**Author details**

S. A. Akinyemi, A. Akinlua

*Fossil Fuel and Environmental Geochemistry Group, Department of Earth Sciences; University of the Western Cape, Bellville, South Africa*

#### L. F. Petrik

64 Analytical Chemistry

Sample %

Moisture

Note: OM % = C %\*1.7.

2008; Nasirudeen and Jauro, 2011).

**4. Conclusions and summary**

ash samples used in this study.

hematite, calcite, lime, anorthite, mica and enstatite.

**Table 5.** Proximate and ultimate analyses of South African coal sample *(n = 3)*

% Ash (dry basis)

particles (i.e. pyrite) encrusted with Al, Si-rich particles (i.e. kaolinite).

The organic matter content calculated (OM %) was calculated from the carbon content by multiplying with a value of 1.7 (Table 3). The derived organic matter content of the coal sample used in the present study is comparatively higher than Lafia-Obi coal (Jauro et al.,

Sample N % C % H % C/N H/C OM % SAC 1.16 45.75 3.50 39.55 0.08 77.78

**Ultimate analysis of coal sample**

% Ash (wet basis)

**Proximate analysis of coal sample**

SAC 0.8 94.43 93.67 5.6 6.3

Volatile matter (dry)

Volatile matter (wet)

The XRD spectra showed that the coal sample mainly composed of siliceous mineral (such as quartz and kaolinite) and the non-siliceous mineral (such as potassium selenium chloride) and little quantities of pyrite. The results of the XRD analysis of samples of the drilled weathered dry disposed fly ash aged 2 week, 1 year and 20-year-old showed quartz and mullite as main crystalline mineral phases. Other minor mineral phases identified are;

The IR spectrum revealed the presence of quartz, kaolinite, potassium selenium chloride and pyrite in coal sample. SEM image of coal ash reveals spherical shaped and aggregate that contains varying sizes and quantity of particles. Conversely, the coal sample consists of irregular shaped pyrite crystal coated with kaolinite. TEM images of coal ash sample show nearly spherical shaped haematite structure and cluster texture agglomeration of ultrafine particles. Conversely, the TEM images of coal sample show irregular shaped Fe-rich

The main trend in the major oxides indicates that the coal used in the present study is a higher-ash coals which is enriched in elements associated with probable detrital minerals. The 1-year-old ash core samples were both sialic and ferrocalsialic in chemical composition (i.e. essentially Fe, Ca, Al and Si). Although, the 2 week and 20-year-old dry disposed ash core samples were sialic in chemical composition (i.e. essentially dominated by Al and Si).

Major elements such as Fe, Ca, Mg, Mn and Ti were as expected in coal samples but significantly enriched in the coal ash. Although, P, Na and K are slightly enriched in the coal

Trace elements such as U, Cr, Th, V, Ni, Cu, Zn, Rb, Sr, Mo and Sn are slightly enriched in the coal ash. This slight enrichment of these trace elements in the coal ash is attributed to the combustion process. Nevertheless, trace elements (such as Hf, Ta, Pb, Cr, Zr and Nb) *Environmental and Nano Sciences Group, Department of Chemistry; University of the Western Cape, Bellville, South Africa*

#### W. M. Gitari

*Environmental Remediation and Water Pollution Chemistry Group, Department of Ecology and Resources Management, School of Environmental Studies, University of Venda. X5050, Thohoyandou, South Africa*

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**Chapter 3**

© 2012 Radić and Kukoc-Modun, licensee InTech. This is an open access chapter 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

distribution, and reproduction in any medium, provided the original work is properly cited.

© 2012 Radić and Kukoc-Modun, licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

**Kinetic Methods of Analysis with Potentiometric**

The basic types of reactions used for determinative purpose encompass the traditional four in equilibrium-based measurements: precipitation (ion exchange), acid-base (proton exchange), redox (electron exchange) and complexation (ligand exchange). These four basic types, or cases that can be reduced to them, are also found in kinetic-based measurements with some distinguishable trends. The influence of concentration on the position of a chemical equilibrium is described in quantitative terms by means of an equilibrium-constant expression. Such expressions are important because they permit the chemist to predict the direction and completeness of a chemical reaction. However, the size of one equilibrium constant tells us nothing about the rate (the kinetic) of the reaction. A large equilibrium constant does not imply that a reaction is fast. In fact, we sometimes encounter reactions that have highly favorable equilibrium constants but are of slight analytical use because their rates are low. Commonly used kinetic methods based on chemistry of reaction employed

Kinetic methods of analysis are based on the fact that for most reactions the rate of the reaction and the analytical signal increase with an increase of the analyte concentration. In kinetic methods, measurement of the analytical signal is made under dynamic conditions in which the concentrations of reactants and products are changing as a function of time.

