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Fuel Processing Technology, Vol.53, No.1-2, 1-14, 1997
gamma-irradiation of coal and lignite: effect on extractability
The effect of gamma-irradiation on the extractability of lignite and coal has been investigated. The solubility of Kutch lignite and sub-bituminous Samla coal irradiated in aerial, aqueous, and CCl4 media at varying gamma-doses (50, 100, and 150 Mrad) in different solvents, i.e., benzene, ethanol, azeotropic 1:1 ethanol-benzene mixture, and pyridine was determined. The radiation dose of up to 100 Mrad was found to be most effective in increasing the solubility, after which it either decreased or levelled off. Maximum solubility upon CCl4 irradiation was observed in all solvents in comparison to aerial and aqueous irradiation. The increase or decrease in solubility has been attributed to either degradation or cross-linking of polyaromatic groups - or possibly an interplay of both, in the macromolecular structure of coal and lignite during gamma-irradiation, wherein the former, i.e. degradation, gives rise to weakening or breakdown of cohesive secondary forces rather than primary linkages, whilst the constancy or decrease in solubility might be due to polymerisation or cross-linking. The increase in solubility as a consequence of CCl4 irradiation is ascribable to radiation chlorination of coal and lignite during the radiolysis of CCl4.
Keywords:DESULFURIZATION