In situ growth of two-dimensional ZIF-L nanoflakes on ceramic membrane for efficient removal of iodine

Abstract

Radioactive pollutants are in places a serious environmental pollution problem. By virtue of their structural diversity and tunability, two-dimensional (2D) zeolitic imidazolate frameworks-L (ZIF-L) have shown a promising ability for pollutant removal by adsorption. For the first time, we propose a 2D ZIF-L assembled on and in a microporous ceramic membrane for efficient removal of iodine via seed-assisted in situ growth. It is challenging to customize inner pore channels of ceramic membrane due to its irregular structure. This work provides new insights into the crystallographic growth of ZIF-L on the inner irregular pore channels and a homogenous ZIF-L layer on porous silicon carbide (SiC) membranes. The resulting hybrid membrane contains highly loaded ZIF-L nanoflakes on the surface and pore channels of the SiC membrane. These multilayers structure and ZIF-L@SiC synergistic features provide more active sites and improve the mass transfer of molecular iodine dissolved in cyclohexane, thereby enhancing removal efficiency. The removal efficiency of iodine using the hierarchically nanostructured ZIF-L@SiC hybrid membrane is near 100% and 96% at a flux of 9.37 × 103 L m−2 h−1 with iodine/cyclohexane concentrations of 5 mg L−1 and 50 mg L−1, respectively. This porous adsorption membrane, with excellent separation and adsorption capacities for iodine, opens a new way for radionuclide adsorption.