**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.
