capture by synergistic new ammonia method and the process regulation of intermediate products to prepare nano-silica to achieve high-value utilization of interstitial products of carbon capture. This technology may be important to promote the development of CO2 capture technology and CO2 reduction.

**Keywords:** CO2 capture, biochar, new ammonia, rice husk, nano-silica

#### **1. Introduction**

#### **1.1 Current status of CO2 emissions and CCUS technology**

Carbon is cycled between different sources (atmosphere, ocean, terrestrial biota, and marine biota) in the form of carbon dioxide, carbonates, and organic compounds. Human activities have disrupted the balance of this cycle, and a large amount of CO2 emissions has led to an increasingly serious greenhouse effect. Global climate change has caused widespread concern in the international community. According to the report of the International Energy Agency (IEA) [1], to achieve the target of global average temperature increase within 2°C above the pre-industrial level by 2100 and

to try to limit it to 1.5°C, direct CO2 emissions from industrial production need to be reduced by about 30%, and CO2 emissions per unit of GDP need to be reduced by about 60% by 2050 compared with the current level. However, as things stand today, global CO2 emissions from energy combustion and industrial processes will rebound in 2021 to the highest annual level ever recorded (**Figure 1(a)**). Emissions increased by 6% compared with 2020 (**Figure 1(b)**). The largest increase in CO2 emissions by sector in 2021 is from electricity and heat production, accounting for 46% of global emissions (**Figure 1(d)**). Coal accounts for more than 40% of the increase in total global CO2 emissions, a record high (**Figure 1(c)**). As the most important coal-consuming industry, coal-fired power plants are the most important source of CO2 emissions. Hence, the research on CO2 reduction technology for coal-fired power plants has profound significance.

Carbon Capture, Utilization, and Storage (CCUS) technology are considered the most economical and feasible way to reduce greenhouse gas emissions and mitigate global warming on a large scale in a short period. CCUS technology captures CO2 from large point sources such as power plants or directly from the atmosphere. The captured CO2 will be compressed and transported for various applications or injected into deep geological layers for permanent storage. As early as 2005, the Intergovernmental Panel on Climate Change (IPCC) identified CCUS as a key technology in mitigating the greenhouse effect [2]. Today, strengthened climate goals and new investment incentives have created unprecedented momentum for CCUS, and many countries have taken steps to develop CCUS technologies [3–7]. Projections indicate [8] that the least-cost pathway to "≤2°C" is to capture and sequester about 4 billion tons of CO2 per year by 2040 and that the current CO2 capture capacity is still

**Figure 1.**

*(a) CO2 emissions from energy combustion and industrial processes, 1900–2021, (b) annual change in CO2 emissions from energy combustion and industrial processes, 1900–2021, (c) change in CO2 emissions from fossil fuels, 2019–2021, relative to 2019 levels, (d) annual change in CO2 emissions by sector, 2020–2021 [1].*

far from the required amount, making CO2 capture technology critical in the overall carbon reduction and CCUS system.

#### **1.2 CO2 capture**

#### *1.2.1 CO2 capture technology*

There are four main CO2 capture technology routes: pre-combustion capture, oxygen-enriched combustion, post-combustion capture, and chemical loop combustion. In pre-combustion capture technology, fossil fuels are converted to a syngas of carbon dioxide and hydrogen before combustion using gasification or reforming technology so that the "carbon" in the fuel does not participate in the combustion process [9]. Oxyfuel combustion uses oxygen instead of air for combustion and can be used without considering the separation of nitrogen and carbon dioxide, a technically feasible process [10]. Post-combustion capture technologies remove CO2 from the flue gas after combustion has occurred. In recent years, chemical loop combustion (CLC) has also been developed. It uses metal oxides to transport the oxygen required for combustion to prevent direct contact between fuel and air, with its inherent CO2 capture capability [11]. Of the above capture technologies, post-combustion CO2 capture is the most mature and most thorough and is the preferred option for retrofitting existing power plants.

#### *1.2.2 Post-combustion CO2 capture*

Post-combustion CO2 capture technologies mainly include adsorption, absorption, membrane separation, and low-temperature distillation. Low-temperature distillation is a method of separation using the difference in boiling point or volatility of each component gas in the gas mixture. This method has high CO2 separation efficiency and purity and can directly produce liquid CO2 for storage and transportation [12]. The absorption method includes chemical absorption and physical absorption. Physical absorption involves using a physical solvent to dissolve a component gas. The solubility increases with increasing pressure and decreasing temperature; therefore, the optimal conditions for the CO2 absorption process are high pressure and low temperature [13]. The chemical absorption method uses an alkaline absorber to contact and react with CO2 in the flue gas to remove CO2. The salts generated by the reaction will decompose and release CO2 under certain conditions, thus removing and enriching CO2 from the flue gas [14]. The principle of membrane separation is that different components pass through the membrane with different selectivity. The membrane allows only specific gases to pass through, thus achieving separation and enrichment. The performance of the membrane system is influenced by the flue gas conditions [15], the enriched CO2 concentration is low, and the separation conditions are demanding. Adsorption can be divided into physical adsorption and chemisorption, with physical adsorption having a weak binding force, a relatively small heat of adsorption, and easy desorption. On the other hand, chemisorption is caused by chemical bonding between the adsorbent and the adsorbent, the adsorption is often irreversible, and the heat of adsorption is usually larger [16]. Adsorption differs from the absorption process in that the adsorption efficiency is mainly influenced by the specific surface area, selectivity, and regeneration characteristics. **Table 1** compares the above four post-combustion CO2 capture technologies, and all of these methods inevitably have various problems. Therefore, the development of new ammonia decarbonization technology will become the main

#### **Table 1.**

*Comparison of different CO2 capture technologies.*

theme of CO2 capture technology. However, its ammonia escape problem also needs to be further strengthened. The study of solid-phase adsorption combined with ammonia liquid-phase absorption to achieve two-phase synergistic CO2 capture will have farreaching significance in the future.

#### **2. Ammonia-based liquid-phase CO2 capture technology**

#### **2.1 Liquid-phase chemical absorption of CO2**

The commonly used absorbents for chemical absorption targeting CO2 capture are monoethanolamine (MEA), ammonia, and potassium carbonate. The CO2 capture efficiency of MEA is very high, but it has high regeneration energy, a high corrosion rate, and is susceptible to oxidative degradation. The high energy consumption of CO2 capture using aqueous amines is also one of the main drawbacks that limit its wide application. Non-aqueous absorbents have an absorption capacity comparable to aqueous MEAs and higher desorption efficiency, leading to a larger cycle capacity and nearly half the energy consumption (**Figure 2(a)**). Bougie et al. [27] investigated new non-aqueous MEA absorbers that greatly reduced energy consumption and improved CO2 absorption kinetics. The regeneration of MEAs is also a major challenge, with approximately 80% of the total energy consumption in the CO2 capture process occurring in the solvent regeneration process [28]. Many studies have shown that carbonate solutions can be used for CO2 uptake, and K2CO3 solutions have higher capture capacity than other carbonate solutions and are more commonly used in industry [29]. Although carbonate solutions have been extensively studied, the kinetics and thermodynamics of their absorption solutions still need to be investigated, and K2CO3 solvents may be subject to corrosion due to flue gas contaminants and solvent degradation.

