A chitosan-graphene oxide/ZIF foam with anti-biofouling ability for uranium recovery from seawater

Abstract

Biofouling is the most affecting factor in the recovery of uranium due to the presence of large number of marine microorganisms in the seawater. Herein, a chitosan – graphene oxide/ZIF (GCZ8A) foam adsorbent with antifouling properties was prepared via in situ growth of silver ions doped ZIF-8 on a chitosan-GO foam substrate to overcome the challenges of traditional powder types for real applications. The mechanical properties and degradation tests was investigated to confirm that the GCZ8A adsorbent exhibited high mechanical properties with nearly 352.41 KPa of compression stress and low degradation with 3.26% of mass loss in seawater. Moreover, for Nitzschia, the GCZ8A composites not only displayed growth inhibitory behavior (more than 70% cell death rate), but also inhibited cell adhesion on its surface. The maximum U -uptake capacity of antibiofouling adsorbent (361.01 mg g−1) was 1.9 times than pure ZIF-8 (189.75 mg g−1) at pH 8.0, owing to its large specific surface area (200.79 m2/g) and nitrogen/oxygen functional groups. The adsorbent displayed an excellent reusability and achieved the 121.7 mg g−1 adsorption capacity at fifth cycles. Moreover, GCZ8A adsorbent exhibited high U-uptake capacity (12.24 μg g−1) with 66.31% of U (VI)-removal rate in natural seawater (Bohai, China). All of uranium removal rate of GCZ8A was nearly 70% in simulated contaminated seawater, which further affirmed its potential for actual application.