Ultrahigh sorption and reduction of Cr(VI) by two novel core-shell composites combined with Fe3O4 and MoS2.

• Core-shell Fe 3 O 4 @MoS 2 and MoS 2 @Fe 3 O 4 composites were synthesized. • Both Fe 3 O 4 @MoS 2 and MoS 2 @Fe 3 O 4 showed high removal capability for Cr(VI). • Both Fe 3 O 4 @MoS 2 and MoS 2 @Fe 3 O 4 are superparamagnetic. • Fe 3 O 4 @MoS 2 and MoS 2 @Fe 3 O 4 are eco-friendly during the synthesis process and wastewater treatment. • Synergetic reduction makes F@M an outstanding material for Cr(VI) removal. In this investigation, two novel magnetic core-shell Fe 3 O 4 @MoS 2 (F@M) and MoS 2 @Fe 3 O 4 (M@F) composites were synthesized and exploited for Cr(VI) elimination. Eco-friendly preparation methods were applied for the synthesis of Fe 3 O 4 and MoS 2 composites. The experimental results showed that both F@M and M@F have high saturation magnetization values (43.2 emu/g for F@M and 49.9 emu/g for M@F), excellent maximum sorption capacities of Cr(VI) at pH 5.0 and 298 K (324.3 mg/g for F@M, 290.2 mg/g for M@F), remarkable Cr(VI) removal efficiencies (Cr(VI) sorption equilibrium by both F@M and M@F can be reached in 90 min) and nice regeneration properties (the sorption capabilities of F@M and M@F decreased slightly after five consecutive sorption/desorption cycles). Chemical reduction of Cr(VI) to Cr(III) occurred on the surface of F@M and M@F, and the synergetic reduction of sulfur and ferrous ions made F@M an outstanding material for Cr(VI) removal. This paper highlights F@M and M@F as potential, eco-friendly and ultrahigh-efficiency materials for Cr(VI) pollution cleanup. [ABSTRACT FROM AUTHOR]