Use of a novel coupled-oxidation tubular reactor (COTR)/NTP-DBD catalytic plasma in a synergistic electro-catalysis system for odorous mercaptans degradation

In this work, a novel coupled-oxidation tubular reactor (COTR)/non-thermal dielectric barrier discharge (NTP-DBD) catalytic plasma in a synergistic electro-catalysis system was investigated for odorous mercaptans decomposition. In order to enhance the degradation efficiency of electro-oxidation, a novel enhanced Ti/PbO2 electro-catalytic tubular reactor prepared by using flow dynamic electrodeposition was designed and applied as pretreatment process for CH3SNa wastewater. The results indicated that the optimal condition was 7 mA cm(-2) of current density, 10 g L-1 of initial concentration of CH3SNa, 9.0 of pH and 5.0 g L-1 of electrolyte concentration. Addition of Fe2+ and H2O2 and mechanism of COTR system were first put forward. The target species CH3SNa were removed over 90% by this process. In order to treat the CH3SH effusion which was co-produced with CH3SNa aqueous solution, the technology of NTP-DBD catalytic plasma reactor followed by a chemical absorption has been developed. MSH could be removed over 95% under the condition of 2 s of residence time, 15 kV of output voltage with oxygen concentration of 9%. Moreover, the synthetic Ni-doped AC catalyst had the best performance under 0.7 mmol g(-1) of nickel loading. The conclusion was the energetic electrons generated in the DBD reactor played a key role on the removal of MSH, and the major decomposition products of MSH were detected as CH3SSCH3, SO2 and NO2. Moreover, the gaseous products in the plasma exhaust could be absorbed and fixed by the subsequent aqueous NaOH solution. (C) 2018 Elsevier Ltd. All rights reserved.