Removal of uranium contaminant from aqueous solution by chitosan@attapulgite composite

The low cost chitosan@attapulgite composite (CS@ATP) were prepared by self-assembly method and applied for U(VI) removal from aqueous solutions. Scanning Electron microscopy (SEM) images showed the uniform decoration of chitosan (CS) on attapulgite (ATP) surface. X-ray diffraction (XRD) patterns indicated that the coating of chitosan altered the structure of ATP to some extents. Batch sorption results showed that sorption ability of ATP toward U(VI) was greatly improved after CS modification above pH 5.0. The ionic strength independent sorption suggested that inner-sphere U(VI) complexes were formed by mainly bonding to the oxygen-containing functional groups of CS@ATP. In the presence of humic substances, U(VI) sorption on CS@ATP was obviously enhanced under acidic conditions, while restrained in alkaline condition. Moreover, the presence of humic acid provoked the desorption of U(VI) from CS@ATP to a certain extent. These findings herein suggested that CS@ATP composite is a potential and suitable candidate for the preconcentration and separation of U(VI) from contaminated natural wastewater and aquifer.