Reduction and immobilization of Cr(VI) in aqueous solutions by blast furnace slag supported sulfidized nanoscale zerovalent iron

In this study, an industrial waste-blast furnace slag (BFS) supported sulfidized nanoscale zerovalent iron (S-nZVI@BFS) was prepared and used for synergistic reduction and adsorptive removal of Cr(VI) from aqueous solutions. The characterization analysis showed that Fe0 and FeS were well dispersed on the surface of BFS, and the specific surface area of S-nZVI@BFS was 141.986 m2 g−1. Batch experiments demonstrated that the removal capacity of Cr(VI) was as high as 184 mg/g for S-nZVI@BFS. The pseudo-second-order kinetic model fitted the Cr(VI) removal kinetics well. Cr(VI) removal on the S-nZVI@BFS relied highly on pH values. The reduced Cr(VI) precipitated on S-nZVI@BFS mainly as CrxFe(1-x)(OH)3, CrxFe(1-x) OOH and Cr2S3, and the alkaline capacity of the BFS could efficiently prevent the release of Cr(III) from the precipitations in acid condition. Thus, supporting S-nZVI on BFS was an effective and safe method for Cr(VI) removal from aqueous solutions. [Display omitted] •BFS supported S-nZVI (S-nZVI@BFS) was prepared for Cr(VI) removal from water.•The synergic effect of BFS and S-nZVI drastically improved Cr(VI) removal capacity.•Absorption, reduction and precipitation were the main steps in the removal of Cr(VI).•BFS could efficiently prevent the release of Cr(III) from S-nZVI@BFS in acid condition.