#### **2.2 Absorption of CO2 by ammonia**

#### *2.2.1 Ammonia CO2 capture technology*

**Figure 2(c)** shows that reliable absorbents for low concentration CO2 capture without pressurization are amine-based and ammonia-based CO2 capture technologies. Ammonia-based CO2 capture is considered a viable carbon capture technology *Biochar Synergistic New Ammonia Capture of CO2 and High-Value Utilization of Intermediate… DOI: http://dx.doi.org/10.5772/intechopen.105405*

#### **Figure 2.**

*(a) Comparison of aqueous and non-aqueous MEA absorbents [23], (b) Schematic diagram of NH3-CO2-H2O three-phase system [24], (c) Applicable range of different CO2 capture technologies (based on operating pressure and CO2 concentration) [25], (d) Reaction mechanism of CO2 absorption by ammonia method [26].*

due to the high corrosiveness of MEA and regeneration problems over conventional amine-based CO2 capture technologies in terms of technical and economic advantages. The CO2-NH3-H2O system (**Figure 2(b)**) thermochemical properties have been reasonably well explained in recent studies. Although ammonia is the simplest amine, its interaction with CO2 is quite complex, involving gas-liquid-solid three-phase reactions, making the application of CO2-NH3-H2O systems in CO2 capture poses some challenges. Thomsen and Rasmussen [30] developed a thermodynamic model with a temperature. The model can be used not only for gas-liquid systems but also for gas-liquid-solid equilibria, including forming NH4HCO3, (NH4)2CO3-H2O, and NH2COONH4. Que and Chen [31] developed an electrolyte NRTL activity coefficient model that can well represent the thermodynamic properties of the NH3-CO2-H2O system when the CO2 loading reaches a consistent level. The availability of these models allows to reliably calculate the thermochemical properties of the CO2-NH3- H2O system under various conditions and to assess the energy performance of the capture process [32]. The uptake of CO2 by ammonia is a relatively slow process; therefore, it is important to understand the reaction mechanisms/kinetics involved in the uptake chemistry. The most important reaction in the presence of free ammonia is the reaction of NH3 with CO2, and the reaction scheme is shown in **Figure 2(d)**. The equilibrium constant of carbamate of MEA is much higher than that of ammonia, and the yield of ammonia-derived carbamate is lower than that of the equivalent monoethanolic ammonium carbamate, indicating that ammonia possesses a higher CO2 capture capacity.

#### *2.2.2 Ammonia escape*

Ammonia CO2 capture technology has many advantages, but it also has drawbacks in current applications: (1) low CO2 absorption rate; (2) serious ammonia escape; and (3) high energy consumption for desorption and regeneration. The high volatility of ammonia is the main drawback of ammonia CO2 capture technology. The concentration of NH3 escaping from the emission gas of this technology is usually above 10,000 ppm [33], which is much higher than the emission standard of 50 ppm. The high NH3 escape rate also decreases the concentration of NH3 in the solution, which reduces the CO2 absorption capacity [34]. Therefore, it is imperative to develop effective methods to suppress ammonia leakage or recover the leaked ammonia. The use of acid washing, membrane technology, and additives are common strategies to control ammonia escape.

#### *2.2.3 Ammonia-ethanol mixture absorber*

To better solve the above problems, many scholars have proposed the modification of CO2 absorption by ammonia solution using additives, which can inhibit not only NH3 escape but also improve CO2 absorption performance. Many scholars have studied the CO2 capture performance of ammonia with additives [35–41], among which Gao and Zhang et al. [39, 41] have shown significant advantages in various aspects of using ethanol as an additive. Ammonia and additives can, to some extent, promote each other to improve the CO2 uptake rate of ammonia [42]. However, a slight contradiction emerged between the hybrid absorber improving the absorption rate and inhibiting ammonia escape [43]. The additive mainly binds the free ammonia in the ammonia solution by hydrogen bonding and thus inhibits ammonia escape. However, the additive cannot achieve effective ammonia release when this hybrid absorber absorbs CO2, which will reduce the liquid-phase partial pressure of free ammonia and adversely affect the absorption process. The advantages of an "ammonia-ethanol adsorbent mixture" for CO2 absorption and capture are significant [41]. However, many aspects still need to be improved. It is urgent to develop a new ammonia carbon capture technology based on this idea to maintain its advantages and avoid its shortcomings.

#### **3. Biochar-new ammonia synergistic carbon capture**

#### **3.1 Solid-phase adsorption CO2 capture**

The adsorption of CO2 by porous carbon materials is an exothermic process, with the heat of adsorption of physical adsorption processes ranging from −25 to −40 kJ/ mol [44], and the amount of adsorption is directly related to the porous structure of the adsorbent and the active functional groups on the surface. The molecular kinetic diameter of CO2 is 0.33 nm, so micropores (<1 nm) are the main sites for CO2 adsorption (**Figure 3(a)**). Still, only micropores cannot achieve high adsorption capacity, and a suitable pore structure is required [45]. Macropores and mesopores act as channels for diffusive CO2 transport and can facilitate CO2 adsorption in micropores. CO2 being polar and acidic molecules, basic and polar functional groups (e.g., pyridine, pyrrole nitrogen) also plays an important role in adsorption [45]. Therefore, when selecting CO2 adsorbent, the economy and reliability should be satisfied. The adsorbent's pore structure and surface functional groups should be considered to ensure that the distribution of the two reaches a certain balance. Too much pursuit of one side will lead to the deterioration of the other side, resulting in a worse adsorption effect. (**Figure 3(b–e)**) [47].

Non-carbon-based solid adsorbents, mainly MOF and zeolite, are well studied and widely used. Almost all metals and a large amount of organic matter can make MOF, which is widely used in adsorption due to its extremely high porosity and specific

*Biochar Synergistic New Ammonia Capture of CO2 and High-Value Utilization of Intermediate… DOI: http://dx.doi.org/10.5772/intechopen.105405*

**Figure 3.**

*(a) Molecular dynamics and quantum chemical simulation of CO2 adsorption by porous carbon materials [45], (b) various structures in biochar micropores that effectively enhance CO2 adsorption [46], (c) effect of adsorbent porosity and chemical properties on CO2 adsorption performance [47], (d) correlation between CO2 adsorption, micropore, and mesopore volumes at 25°C and 5 bar [48], (e) correlation between different pore ratios and relative CO2 adsorption [45].*

surface area. When the partial pressure of CO2 is low (<0.2 bar), the adsorption capacity of MOF is poor [49], and impurity gases replace the skeletal ligands during the CO2 capture process, leading to degradation of MOF and a decrease in the capture capacity. Zeolites have a regular pore size of 0.5–1.2 nm [50] and have been widely investigated for CO2 capture due to the strong electrostatic interaction between CO2 and alkali metal cations in the zeolite skeleton [51]. Siriwardane et al. [52] showed that natural zeolites with high sodium content exhibited high CO2 adsorption capacity. However, the electrostatic interaction between CO2 and alkali metal cations in the zeolite skeleton is reduced by water [53], and therefore only in dry gas streams is CO2 separation effective. Among the carbon-based materials, activated carbon is one of the most commonly used adsorbents in industry. It is less costly than other adsorbents [54], but its adsorption capacity is only comparable to that of zeolites at high CO2 pressure [55], and the heat of adsorption is lower than that of zeolites. By introducing impurity atoms or acid-base sites, activated carbon can appropriately improve adsorption selectivity and adsorption capacity. As a new carbon-based material, carbon nanotubes have also received attention in gas adsorption [56, 57].

#### **3.2 Biochar adsorbent**

The raw materials of biochar are widely sourced, and the cost is lower than other adsorbents. The biochar prepared from different raw materials is different due to their intrinsic elemental composition ratio and structure. Biochar prepared from raw materials with high strength and carbon content, such as wood chips, coconut shells, date kernels, and rice husks, has a more desirable CO2 adsorption capacity [58]. During preparation, the carbonization temperature affects the structure, surface functional groups, and elemental composition of the final material and 500–800°C is considered

**Figure 4.**

*(a) Dynamic molecular structure of biochar derived from plant biomass [60], (b) Infrared spectra of biochar after heat treatment at different temperatures and comparison of XPS spectra of raw biochar and biochar after heat treatment at 300°C [61], (c) SEM images of different stages of biochar preparation [62], (d) Mechanism of biochar pore classification and group functionalization [2].*

the optimal temperature range for carbonization [59]. Thermal degradation of biomass at high temperatures in limited or complete anoxia is central to biomass conversion into porous carbon. Most biomass consists of lignin, cellulose, and hemicellulose, prepared under different pyrolysis and activation conditions to obtain different pore structures, group ratios, and surface chemistry (**Figure 4(a** and **b)**).

#### **3.3 Biochar modification**

The adsorption of CO2 by biochar is highly dependent on the pore structure and surface physicochemical properties, and the optimal pore size is about twice the kinetic diameter of CO2 molecules. However, the CO2 adsorption capacity of directly carbonized biochar is low. The authors' previous studies [45] have been conducted to enhance the CO2 adsorption capacity of biochar by sequential construction of pore channels and surface functionalization modification through activation (physical and chemical activation). Molecular dynamics simulations were also performed by clearly modeling the hierarchical pore channels to explain the experimental phenomena from a microscopic perspective. The mechanism is shown in **Figure 4(d)**. On the other hand, the carbonization temperature plays a key role in controlling activated porous biochar's functional groups and specific surface area. Therefore, the reasonable selection of the amount of activator and carbonization temperature becomes a necessary part of preparing activated porous biochar materials.

