科研之友
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摘要
Low grade coals with high sulphur contents are not suitable as fuels in thermal power plants due to generation of high ash content and emission of toxic sulphur oxide gases. Here we have demonstrated an alternate use of pyrite rich coal as a source for sustainable generation of hydrogen peroxide and hydroxyl radicals in aqueous medium via solar light induced photo-Fenton process which were utilized for degradation of toxic azo-dyes. The textural, compositional and morphological features of pristine pyritic coals with varying sulphur concentrations are studied by an array of characterization techniques. The dye degradation capacities of pyrite rich coal are studied using model dye solutions e.g., Basic Blue 41 containing single azo group per unit and Trypan Blue containing two azo groups per unit. The rate of degradation (k) is faster for Basic Blue-41 (0.0192 min(-1), similar to 99% degradation) at optimized solar radiation exposure time, pH 6 and dose of 1 g/L pyritic coal. The dye degradation is presented as a measure of solar radiation accumulation energy per unit volume, and it is attributed to in-situ generation of hydrogen peroxide and hydroxyl radicals, and re-confirmed from scavenging studies. The dye degradation mechanism by pyritic coal is discussed in the light of solar photo-Fenton mechanism with respect to (1) qualitative identification of trace quantities of degradation products by gas chromatography-mass spectrometry technique; (2) leaching of 2700 mg/L iron in the reaction medium, estimated by inductive coupled plasma optical emission spectrometry, and (3) and changes in the chemical speciation of iron, sulphur and oxygen in the used coal by X-ray photoelectron spectroscopy.
- 出版日期2018-9-10
