A Study on the Rule of Arsenic Precipitation by H2S in High Concentrations of H2SO4

Herein, targeting arsenic-containing acidic wastewater generated from washing arsenic-containing flue gas with concentrated sulfuric acid, the arsenic removal efficiency using H2S was investigated. The effects of H2S concentration, the gas flow rate, H2SO4 concentration, temperature, and Cl−/F− ions on arsenic removal were studied. Results indicate that H2S concentration is the primary factor. Arsenic was precipitated as amorphous As2S3, reducing residual arsenic to 0.28 mg/L. Cl− enhanced arsenic removal, yielding a residual concentration of 0.68 mg/L, while F− exhibited a dual effect: the inhibition at low concentrations and promotion at high concentrations. At 100 g/L F−, the residual arsenic was 29.59 mg/L. These effects are attributed to Cl−/F− altering the surface electrochemical properties of As2S3 particles. Additionally, both ions improved As2S3 hydrophobicity. This study provides insights for purifying arsenic-containing sulfuric acid.