#### *3.3.1 Biochar pore hierarchy construction*

According to the International Union of Pure and Applied Chemistry (IUPAC) standards, biochar is classified as macroporous, mesoporous, and microporous.

*Biochar Synergistic New Ammonia Capture of CO2 and High-Value Utilization of Intermediate… DOI: http://dx.doi.org/10.5772/intechopen.105405*

**Figure 5.** *Relationship between specific surface area and pore volume of biochar and CO2 adsorption capacity [64–74].*

Usually, the pore size of macroporous exceeds 50 nm, mesoporous is 2–50 nm, and microporous is less than 2 nm. For the CO2 adsorption process, macropores and mesopores help diffusive transport of CO2 molecules, while micropores provide adsorption sites as direct storage sites for CO2. Therefore, a reasonable construction of graded pores can effectively enhance the CO2 capture performance of biochar. Lingyu et al. [46] prepared biochar from seven types of straw and wood biomass to study their CO2 adsorption performance and found that wood biochar has better pore structure than straw biochar with 2.73–4.40 times larger specific surface area, and biochar with super pore structure has higher CO2 adsorption capacity. Capacity was higher, and good pore structure played a crucial role in the CO2 adsorption. Avanthi et al. [63] prepared biochar using pine sawdust and steam activated it at the same temperature for 45 min after completion of pyrolysis. Due to the high surface area and microporosity, pine sawdust biochar showed significantly higher CO2 adsorption capacity than paper mill sludge biochar, which may be due to the Steam activation increased the microporosity, surface area, and oxygen-containing basic functional groups. In this paper, we summarized the literature that studied the CO2 adsorption capacity of biochar with different pore structures in recent years, and the relationship between their specific surface area, pore-volume, and biochar CO2 capture capacity is shown in **Figure 5**.

#### *3.3.2 Biochar functionalization construction*

The adsorption of CO2 on the biochar surface is influenced by the chemical properties of the biochar surface. Many studies have shown that the introduction of basic nitrogen functional groups can increase the alkaline sites on biochar and enhance the adsorption of acidic CO2 [75]. Nitrogen-containing functional groups are the main contributors to the alkalinity of the biochar surface, and activation in different nitrogen-containing reagents was performed to introduce nitrogen-containing functional groups to the biochar surface. The commonly used activation reagents are

KOH, NaOH, CO2, and K2CO3. Activation of biochar with KOH or NaOH can dissolve compounds such as ash, lignin, and cellulose, thus increasing the O content and surface alkalinity of biochar. Some new activation reagents such as NaNH2, CH2COOK, and H2SO4 have been gradually investigated. He et al. [76] prepared activated carbon by KOH activation using rice husk as raw material and modified biochar with chitosan as a nitrogen source. They found that the modified AC exhibited better CO2 adsorption performance in comparison. Yang et al. [77] prepared N doped porous carbon, and the CO2 adsorption capacity could reach 6.33 mmol/g at 273.15 K and 100 kPa, which was significantly higher than most of the carbon-based adsorbents reported in the literature due to the introduction of nitrogen-containing functional groups that increased the CO2 adsorption sites. In addition, unlike the acid-base interactions between CO2 and biochar surfaces, it has been shown that the presence of oxygen-containing acidic functional groups such as hydroxyl and carboxyl groups also promotes hydrogen bonding between CO2 molecules and carbon surfaces, thus increasing CO2 adsorption on carbon-containing surfaces [78]. Ma et al. [79] synthesized a series of carbon materials with different functional group contents. The experimental results showed that introducing oxygen functional groups into the carbon framework can again improve CO2 capture efficiency in N-doped porous carbon. According to the theoretical calculations (**Figure 6**), the carbon framework with high oxygen content further enhanced the hydrogen bonding and electrostatic interaction for CO2 adsorption. Wu et al. [80] prepared biochar from corn kernels by KOH activation, and the samples possessed a very high number of oxygen functional groups (45.5%) and exhibited a large CO2 adsorption capacity. The presence of alkali and alkaline earth metal (AAEM) elements such as Na, K, Ca, and Mg can also promote the formation of basic sites, which have a strong affinity for CO2 with acidic properties [81]. Therefore, the presence of biochar's AAEM elements may enhance the CO2 adsorption capacity of biochar, and the introduction of alkaline metal sites in the biochar skeleton may also enhance the CO2 adsorption of biochar in the order of Mg > Al > Fe > Ni > Ca > Raw biochar > Na [75].

### **3.4 "Biochar-new ammonia" CO2 capture system**

The excellent CO2 adsorption performance and low regeneration energy consumption of biochar are closely related to its well-developed specific surface area,

#### **Figure 6.**

*(a) modification of rice husk-based biochar and CO2 adsorption capacity [76], (b) preparation of N-doped porous carbon from chitosan and NaNH2 for CO2 adsorption [77], (c) hydrogen bonding between CO2 and functionalized biochar surface [79], (d) adsorption energy of different functional groups of biochar for CO2 [45].*

#### *Biochar Synergistic New Ammonia Capture of CO2 and High-Value Utilization of Intermediate… DOI: http://dx.doi.org/10.5772/intechopen.105405*

three-dimensional through-gradient pore structure, and unique oxygen/nitrogen surface chemistry. Dagaonkar et al. [82] estimated the effective diffusion coefficient of CO2 within biochar to be 9.645 × 10−7 m2 s−1. Suppose biochar particles are used as a modified material to enhance the mass transfer properties of the liquid phase. In that case, their stronger CO2 diffusion properties can be fully utilized to improve the overall reaction rate of the carbon capture system. Biochar has also been used to adsorb ammonia nitrogen, and more than half of the mass of ammonia nitrogen adsorbed was completed within 2 h [83]. In view of this, biochar can be applied in ammonia water CO2 absorption systems to achieve effective inhibition of ammonia escape through the sequestration of free ammonia by its active surface groups.

By combining the respective development potentials of biochar adsorbent and ammonia-ethanol absorber, biochar adsorbent was cross-linked with ammoniaethanol absorber to realize the functionalized cross-linking of the biochar-enhanced new ammonia carbon capture mass transfer-crystallization process (**Figure 7(a)**).

**Figure 7.**

*(a) Functionalized cross-linking of biochar-enhanced novel ammonia-based carbon capture mass transfercrystallization processes, (b) Enhanced mass transfer mechanism of biochar in ammonia-ethanol mixed absorbent [2].*

This system transforms the carbon capture process from the traditional ammonia carbon capture gas-liquid two-phase reaction to a gas-liquid-solid three-phase process. The system can achieve CO2 adsorption and enrichment in micropores, CO2 diffusion and transport in mesopores/macropores, and dynamic sequestration of free ammonia by regulating the hierarchical structure of biochar nanopores and the orderly grouping of active functional groups on the surface. The cross-scale multiphase system processes, such as functionalization, pore gradation, biochar/NH4HCO3 dissolution and crystallization, and adsorption/absorption coupling, are cross-linked by crystal regeneration instead of liquid-rich regeneration. The synergistic effect of "graded adsorption—efficient absorption—dissolution crystallization—crystal regeneration" in the system is accomplished. The multiple goals of ammonia carbon capture, such as increasing absorption rate, suppressing ammonia escape, and reducing system energy consumption, are achieved. This process can improve a series of shortcomings of ammonia CO2 capture and overcome the shortcomings of biochar adsorbents. The synergy of the CO2 capture process in the solid-liquid system of "biocharammonia-ethanol" is achieved by "taking the advantages of each and avoiding the shortcomings."

