Design of ion-imprinted cellulose-based microspheres for selective recovery of uranyl ions.

ABSTRACT

Herein, cellulose was selected as the raw material for the production of sorbent microspheres for the selective separation of uranyl (UO22+) ions by ion-imprinting technique due to their low cost, biodegradability, and renewability. To begin, an amidoxime cellulosic derivative (AOCE) is synthesized by a Michael addition followed by an amidoximation reaction, both of which are homogeneous reactions. In the end, microspheres of ion-imprinted U-AOCE sorbent were made by mixing the developed AOCE derivative with UO22+, crosslinking the UO22+ polymer complex with glyoxal, and eluting the coordinated ions with H+/EDTA. U-AOCE smartly recognized the target ions for fitting the cavities generated during the UO22+-imprinting process, resulting in a much greater adsorption capacity of 382 ± 1 mg/g and enhanced adsorption selectivity for UO22+. A pseudo-second-order model fit the data well in terms of kinetics, while the Langmuir model adequately explained the isotherms, indicating chemisorption and adsorption via UO22+ chelation. The coordination between UO22+ and both the -NH2 and -OH groups of the amidoxime units is the primary adsorption process, as shown by NMR, XPS, and FTIR studies. For UO22+ biosorption from aqueous effluents, the results of this study deliver new guidance for the design of biosorbents with high removal capability and excellent selectivity.