The Study On The Degradation Of Aqueous Phenol By Supported Bipolar Three-dimension Particle Electrodes

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)", the preparation, selection and optimum design of the supported particle electrodes were investigated. The electro-catalysis of the particle electrodes and the degradation mechanism of the aqueous phenol were discussed.A bipolar three-dimension particle electrodes electrochemical reactor cell was developed. Wetness impregnation method was employed to prepare the particle electrodes packed in the cell with the first-row transition metal oxide supported on 13X molecular sieve and γ-Al₂O₃. It was founded that γ-Al₂O₃ was the better carrier. Among the active components, Mn and Sn perform the best which can be combined to optimum design of the particle electrodes. The prepare condition was decided: the Mn/Sn ratio in the dipping solution is 2:1 and the calcination temperature is 823K(550°C). BET, X-ray diffraction (XRD) and scanning electron microscope (SEM) were applied to characterize the particle-electrodes. It was shown that the particle-electrode had high catalytic activity and stability.The effects of pH, electrolyte concentration, cell voltage, initial phenol concentration, reaction temperature and airflow on phenol conversion were elucidated. When the operating conditions were voltage 6.5V, pH 6.4, air flow 0.5Lmin^-1, electrolyte concentration 0.025mol·L^-1 and temperature 25℃, the conversion rate and total organic carbon (TOC) removal efficiency after 150min treatment for aqueous phenol with the concentration 200mg·L^-1 were above 90 % and 80%, respectively.The electro-catalysis of particle electrodes originated from the hydroxyl radical generated from the water catalyzed by supported metal oxide, which proved by the experiments adding radical scavenger. The degradation of aqueous phenol was the combination of direct discharging on anodes and indirect oxidation by active intermediate. According to the UV-scanner and GC-MS analysis, possible pathwayfor the electrochemical oxidation of phenol was presented.The electro-catalysis properties and mechanism of the bipolar particle electrodes should to be uncovered.