Mechanisms of Jarosite Formation and Arsenic Co-precipitation during Neutralization of Sulfate-Rich Copper Smelter Effluents: Effects of Sulfate Concentration and Iron Dosing on Precipitate Formation and Arsenic Stability

Arsenic in acidic, sulfate-rich effluents from copper smelting operations poses a significant environmental risk. Conventional lime treatment often produces unstable arsenic-bearing sludge. This study investigates the controlled co-precipitation of arsenic (V) with potassium jarosite as a robust immobilization strategy. A synthetic effluent, representative of challenging industrial solutions (۱۳۲۰ mg/L As, ۴۳.۳ g/L sulfate), was neutralized to pH ۲.۸ at ۹۵ °C using a high Fe:As molar ratio (۲۱.۴:۱). The resulting precipitates were characterized by XRD and ICP-OES, and their stability was assessed via aggressive acidic leaching (pH ۱.۵). The process demonstrated a high arsenic removal efficiency of ۹۸.۵%. XRD analysis revealed the final product was a composite material, consisting predominantly of crystalline potassium jarosite (۹۴ wt.%) with a minor amorphous iron oxyhydroxide component (۶ wt.%). The final solid contained ۱۸,۲۰۰ mg/kg of arsenic. Despite the presence of the minor amorphous phase, the product exhibited exceptional stability, with only ۱.۸% of the total sequestered arsenic being mobilized during the leaching test. These findings demonstrate that co-precipitation with jarosite is a highly effective method for producing a stable, arsenic-bearing solid, offering a superior and more reliable alternative for the long-term management of arsenic in industrial wastewater.

کلیدواژه ها:

Arsenic immobilization ، Potassium jarosite ، Co-precipitation ، Acidic sulfate effluent ، Stability assessment ، Copper smelting wastewater