A robust polyethyleneimine-based supramolecular hydrogel towards uranium adsorption and deposition

Polymer hydrogels, with abundant ion diffusion paths, are promising for uranium capture in aqueous solutions. Herein, a robust supramolecular hydrogel with superior structural stability and mechanical strength is fabricated under acidic conditions via hydrogen bonding interactions between polyethyleneimine and cellulose nanofibers. The supramolecular hydrogel has a maximum uranium uptake capacity of 641 mg-U/g at pH= 7, together with a high tolerance towards interfering metal cations. The uranium uptake proceeds via adsorption and subsequent deposition; in the latter the adsorbed uranyl ions are partially combined with local hydroxide ions induced by polyethyleneimine. The supramolecular hydrogel, with the merits of easy fabrication and cyclic utilization, has great potentials for uranium removal and recovery from uranium-containing wastewater.