Electrochemical Sulfur Removal at Controlled and Uncontrolled pHs with an Iron Anode

In this study, sulfide removal was carried out in the Electrocoagulation process under controlled and uncontrolled pH conditions. Under optimum conditions, electrocoagulation took place in less than 40 minutes at uncontrolled pH and less than 30 minutes at controlled pH to reduce the sulfite concentration of the effluent below 0.5 mg/L. The reaction rate constant and iron-sulfide molar ratio for sulfide removal were 14.09 × 10^–2 min^–1 and 0.97 mol/mol, respectively; under uncontrolled pH conditions, they were 22.88 × 10^–2 and 0.97 mol/mol at controlled pH. The mg sulfide removed per g Fe was calculated as 654.0 mg S^2–/g Fe at uncontrolled pH and 508.46 mg S^2–/g Fe at controlled pH. The operating costs for uncontrolled and controlled pH conditions were also calculated as 2.063 $/m³ (0.747 $/kg S) and 0.842 $/m³ (0.628 $/kg S), respectively. Controlled pH conditions were important in sulfide removal by the Electrocoagulation process.