Magnetic Fe3O4-FeS nanocomposites with promoted Cr(VI) removal performance

In this study, amorphous FeB alloy modified magnetite nanocomposites (Fe3O4-FeB) were facilely synthesized by interfacial reduction of commercial Fe3O4 nanoparticles with NaBH4. TEM, CS-STEM integrated with EDS, Mossbauer spectroscopy analysis confirmed the formation of Fe3O4-FeB, where a shell of amorphous FeB nanoparticles with 2-4 nm in size was surrounded on the inner magnetite Fe3O4 part. Fe3O4-FeB displayed a promoted Cr(VI) removal efficiency compared with the bare Fe3O4 counterpart, the interfacial reduced Fe3O4 nanoparticles with hydrogen and/or with hydrazine hydride. XPS analysis evidenced that reduction of Cr(VI) on surface of the Fe3O4-FeB was the major contribution to the Cr(VI) removal. Tafel polarization analysis of the Fe3O4-FeB and aqueous boron species measurement indicated that high Cr(VI) removal efficiency with Fe3O4-FeB was highly depended on amorphous FeB alloy shell, in which boron element containing free electrons could accelerate the electron transfer from Fe to the adsorbed Cr(VI), as well reduce Fe(III) to Fe(II) and thus promote the Fe(III)/Fe(II) cycles. The efficient Cr(VI) removal under a wide range of pH values and its easy magnetic separation make the Fe3O4-FeB be a potential for Cr(VI) contaminated water treatment. (C) 2015 Elsevier B.V. All rights reserved.