Generally, in analytical chemistry many methods of analysis are based on the equilibrium state of the selected reaction. In contrast to kinetic methods, equilibrium or thermodynamic methods are performed on systems that have come to equilibrium or steady state, so that the analytical signal should be stable during measurements. Kinetic and equilibrium parts of the

**and Spectrophotometric Detectors –**

**Our Laboratory Experiences**

Njegomir Radić and Lea Kukoc-Modun

http://dx.doi.org/10.5772/52185

**1. Introduction**

have been selected [1, 2].

Additional information is available at the end of the chapter

properly cited.

selected chemical reaction are illustrated in the figure 1.


**1.  MSF IDPs can adopt a stable structure during the interaction, without a pre-existing folded partner [1–4]. At the time of the mutual synergistic folding process, the participating IDPs of these complexes synergistically fold into a stable, globular complex. Demarest et al. (2002) investigated the first MSF interaction between the p160 transcriptional coactivator protein ACTR and the tumor suppressor CBP proteins. They found that this MSF complex contains many hydrophobic side-chains and highly specific intermolecular hydrogen bonds, as well as buried intermolecular salt bridges, which help to fold the complex [5]. Since IDPs often have a high net charge, and they have a small content of hydrophobic residues, they are usually not able to form a hydrophobic core [6]. However, MSF complexes contain more hydrophobic residues, presenting an exception to a general view of IDPs [7,8].

While IDPs mostly have low sequence complexity, MSF complexes are rather heterogeneous, like globular proteins. Furthermore, MSF proteinsare also heterogeneous in amino acid composition similar to globular proteins [8]. The residue-based disorder prediction methods, developed for identifying segments bound to folded proteins, cannot be used for detecting of MSF complexes. Systematic analyses are required to understand and predict these MSF interactions. Nevertheless, this is difficult to implement since a severe weakness of the literature is the little information available about these complexes. At present, the most comprehensive and systematic catalog of MSF complexes is the MFIB (Mutual Folding Induced by Binding) database containing 205 entries [9].

A protein in aqueous solution is only stable when it contains a hydrophobic core buried from water by polar residues. Furthermore, these polar residues shield most of the hydrophobic residues from the solvent. For the first criterion, the protein should contain more residues than a required minimum either as a monomer or as an oligomer. The fulfillment of the second criterion depends on the ratio of the polar and hydrophobic residues because the ratio of the surface and buried residues rapidly decreases by increasing the total number of residues. For a given hydrophilic/hydrophobic ratio, either a long polypeptide chain or oligomerization is needed. MSF proteins fulfill both criteria by oligomerization.

Recently, the physical background of homodimeric MSF complexes from MFIB [7] was analyzed. We identified the residues with solvent accessible main-chain patches (RSAMPs) and studied the "under-wrapped" hydrogen bonds (dehydrons), which are not shielded well enough from solvent [10]. Our results suggested that homodimeric MSF complexes contain more RSAMPs and dehydrons than homodimeric complexes where all the interacting chains are globular in their monomeric form. These properties should contribute to their disordered nature in monomeric form and to their folding in the oligomeric state. In this study, the role of this phenomenon for heterodimeric MSF complexes will be discussed. In the case of heterodimers, the interacting polypeptide chains have different amino acid compositions, which discriminates heterodimers from homodimers. The MFIB database contains, unfortunately, a much lower number of heterodimeric structures when compared to homodimeric ones. Furthermore, there are highly similar proteins among them, which makes redundancy filtering necessary.


**4. Results**

resistance in comparison with other existing commercial supports. They also combine dual hydrophilic/hydrophobic, inorganic/organic surface properties; this is the main property

The process of preparation of the composite supports is described in **Figure 2**. It comprises

**4.** Polymerization of the organic phase by means of the thermal activation of the polymeri-

In the preparation of the composite precursors the following polymeric phase precursors were used: bisphenol A glycerolate dimethacrylate (BGMA), triethylene glycol dimethacrylate (TEGDMA), and diurethane dimethacrylate (UDMA). The thermally activated polymerization starter used was benzoyl peroxide (BPO). **Figure 3** shows the chemical structure of the monomers and the polymerization starter used during the preparation of the UTAl and

