Effective adsorption and immobilization of Cr(VI) and U(VI) from aqueous solution by magnetic amine-functionalized SBA-15

Herein, a magnetic amine-functionalized mesoporous silica SBA-15 (Fe3O4@SBA-15-PDA/HBP-NH2) adsorbent was fabricated by loading Fe3O4 nano-particles on amino-terminated hyperbranched polymers (HBP-NH2) functionalized SBA-15 and exploited for chromium (VI) and uranium (VI) elimination. The morphologies and microstructures of as-obtained materials were observed using different physicochemical and spectroscopic techniques. Meanwhile, batch experiments were performed to investigate the impacts of various water environment conditions on removal process including solution pH, equilibrium time and temperatures. The maximum adsorption capacities of U(VI) and Cr(VI) on Fe3O4@SBA-15-PDA/HBP-NH2 reached up to 77.4 mg/g and 66.5 mg/g under optimal water environment conditions. Moreover, the characterization analysis manifested that removal of U(VI) was fulfilled through the surface complexation with amino and phenolic hydroxyl groups, while Cr(VI) were firstly electrostatically adsorbed, and subsequently reduced to less toxic Cr(III) by phenolic hydroxyl groups. These findings demonstrated that this new magnetic amine-functionalized SBA-15 could be considered as valuable materials in environmental cleanup.