Preparation of Free-Standing Defect-Free ZIF-8/PVA Membranes via Confined Reaction at the Quasi-Interface

Developing a facile strategy to synthesize free-standing defect-free metal-organic framework (MOF) membranes with high separation selectivity and good mechanical stability is very appealing but challenging. Herein, by confining the reaction of metal and ligand at the quasi-interface, a representative membrane composed of a continuous ZIF-8 layer and poly(vinyl alcohol) (PVA) was fabricated. The continuous ZIF-8 layer endowed the membrane with high separation efficiency, while PVA acted as a filler to eliminate the defection, synergistically achieving high selective ion transport and good mechanical stability. The continuous defect-free ZIF-8/PVA membrane showed excellent separation performance of selective ion transport with high Li+ permeance of 17.83 mol·m-2·h-1 as well as decent Li+/Mg2+ and Li+/Ca2+ selectivities of 24.60 and 244.58, respectively. The separation performance of the ZIF-8/PVA membrane remained stable after 10% strain, indicating its good mechanical stability. This work will promote the development of MOF-based membranes in practical applications.