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In this paper, the intermediate and final reaction products of catalytic oxidation of inorganic sulfides in the presence of oxygen dissolved in the kerosene fraction and 3,3′,5,5′-tetra-tert-butyl-4,4′-stilbenequinone were investigated. The thiosulfate and sulfate are major products of the oxidation of sodium sulfide under these conditions. The intermediate and final products in the catalytic oxidation of sulfide sulfur do not affect the rate of its oxidation. The yield of catalytic oxidation products depends on the nature of the sulfide and on the pH of the solution. The catalytic cycle for sulfide oxidation in the presence of 3,3′,5,5′-tetra-tert-butyl-4,4′-stilbenequinone is shown. The role of 3,3′,5,5′-tetra-tert-butyl-4,4′-stilbenequinone is to create a new and a more effective way of electron transfer from the reducing agent (sulfide) to the oxidant (oxygen). [ABSTRACT FROM AUTHOR]

In this study, the kinetic degradation of several typical organic pollutants was performed on a synthetic electrode (Ti/SnO 2 -Sb/Co-βPbO 2 ). The surface structure and the electrochemical properties of the prepared electrode were investigated, confirming the successful preparation of the electrode using an electrochemical deposition method. The outer layer (Co-βPbO 2 ) played an important role in reducing the resistance of the electrode and improving its degradation efficiency. The results showed that indigo carmine (IC), p-nitrosodimethylaniline (RNO), and clothianidin (CLO) were effectively degraded within 20 min of electrolysis. Their degradation in the electrochemical process followed the first-order kinetic model with the degradation rate constant of IC being higher than that of RNO and CLO. This was proved by the difference in the reactivity of the target pollutants toward oxidizing radicals (i.e., •OH, SO 4 •- , and Cl•). Their second-order rate constant towards radicals were in the range of 10 9 - 10 10  M -1  s -1 with the highest value being that for IC: k ·OH,IC  = 15.1 × 10 9  M -1  s -1 and [Formula: see text]  = 7.4 × 10 9  M -1  s -1 . The study calculated the contribution of some oxidizing species, including direct electron transfer (DET), •OH, SO 4 •- , and other reactive oxygen species (ROS). Solution pH, supporting electrolyte, and water matrix affected the degradation efficiency of pollutants and the contribution of the oxidizing species. Br - and I - ions enhanced the degradation rate of organic pollutants, while Fe 2+ , HCO 3 - , and humic acid (HA) reduced it. In addition, the toxicity, total organic carbon (TOC) removal, mineralization current efficiency (MCE), energy consumption, recyclability and stability of the prepared electrode were studied, suggesting that the prepared Ti/SnO 2 -Sb/Co-βPbO 2 is a good candidate for treating organic pollutants using the electrochemical oxidation process., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)