Electrochemical advanced oxidation for removal of xanthate from flotation process water

Abstract

In this work, the removal of xanthate from flotation process water by electrochemical advanced oxidation processes (EAOPs) was investigated. An electrochemical cell was fabricated using a pair of carbon electrodes as the anode and cathode. Electrodes were prepared by depositing an aqueous slurry of activated carbon and PVA binder onto graphite sheets. Carbon disulfide (CS2) was produced during the process and removed to some extent by absorption of carbon electrodes and/or further oxidation to sulfate (SO42−).The effect of operating parameters such as applied voltage, flow rate, and influent concentration on process efficiency was evaluated to achieve efficient xanthate removal. Application of various potentials ranging from 1 V to 7 V showed that xanthate removal efficiency increased at higher voltages. The effluent concentration was cleaner and the salt removal efficiency was higher at slower flow rates. The highest removal efficiency of 95% was achieved at a flow rate of 0.5 mL/min. Since the density of ions between the electrodes increased with increasing influent concentration, the total xanthate removal increased from 599.4 mg/m2 at 5 mg/L influent concentration to 12834.2 mg/m2 at 40 mg/L. Long-term stability tests showed that electrode performance degraded steadily and the removal efficiency decreased from 85% to 56% in 30 h.Batch mode experiments in the presence of ion exchange membranes showed that xanthate was oxidized to CS2 at 0.8 V and 1.0 V and to monothiocarbonate (ROCSO−) at 1.2 V. 96% of xanthate was removed from 5 mg/L xanthate solution at a flow rate of 0.5 mL/min at 1.0 V.The effect of real mine water components on xanthate removal efficiency was investigated by using flotation process water from a copper mine in Turkey. The results showed that the process efficiency decreased from 67% to 32% in the presence of mine water, which could be attributed to electrode fouling.