Photocatalytic anti-biofouling coatings with dynamic surfaces of hybrid metal-organic framework nanofibrous mats for uranium (VI) separation from seawater

Abstract

• Anchoring ZIF-8 by polyphenol-metal coordination, covalent and noncovalent bonds. • Self-renewing ZIF-8/TA coatings with zinc-ions-releasing and ROS-producing abilities. • Synergetic uranium adsorption by pyrogallol, amidoxime, and imidazole groups. For the commercial development of nuclear technology, the isolation of uranyl ions from sea water becomes a strategic key work. However, a major challenge remains in uranium extraction to resist marine biofouling, through suppressing microorganisms' growth and adhesion on the surface of the adsorbent. In this study, by introducing a hydrolyzable tannic acid (TA) cross-linked coating with dynamic surface, we synthesized a self-polishing hybrid zeolitic imidazolate framework-8 (ZIF-8)/amidoximed polyacrylonitrile (AOP) nanofibrous mat (AOP@ZIF-8/TA) that has durable and outstanding anti-fouling performance. Subsequently, a variety of batch adsorption tests have been undertaken to determine the efficiency of the adsorbent. As a result, the maximum uranium-adsorbing capability of 1387.37 mg/g could be acquired at pH 5.0, and the sorption of uranium was not influenced by other co-existing ions. AOP@ZIF-8/TA mat also showed a long service life with favourable sorption capability after at least 5 adsorption-desorption cycles. Most importantly, the prepared hydrolyzable ZIF-8/TA coatings with zinc-ions-releasing and ROS-producing abilities form a dynamic self-renewing surface and contribute to high resistance to biofouling. After a 25‐day uptake measurement in natural sea water, the uranium sorption equilibrium was reached with the maximal adsorption capability of 11.17 mg·g −1 . Therefore, the self-peeling surface coating has the promise to be used in the production of U(VI)-binding antibiofouling adsorbents in the raw seawater.