Functionalization of mesoporous Fe3O4@SiO2 nanospheres for highly efficient U(VI) adsorption

Novel mesoporous Fe3O4@SiO2 nanospheres (MSN) functionalized with N/O-containing groups (MSN-DA and MSN-DATA) were prepared and characterized. Both MSN-DA and MSN-DATA were core-shell magnetic nanospheres, and they had high affinity for U(VI) sorption. The XPS analysis indicated that U(VI) sorption on both sorbents (MSN-DA and MSN-DATA) was mainly through the inner-complexation mechanism, but for MSN-DATA, cation-exchange also played a significant role. The maximum sorption capacities reached 139.1 mg/g for MSN-DA and 103.9 mg/g for MSN-DATA. Both the functionalized sorbents exhibited fast sorption rate, excellent selectivity to co-existing cations, and good reusability for uranium sorption, however, MSN-DA was more effective for U(VI) sorption (compared to MSN-DATA) due to less molecular hindrance and more amine/amino groups for chelating U(VI). These findings indicated that MSN-DA and MSN-DATA could be potentially used for the efficient sorption/separation of U(VI) from wastewater.