Electrochemical oxidation of sulfide in oil wastewater using Ti/Iro2 anode

The removal of sulfide from the effluent of oil wastewater containing high concentrations of chloride ions was studied with an electrochemical oxidation technique using a Ti/IrO2 anode. It was found that current density can enhance the removal of sulfide. At a current density of 25 mA/cm2, nearly 90.5% sulfide was oxidized in 10 min. At a fixed current density of 16.67 mA/cm2, a low initial concentration of sulfide (4.21 mg/L) was completely oxidized in 5 min while a high initial concentration of sulfide (50 mg/L) required 25 min for full oxidation. A synthetic solution was also used to investigate the effect of NaCl concentration, pH, and temperature on sulfide removal, and the results were discussed. NaCl concentration, acid conditions, and high temperature can all increase the removal of sulfide. The removal of sulfide was also investigated by using oxidation reduction potential (ORP). When the sulfide was completely oxidized, the ORP of the solution changed from negative (-300 to -600 mV) to positive. This study shows that, in general, the electrochemical method was effective for the removal of sulfide from oil wastewater. (C) 2011 American Institute of Chemical Engineers Environ Prog, 2011