Removal of U(Ⅵ) From Aqueous Solution by Supported Zerovalent Zinc on GMZ-Sodium Bentonite and Investigation of Mechanism

It is the first time that zero-valent zinc(ZVZ), sodium bentonite(Na-bent) supported zero-valent zinc(ZVZ/Na-bent) and AlCl₃ solution pillars modified Na-bent supported zero valent zinc(ZVZ/Al/Na-bent) were prepared in our experiment. The effects on removing U(Ⅵ) from aqueous solution of ZVZ, Na-bent, ZVZ/Na-bent and ZVZ/Al/Na-bent were studied. The U(Ⅵ) adsorption mechanism of above four adsorbents was investigated by X-ray powder diffraction(XRD), scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) and X-ray photoelectron spectroscopy(XPS). The results show that ZVZ has a layered stack structure, which can be significantly eliminated by doping bentonite. The maximum adsorption capacity of uranium by ZVZ/Na-bent and ZVZ/Al/Na-bent are about 250 mg/g, while the adsorption capacity of ZVZ can be as high as 505 mg/g. All of the adsorption processes of the four adsorbents have positive ΔS, ΔH and negative ΔG, which are agreed well with the Langmuir model. The removal mechanism of U(Ⅵ) is mainly chemical reduction, hydrolytic precipitation and ion exchange.