The Preparation Of Modified Tin Antimony Oxide Electrode And Its Applications To Ammonia Nitrogen Treatment In High Salinity Wastewater

With the development of Chinese economy and society, water entrophication problem caused by ammonia wastewater discharge has been more serious.Due to the growth of microorganisms in high salinity wastewater is inhibited and poisoned, it is a problem to remove ammonia in high salinity wastewater with high efficiency. People pay a lot of attention on electrochemical oxidation degradation, which has no secondary pollution, controllable, mild reaction conditions, simple device and much more. The degradation of pollution is determined by the anode, at which the electrochemical oxidation occurs. With the high oxygen evolution potential, excellent electro-catalytic activity and low prices, Ti/SnO2Sb2O5 electrode has become the focus of catalysis oxidation field.In this paper, Ti/SnO2Sb2Os electrode was prepared by brushing-thermal decomposition method. The electro-catalytic activity and stability of Ti/SnO2Sb2Os was improved by replacing the solvent and surface doping.Surface morphology and elemental composition was characterized by SEM and EDS; the electrochemical properties of electrodes were tested by the means including polarization curve, cyclic voltammetry, fluorescence spectroscopy, strengthening life. It was studied that the removal of NH4+-N and CO(NH2)2-N in high salinity wastewater was effected by [Cl-], the current density, initial pH value.(1) The Ti/SnO2Sb2O5 electrode prepared by n-butanol as solvent has the significant "crack" morphology. The Ti/SnO2Sb2Os electrode prepared by polymer precursor (diethanol citrate), which was prepared by mixing citric acid and diethanol at the ratio of 3:7 at 60℃, which has a more compact shape and was covered with irregular particles. The electrode prepared by polymer precursor has higher activity for oxygen evolution and cholrine evolution than the electrode prepared by n-butanol as solvent. The strengthening life of Ti/SnO2Sb2O5 electrode is improved by using the polymer as the solvent, the strengthening life of the electrode is increased from 10 min to 103 min.(2) The electrode was modified by doping Cu into coating solution. The amount of local crack is further reduced, and the strengthening life of the electrode increases from 103 min to 297 min. The Cu-doped electrode has higher oxygen evolution potential, better catalytic activity of chlorine evolution and better ability to produce hydroxyl free radical than non-doped electrode. In the sulfate system, the cyclic voltammetry of NH4+-N on the electrode is no response, but the cyclic voltammetry of CO(NH2)2-N on the electrode has response. In the NaCl system, the cyclic voltammetry NH4-N and CO(NH2)2-N on the electrode had obvious electrochemical response.(3) The removal of NH4+-N in the high salinity was achieved with producing active chlorine in the surface of the modified Ti/SnO2Sb2Os. The effectivity of NH4+-N degradation increases with adding the concentration of Cl- when the concentration of Cl- is less than 10 g.L-1, while there is no significant change in NH4+-N removal rate with adding the concentration of Cl- when the concentration of Cl- is greater than 10 g.L-1. The removal rate of NHU+-N increases with raising the current density, however, there is no effect on the electrolysis current efficiency when current density raises. The efficiency of NH4+-N removal increases with improving initial pH value of wastewater, the effect of NH4+-N removal is improved obviously in the acidic solution.(4) CO(NH2)2-N in the high salinity wastewater is removed by direct and indirect electrochemical oxidation at the electrode surface.32% of CO(NH2)2-N is removed by direct electrochemical oxidation, and is removed completely when CI- is added. The effect of CO(NH2)2-N degradation is raised linearly with adding the concentration of Cl- when the concentration of Cl- is less than 5 g.L-1., and the rate of the removal effect is slight at the concentration of Cl-being less than 5 g.L’1.The removal rate of CO(NH2)2-N is improved with the current density raised, while there is no effect on the electrolysis current efficiency. The efficiency of CO(NH2)2-N removal increases with improving initial pH value, while the change of initial pH has a smaller impact on the removal of CO(NH2)2-N than the removal of NH4+-N.