Preparation And Electro-Catalytic Activity Of Composite Oxides Supported Zeolite Particle-Electrodes For Organic Wastewater Treatment

At present, it is a problem of wastewater treatment that it is difficult for organic wastewater including pharmaceutical wastewater,pesticide wastewater and printing and dyeing wastewater to be effectively degraded by bacteria. Advanced oxidation technology, especially electro-catalytic technology, can effectively degrade this kind of wastewater. But because of the problems of low current efficiency and high energy consumption, its practice is very difficult. According to the essence of treating wastewater in the method of electro-catalytic, our work designs a new kind of particle electrodes, discuss the way to raise the catalytic activity of particle electrodes and optimize preparation process. The aim of treatment is the typical organic wastewater such as antibiotic wastewater. By the characterization and performance test of particle electrodes, the reasonability of design idea and project is confirmed.Particle electrodes compose of porous vector and electro-catalytic membrane that is deposited in the channel of supporter. By experiments, sol-gel method is employed to prepare the particle electrodes with the first-row transition metal oxide supported on natural mordenite zeolite. It is shown that new-type particle electrode, SnO₂-TiO₂ composite oxides supported on zeolite, has the high electro-catalytic activity. The molar ratio of Sn to Ti, the membrane pH value and annealing temperature are the three primary influence factors of particle electrode electrochemical activity. By controlling the molar ratio of Sn to Ti at 1:10, pH value of sol at 3 and annealing temperature at 450℃, the Sn-Ti/zeolite particle electrode was found to have the highest electro-catalytic activity in treating penicillin wastewater. In this case, we can get up to 89% COD removal ratio, 74.37% current efficiency and 18.24 kwh·kg_COD^-1 energy consumption. The results of SEM, XRD and EDS show that thin membranes of titanian and tin oxide are uniformly distributed in the channel of zeolite.The electro-catalytic essence of particle electrodes is: membrane of Sn doped nano-TiO₂ supported on zeolite is a kind of semiconductor. Its conductivity is lower than metal but higher than nonconductor. Particle electrodes are filled in the beam electrode of electro-catalytic reactor. On the role of current, electrostatic induction happens to product·OH to oxide and decompose the difficultly-degraded organics on the surface of particle electrodes.