Electrochemical Oxidation Of Acid Orange Ⅱ Under Potentiostatic And Galvanostatic Model

Dye wastewater is characterized by complicated components, strong color, highly fluctuating pH, high COD, TOC concentration and suspend solids, low biodegradability, and widely varied quality and quantity, so it has been rather difficult to treat dye wastewater. As an eco-friendly technology, electrochemical method added little or no additional chemicals without secondary pollutants for wastewater treatment. In recent years, there has been increasing interest in the use of electrochemical methods for the treatment of dye wastewater.Dye wastewater can be decolorized by electrochemical oxidation through direct or indirect electrooxidation, which degrades the dye by electrogenerated oxidizing agent. Forming hypochlorite, an important oxidizing agent and mediator in wastewater treatment, from chloride is a general indirect electrooxidation method that most regarded study was conducted with cell voltage or current constantly controlled and the parameters of voltage, current density, wastewater conductivity, pH, current efficiency and energy consumption were evaluated. However, there are few reports on the relationship between decolorization and electrode potential. Besides, a great number of experiments were performed in a single compartment electrolytic cell. As a result, it is difficult to make sure the pure contribution of electrooxidation and electroreduction for the decolorization of dye wastewater because of the cross- interference of the anode and cathode.The electrochemical oxidation of Acid Orange â…¡ was carried out potentiostatically and galvanostatically respectively in a two-compartment cell separated by cation exchange membrane using metallic oxide coatings( DSA(?) ) as anode. The influences of key factors, such as electrode potential, current density, NaCl concentration, initial dye concentration, supporting electrolyte Na2SO4 concentration, temperature and PH have been investigated. Under both galvanostatic and potentiostatical model, color removal ratio could reach 100% and the naphthalene ring was destroyed in a certain extent, yet no obvious mineralization of the dye occurred; indirect electrooxidation predominated in the process compared with the direct one.Under potentiostatic model, decolorization follows the first order kinetics and the reaction rate constants are related with electrode potential, NaCl concentration and initial dye concentration by exponential function, linear relationship and reciprocal function respectively; furthermore, the decoloration rate was reduced obviously by high temperature. Undergalvanostatic model, decolorization follows the zero order kinetics and the reaction rate constants are related with current density, NaCl concentration, initial dye concentration and temperature by linear relationship respectively as well as a reciprocal function exists between the rate constant and supporting electrolyte Na2SO4 concentration; furthermore, high pH reduced the decoloration rate obviously.Under a certain condition, the simulated galvanostatic decoloration kinetics process, based on the kinetics conclusion that the potentiostatic model experiment draws together with the electrochemical parameter (anode potential) of the galvanostatic model, fits the real decoloration kinetics process well. Thereby a caculating path was found to get the target(dye) concentration by measuring the electrochemical parameter(potential).