Degradation Pathway and Kinetics of 4-chlorphenol by Sn/Sb-Mn-GAC Composite Particle Electrode

A composite particle electrode Sn/Sb-Mn-GAC was prepared by impregnation with granular activated carbon (GAC) as carrier. The surface morphology, phase composition and electrochemical properties of the particle electrode were characterized by scanning electron microscopy, X-ray diffraction and electrochemical workstation. The results show that the Sn/Sb-Mn-GAC particles have uniform grain size, good dispersity and high oxygen evolution potential. The Sn/Sb-Mn-GAC particle electrode was used to the electrochemical degradation of 4-chlorophenol. It was shown that 4-chlorophenol was almost completely removed after electrolyzing for 60 min. A large number of intermediates were produced during the degradation of 4-chlorophenol in the experimental system. The main intermediate products were benzoquinone, 4-chlorocatechol, hydroquinone, fumaric acid, oxalic acid, etc., eventually mineralized into water and carbon dioxide. The degradation pathway of 4-chlorophenol were preliminarily suggested through the analysis of intermediates in degradation process. The supported Sn/Sb-Mn-GAC particle electrode can be repeated used 4 times in three-dimensional electrochemical reactor and the kinetic model for the electrochemical oxidation of 4-chlorophenol was established. The experimental results show that the degradation process of 4-chlorophenol accords with the first-order kinetic model, the correlation coefficient is 0.98 or more. The kinetic rate constant k of Sn/Sb-Mn-GAC particle electrode is reduced when it is repeated used, but the treatment efficiency of 4-chlorophenol is still better. The results of research show that the three-dimensional electrochemical reactor using Sn/Sb-Mn-GAC particle electrode has promising application prospects in the treatment of phenolic wastewater.