Spinel ferrite-enhanced Cr(VI) removal performance of micro-scale zero-valent aluminum: Synergistic effects of oxide film destruction and lattice spacing expansion

Zero-valent aluminum (ZVAl) as a cost-effective additive with excellent reducibility is a promising material for application in heavy metal elimination. However, dense surface oxide films suppress the reactivity of ZVAl. Herein, we prepared mZVAl/MFe2O4 (M = Mn, Zn, Ni) composites via an accessible ball milling process and confirmed their satisfactory adsorption–reduction performance for Cr(VI) removal. The removal efficiency was not significantly affected by the changes in pH and presence of ions and humic acid. Direct spectroscopic analyses and density functional theory calculations revealed that ball milling with MFe2O4 destroyed the oxide film and increased the lattice spacing of mZVAl. The enhanced adsorption and reduction performances of ZVAl after ball milling was the primary reason for the improvement in Cr(VI) removal. This study presents a new pathway for the development of reductive materials for heavy metal removal in wastewater treatment.