Preparation of 4-sulfonylcalix[6]arene modified Fe3O4 as adsorbent for adsorption of U(VI) from aqueous solution

The 4-sulfonylcalix[6]arene modified Fe3O4 (MFS) was characterized by FT-IR, SEM, VSM, TGA, etc., which showed that its saturation magnetization was 64.99 emu g−1 with the particle size 10–40 nm. The maximum adsorption efficiency by MFS for 2.5 mg L−1 U(VI) solution amounted to 94.39%, which was higher than that by Fe3O4 (65.22%) under its optimum adsorption conditions. The adsorption of MFS and Fe3O4 were both followed the pseudo-second order model and the Langmuir isotherm model. The Gibbs free energy change and enthalpy change revealed that the adsorption of U(VI) by MFS was a spontaneous and endothermic process.