#### *3.4.1 Biochar efficiency transfer*

The absorption of CO2 by ammonia is a typical non-homogeneous reaction process in which CO2 in the gas phase is first dissolved in the absorption solution and then reacts with NH3 in the liquid phase. Therefore, the absorption rate is controlled by the "chemical reaction in the liquid phase" and the "mass transfer characteristics between gas and liquid." The generation and hydrolysis of carbamate in the reaction process is the most important factor affecting the chemical reaction rate, roughly divided by the carbonation degree of ammonia absorption CO2 solution ≈0.5, as shown in **Figure 7(a)**. The liquid membrane mainly controls the mass transfer resistance of ammonia absorption CO2 reaction process, when the hydrolysis of ammonium carbamate mainly controls the carbonation degree >0.5, ammonia absorption CO2, so that the liquid phase carbon capture rate is significantly reduced, and this process has been the bottleneck to improve the absorption rate in the later stage of the reaction in the traditional process. This process has been the bottleneck to improving the absorption rate in the later stage of the reaction in the traditional process. The key to reducing the liquid film mass transfer resistance in the process of CO2 adsorption by ammonia and improving the low CO2 absorption rate is to get rid of the influence of carbonation degree on the regeneration energy consumption and to control the CO2 absorption reaction by ammonia only in the rapid generation phase of ammonium carbamate with carbonation degree <0.5. The mechanism of mass transfer characteristics of the new ammonia carbon capture process with biochar efficiency enhancement is shown in **Figure 7(b)**. Using the highly efficient adsorption performance of biochar hierarchical pore channels, the initial rapid CO2 sequestration is completed, and the biochar is used as a carrier to bring CO2 into the ammonia absorption system. Subsequently, the transfer of CO2 from solid particles' adsorption space to the ammonia liquid phase's absorption space is further realized. The release of CO2 from biochar and the absorption of CO2 by ammonia is completed, which greatly increases the contact time between CO2 and ammonia liquid phase, thus realizing the reduction of liquid film resistance and prolonging the residence time of CO2 in the solid-liquid phase system to increase the material transfer and chemical absorption rate in the ammonia liquid phase system. The liquid-liquid phase ammonia system can be used to increase the rate of material transfer and chemical absorption.

*Biochar Synergistic New Ammonia Capture of CO2 and High-Value Utilization of Intermediate… DOI: http://dx.doi.org/10.5772/intechopen.105405*

#### *3.4.2 Limiting ammonia escape*

The ammonia escape process is shown in **Figure 8**. Among many parameters affecting ammonia escape, the temperature is one of the most sensitive [84]. From the ammonia escape point of view, the absorption temperature should be as low as possible, requiring a large amount of energy to maintain cold ammonia. For the solid-liquid two-phase CO2 capture system, the pore surface functional groups in the solution permeable region of biochar/macropore can undergo cation exchange with NH4+ in solution [85], which promotes the reverse migration of the hydrolyzing process of ammonia monohydrate. At the same time, the free ammonia in the liquid phase was held by the van der Waals force and chemical hybrid force [86] so that the production of free ammonia in the liquid phase could be effectively controlled. Therefore, the hierarchical functionalized construction of biochar pore structure ensures the hierarchical adsorption of CO2/NH3 by biochar particle pore, improves the material transfer and chemical absorption rate in the ammonia liquid phase system, and makes the dynamic balance of NH3 adsorption and fixation in unsaturated solution impregnation space present in biochar pore. To a great extent, the effective concentration of free ammonia that can participate in the reaction in the liquid phase system is ensured, the dynamic partial pressure of free ammonia in the liquid phase is maintained, and the ammonia escape is limited.

#### *3.4.3 Dissolution crystallization instead of rich liquid regeneration*

The traditional ammonia-rich liquid thermal regeneration process is the largest energy-consuming part of the whole ammonia carbon capture process. The regeneration energy consumption is mainly composed of three parts: the sensible heat of rich liquid warming, the latent heat of vaporization, and the heat absorption of

**Figure 8.** *Ammonia escape mechanism.*

regeneration reaction, of which 50–70% of the energy is consumed in the warming and vaporization of rich liquid solvent [87]. The solubility of the product of the reaction process of CO2 absorption by ammonia is known: ammonium carbamate is soluble in water and ethanol; ammonium bicarbonate is soluble in water-insoluble in ethanol. The main mechanism of solvation crystallization is to use the different chemical structures of the main solvent molecules and solvating agent molecules to make a difference in the microscopic forces between the ions of the substances to be separated and to change the macroscopic properties of the mixed solvent by changing the microscopic forces of the particles in the solution, thus greatly reducing the solubility of the solute, and using the solubility difference as the driving force to make the solute continuously precipitate out of the liquid phase in the form of crystals, so that the solvent and the solute are separated. The solvent and solute are separated. In the "biochar-ammonia-ethanol" carbon capture system, the crystallization process is strengthened by the solvation and precipitation method, and the regeneration of crystals replaces the regeneration of carbon-rich liquid, which greatly reduces the energy consumption of regeneration. The biochar functionalized Meso-/macropore pores ensure the NH3/NH4+ concentration in the liquid phase. The pores' active surface structure provides nucleation sites for the crystallization process, which accelerates the formation and growth of carbonated liquid solvation crystals in the liquid phase system. The dynamic balance between the crystallization process's residence time and the biochar's saturation time for efficient adsorption can provide a stable CO2 adsorption-absorption-crystallization series process.

#### **3.5 High-value utilization of carbon capture products**

The main crystallization product of the novel ammonia CO2 capture technology described above is ammonium bicarbonate, which is widely used in agriculture, food, pharmacy, and ecological management, but its utilization process's complexity and economics have prevented its use widespread development. Therefore, further optimization of the new ammonia CO2 capture technology and high-value utilization of the intermediate product ammonium bicarbonate have also become key issues. Rice husk is widely available, and its internal structure has a lignocellulose-SiO2 crossover network, and the SiO2 in it can be dissolved to construct pore channels of a specific size. With this unique structural advantage, rice husk is the best raw material for preparing graded porous carbon [88]. The particle size of SiO2 in rice husk is mainly concentrated in the range of 8–22 nm, with a small fraction of SiO2 in the range of 1–7 nm [89], indicating that SiO2 in rice husk can be used as a natural template to induce mesopore generation in situ after solubilization. The chemical activation of agricultural waste rice husk as a raw material enables the orderly construction of high-quality rice husk-based biochar with a hierarchical pore structure and high specific surface area. Combined with the new ammonia carbon capture technology, the rice husk-based biochar-ammonia-ethanol system was constructed, and the nano-silica carbon black was produced by the acid-base neutralization and redecomposition reaction between NH4HCO3, an intermediate product of the new ammonia carbon capture, and silicate, an intermediate product of the rice husk-based biochar (**Figure 9**). This route greatly solved the problems of carbon capture product consumption and agricultural waste pollution and produced high-value products of rice husk-based biochar carbon and nano-silica at the same time.

*Biochar Synergistic New Ammonia Capture of CO2 and High-Value Utilization of Intermediate… DOI: http://dx.doi.org/10.5772/intechopen.105405*

#### **Figure 9.**

*Technology roadmap for high-value utilization of process products from rice husk-based biochar-new ammoniabased carbon capture technology.*

#### **4. Summary and outlook**

CO2 capture is a crucial part of CCUS technology, and absorption and adsorption have been widely studied as the main means of CO2 capture. The mainstream CO2 liquid-phase chemical absorption method is difficult to avoid high regeneration energy consumption, degradation problems, and high corrosiveness. In contrast, the "ammonia-ethanol" system effectively avoids these problems but still has serious ammonia escape problems and crystallization control difficulties, and the technology needs to be improved. Biochar has excellent CO2 adsorption performance due to its specific surface area, three-dimensional through-gradient pore structure, and unique oxygen/nitrogen surface chemistry. However, it still has many problems, such as poor CO2 selectivity, limited adsorption capacity, high cost, and short service life. Combining the above-mentioned new ammonia carbon capture technology, the carbon capture process is transformed from the traditional ammonia carbon capture gas-liquid two-phase reaction to a gas-liquid-solid three-phase process, which maximizes the efficiency of CO2 capture by graded adsorption of biochar and efficient absorption of ammonia-ethanol solution:

1.Enhancement of mass transfer between solid and liquid phases to improve the carbon capture rate;

In order to realize the high-value utilization of intermediate products, we propose a system of rice husk-based biochar—new ammonia method—process product resource synthesis—process regulation, which provides new ideas and directions for the CO2 capture industry.

