Polyethyleneimine assisted zeolitic imidazolate frameworks foam embed silver to enhance the uranium recovery from seawater

Abstract

The powder structure, poor surface wettability and biofouling significantly limited the application potential of ZIFs (zeolitic imidazolate frameworks) in uranium extraction from seawater. Herein, a superhydrophilic polyethyleneimine assisted zeolitic imidazolate frameworks foam embed silver (CPEZ8A) was successfully prepared by simple chemical cross-linking and in-situ growth methods to explore the effects of hydrophilic matrix and silver antimicrobial agent on the uranium adsorption properties of ZIFs materials. The mechanical property and water contact angle test of CPEZ8A foam were performed to confirm its higher compression stress (with 1.314 MPa) and surface superhydrophilic. Moreover, CPEZ8A foam displayed an excellent resistance to biological attachment after 7 days in algae solution. Importantly, CPEZ8A showed the maximum U (VI) uptake capacity (775.19 mg/g) with 4.37 times of pure ZIF-8 at nearly seawater pH and retained relative high U-uptake amount during the broad pH range (4.0–9.0). Ion competition experiments were also investigated to verify the CPEZ8A foam excellent selectivity (Kd = 15,072.1 mL/g). Notably, the removal rate of CPEZ8A foam reach 81.31 % in natural seawater and remain nearly 80 % in simulated contaminated seawater. Therefore, this work provides an effective strategy to develop highly efficient ZIFs adsorbents for uranium capture.