Synthesis and characterization of uranyl ion-imprinted microspheres based on amidoximated modified alginate

Surface ion-imprinting technique was utilized for the preparation of surface ion-imprinted chelating microspheres based on amidoximated modified alginate (U-AOX) in presence of uranyl ions as a template and glutaraldehyde cross-linker. Different instrumental techniques such as elemental analysis, scanning electron microscope (SEM), FTIR, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction spectra were employed for full investigation of the manufactured materials. The synthesized microspheres displayed a higher ability for selective extraction of UO22+ when compared to the non-imprinted microspheres (NI-AOX). In addition, the essential parameters such as pH, temperature, time and initial uranyl ion concentration were evaluated in order to optimize the conditions of the adsorption process. The results indicated that pH 5 was the best for the UO22+ removal, also, the adsorption was endothermic in nature, follows the second-order kinetics and the adsorption isotherm showed the best fit with Langmuir model with maximum adsorption capacity of 155 ± 1 and 64 ± 1 mg/g for both U-AOX and NI-AOX respectively. Desorption and regeneration had been carried out using 0.5 M HNO3 solution and the results indicated that the microspheres maintained about 96% of its original efficiency after five consecutive adsorption-desorption cycles.