γ-Radiation synthesis of bis-amidoxime-based three-dimensional hydrogel uranium adsorbent based on nano-rubber toughening

With the advancement of nuclear energy, the recovery and reuse of uranium pose extremely challenging tasks. This paper commences by toughening polyacrylamide (PAM) with nanorubber polybutadiene (PB) through the radiation-induced graft polymerization (RIGP) method, and diaminomaleonitrile (DAMN) is introduced and amidoximated, giving rise to a three-dimensional network hydrogel named as bis-amidoxime (AO) -based three-dimensional hydrogel uranium adsorbent based on nano-rubber toughening (PAM/PB/DAMN-AO). This hydrogel not only retains the favorable hydrophilicity and chemical stability of PAM but also experiences a significant enhancement in mechanical properties due to the addition of nanorubber PB. In the tests of 10 cyclic compressions (with a strain of ε  = 80 %), the compressive strength remains nearly unchanged, indicating a stable structure. During the amidoximation reaction and uranium-adsorption process, the pore structure of the hydrogel has been modified, evolving into a structure more conducive to uranium adsorption. In a 100 ppm uranium solution, the adsorption capacity reaches 154.4 mg·g −1 . The kinetic and isotherm models are evaluated, and the adsorption process is found to be more consistent with the pseudo-second-order kinetic model ( R 2  = 0.992) and the Langmuir adsorption isotherm model ( R 2  = 0.997). It exhibits high selectivity in the presence of competing ions and can still maintain an adsorption efficiency of over 90 % after 4 adsorption-desorption cycles, demonstrating excellent recyclability. The prepared hydrogel has a high adsorption capacity for uranyl ions and rapid adsorption kinetics, showing potential application prospects in the fields of nuclear wastewater treatment and uranium resource recovery.