Preparation Of Oxide Modified Electrodes And Its Application In Phenolic Wastewater Treatment

The composition and preparation method of electrode are the main influence factors on the structure of electro-catalytic electrode, which is important to electro-catalytic characteristics and stability of electrodes. This paper focused on the preparation of SnO₂ electrode, and investigation on its characteristics. Taking phenol as model substrate, the factors that influence the electrochemical degradation of phenol was investigated. The relationship of electrode structure with the electrocatalysis characteristic, as well as the electrochemical degradation mechanism of phenol was preliminary researched.The SnO₂/Ti electrode doped with Sb was prepared by thermal deposition. The preparation conditions, including the layer thickness, the temperature of thermal treatment and the doping amount of Sb were studied in detail. As a kind of electrodes with high catalytic efficiency, the SnO₂/Ti electrode prepared in this paper can be used in organic wastewater treatment, which can not be easily degraded by conventional biological treatment process. Fe was selected as a promoter for Ti-base SnO₂/Sb electrode to improve the electro-catalytic ability in wastewater treatment. The micrograph of the electrode surface, the element composition of different layers and the structure of the electrode surface were analyzed by SEM, EDX and XRD. The impact of Fe on properties and stability of the SnO₂ electrode was studied. Experimental results showed that Fe doping of right amount was in favor of grain refining and could help to enhance the electrical conductivity and electro-catalytic ability of electrodes.We use this new type of electrode as anode, and regard the Ti plate as cathode to degrade stimulant phenol waste water in a no dissepimental electrobath. The factors such as initial phenol concentration, pH, current density, concentration of assistant electrolyte, Cl^-, temperature and electrode material are the systematic research in the process of degrading phenol. COD removal rate is decreased as increasing the initial phenol concentration, but the absolute wiping off value is increased wholly; Acidic condition is better than neutral and alkaline condition for phenol degradation; COD removal is increased as the increasing of current density, the suitable condition is 30mA/cm²; There is an optimal condition for assistant electrolyte concentration, The value is 0.2mol/L in the system; Both Cl- and high temperature can accelerate the removal of COD; The degradation of phenol on Fe doped Ti-based SnO₂/Sb electrode was better than other electrodes.Using potentiostat/galvanostat 100B/W made in America by BAS company, we study the electro-oxidation degradation behaviors and kinetic of phenol on SnO₂ electrode by cyclic voltammetry and linear potential sweep technology. It is disclosed that oxidation of phenol on SnO₂ electrode occurred mainly in the range of oxygen evolving potential with no phenol oxidative polymerization. So the SnO₂ electrode showed the merits of good catalytic activity and steady in the oxidation process.The UV spectroscopic study shows that the electrolyzing reaction of phenol first produces quinone,then the benzene rings will be opened and finally CO₂ and H₂O are produced. The research on the electrochemical degradation mechanism of phenol indicates that the electro-oxidation of phenol on the SnO2 electrode is result from the hydroxyl radical on the electrode surface.