Ion cross-linking assisted synthesis ZIF-8/chitosan/melamine sponge with anti-biofouling activity for enhanced uranium recovery

Micro/mesoporous powders structure and marine microorganisms biofouling directly limited the potential of ZIFs in uranium recovery from seawater. Herein, an anti-biofouling ZIF-8/chitosan/melamine sponge adsorbent (CFZ8) with three-dimensional porous structure was successfully prepared. The adsorbent was achieved via using zinc ions and chitosan as pre-crosslinking agents to promote the growth of ZIF-8 on the surface of melamine sponge. The mechanical and anti-biofouling properties of sponge was determined by the compression and algae tests. Relative to the ZIF-8 powders, the CFZ8 sponge exhibited superior mechanical and anti-biofouling properties with 0.565 MPa of compressive stress and 35% of algae cell death rate. The adsorption capacity of CFZ8 sponge was 129.90 mg/g at pH 8.0 and 95.47 mg/g at the fifth adsorption-desorption cycle, which were higher than that of ZIF-8 powder (91.45 mg/g). Furthermore, the excellent low-concentration U(VI) adsorption performance of CFZ8 at natural seawater (Bohai) also confirmed its practical application potentiality.