RESUMEN
In this study, the kinetic degradation of several typical organic pollutants was performed on a synthetic electrode (Ti/SnO2-Sb/Co-ßPbO2). 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-ßPbO2) 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., â¢OH, SO4â¢-, and Clâ¢). Their second-order rate constant towards radicals were in the range of 109 - 1010 M-1 s-1 with the highest value being that for IC: k·OH,IC = 15.1 × 109 M-1 s-1 and [Formula: see text] = 7.4 × 109 M-1 s-1. The study calculated the contribution of some oxidizing species, including direct electron transfer (DET), â¢OH, SO4â¢-, 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 Fe2+, HCO3-, 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/SnO2-Sb/Co-ßPbO2 is a good candidate for treating organic pollutants using the electrochemical oxidation process.
Asunto(s)
Contaminantes Químicos del Agua , Agua , Carmin de Índigo , Titanio/química , Electrodos , Contaminantes Químicos del Agua/química , Oxidación-ReducciónRESUMEN
Oxidation reactions by radicals constitute a very important class of chemical reactions in solution. Radiation Chemistry methods allow producing, in a controlled way, very reactive oxidizing radicals, such as OHâ¢, CO3â¢-, NO3â¢, SO4â¢-, and N3â¢. Although the radical cation of water, H2Oâ¢+, with a very short lifetime (shorter than 1 ps) is the precursor of these radicals in aqueous solutions, its chemistry is usually known to be limited to the reaction of proton transfer by forming OH⢠radical. Herein, we stress situations where H2Oâ¢+ undergoes electron transfer reaction in competition with proton transfer.