4-Sulfonylcalix[6]Arene Modified Fe3O4@Aspergillus Niger Biosorbents for Effective Removal of Uranium(VI) from Aqueous Solutions

: A biosorbent, 4-sulfonylcalix[6]arene modified Fe₃O₄@Aspergillus Niger (MFSC), was successfully prepared through a two-step route for the effective removal of uranium (U(VI)) from aqueous solutions with high selectivity. The structure of MFSC was characterized by FT-IR, SEM, XRD, TGA and VSM, respectively. The impacts of various experimental parameters were investigated in detail. The results indicated that the biosorption of U(VI) on MFSC was mainly attributed to the electrostatic attraction (91% within 8 hours for U(VI)). The adsorption kinetics and adsorption isotherm of U(VI) were found to follow the pseudo second-order model and to be fitted by the Langmuir model, respectively. The thermodynamic parameters revealed that the adsorption process was spontaneous and endothermic. The findings herein highlight the MFSC with high ability for removal of U(VI) from aqueous solutions.