Synthesis of amino acid modified MIL-101 and efficient uranium adsorption from water

Three novel uranium adsorbents were synthesized by modifying MIL-101 with three amino acids: glycine, histidine and cysteine. The BET (Brunauer-Emmett-Teller) specific surface areas of amino acid modified MIL-101 (MIL-101-Gly, MIL-101-His and MIL-101-Cys) are 429 m2∙g−1, 713 m2∙g−1 and 104 m2∙g−1, respectively, indicating that the modified MIL-101 retained high specific surface area. All the modified MIL-101 s showed good uranium adsorption performance, in which the uranium adsorption performance of MIL-101-His is the best that can reach 345 mg·g−1 at pH = 6. The adsorption process of three amino acid modified MIL-101 s all accord with Langmuir and pseudo-second-order model for monolayer chemical adsorption. In the existence of K, Ca, Na, Sr, Ba, Cd, Co and Pb, the uranium (VI) removal rate of MIL-101-His can reach 74% indicating its excellent selectivity. After five adsorption–desorption cycles, the adsorption capacity of MIL-101-His still remains good capacity of 300 mg·g−1. In short, we prepared three novel amino acid modified MIL-101 s, and the histidine modified MIL-101 showed the best uranium adsorption performance, including adsorption capacity, selectivity and recyclability.