Preparation of hierarchically nanofibrous membrane and its high adaptability in hexavalent chromium removal from water

Removal of hexavalent chromium Cr (VI) from water is a key problem in environmental remediation due to its high toxicity. In this work, a special sol of iron alkoxide was first prepared and added into a polymer (thermal plastic elastomer ester (TPEE)) solution to form the electrospinning precursor, then for the first time, hierarchically nanofibrous membrane was fabricated by electrospinning technique combined with hydrothermal strategy. The synthesized membrane exhibited high efficiency for the removal of Cr (VI) from water. X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed that the resulting nanofibrous membrane posses high crystallinity as well as hierarchical structure. The controlled experiments results and X-ray photoelectron spectroscopy (XPS) characterization indicated that the Cr (VI) removal ability of the membrane was mainly attributed to the adsorption and reduction of Cr (VI)–Cr (III), which is much less toxic, because of the hierarchical structure and the exposed iron oxide active sites. The research of adsorption isotherm suggested that the adsorption of Cr onto the membrane was Freundlich adsorption, which further displayed that the main Cr (VI) removal was attributed to the reduction of Cr (VI)–Cr (III). Therefore, this study provides a promising hierarchically nanostructured membrane with desirable Cr (VI) removal ability and easy solid–liquid separation property.

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► The iron alkoxide was added into a polymer solution to form electrospinning precursor solution.
► Hierarchically nanofibrous membranes were fabricated by electrospinning via in situ growth.
► The obtained membranes show high Cr (VI) removal efficiency by adsorption and redox reaction.