Preparation Of Ce-doped Ti/Sn-Sb Anode And Study On Catalytic Oxidation Of Phenol

In this paper,the Ce-doped Ti/SnSb electrode was prepared by electrodeposition and thermal decomposition methods.Ti/SnSb electrode was optimized with catalytic properties and cell voltage as the main assessing items and finally,the optimum doping ratio and thermal oxidation temperature was determined.The microstructure,element compositions and distributions,phase compositions of the Ce-doped Ti/Sn-Sb electrode had been studied by means of scanning electron microscopy with energy dispersive X-ray(SEM-EDX),electron probe microanalysis(EPMA),X-ray diffraction(XRD).The effects of Ce doping and thermal oxidation temperature on the properties of electrode were investigated and the results have shown that grains can be facilitated in fine size with suitable content of Ce,the anode has a compact texture,the oxide of its coat distributes equably and completely covers the Ti matrix,it has catalysis for the oxidative degradation of phenol.However,SnO₂ crystal lattice can be destroyed and the performance of electrode can be decreased with excess content of Ce. Thermal oxidation temperature has significant effect on the performance of the electrode.The micrographs of the surface layer,oxygen evolution potential,electrical conductivity differ with diffrient oxidation temperature and the suitable oxidation temperature is about 550℃.Take the optimized electrode as anode,titanic plate as cathode,the simulant phenolic wastewater is degraded in a electrolytic cell without diaphragm.The effects of influencing factors of degradation of phenol such as electrolyte concentration,original pH value of electrolyte,initial concentration of phenol,electrical current,electrolyte temperature,electrode material on degradation of phenol are systematically investigated.It has been found that,the greater the Na₂SO₄ concentration,the better the removal effect of phenol and COD in the concentration range of 0.1 to 0.5 mol/L;the best removal effect of phenol is in the original pH value from 5 to 7 of electrolyte and the worst is under the condition of high pH value;phenol and COD removal rate decrease as initial phenol concentration increases,but the absolute wiping off value increases obviously;the removal effect of phenol and COD increase with increasing of electrical current,but the current efficiency decrease;An increase in electrolyte temperature is found to reduce cell voltage and have a beneficial effect on the phenol oxidation degradation;catalytic properties of different electrode vary considerably, SnSbCe/Ti anode is the best,SnSb/Ti anode is in the middle,RuO₂/Ti anode is the worst.Using electrochemical test System,the oxidation degradation behaviors of phenol on SnSbCe/Ti electrode were studied by cyclic voltammetry and polarization curves.The results of the tests indicate that,the process of anodic oxidation of phenol on SnSbCe/Ti electrode is irreversible,and it is controlled by diffusion process;catalytic activity of the electrode is closely bound up with oxygen evolution potential,high oxygen evolution potential can improve catalytic activity for phenol;there is no variation of oxygen evolution curve with the increase of phenol concentration,there was no phenomena of organic matter polymerization during the reaction and the electrode keeps good catalytic activity for oxidation of high concentration phenol;cyclic voltammetry curve remains the same after 40 times scans,the electrode shows the merit of good stability.The results of high performance liquid chromatographic analysis of electrolyte with different degradation time show that degradation of phenol with high concentration is complex and the degradation process inclines to electrochemical conversion;first,phenol is adsorbed on the surface of electrode and is oxidized to intermediate products,and then intermediate products are converted to organic acids along with the break of benzene ring, finally the organic intermediate products are oxided to CO₂ and H₂O;the degradation process of low concentration inclines to electrochemical combustion,the degradation is more thorough and there is no organic intermediate product in the process of the degradation.