### **Author details**

Yu Zhang, Yalong Zhang, Dongdong Feng\*, Jiabo Wu, Jianmin Gao, Qian Du and Yudong Huang School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, Heilongjiang, China

\*Address all correspondence to<EMAIL_ADDRESS>
© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Biochar Synergistic New Ammonia Capture of CO2 and High-Value Utilization of Intermediate… DOI: http://dx.doi.org/10.5772/intechopen.105405*

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#### **Chapter 11**

## Microwaved Flux Matter- Char Sand Production of Waste Coal Char/Biochar/Gypsium Ash and Fly Ash Mixtures for Mortar- Fire Retardent Composite

*Yıldırım İsmail Tosun*

#### **Abstract**

Fire inhibiting materials as cement filler are used in mortar constructions especially using gypsium board, similar isolator mortars. The mortar covered char and ash sand mixtures insulate heat and reduce fire blazing activity. Ytong, or porous briquettes and clay is the world's most popular insulating construction material retarding blaze due to its porous durability, processability, and cost. However, producing concrete or mortar with high isolation with HD styrene panels is insulating the structure, protecting the cement board against flammable fire risk. Slag-type masonry requires high heavier fire inhibiting matter in construction. Styrene type isolation provides fire inhibiting at lightweight masonry or mortar generation with the use of waste gypsium fines and waste coal slimes and high ash char "char sands" and ash fines. The growing environmental concerns motivated researchers to search for char waste slag-type inhibiting materials using gypsium fines and biomass waste char fines leading to alternative routes of fire-retardant mortar construction. In this way, several alternative materials of isolation mortar have prompted.

 Introduction**

Molten plastic extruded belts or strips may easily be produced through the nozzle hole of pressed waste plastic fluids by microwave radiation till 300°C for recycling waste materials as granule compost [1, 2]. The use of waste concrete debris and broken glass or plastic slags cause an important cost decrease in masonry stone production [3, 4]. Even the use of waste materials as aggregate and sand size make them beneficial in concrete mixture evaluation in most light weight constructions [5, 6]. The melted plastics and bitumen asphalt may be replaced by cement in masonry brick and roof tile production as binder compound while providing impermeable and high resistive durability to thaw and freezing in cold climates. Plastic extrusion may need suitable fluidization quality and antifouling powders use such as clay at a certain amount. Presently, around 70% of the construction is produced through the conventional slag-type masonry as inhibiting masonry constructions [3, 4].

In the region, the municipal bottom ash wastes of asphaltite combustion in boilers as wastes, containing the high porous content. 70–80% content of bottom ash is over 25 mm size suitable as lightweight aggregate discarded and collected.  The biomass waste collected in the region is combusted and bottom ash mixed with asphaltite bottom ash at the density of 0.7 kg/l is about 450 thousand tons for wet production [7–9]. The wood char fine in Siirt and Hakkari is evaluated for fire inhibitor. The waste plastics are collected as sludge waste and shredded wet and converted plastic pellet noodles. The plastic noddle products and belts both should be evaluated by pyrolysis oil content below 350°C and the other slag plastics is becoming hard porous slag such as, fine matters gradation of aggregate subjected to mixing and melted asphalt briquetting of the sludge waste and subsequently briquetted products for concrete compost aggregate below 25-50 mm [10–12].

In this study; the effect on the physical parameters of briquetting, shear model patterns making preliminary tests to determine the briquetting and processing conditions, indention and sawing shear rate were investigated for rock and waste plastic or asphalt compost aggregate concrete in comparison with cemented aggregate [13]. This assay has been determined to be advantageous in the plastic and asphalt bound aggregate briquette production from sludge content solution with the waste plastic and their mixture rate with porous local stone [14–16].

#### **1.1 Carbon source-biomass potential of Turkey**

In the cement and retardant material consumption, use of waste materials as a carbon source from agricultural biomass waste and forest biomass waste depending on crop production in the market and waste straw used for various purposes, such as other waste cotton stalks, corn stalks, sunflower stalks, nut leafs are evaluated in production of retardend carbon source at finer sizes as filler material. The total amount of different wastes are given in the **Table 1** [14]. The total waste field crops in Turkey and waste quantities are given in **Table 2** [17, 18].

Biomass wastes are evaluated in char carbon production as active carbon or fireretardant carbon even in the low-quality high ash containing matter as waste source. The biochar carbon resources may be produced from country oil resources, or crop oil, oily wastes as composted sources as given in **Table 2** in Turkey [17].

The asphaltite coal type is widely deposited in the Şırnak province with high amount of shale content. The shale ash content is illustrated in **Figure 1**. The combustion is retardent act over 45% ash content leaving about 20% unburned carbon in the ash [19, 20]. The ash content change of Şırnak asphaltite coal and char used as fire-retardant in this study in terms of density is illustrated in **Figure 1**.

#### **1.2 Gradation**

Aggregate size distribution is changing by ASTM standards of soil classification over the foundation stability research in detailed [14] is given with Sieve analysis

*Microwaved Flux Matter- Char Sand Production of Waste Coal Char/Biochar/Gypsium Ash… DOI: http://dx.doi.org/10.5772/intechopen.101559*

#### **Table 1.**

*The total amount of municipal waste divided into actual values in Turkey and eastern Anatolian region in 2019 [17].*

#### **Table 2.**

*The total annual production of biomass waste in Şırnak and eastern Anatolian region [17].*

**Figure 2.** *The soil -aggregate classification in ASTM standard [14].*

results as shown in **Figure 2**. The permeability of soil is also determined regarding the chart illustrated in Standard as **Figure 3**. Physical properties of the clay material [21, 22] Parameter Value Color Dark Brown Specific Weight 2.69 Sand Content (%) 17.33 Silt Content (%) 6.22 Clay Content (%) 76.44 Liquid Limit (%) 43.9 Plastic Limit (%) 21.8 Ground Class (USCS) CL 10%, 30%, 50% liquid limit values of the waste Şırnak asphaltite slime and clay material mixed into the clay sample were calculated. The liquid limit value of the clay sample containing 10% waste slime clay corresponding to the sinking of 20 mm was determined as 28%. The textural and strength properties of the Şırnak shale clay showed that the water absorption of the texture is high and the chlorite mineral is suitable for volume changes. Due to this structure of the clay, the plasticity and strength of the material changes and the swelling and shrinkage activities of the clay can lead to different behaviors and cause structural problems. For this reason, it is of great importance to perform volumetric shrinkage tests of asphaltite slime or ash slime.

#### **1.3 Fire retardent slags**

The recycling needs of waste plastics in housing in cities forced to energy use and construction use of polymer wastes and many other filler areas such as fly ash composted ornaments and masonry areas are increasing. The large-scale reconstruction projects offer the use of demolished buildings concrete, transportation of those debris materials and crushing and compacted with water and cement cause a high amount of cement and water even increase cost elements. The dams, factories and the construction sector, which aims to protect the stability of concretre structures, gradually need much cheap aggregate production. To meet the cost reductions of all masonry and mortar construction, waste materials are evaluated similarly to masonry bricks regarding strength and durability [23, 24]. Although, the aggregate materials obtained from the quarries can be widely used in the construction

*Microwaved Flux Matter- Char Sand Production of Waste Coal Char/Biochar/Gypsium Ash… DOI: http://dx.doi.org/10.5772/intechopen.101559*

**Figure 3.** *The soil permeability regarding void in soil classification in ASTM standard [13].*

**Figure 4.**

*(a) extruding ball die, (b) plastic waste and asphaltite slag and slime asphaltite char mixing briquetting [22].*

industry. Lightweight materials are waiting in high house constructions as surplus stock. Crusher residue fine-grained materials are scattered around by 10–15% at depending on the crusher type. As a result, the waste plastic nodules or belts may compost as slag waste sand, fine material that remain in the dust collectors. Therefore, the general standard provisions stated in the construction materials fire resistivity for plastic contents not over 30% volume regarding bitumen asphalt or other masonry mixing fines [25–28]. In the mortar tests, the mixed waste briquettes are aimed to prevent fire reaction that occurs as a result in the blazing fire contact, degradation of stability of residents. The importance of fire inhibiting or control practices in the evaluation, the regulation was emphasized on that way. Disposal of plastic waste heaps is in the form of shredded waste and can be used by extruding.

