Oxidation–Reduction Potential Characteristics Of Phenol-Containing Aqueous Solutions During The Electro-Oxidation Process

Oxidation–reduction potential is an indicator of the comprehensive redox characteristics in chemical reaction system.Every substance has its unique redox ability,and the reaction between them could be reflected by a specific ORP value at macroscopic level.As a flexible,low cost and easy method to control parameter,oxidation–reduction potential has been widely used in many fields.Electro-oxidation is a green and effective advanced oxidation process for treating wastewater.It can split organic matter into small molecules or completely demineralize it into carbon dioxide,water,and other inorganics.Optimization of the equipment control parameters can reduce its power consumption in wastewater treatment.It will have a wide and specific application prospect on electrochemical control of water pollution and resource recovery.ORP characteristics of phenol-containing aqueous solutions during electrolysis were investigated for the first time in this paper.This paper identified the effect of current density,pollutants,electrolyte on pollutants removal rate and ORP values in electrochemical system.Our study found that phenol in wastewater could be efficiently removed and its removal efficiency could be enhanced by increasing current density,but there was no significant effect of electrolyte concentration.The experimental results indicated that ORP values in aqueous solution with NaCl as electrolyte present V shape change curves and the final stable level was about 800 mV.And the variations of ORP values were closely related to the current density and electrolyte concentration: high current density and high NaCl concentration shortened the time before the shape of ORP curve changed.However,the ORPs did not show significant change which just vary around 200 mV in the Na2SO4 system.In our preliminary analysis,chloride component and p H in solution did key affect on the ORP variations.NaCl was involved in the electrolytic reaction and transformed into ClO3-but other than Na2SO4.ClO3-accumulated in solution contributed to the rapid growth of ORP values for its strong oxidation capacity.All in all,a potential relationship existed among pollutant content,ORP,current density,electrolyte concentration and pH.Therefore,it was feasible to develop a novel method of using ORP monitoring to optimize the power input in electrolysis process for wastewater treatment.