A novel magnetic functionalized m-carboxyphenyl azo calix[4]arene symmetric sulfide derivative: synthesis and application as a selective adsorbent for removal of U (VI)

A novel adsorbent magnetic functionalized m-carboxyphenyl azo calix[4]arene symmetrical sulfide derivative (Fe 3 O 4 /M-CCSSD) was fabricated by a series of simple reactions and characterized by FT-IR and SEM. The effects on U (VI) adsorption process were investigated at several conditions. The calculated data disclose that the adsorption process of U (VI) by Fe 3 O 4 /M-CCSSD is an endothermic spontaneous process, which well fits with the pseudo-second-order kinetic and Freundlich isotherm model. In the most favorable conditions, accounting for approximately 89% of U (VI) was removed. In addition, Fe 3 O 4 /M-CCSSD showed high selectivity for U (VI) and exceptional reusability.