Degradation For Nitrogenous Pollutants In Water By Electrochemical Oxidation

With the development of society,the type and quantity of nitrogenous pollutants discharged into the water by people continue to increase.In order to prevent the eutrophication of water,the nitrogenous wastewater must to be treated effectively.In this dissertation,the degradation for nitrogenous pollutants in water by electrochemical oxidation is studied.The experiment was carried out to study the influence of doping element on the electrocatalytic performance of PbO₂ anode,the reaction mechanism of aniline and ammonia nitrogen by electrochemical oxidation,optimization of reaction conditions and the application on the actual wastewater.The micrographs and crystal structures on the surface of graphite-based PbO₂ anodes were analyzed by SEM and XRD.The bottom layer is graphite. The middle layer isα-PbO₂.The activated surface layer is dopedβ-PbO₂.The performances of PbO₂ anodes are enhanced by doping.Furthermore the performance of Fe-PbO₂/C is better than that of La-PbO₂/C.By doping,the surface microstructures of anodes are improved,and the electrocatalytic abilities are enhanced.Simulated aniline wastewater is treated by electrochemical oxidation to study the influences of anion,chloride ion concentration,current density, influent concentration and initial pH on removal rates of aniline and COD. Electrochemical oxidation of aniline accords with the first order kinetics using Fe-PbO₂/C as anode.The new product may be benzoquinone in the process of degradation investigated by means of Uv-Vis.The amidocyanogen is separated from the benzene ring to produce ammonia nitrogen,and the transformation from organic amine to inorganic ammonia is one important step in the whole reaction.Simulated ammonia nitrogen wastewater is treated by electrochemical oxidation to study the influences of influent concentration,current density, electrode space,chloride ion concentration and initial pH on removal rates of ammonia nitrogen and total nitrogen.Taking graphite and Fe-PbO₂/C as anode respectively,electrochemical oxidation of total nitrogen accords with the first order kinetics.The removal rate of ammonia nitrogen using Fe-PbO₂/C is higher than that using graphite.Most of ammonia nitrogen is removed as N₂, and the proportions of nitrate and nitrite are very small in the total nitrogen.The treatment effects of actual nitrogenous wastewater are satisfactory by electrochemical oxidation using Fe-PbO₂/C.The surface of electrode has not occurred desquamating and melting obviously,hence the electrode is firm.