Simultaneous Degradation of p-Nitrophenol and Recovery of Copper from Wastewater in Electrochemical Reactor Under High Salinity

Abstract

Ti/RuO2–IrO2 electrode was used in this study as an anode, while titanium plate (Ti) was used as a cathode for electrochemical oxidation process, to explore the influences of related parameters on degradation of p-nitrophenol (PNP) and removal of Cu2+ from mixed simulated wastewater. Using a single chamber reactor, we tested the influence of various factors on the PNP degradation and Cu2+ elimination. The factors that were tested are as follow; the type of electrolyte, density of the current, various values of pH and different concentrations of Cu2+. Furthermore, a dual-chamber diaphragm reactor compartmentalized by cationic membrane was utilized to explore the removal mechanism of PNP and Cu2+. Results showed that, treatment of PNP-Cu2+ simulated wastewater, with NaCl as electrolyte, had a better effect compared with Na2SO4, which had characteristics such as shorter reaction time and higher degradation efficiency for PNP. Removal of Cu2+ had no obvious advantage over Na2SO4. The degradation of PNP and removal of Cu2+ were improved with increased current density when the rang was increased from 10 to 40 mA/cm2. Cu2+ concentration when increased initially promoted the degradation of PNP. At the same time, Cu2+ acted as electron acceptor at the cathode that slowed down the consumption of H+ through reduced combination of H+ with electrons. The degradation rate of PNP decreased with increased initial pH, but the Cu2+ was opposite. In this experiment, the degradation of PNP was positively correlated with indirect oxidation of active chlorine, and the Cu2+ was removed by cathodic electrodeposition.