Research On Electro-oxidative Degradation Of Coking Wastewater By Modified Lead Dioxide Electrode

With the rapid development of industry,the discharge of coking wastewater is daily on the increase,which cause increasingly serious harm to the environment and human beings.Electrochemical oxidation is the process of directly or indirectly oxidizing pollutants on the electrode surface to harmless substance and removing it by applying current.In the field of industrial wastewater treatment,the technology has attracted more and more attention due to its characteristics of no secondary pollution,strong oxidation capacity and automatic operation.So the modified lead dioxide electrode(ESIXPb-I)was used to degrade coking wastewater by electrooxidation treatment in the research.In order to realize the?zero discharge?standard of coking wastewater,ESIXPb-I electrode was used to degrade actual coking wastewater by electrooxidation treatment in this study.The effects of current density,initial p H and chloride concentration on the degradation were investigated.Besides,the reaction mechanism of coking wastewater degradation was discussed.The results showed that ESIXPb-I electrode had high crystallinity and good conductivity.The ESIXPb-I electrode?s oxygen evolution potential(1.84 V)and accelerated life(75 h)were higher than that of Ti/Pb O₂ electrode.Using ESIXPb-I electrode to degrade coking wastewater,the increase of current density promoted the degradation rate of pollutants.The alkaline condition was conducive to the generation of·OH and Cl O^-,promoted the indirect oxidation of ammonia nitrogen and organic matter to nitrogen,carbon dioxide and water.The removal rate of pollutants could be increased by the appropriate concentration of chlorine ion.Under the condition of 30 m A·cm^-2,initial p H values at 9 and 700ppm Cl^-,the removal efficiency of ammonia nitrogen and COD reached 100%after 30 min reaction,and the degradation process was in accordance with pseudo first-order kinetics.In order to achieve the effective removal of phenolic compounds in coking wastewater,phenol was treated in this study.ESIXPb-I electrode was used to catalyze the electrooxidation degradation of coking wastewater containing phenol.The effects of current density,electrolyte concentration and initial phenol concentration on the degradation were investigated.The results showed that the increase of current density could improve the yield of oxidant,and promoted the degradation of phenol.The increase of electrolyte concentration enhanced the generation of conductivity and active chlorine.The increase of initial phenol concentration promoted the catalytic reaction between HCl O,ozone,·OH and phenol,improved the removal efficiency of phenol.Therefore,in the conditions of 20 m A·cm^-2,0.02 mol·L^-1 Na Cl and 300 ppm phenol,the phenol removal efficiency reached 94%after 120 min,and the degradation process accorded with the pseudo first-order kinetics.In addition,the phenol treatment efficiency of ESIXPb-I electrode and Ti/Pb O₂ electrode was contrasted.The results indicated that the electrocatalytic performance of ESIXPb-I electrode was better than Ti/Pb O₂ electrode.The process of using ESIXPb-I electrode to degrade phenol had high current efficiency and low energy consumption.At the same time,the electrochemical oxidation process of phenol was indirect oxidation,and the main oxidants were active chlorine and ozone.The ESIXPb-I electrode of high activities was used to electrooxidize the actual coking wastewater.The ammonia nitrogen and COD were completely removed,and the?zero discharge?standard of wastewater was realized.Application of ESIXPb-I electrode had great guiding significance for its industrial application,which provided new ideas for enterprises to save energy and reduce emissions,improved economic benefits and social benefits of enterprises.In addition,the process of electrochemical oxidation of coking wastewater containing phenol by ESIXPb-I electrode had low energy consumption and high removal efficiency of phenol,which can be widely used.Therefore,ESIXPb-I electrode had a strong advantage in coking wastewater treatment.