NH2-grafting on micro/nano architecture designed PS/TPU@SiO2 electrospun microfiber membrane for adsorption of Cr(VI)

Abstract

Removal of hexavalent chromium [Cr(VI)] from surface water is a key problem in environmental remediation due to its carcinogenicity and mutagenicity to living organisms. In this work, we developed an effective adsorbent for Cr(VI) removal by incorporating SiO2 nanospheres into electrospun microfiber membrane (polystyrene/thermoplastic polyurethane) and then modifying with amine-terminated organosilicon (3-aminopropyltriethoxysilane, APTES). The obtained aminated composite microfiber membranes exhibited unique multi-dimensional micro/nano architecture and possessed high adsorption capacity and removal efficiency for Cr(VI). Results shown that the adsorption capacity can reach 57.73 mg g-1, moreover, removal efficiency could be maintained over 60% after three cycles of regeneration. Interestingly, the SiO2 nanospheres were distributed along the polymeric microfiber uniformly, which created more surface hydroxyl groups interacted with amine groups (-NH2), leading to more active -NH2 terminal groups graft on the membrane surface and higher Cr(VI) adsorption capacity. Furthermore, the incorporation of SiO2 nanospheres did not deprive the flexibility of electrospun microfiber membranes. The results provided new insights for the removal of heavy metal ions by multi-scaled micro/nano structured fibrous membranes from wastewater with high adsorption capacity and well recyclability.