Preparation of Sulfidated Copper-Iron Bimetallic Composited Material and Its Mechanism for Chromium Removal

Abstract

Sulfidated copper-iron bimetallic particles (S-Fe-Cu) were prepared by sulfidation of copper-iron bimetallic particles (Fe-Cu) obtained by the replacement reaction in the liquid phase. The influencing factors of S-Fe-Cu in removing Cr(Ⅵ) in water were determined. BET, SEM-EDX, and XPS were used to analyze the superficial structure and mineralogy of S-Fe-Cu. Combined with batch experiments, the mechanisms of Cr removal were analyzed. The results showed that FeSx was successfully loaded on the surface of S-Fe-Cu, and the optimum S/Fe molar ratio and Cu/Fe mass ratio in theory were 0.056 and 0.025, respectively. Compared with Fe-Cu, the specific surface area of S-Fe-Cu increased by 2.1 times, and the Cr removal efficiency increased by 6.1 times under a pH of 5. A high Cr removal efficiency was maintained under alkaline conditions. Meanwhile, chloride ions could penetrate the passivation layer of iron-based material, which was beneficial to the direct oxidation of Fe0 to produce Fe(Ⅱ) and advance the performance of S-Fe-Cu for Cr removal. The XPS results showed that the removal mechanism of Cr(Ⅵ) in water included adsorption, reduction, and coprecipitation.