Electrochemical removal of sulfide ions and recovery of sulfur from sulfide ions containing wastes

In this work a two-compartment galvanic cell with two graphite rod electrodes and two types of cation exchange membranes: namely the Nafion membrane and synthetic fabric membrane is tested in treating sulfide containing wastes and recovery of elemental sulfur. The cell reactions are sulfide oxidation at the anode and chromium (VI) reduction at the cathode. The effect of different parameters such as external resistance, initial concentration of K2Cr2O7 solution, H2SO4 concentration, and initial concentration of Na2S, the pH of the solution, NaCl concentration, and temperature of the solution is investigated. The cell performance as a reactor and as an energy converter is expressed in terms of % sulfide removal and current-voltage plots, respectively. Depending on the effects of the aforementioned factors, the optimal conditions that give the highest performance were determined, and then the cell was tested on real wastes from refinery processing at those conditions. The cell showed high selectivity in sulfide removal and sulfur recovery with almost no interference with other contaminants.