Influence of Na2so4 Concentration on Electron Transfer Characteristics During Phenol Electrochemical Oxidation

Abstract

Electrocatalytic oxidation technology is a promising method for treating salt-containing organic wastewater by electron transfer process. To enhance the degradation of organic matter, it is of great importance to study the impact of different salt contents on electron transfer characteristics. In this study, electrochemical tests including linear sweep voltammetry(LSV),cyclic voltammetry (CV) and electrochemical impedance spectroscopy(EIS) tests were carried out to investigate the electron transfer process with Na2SO4 as the electrolyte and phenol as the characteristic pollutant at different Na2SO4 concentrations. By analysing the dynamic diffusion process of substances, a new method for calculating the electron transfer number (N) is proposed, which improves the accuracy of the electron transfer value. In addition, with an increase in Na2SO4 concentration from 0.8% to 6%, the diffusion coefficient exhibited a decreasing trend followed by an increase, reaching a minimum at 3%. Water treatment experiments with two electrodes (Pt/Ti and IrO2-Ta2O5/Ti) were performed, and the results validated the N-values for determining the necessary electrons for oxidation while presenting a means to assess anode materials. Furthermore, quenching experiments and Density Functional Theory (DFT) calculation disclosed the mechanism of electron distribution under salinity influence: under low or high salt concentrations, electrons tended to produce free ·OH radicals with OH- rather than binding directly to organic matter.

Keywords: Electron transfer characteristics, Degree of oxidation, Salt concentration, Diffusion coefficient, electrocatalytic oxidation