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A combined plasma photolysis (CPP) reactor that utilizes a dielectric barrier discharge (DBD) plasma and 207nm UV radiation from discharge-driven KrBr∗ excimers was designed and constructed. Gas streams containing CS2 were treated with stand-alone DBD and CPP at atmospheric pressure. In comparison to DBD, CPP greatly enhanced the removal efficiency at the same applied voltage, waste gas concentration and gas residence time. Thus the applied voltage could be reduced to a certain extent in the plasma processing of industrial wastes. Influences of the KrBr∗ radiation, inlet CS2 concentration and gas residence time on CS2 removal by CPP were also studied. In addition, the likely reaction mechanisms for the removal of CS2 by CPP are suggested based on the byproducts analysis. The enhanced removal efficiency and reaction mechanisms implied that the CPP process would probably be suitable for the removal of a large number of gaseous pollutants. [Copyright &y& Elsevier]

Abstract: The photolysis of simulating low concentration of hydrogen sulfide malodorous gas was studied under UV irradiation emitted by self-made microwave discharge electrodeless lamps (i.e. microwave UV electrodeless mercury lamp (185/253.7nm) and iodine lamp (178.3/180.1/183/184.4/187.6/206.2nm)). Experiments results showed that the removal efficiency () of hydrogen sulfide was decreased with increasing initial H2S concentration and increased slightly with gas residence time; H2S removal efficiency was decreased dramatically with enlarged pipe diameter. Under the experimental conditions with pipe diameter of 36mm, gas flow rate of 0.42standardls−1, was 52% with initial H2S concentration of 19.5mgm−3 by microwave mercury lamp, the absolute removal amount (ARA) was 4.30μgs−1, and energy yield (EY) was 77.3mgkWh−1; was 56% with initial H2S concentration of 18.9mgm−3 by microwave iodine lamp, the ARA was 4.48μgs−1, and the EY was 80.5mg kWh−1. The main photolysis product was confirmed to be with IC. [Copyright &y& Elsevier]

The 355nm photon-initiated microscopic reaction mechanisms of the mixed aqueous solution of nitrobenzene and nitrous acid in the presence or absence of O2 were studied by the laser flash photolysis technique. The main transient absorption peaks in the recorded spectra were assigned and the growth/decay trends of several transient species were investigated. It was found that the OH radical formed from the photolysis of nitrous acid triggered most of the subsequent radical reactions. The rate constant of the reaction between OH radical and nitrobenzene was measured to be (3. 4±0. 1)×109 lmol−1 s−1. The product from this reaction, namely C6H5NO2–OH adduct, was found to react with O2 to yield C6H5NO2–OHO2 adduct with a rate constant of (1. 6±0. 2)×109 lmol−1 s−1. Final steady-state products were identified by GC/MS analysis and were in accordance with the transient spectroscopic results. The possible reaction pathways were proposed. [Copyright &y& Elsevier]