Many plastic waste recycling articles dealing with many issues such as such are included in the literature [29–32]. As an industrial raw material, lightweight volcanic cinder instead of broken glass is used as the main raw material and additive material in lightweight brick sectors depending on the masonry use. The aggregates obtained by crushing, sieving and sizing according to the sector in which porous stone will be used are evaluated in appropriate gradation sizes according to the geotechnical strength purpose in briquetted brick use. However, the fine-grained material remaining under the sieve during the sizing process is awaiting stock surplus in the local dumps' areas. Şırnak asphaltite bottom ash slag with high porosity is in search of new areas of use to utilize the organic soils they obtain as waste other than dumping activities. In this respect, the light weight mixture with the recycled waste plastic product that occurs in retort furnace is searched detailed for lightweight briquette production without causing environmental pollution. In addition, shale fine in soil environments, which are quite commonly layered in certain regions of Şırnak is used for gradation mixing encountered for high strength. In this study, it was aimed to examine the behavior of these two different types of materials by mixing them in variable ratios because of the optimum gradation amount of these materials in the region and the specific characteristics of briquetted materials without cement are evaluated. It is stated that pumice is a suitable additive for the stabilization of high plasticity clay. It is emphasized the usability of plastic waste materials in improving the engineering properties of briquette with shale powder and porous limestone added to briquette blocks cemented in certain proportions. It was also determined that in the asphalt-based mixtures prepared by using fly ash and limestone fine in the improvement of the fine-grained ground sample, the limestone aggregate decreased the shrear strength by 35% and the volcanic cinder increased by 22% [33–36]. Indentation and shear properties of the briquetted materials by plastic waste melted and asphalt melted to be used in the experiment were carried out in the Şırnak University.

#### **1.4 Fire retardant chemical materials**

Fire retardent salts such as the construction materials used in the environments we live, the building materials are non-combustible and are produced from salt hydrates, chlorides as chemical materials. Since slag chars or melted/foam salts ignite and shine more quickly than natural materials, a possible fire spreads quickly. The heat from the flame source destroys the oxygen in the environment very quickly and starts to pose life risks in 90 seconds. It is not possible to prevent a fire in a closed environment after 3 minutes without external intervention. In a fire, blazing hazard and toxic gases hazard, chemical gas hazards, explosion and sustainable fire hazard, structure collapse occur. Again, in a possible fire, the temperature rises to 550°C in the first 5 minutes and to 720°C after half an hour. The temperature can reach 950°C degrees after 90 minutes and 1100°C degrees after 3 hours. In some large fires, it is claimed that a temperature of 1500–1700°C occurs [35]. From dripping bricks in buildings fire, which is an exothermic chemical reaction, continuously generates heat and enlarges and spreads the adjacent materials in a chain way by reaching their ignition temperature. In order to eliminate the devastating effects of risk factors in an indoor fire prompt the use of fire retardent construction materials that slow down and stop the progression and spread of fire; Various substances were Flame Retarder. The commonly used salt materials are

*Microwaved Flux Matter- Char Sand Production of Waste Coal Char/Biochar/Gypsium Ash… DOI: http://dx.doi.org/10.5772/intechopen.101559*

Regarded the fires encountered the retardant material need have revealed the importance. The necessity of fire-proof materials in the world, especially the wood industry, cable (plastic) industry, and the textile industry have started to produce fire-resistant materials [36–38].

Fire retardant coating and mortars are needed for insulater's coverings and construction boards and plates. The gypsium is providing a good retardant protection however the strength and heat insulation change the strength stability of boards as given in **Table 3** [38].

#### **1.5 Şırnak fly ash, waste ash slag and Şırnak asphaltite char with ash materials**

The geological petrographic, geochemical and physical properties of the fine-grained slag and cinder material are found in the local quarry in Tatvan and Şırnak region. The volcanic cinder such as pumice stone, iso foam stone, ash slag stone, are two types of porous texture and contain at least 70–80% porous formation as a result of basic volcanic gaseous activities. The Tatvan basic volcanic cinder is similar to acidic pumice, which is the most widely found and used in the world, has a white dirty appearance and a grayish-white color. The silica ratio is higher in acidic pumices, and it can be widely used in the construction industry [12–15]. A volcanic cinder is a browny reddish porous, glassy volcanic rock that is formed as a result of volcanic gaseous eruptions highly sponge and resistant to chemical reactions at high abrasion strength. It contains pores from macro to micro scale due to the sudden release of the gases in the body during its formation and its sudden cooling. Volcanic cinders have high permeability and high heat and sound insulation. Its hardness is 5–6 according to the Mohs scale. In Eastern Anatolia, severe volcanic events have occurred in very wide areas since the Middle Miocene. Tectonic activity is covering wide areas near Van Lake as volcanic craters lake,

#### **Table 3.**

*Fire retardent chemical materials classification.*

craters heel, disseminated tuff covers and tuff debris lava remnants carried by waterfloods. It has been active starting from the Mid Miocene period until the end of the Quaternary [36]. Tatvan unit consists of volcanic cinders with 78–83% porous cinders as block flows, debris of flow tuffs, and andesitic, basaltic and rhyolitic lavas [37]. Pumices are light browny macroscopically and dark gray colored in certain places. It has a vesicular texture formed by the cavities left by the gases that expand as a result of sudden pressure decrease under atmospheric conditions. The gray acidic cinder contains coarse plagioclase minerals showing feldspat, biotite minerals and chlorite minerals as accessories are observed in the rock [38–44].

#### **2. Method**

The method of compaction for retardant wet material at 15% optimum fluid weight rate as water muddy content pushed to nozzles of the extruder for board plaque production as illustrated in **Figure 4a**. The aggregate mixing the retort mixer is used in laboratory-scale a meter and 30 cm diameter retort used in 10 minutes for mortar homogenized wetting at optimum retardant compositions as showed in flowsheet procedure followed in **Figure 4b**.

In the fire-retardant mixture, preparation used volcanic cinder prepared as slag based on the main element iron, manganese oxide and trace elements given in **Table 4**, the analysis results of the waste Şırnak Asphaltite bottom ash slag material of ultrabasic magma (**Table 5**).

#### **2.1 Porous char slag asphalt sand production**

Material is located in Şırnak Province, Southeastern Anatolia Region, are located in the south part of Tatvan and chlorite shale formations limestone formations

#### **Table 4.**

*Composition of the waste cinder and Şırnak bottom ash slag material.*

*Microwaved Flux Matter- Char Sand Production of Waste Coal Char/Biochar/Gypsium Ash… DOI: http://dx.doi.org/10.5772/intechopen.101559*

#### **Table 5.**

*Physical properties of waste volcanic cinder.*

contained quartz, feldspar, calcite, dolomite and limonite, hematite minerals and asphaltite slag is red color due to the hematite mineral in its composition at 17%. It can be found in light yellow colors depending on the ratio of limonite in the gray shale ground [21–23]. The porous limestones shale texture, marl shows a heterogeneous texture (**Figure 2**).

#### **2.2 Particle size distribution- gradation**

M mass of aggregate is, the void is affected by compaction of briquetting and binder distribution. Especially melted asphalt and ash distribution are controlled by volume % of compaction. The bulk sand eating by microwave will also be controlled by the amount of little as 1% binder ash bound as a volume.

where, γ*g* = \_density of aggregate, g/cm3; *V(r)* and *dN(r)* are the volume and particle amount of aggregate in the size region of integration of cumulative pile from *r, to r* + *dr*), respectively. *V*e volumetric equation is calculated as,

$$d\mathbf{M}r = \eta \mathbf{g} \text{ V}(\mathbf{r}) d\mathbf{N}(\mathbf{r}) \tag{1}$$

$$V(\mathbf{r}) = k \, r^3 \tag{2}$$

where, *k* is the shape factor. Substitute Eqs. (1) and (2) using.

#### *2.2.1 Aggregate particle size distribution*

Particle size distribution is defined by aggregate crushing matter, the type of milling affects the size distribution and the fineness matter ranged below 20 microns determined as given the Eq. (3) below; and RRS logarithmic size distribution is defined as given I Eq. (4) below [24].

$$\mathbf{u}(\mathbf{x}, \mathbf{d}\_{\mathbf{f}}, \mathbf{c}) = \left(\chi/\mathbf{d}\_{\mathbf{f}}\right) \left(\mathbf{1} + \mathbf{k}/\mathbf{d}\_{\mathbf{f}} \cdot (\mathbf{x} - \chi)\right)^{-1/\mathbf{k}} \tag{3}$$

$$R\mathbf{s}(n) = f(n)W(n)\sum\_{m=1}^{n} \mathbf{x}'/(\mathbf{x} - r)^{m} \tag{4}$$

**Figure 5.** *The Şırnak Fly ash and Şırnak asphaltite slime particle size distribution in gradation in ASTM standard.*

The weight of fineness below 100 microns is determined by hydrolic settling analysis. The rate of material used in the experimentation is illustrated in **Figure 5**. The d60 values of the particle distribution of Şırnak Fly ash, Şırnak char slime and waste slime are below 100-micron fine size.

