Effective and selective adsorption of uranyl ions by porous polyethylenimine-functionalized carboxylated chitosan/oxidized activated charcoal composite

Composite materials have elicited much interest because of their superior performance in the removal of toxic and radioactive uranyl ions from aqueous solutions. With polyethyleneimine as a functional group, carboxylated chitosan as a matrix, and oxidizing activated carbon as a nanofiller, this study synthesized a novel environment-friendly polyethylenimine-functionalized carboxylated chitosan/oxidized activated charcoal (PCO) biocomposite with a unique three-dimensional porous structure. PCO was synthesized through an easy chemical cross-linking method. Detailed characterization certified the formation of the unique three-dimensional porous structure. The obtained PCO was used to remove uranyl ions from an aqueous solution, demonstrating the maximum adsorption capacity of 450 mg·g−1. The adsorption capacity of PCO decreased by less than 7.51% after five adsorption-desorption cycles. PCO exhibited good adsorption selectivity (Kd = 3.45 × 104 mL·g−1) for uranyl ions. The adsorption mechanism of PCO was also discussed. The material showed good potential for application in the treatment of wastewater containing uranyl ions.