Simultaneous reduction and sequestration of hexavalent chromium by magnetic β-Cyclodextrin stabilized Fe3S4

Abstract

In this study, β-Cyclodextrin (CD) modified Fe₃S₄ nanomaterials were synthesized by a one-step facile strategy and investigated for the removal of Cr(VI). The resulted CD-Fe₃S₄ exhibited enhanced removal efficiency toward Cr(VI) than bared Fe₃S₄ with a maximum capacity of 220.26 mg·g^-1 as the molar ratio of CD-to-Fe₃S₄ at 0.2. The effective performance of CD-Fe₃S₄ toward Cr(VI) could well maintain under oxic conditions and a wide pH range of aqueous solution. A high selectivity for Cr(VI) was achieved in the presence of coexisting cations and anions. More significantly, a single treatment step of CD-Fe₃S₄ effectively removed chromium from actual electroplating wastewater to the detection limit of 0.004 mg·L^-1 that far below the WHO limitation of Cr (VI) (<0.05 mg·L^-1) combing with the rapid magnetic separation without adjusting the pH value of wastewater at 7. The effective removal of Cr (VI) by CD-Fe₃S₄ involved a complex process of surface adsorption/reduction, and solution homogenous reduction and subsequent sequestration of Cr(III) achieving the effective removal of aqueous total Cr. The superior Cr (VI) removal capability and facial separation of CD-Fe₃S₄ attained its prominent potential application as an effective material for the Cr(VI) removal.

Keywords: Cr (Ⅵ) removal; Magnetic-separation; Mechanism; Reduction.