#### **2.3 Fire tests**

Flame gas brulor is blazed on the thick 10 mm board and the resistance to fracture and bubbling on a 5 minutes time flash burning at a distance far from 10 mm. The depth of disturbed face of board in the fire resistivity test is determined as an opened hole or as weight rate of burning natter weight. The time of burning of fire contact according to ASTM D-635 was investigated over the extent of depth measured by extensometer of mortar boards reported if the specimen does not burn on the board of 10 mm thickness. An average burning depth rate was also determined.

*Microwaved Flux Matter- Char Sand Production of Waste Coal Char/Biochar/Gypsium Ash… DOI: http://dx.doi.org/10.5772/intechopen.101559*

#### **3. Results and discussion**

#### **3.1 Gradation of retardent mixture-** *asphalt ash/char amount and briquette porosity*

#### *3.1.1 Particle İndex*

The coarse particle distribution avoids the heat conduction so that fineness of particle size distribution in the construction gradation provides optimum fire retardent heat activity on the surface without breaking the mortar face.

$$I\mathfrak{a} = \mathfrak{1}, \mathfrak{2}\mathfrak{F}V\_{10} - \mathfrak{0}, \mathfrak{2}\mathfrak{F}V\_{\mathfrak{5}0} - \mathfrak{3}\mathfrak{2} \tag{5}$$

where Ia is particle index, V10 is voided in aggregate compacted at 10 drops per layer, V50 is voided in aggregate compacted at 50 drops per layer. Especially fly ash content in the retardent mixture was decreasing compaction ability. The amount of reaching 30% fly ash addition reduced the permeability of texture compacted in the mortar briquettes at 27% volume rate decrease.

The sand matters are thought as rounded and smooth particles as an ideal form. This may have a low particle index of around 6 or 7, while silty sands composed of angular, rough particles may have a high particle index of between 15 and 20 or more.

#### *3.1.2 Fineness modulus*

The fire retardent mortar sands may contain optimum gradation with very fine clays or fly ash on standard content description as happening in ASTM C 125 with a gradation curve as illustrated in **Figure 2**. In this study, the fly ash fineness is determined by the RRS diagram and n distribution coefficient as in Eq. (6) below and illustrated in **Figure 6** for the samples studied as fire retardent.

$$\mathbf{F}(\mathbf{d}; \mathbf{t}; i) = \sum\_{i=0}^{n} \mathbf{u}(\mathbf{x}, \mathbf{t}) + \phi(\mathbf{x}; \mathbf{t}; i).e^{-\mathrm{int}} \tag{6}$$

#### **3.2 Compressive strength test**

It is based on the determination of the compressive strength from the indenting of the briquette sample in seconds as drilling bit penetration on rock sample [21]. Then, the indenting depth is determined using the extensometer dipping measure by the pattern is obtained for rock samples used in Şırnak. The fire retardent additives show stable porosity and strength suitable for mortar mixture while cement is locking the fixed coverage over wood in the fire flame tests (**Figures 6** and **7**).

#### *3.2.1 Mortarcompost - porous texture strength*

The massive mortar mixture of rock sands show different porous structures and strengths. The compaction indentation depth for porous rock stones and fire retardent materials are depended on particle size and fines amount as given below Equations;

$$Elasticity(\mathbf{0}) = -qf \sum\_{m=1}^{M} Cm(\mathbf{1} + Xr)^{m} \tag{7}$$

#### **Figure 6.**

*The fineness of Şırnak fly ash and Şırnak asphaltite slime and char slime regarding gradation, RRS distribution factor of 0.45.*

**Figure 7.**

*The Şırnak Fly ash and Şırnak asphaltite slime compost compaction regarding gradation factor below 100 microns solid.*

$$E\operatorname{deformation}(\mathbf{0}) = f \sum\_{m=1}^{M} \operatorname{Cm}(\mathbf{1} + Xr)^{m} \tag{8}$$

After this process, the sinking amount of the cone was determined from the electronic measuring stick on the device. Some samples taken from the submerged *Microwaved Flux Matter- Char Sand Production of Waste Coal Char/Biochar/Gypsium Ash… DOI: http://dx.doi.org/10.5772/intechopen.101559*

part of the cone were dried in the oven and the water content corresponding to the determined sinking was found.

Samples with volume 10%, 20%, 30% and 40% waste phospahate salt and char/ salt flux composts blazed on the depth-averaged from three different points for fire retardent manner. The sample used is thick at 5.425 mm for 10 mm wood. The advantage of this experiment is that it minimizes the errors of the candle fire flame over 50 mm experiment according to the standard gradation.

Considering inferences, extreme deformations can be observed under fire load on wood-covered fire retardent mortar that is saturated with a dried binder depending on firing time. Due to these negative weight effects, various chemical burning weight changes on the wood are required for the unflammable ground environment to reduce fire weight decrease, reduce cracking and prevent the negative consequences of bubbling melting in the ground structure. The plastic slag and char regulate the air mixing and permeability on the wood substrates where it is criticized in **Figure 8**, while Şırnak asphaltite char addition reduces air diffusion and reduces heat conduction to wood (**Figure 9**).

The optimum mixing fineness content of the ash sample containing 3% plastic was determined as 30.5% and the maximum dry unit volume weight was 17.52 kN /m<sup>3</sup> . The dry unit weight graph of the plastic slag sample containing 50% waste plastic, the optimum mixing binder content of 25.25% and the maximum dry unit weight of 16.13 kN /m<sup>3</sup> for Şırnak asphaltite char.

Accordingly, the results revealed that the asphalt mixing values decrease with the increase of the ratio of plastic slag chars because plastic char slag is a binding material. As a result of the indentation experiments, the optimum Optimum mixing fineness content as below 5-micron content and dry unit weight reduction in fire tests as given in **Figure 10**.

**Figure 8.** *The char/ ash and phosphate salt slime with retardation to board depth.*

**Figure 9.** *The Şırnak fire-retardant mortar sand types regarding strength vs. porosity change.*

*Microwaved Flux Matter- Char Sand Production of Waste Coal Char/Biochar/Gypsium Ash… DOI: http://dx.doi.org/10.5772/intechopen.101559*

#### **4. Conclusions**

All materials undergo deformation when the load is applied. It is predicted that soils are also compact without shear deformation together with the decrease in volume under stress. However, this decreases in the volume of the soil mass, the compression of the plastergrains, the type of voids, the structure and its continuity reveal different types of behavior depending on the way and duration of removal of mixing light weight plaster and air in the cavities. In this context, the study emphasizes the importance of positively improving engineering properties such as compaction and fire inhibiting mortar mixing, char, plastic slag binder content by using different types of materials together.

Salt content over 20% with char and fly ash fire retardent sands the depth of deterioration decreased 200%.

As the amount of Şırnak asphaltite char and plastic slag in the briquette sample increases fineness weight rate with fire weight rate reduction rate, the optimum mixing binder content increases and the maximum dry unit volume weight decreases. This behavior is an expected situation by adding certain proportions of aggregate high- sand rate mixtures because of the plastic unit weight value of the used sand to low ash. The unit weight value of briquette with cinder decreased the bulk density of the mixture. The utility of briquette as lightweight concrete takes attention to the low cost of the material. In this text, the gradation of the much finer potential of fly ash is reducing density with char being critical in fire retardation for oxygen uptake as construction materials.

