Boosting the precise separation of specific molecules using molecularly imprinted membranes through the synergism of hierarchically structured porous and thin selective layers

Molecularly imprinted membranes (MIMs) offer significant promises for advanced water treatment due to their targeted separation capabilities. However, achieving simultaneously high permeability and selectivity in the separation of low-concentration target substances remain a major challenge. Herein, we designed and constructed novel metal-organic framework (MOF)-based hierarchical porous MIMs (MHP-MIMs) through a strategy that optimizes pore structure in conjunction with a thin selective layer. A polydopamine (PDA)-assisted assembly technique was developed to efficiently modify heterogeneous porous MOFs into a porous polyvinylidene fluoride (PVDF) substrate. The resulting hierarchically structured pores, combined with the thin imprinted layer, not only facilitate the formation of denser and more numerous imprinting recognition sites but also ensure their accessibility while reducing mass transfer resistance. Notably, the selective separation performance of the prepared MHP-MIMs exhibits a significant anti-trade-off effect, meaning that both the selectivity and flux of the membrane are simultaneously enhanced. Furthermore, the hierarchically structured pores endow the MHP-MIMs with improved selective separation performance during continuous separation processes, achieving efficient selective separation of ppm-level atrazine (ATZ) in simulated actual samples, with a separation efficiency for ATZ of 49.86 %. This proposed strategy provides novel insights for designing sophisticated MIMs to overcome the trade-off effect in the separation of low-concentration target substances.