Photocatalytic decomposition of hexachlorobenzene on nano-titanium dioxide films—Experimental study and mechanistic considerations

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The photocatalytic decomposition of hexachlorobenzene (HCBz) was studied in a laboratory-scale reactor on nano-titanium dioxide (TiO2) catalyst films in this study, and the effects of initial amount of HCBz dripped on the catalyst, UV light intensity, reaction time, and atmosphere (air and nitrogen) on photocatalytic decomposition efficiency (PDE) were investigated. Both increasing UV-light intensity and decreasing initial amount of HCBz remarkably promote PDE. The catalyst film thickness is theoretically calculated to be 76.9 μm. Moreover, PDE is obviously higher in the air as carrier gas than in the nitrogen. Experimental data is confronted with tentative mechanism explanations to show the reaction mechanism: dechlorination and ring cleavage are the main pathways under aerobic and anaerobic conditions, respectively. Kinetic analysis is carried out to evaluate the effects of various parameters on reaction rates and find out that PDEs vary with reaction time according to first order kinetics. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 458–464, 2013