Research Of Electrocatalytic Degradation Of Phenol Wastewater By The Ti/IrO₂-Ta₂O₅Electrode Under High Gravity Field

Phenol wastewater is unfriendly to the environment and humans, therefore，the treatmentof phenol wastewater is of great importance. Electrocatalytic oxidation is a kind of green,environmental protection method in various treatment methods of phenol wastewater due tothe advantages of mild reaction condition, clean technology and simple operation andequipment. Catalytic electrode used as anode material can inhibit oxygen evolution sidereaction to some extent in the process of electrocatalytic oxidation degradation of phenolwastewater. And because of the catalytic activity of the electrode, so the degradationefficiency of organic matter can be improved. But hydrogen evolution and oxygen evolutionside reaction will inevitably occur in the electrolysis process. The problems of bubble effectand mass transfer limited have not been resolved. The efficient mass transfer technology isneeded to solve these problems. The high gravity technology can promote the process ofalternate micro-mixing and strengthen mass transfer. So the research of electrocatalyticdegradation of phenol wastewater under high gravity field is proposed combining the highgravity technology and the Electrocatalytic method, which explores a new way on theresearch of phenol wastewater treatment method.The electrocatalytic oxidation degradation of phenol wastewater was studied by using thetitanium-based IrO2-Ta2O5electrode as anode and stainless steel electrode as cathode underhigh gravity field. The effects of high gravity factor, current density, electrolysis time,electrolyte concentration, liquid circulation flow rate and initial concentration of phenol onthe removal efficiency of phenol in waste water were systematically investigated. Resultsindicated that: for the water containing100mg/L phenol, the removal rate of phenol and CODcould reach up to98.7%and43.5%respectively after7h under the most suitable condition. The removal rate of TOC reached up to40.42%. The result of dynamics of ectrocatalyticoxidation degradation of phenol wastewater under high gravity field showed that the reactionfollows first order kinetics reaction model.Mass transfer process was the rate determining step in the initial reaction stage of theectrocatalytic oxidation degradation of phenol wastewater under high gravity field. Thestrengthen effect of the mass transfer process by high gravity was obvious. Electrochemicalreaction step was the rate determining step in the later reaction stage. The strengthen effect ofthe mass transfer process by high gravity was weakened. The electrocatalytic oxidationdegradation coupled with the Fenton method of phenol wastewater was studied under highgravity field in order to achieve the goal of high efficient wastewater treatment in a short time.The effects of initial pH value of electrolyte, dosage of H2O2and FeSO4·7H2O, high gravityfactor, current density, electrolysis time, liquid circulation flow rate, initial concentration ofphenol and the number of H2O2application on the removal efficiency of phenol in wastewater were systematically investigated. Results indicated that: for the water containing100mg/L phenol, the removal rate of phenol and COD could reach up to99.56%and65.43%respectively after1h under the most suitable condition. The removal rate of TOC reached upto70.99%. The removal rate of phenol and COD can reached up to71.51%and46.55%respectively with the electrocatalytic oxidation degradation coupled with the Fenton methodunder normal gravity field. Therefore, the appliance of high gravity technology couldstrengthen the mass transfer process and achieve efficient phenol removal efficiency in theelectrolysis reaction.Through the analysis of HPLC of phenol wastewater, wastewater degradation processwas inferred phenol was become catechol, hydroquinone and resorcinol, then benzoquinoneand organic acid, finally was CO2and H2O.