Two different composites, that is, UTAl and BTAl used in this work were made by mixing γalumina powder, two monomers, and BPO. The main difference between composites supports was the type of monomers used; UDMA and TEGMA were used for composite called UTAl, and BGMA and triethylene glycol dimethacrylate(TEGMA) were used for composite called

UTAl and BTAl were prepared as describe by Badano et al. [31], monomers joined BPO were intimately mixed with 45 wt% γ-alumina. Then, mixture was desgassed and extruded into a cylinder of 2 mm diameter. Polymerization of the paste was carried on a stove at 393 K for 1

Gamma alumina (CK-300, Ketjen), activated carbon (NORIT RX3 Extra and CNR), and composite support, BTAl and UTAl were used as supports to prepared metal catalyst. Platinum was loaded with PtCl2 and H2PtCl6H2O by incipient wetness technique. After impregnation, catalysts were dried at 393 K in an oven for 24 h and were maintained in desiccator for further

**1.** Weighing of monomers, polimerization starters, and inorganic material.

**2.** Mixing of the monomers, polimerization starters, and inorganic material.

**5.** Making the support ready for use in the preparation of the metal catalyst.

BTAl. The alumina used was γ-alumina with a particle size of 0.074 mm.

h. The final composite were pellets of 2 mm diameter and 2–3 mm long.

use. The catalysts were reduced in a H2 flow at 503 K for 1 h after catalytic test.

**3.** Shaping of the support by means of extrusion, pelletizing, etc.

behind the preparation of egg-shell catalysts.

186 New Advances in Hydrogenation Processes - Fundamentals and Applications

the following steps:

zation starter.

BTAl supports.

**2.2. Catalysts preparation**

#### **4.1. Catalysts characterization**

Values of the axial and radial mechanical resistance of the pellets were obtained in an universal rehearsals equipment. A compression rate of 1 mm min–1 was used. The attrition resistance was assessed by means of the method depicted in the ASTM D 4058 norm.

The specific surface area (SBET) values were obtained from nitrogen physical adsorptiondesorption isotherms at 77 K. In order to get a surface free of water and adsorbed compounds, the samples were degassed overnight at 523 K in vacuum (<10–4 Pa) before adsorption.

The palladium and platinum content of the catalysts was obtained by digesting the sample and then analyzing the liquors in ICP equipment. Hydrogen chemisorption measurements were performed in a pulse apparatus at atmospheric pressure. Before the test the samples were reduced in a gas mixture containing 5% v/v H2/Ar for 1 h and degassed in an Ar flow at the same temperature of reduction for 3 h. After that, the samples were cooled in an argon flow, and the chemisorption test was done by injecting hydrogen pulses to the flowing stream until the samples became saturated.

X-ray photoelectron spectroscopy (XPS) was done over the reduced catalysts with a VG-MicrotechMultilab equipment.

Samples were analyzed using scanning electron microscopy (SEM) equipped with an energy dispersion system (EDAX) that enablesto analyze elementary chemical with an X-ray microbeam. This technique is known as electron probe microanalyzer (EPMA) and it was allowed to elucidate metal distribution and create elemental mappings. Before measure, catalyst pellets were coated with thin carbon film in order to avoid influence of charge effect during the SEM operation. The scanning speed was 0.02 mm min–1 and the acceleration voltage of electron beam was 20kV.

The thickness of the metal surface shell was also determined optically with the aid of micrographs of the cross section of the catalysts. Micrographs were obtained with a microscope equipped with a color video printer. To analyze the samples, this technique required to be encapsulated with a thermoplastic resin and then polished with sandpaper. Sanding encapsulated samples were done with finer paper (down 500 grit) until exposing the cross section of catalyst particles. The finest paper used was 2500 grit.

The XRD measurements were performed in a diffractometer with CuKα radiation filtered with Ni. Spectra were scanned at a rate of 0.25 min–1 in range between 25 and 80°. Catalyst required different preparation before analyzing. For alumina and carbon samples, material was grinded and reduced in hydrogen flow. In the case of composites, a slab of 1 cm2 of area was impregnated with Pt or Pd, then was grinded and reduced as previous samples thermo gravimetric analysis (TGA) traces were also obtained. These traces show the dependence of the thermal weight loss of a sample as a function of the temperature. In the experiments catalyst samples (about 10 mg) were heated in an air flow of 40 mL min–1 from room temperature up to 1173 K at a heating rate of 5 K min–1.

To measure the acidity of the supports, the reaction of dehydration of 1,4-butanediol to tetrahydrofurane (THF) was followed.