Recent progress in developing 2D MOFs/COFs/Zeolites nanosheets membranes for water purification

Membrane-based separation is an essential part of water purification, however, traditional polymeric membranes suffer from a trade-off limitation between selectivity and permeability. In recent years, owing to high porosity and adjustable pore structure, 2D metal-organic frameworks (MOFs), covalent-organic framework (COFs), and zeolites exhibit promising potential in the separation membranes to break the trade-off law. In this comprehensive review, we endeavour to present the state-of-art progress on 2D MOFs, COFs and zeolites nanosheets as ideal candidates for membrane separations with a particular emphasis on the water-related applications. Recent researches on the typical fabrication methods for the above 2D porous nanosheets are summarized. The assembling strategies into pure 2D porous membranes involve in-situ growth and layer stacking assembly, while 2D MMMs normally employ phase-inversion or interfacial polymerization methods. Subsequently, particular attention is devoted to introduce the latest advances on these novel membranes for water-related separation processes, including desalination, heavy metals removal, oil/water separation, dyes, pharmaceutical and agricultural pollutants separations. Finally, challenges and future perspective for the industrial implementation of these membranes are pointed out. This review is expected to provide an insight view for the production and applications of highly efficient 2D porous membranes in water-related separations.