Electrocatalytic Oxidation Of Organic Pollutants In Electroplating Wastewater

The primary contaminants in the electroplating wastewater are heavy metal irons and organic pollutants, which limit its treatment and recycling. In recent decades, the control technology of heavy metal irons in electroplating wastewater has received extensive research and application, but little attention is paid to the treatment of organic pollutants. With the introduction of new emission standards, the treatment of organic pollutants in electroplating wastewater is imperative.The electrocatalytic oxidation of electroplating wastewater was studied in the pilot scale. And the factors affected the removal of organic pollutants, including the current density, the initial pH, and the reaction time were investigated to optimize the process parameters. The paper also researched the effect of magnetic field on the electrocatalytic oxidation of electroplating wastewater, and the related reaction mechanism was discussed. The results were as follows:1. The reaction time, current density and initial pH had significant effect on the removal of COD. The removal rate of COD increased with the current density and the reaction. The optimized experimental parameters were:the current density was 100 A·m-2, the reaction time was 3 h, and the initial pH was neutral.2. The stability of electrocatalytic oxidation was good. In continuous experiments, when the residence time was 3 h, the current time was 100 A·-2, and the pH was neutral, the COD of effluent could be stabilized at 70 mg·L-1, while the COD of influent was 439 mg·L-1. The energy consumption was 5.7 kW·h·t-1.3. The high polymer organic substances in the electroplating wastewater including long-chain alkanes which were difficult to degrade biologically were broken down into small molecules by electrocatalytic oxidation, and the biodegradability of wastewater was greatly improved.4. The introduction of magnetic field into electrocatalytic oxidation promoted the degradation and mineralization of organic pollutants in the electroplating wastewater. When the magnetic field intensity was 22 mT, the current density was 50 A·m-2, pH was 1.80, the reaction time was 2 h, the COD removal rate was increased by 15.2% compared with no magnetic field.5. The introduction of magnetic field promoted the production of H2O2 during the reaction, enhanced the Fenton reaction, thus the degradation of organic pollutants was advanced. When the current was constant, the introduction of magnetic field reduced the voltage, and increased current efficiency, thus the energy consumption reduced.