Improved performance and applicability of copper-iron bimetal by sulfidation for Cr(VI) removal. (October 2021) - Qu, Min
Abstract: The reactivity of zero-valent iron (ZVI) for the Cr(VI) removal in groundwater is mainly limited by the formation of a passivation layer during its application in permeable reactive barrier (PRB). A kind of sulfidated copper-iron bimetal (S-ZVICu) with high reactivity for Cr(VI) removal was prepared by depositing FeSx onto copper modified ZVI via a one-pot method. The surface characteristic, reactivity and Cr(VI) removal performance of S-ZVICu were investigated. It was found that S-ZVICu had a Cr(VI) removal capacity as high as 67.5 mg/g and little risk of secondary contaminant of Cu(II). The optimal Cu/Fe mass ratio and S/Fe molar ratio were 0.0125 and 0.084, respectively. The S-ZVICu exhibited great superiority of Cr(VI) removal compared with ZVI, sulfidated ZVI (SZVI) and coper-iron bimetal (ZVICu). Mineralogy and morphology analysis showed that S-ZVICu had a hierarchical structure of Fe 0 /Cu 0 /FeSx, which could effectively reduce the risk of secondary contaminant of copper ions. The mechanism analysis suggested that the copper and FeSx successively plated on the surface of ZVI played a dual role in promoting the corrosion of zero-valent iron, and was facilitated to electron transfer between Fe 0, Cu 0, FeSx and Cr(VI). In addition, the loose FeSx layer had a positive effect on alleviating the oxidation of ZVI in air, which was helpful in maintaining the reactivity of S-ZVICu in the air. S-ZVICu is an environmentally friendly material for sustainable and effective removal of Cr(VI) in groundwater. Graphical abstract: Image 1 Highlights: Sulfidated coper-iron bimetal with hierarchical structure of Fe 0 /Cu 0 /FeSx was successfully prepared. Sulfidation enhanced the chromium removal capacity of ZVICu. Sulfidation enhanced the stability of ZVICu. FeSx deposited on the surface of S-ZVICu inhibited the oxidation of superficial Cu 0 to Cu(II).