Lignites, coals and carbonaceous

Carbonaceous exchangers Ion-exchange materials of limited capacity pre- pared by the sulfonation of coal, lignite, peat, and so on. 

Activated carbon is manufactured from carbonaceous materials, such as petroleum coke, sawdust, lignite, coal, peat, wood, charcoal, nutshells, and fruit pits. Activation is a physical change wherein the surface of the carbon is increased by the removal of hydrocarbons by any one of several methods. The most widely used methods involve treatment of the carbonaceous material with oxidizing gases such as air, steam, or carbon dioxide, and the carbonization of the raw material in the presence of chemical agents such as zinc chloride or phosphoric acid. 

PHYSICAL PROPERTIES dark-brown to black solid dispersed in air physical properties vary depending upon the specific coal type lignite is distinguished as a soft brown coal bituminous coals can be classified according to their degree of carbonification into flame coal, flame-gas coal, gas coal, fat coal, steam coal, lean coal and anthracite the carbonaceous content rises from 50 to 91.5%, the oxygen content falls from 44 to less than 2.5%, and the moisture content from 6 to less than 3.8% in the sequence wood, peat, brown coal, bituminous coal, anthracite soft brown coal contains 30-65% moisture, bituminous coals may contain up to 7% moisture and up to 30% ash spectroscopy and chemical analyses show that bituminous coal is predominantly of aromatic character material is insoluble in water. 

PHYSICAL PROPERTIES dark-brown to black solid dispersed in air physical properties vary depending upon the specific coal type lignite is distinguished as a soft brown coal bituminous coals can be classified according to their degree of carbonification into flame coal, flame-gas coal, gas coal, fat coal, steam coal, lean coal and anthracite the carbonaceous content... 

Where terrestrial vegetable matter accumulates, peat is formed which, after burial, is transformed in various steps into lignite, bituminous coal and, eventually, anthracite. The coalification process is initiated by anaerobic bacteria and continues under the action of temperature and pressure over a period of millions of years. Upon maturation, the volatile gaseous and liquid hydrocarbons are progressively lost, leaving only solid carbonaceous compounds. Consequently, coals are solid compounds with a relatively high carbon and low hydrogen content. 

G. The principle criteria for selection of the Carbonaceous raw material to activate is often cost, or its counterpart - availability. Sources include flax shive (the stems of flax fiber), cotton gin waste, nutshells, peat, pine wood, coir (fiber from the husk of coconut, produced in Sri Lanka and India), the coconut shell itself (from the Philippines), lignite, coal, petroleum pitch, peach or olive pits, eucalyptus, rice husk, apricot stones, grape seeds. 

To achieve a significant adsorptive capacity an adsorbent must have a high specific area, which implies a highly porous structure with very small micropores. Such microporous solids can be produced in several different ways. Adsorbents such as silica gel and activated alumina are made by precipitation of colloidal particles, followed by dehydration. Carbon adsorbents are prepared by controlled burn-out of carbonaceous materials such as coal, lignite, and coconut shells. The crystalline adsorbents (zeolite and zeolite analogues are different in that the dimensions of the micropores are determined by the crystal structure and there is therefore virtually no distribution of micropore size. Although structurally very different from the crystalline adsorbents, carbon molecular sieves also have a very narrow distribution of pore size. The adsorptive properties depend on the pore size and the pore size distribution as well as on the nature of the solid surface. 

Bituminous coal baked in an oven yields a solid carbonaceous material called coke, which is used as a reducing agent in the smelting of iron. Jet is a term applied to high-quality specimens of lignite that have been used to make decorative objects and jewelry. Jet and peat, which is compressed, partially decayed plant matter, will be discussed in Chapter 4 Plants. Cannel coal is another term for hard, compact lignite. This name has been applied to material from Whitby, where most commercial jet comes from, and from Scotland. Objects made of this material date back at least to the Bronze age in Britain (2100-1700 BC). 

Threonine and allothreonine are thermally unstable amino acids. The same is true for the simplest hydroxy amino add, (S)-serine (39). High levels of this amino add have however been reported from certain petroleum brine waters and its preservation may be due to the formation of stable chelates. Ahrens has suggested that metal-amino acid chelates may be important in the sedimentary cycle, and the uptake of certain metals in sediments, particularly in binding of metal-amino acid chelates to clays, has been proposed as a possible mechanism for the incorporation of metal ions in carbonaceous materials. Similar complexes are thought to contribute to the stabilization of amino acids in coals, lignites and peats, but, as has been outlined in a previous section, many other ligands are also present in these media, and their relative importance is difScult to assess. Much of this work is unfortunately of a speculative nature since no well-characterized complex of an amino acid has been isolated from a geological source, as far as the author is aware. 

The first coal briquetting trials were carried out in the 1840s. In Belgium, France, and the UK bituminous coal fines were briquetted with sticky binders while in the USA and Germany peat, lignite, and other carbonaceous fines were dried and shaped... 

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