#### **Author details**

Yıldırım İsmail Tosun Engineering Faculty, Mining Engineering Department, Şirnak University, Şirnak, Turkey

\*Address all correspondence to<EMAIL_ADDRESS>
© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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**Chapter 12**

## Biofuel and Biorefinery Technologies

*Abdulkareem Ghassan Alsultan, Nurul Asikin-Mijan, Laith Kareem Obeas, Aminul Isalam, Nasar Mansir, Maadh Fawzi Nassar, Siti Zulaika Razali, Robiah Yunus and Yun Hin Taufiq-Yap*

#### **Abstract**

The global demand for energy is expected to rise up to 59% by the year 2035. This is due to the increasing technology developments and contemporary industrialization. Continues trends of these simultaneously will affects the crude fossil oil reserves progressively. Therefore, biofuels that are predominantly produced from the biomass based feedstocks such as plant, algae material and animal waste. Liquid or gaseous biofuels are the most simple to ship, deliver, and burn since they are easier to transport, deliver, and burn cleanly. The key contributor to the elevated green house gaseous concentration is carbon dioxide (CO2). Two-thirds of global anthropogenic CO2 emissions are due to fossil fuel combustion, with the remaining third attributed to land-use changes. Interestingly, recent literature has announced that the utilization of liquid biofuels capable of reducing the CO and CO2 emissions. Other positive impacts of the liquid biofuels are; (1) reduce the external energy dependence, (2) promote the regional engineering, (3) increase the Research & Development activities, (4) reduce the environmental effects of electricity generation and transformation, (5) improve the quality of services for rural residents and (6) provide job opportunities.

**Keywords:** catalysis, bioenergy, biofuel, hydrogen energy, green fuel

#### **1. Introduction to biofuel**

The global demand for energy is expected to rise up to 59% by the year 2035 [1–7]. This is due to the increasing technology developments and contemporary industrialization. Continues trends of these simultaneously will affects the crude fossil oil reserves progressively. Therefore, biofuels that are predominantly produced from the biomass based feedstocks such as plant, algae material and animal waste [2, 3].  The key contributor to the elevated green house gaseous concentration is carbon dioxide (CO2). Two-thirds of global anthropogenic CO2 emissions are due to fossil fuel combustion, with the remaining

third attributed to land-use changes. Interestingly, recent literature has announced that the utilization of liquid biofuels capable of reducing the CO and CO2 emissions [5, 6]. Other positive impacts of the liquid biofuels are; (1) reduce the external energy dependence, (2) promote the regional engineering, (3) increase the Research & Development activities, (4) reduce the environmental effects of electricity generation and transformation, (5) improve the quality of services for rural residents and (6) provide job opportunities [7].

#### **1.1 Type of biofuels**

The oxygen content is the most important difference between biofuels and petroleum based fuels [8]. The biofuels produced from different renewable resources are typically non-toxic, accessible and abundant. Biogas, syngas, biobuthanol, bioethanol, biodiesel, bio-ether, and green fuel are various forms of biofuels. Gaseous biofuels are commonly used for heat and energy production purposes.

Biogas, is a gas fuel that burns much like fossil fuels, and for this reason, it gradually gains its position. Biogas consists mainly of methane gas, although it is produced from the degradation of anaerobic biomass. Many agricultural businesses use biogas, and the fuel is currently being packaged for domestic use in gas cylinders. The fuel is extracted from a combination of flora and fauna since each provides a specific ingredient (animals and plants). Plants have significant carbon and hydrogen in them, while they have nitrogen in them for animals. The components above are necessary and required for the production of biofuels.

Liquid biofuels, on the other hand, are widely used in the automotive industry. Biogas, obtained by anaerobic fermentation from organic materials, has a 40–70% CH4 composition, 30–60% CO2 and other gases such as H2S, H2, N2 and CO. Biobutanol is capable of replacing both petrol and diesel. Using a bacterium to ferment biomass appears to be the most promising approach for processing biobutanol at the moment. The acetone-butanol-ethanol process is the name of the method. Acetone (propanone), butanol and ethanol are produced here. Clostridium species such as *Clostridium beijerinckii, Clostridium acetobutylicum*, *Clostridium saccharoperbutylacetonicum* and *Clostridium saccharobutylicum,* are used for the fermentation process of acetone-butanol-ethanol to produce biobased butanol [9]. Algae, sugar beet, sugar cane, maize, sorghum and cassava are the feedstocks used successfully so far. To make pure butanol, the materials are fractionally distilled. Bioethanol is a transparent liquid that is biodegradable, non-toxic, and environmentally safe. It's chemically known as ethyl alcohol, and it's made from the plant's fermentable sugars (such as glucose, sucrose, and other sugars) through microorganisms. It is possible to mix bioethanol with gasoline as well. Fermentation of bioethanol is a biological process in which microorganisms convert sugars to produce bioethanol and CO2. Yeasts are the most widely used microorganism in the fermentation process and Saccharomyces cerevisiae is the preferred option for bioethanol fermentation among yeasts [10]. For example, fermentation bacteria used are *Clostridium acetobutylicum, Lactobacillus fermentum* etc. The basic schematic fermentation process is as follow (**Figure 1a**).

Green fuels (green-diesel and green-gasoline) are an oxygen-free hydrocarbon comprised of short chain and long chain carbon fractions within a range of C8–C12 and C13–C20, respectively. The green fuels also free from sulfur and aromatic compounds. They contain *n*-alkanes and *n*-alkenes, which similar to those found in the petroleum-based gasoline and diesel. As the green fuel is entirely compatible as the petroleum-derived fuels, their fuel properties are vastly similar to each other.

*Biofuel and Biorefinery Technologies DOI: http://dx.doi.org/10.5772/intechopen.104984*

**Figure 1.**

*(a) Fermentation process, (b) Transesterifcation reaction of triacylglycerol using methanol and (c) Transesterification of triacylglycerol using ethanol.*

However, green fuel is completely different in chemical structure as compared to the well-established commercialized biodiesel [11–13]. To produce green diesel, biological oil feedstocks such as algae, vegetable or plant oils, and animal fats are thermally catalytically hydrocracked. Hydrocracking is a refinery process that uses elevated temperatures and pressure to break down these larger molecules (natural oils) into a shorter mixture of hydrocarbon chains in the presence of strong chemical heterogeneous catalysts. Green diesel also known as renewable diesel [14]. One of the most well-established liquid biofuels is biodiesel or fatty acid methyl ester (FAME), not only because of its lower environmental effect, but also because it provides the benefits of being renewable, biodegradable and non-toxic. By transesterification reaction with alcohol, biodiesel will be fabricated from either vegetable oils or animal fats using required catalyst [15]. It can be used as a diesel engine fuel in its pure form (B100) or in mixtures (B10, B15), but it is typically used as a diesel additive to reduce the levels of diesel-powered particulates, CO and hydrocarbons. The following is a diagram of the transesterification process (**Figure 1b**). Biodiesel fuel used in car and lorry engines typically comprised of higher boiling FAME fraction and its alkanes contain 14–22 carbon atoms [16]. Biodiesel also can be a mixture between their FAME and fatty acid ethyl ester (FAEE) and FAEE is prepared as following reaction (**Figure 1c**).

**Table 1** depicts the most recent global developments on modern transportation fuels in 2019, published by NS Energy [17]. There are three liquid biofuels – bioethanol, biogasoline and biodiesel account for the vast majority of global biofuel production and use today. The United States is on the first world rank of biofuel

#### **Table 1.**

*Top countries for biofuel production across the globe in 2019 [17].*

manufacturer followed by Brazil. In Europe, Germany is the largest producer. Argentina produced almost similar production amount with the Germany. As been expected, China is the leading country for biofuel production in Asia. The majority of biofuels were produced from soybean, sugarcane, rapeseed, corn and waste cooking oil (WCO). In the case of China, bioethanol and ethanol-blended gasoline are primary products. In the United States and Brazil, soybean oil is widely used. Many European countries, primarily Germany, use rapeseed oil for biofuel production. Note that Germany also utilized the WCO as a biofuel feedstock. It should be noted that the WCO derived biofuels initiative is also used in many nations, including Australia, China, Italy, Portugal, the United Kingdom, the United States, Austria and Spain. Brazil also produced WCO-based biodiesel, but it only accounted for 0.5% of total biodiesel production. In Brazil, only 2.5% of the WCO produced in Brazil is estimated to be reused for biofuel production, while the rest is improperly discarded [18]. Sugarcane is widely used in Brazil and Argentina. Brazil is the global leader in producing bioethanol from sugarcane.

Overall, all liquid biofuels are made mainly from agricultural commodities, such as grain and sugar (bioethanol) and vegetable oil, based on the above results (biodiesel, bio-gasoline). It can be observed that each nation concentrated on distinct feedstock. Lowest oil price, high oil content, required fatty acid composition (saturated or unsaturated acid), low cultivation maintenance and expense, controllable growth and harvesting season, consistent seed maturity rates, and potential demand for agricultural by-products are all desirable characteristics when choosing the best biofuel feedstock [19].

#### **1.2 Biofuel uses**