Immobilization of in-situ formed Ni(OH)₂ nanoparticles in chitosan beads for efficient removal of U(VI) from aqueous solutions

Both metal hydroxides and chitosan have been recognized as effective scavengers for nuclide ions. However, the aggregation of metal hydroxides and the weak mechanical strength of chitosan beads greatly restricts their application. Herein, the in-situ formed Ni(OH)₂ nanoparticles was immobilized in chitosan matrix to obtain a novel hybrid sorbent (CSNi) for U(VI) adsorption. The CSNi showed high affinity for U(VI) sorption, with the inner-sphere complexation as the main mechanism. The maximum mono-layer adsorption capacity for U(VI) at 298 K reached 164.2 mg/g. The U(VI) sorption was endothermic and spontaneous, and kinetically followed the pseudo-second-order model. These findings highlight the possibility of using CSNi for efficient removal of U(VI) from wastewater. (author)