Research On Treating Phenol Wastewater With Synergy Of Combining Electrochemical Oxidation And Catalytic Wet Oxidation

Catalytic Wet Oxidation (CWO) is one of the most promising technologies for the effective treatment of industrial wastewater with high-concentration and biorefractory organic pollutants. However, the severe reaction conditions of high operating temperature and pressure needed in CWO prevent it from a broad industrial application. So we attempt to combine the electrochemical oxidation and catalytic wet oxidation, and aim to investigate the feasibility of the synergy.As one part of Chinese National Natural Science Foundation programe: "Mechanism study on synergy of combining electro-catalysis and catalytic wet air oxidation in the degradation of phenol (No.50378066)" and Development Foundation of Shanghai Education - Shuguang Plan (No. 03SG17), the main purpose of this research is to selection one particle electrode which had been designed by a former research about electro-catalysis reaction also performing suitably as catalyst in the wet air oxidation, then try to find the synergic effect of combining electro-catalysis and catalytic wet air oxidation to remove of the aqueous phenol, and further investigate the factors influencing this synergic function.A flow chart of micro-trickle combined with bipolar three-dimension particle electrodes electrochemical bed reactor was developed at the beginning of the study.Morphologies and microstructures were characterized by BET specific surface area (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). After that, the Mn-Sn-Sb/Y-Al₂O₃ catalyst was further investigated and optimized in the setup for the combination system, which has both good catalytic activity and stability.The result of the tentative study of synergy of combining electro-catalysis and catalytic wet air oxidation shows that the synergic function is obvious. Th results showed that good electroassisted catalytic wet oxidation efficiency was obtained in the setup for the combination system even at mild conditions (T=130℃, P_O2=10 MPa) that the phenol conversion and TOC reduction were up to 94.0% and 88.4% after 27 min treatment, respectively. The effect of reaction temperature (120-150℃), oxygen partial pressure (0.6～1.4MPa), current intensity (0.25-1.0A), initial phenol concentration (1500-3000 mg/L), inlet pH value (3.33-9.50) and catalyst diameter (20 meshp<10 mesh) on synergetic effect were also investigated. In the study of the influencing factors on the synergy of combining electro-catalysis and catalytic wet air oxidation, it indicates that the reaction temperature, partial pressures of oxygen, current intensity, initial phenol concentration, pH values, catalyst particle size all influence the removal effect of the aqueous phenol.According to the UV-scanner and GC-MS analysis, possible pathway for the electroassisted CWO of phenol was presented. The results showed that the oxidation reaction paths of phenol were similar as the ECO and CWO.