• • DSS-ISB achieved >97% Cr(VI) removal efficiency at a dosage of 1.8 mg/g and liquid-to-solid ratio of 5 mL:10 g, reducing leachate concentration from 15.03 mg/L to 0.03 mg/L, far below the 5 mg/L regulatory limit (GB 5085.3—2007).
• • The slurry's particle size of ~200 nm and inorganic dispersant modification ensure stable suspension and high reactivity, overcoming aggregation and passivation issues common in nano iron-sulfur materials.
• • Compared with FeSO4 and Na2S, DSS-ISB increased unit mass removal capacity by 92.43% and 77.08%, respectively, while reducing reagent cost per ton of COPR to RMB 36.40—a 33.82% and 26.02% cost saving.
• • The remediation mechanism combines chemical reduction (Fe2+/S2- dual electron donors) and surface adsorption, converting Cr(VI) to stable Cr(III) precipitates, as confirmed by XPS and BET analyses.