New Insights into the Sorption and Detoxification of Chromium(VI) by Tetraethylenepentamine Functionalized Nanosized Magnetic Polymer Adsorbents: Mechanism and pH Effect

In this study, sorption and detoxification mechanisms of chromium(VI) by tetraethylenepentamine (TEPA)-functionalized nanosized magnetic polymer adsorbents, named as TEPA-NMPs, have been studied. Mechanisms of adsorption and solid state in situ redox of Cr(VI) at different pH were proposed based on batch tests, thermodynamic and kinetic studies, and XPS, XRD, and FTIR analyses of the adsorbents before and after Cr(VI) adsorption/desorption. The results showed that the adsorption of Cr(VI) on TEPA-NMPs could be related to electrostatic attraction, and partially formation of Cr(III) through solid state in situ reduction of Cr(VI) via charge transport on the surface of the TEPA-NMPs, and further coordination interactions between Cr(III) and amine groups (-NH2). The Fe3O4 magnetic core, C-O-C and C-OH groups in the adsorbents might play important roles during the redox process. TEPA-NMPs were testified to be potential adsorbents for detoxification of Cr(VI) with high efficiency.