Solvent desalination nanofiltration (SDNF) membranes with rigid microporous network

Solvent-resistant nanofiltration (SRNF) for desalination from organic solvent/water systems is crucial in electronics manufacturing. However, the development of high-performance membranes is persistently challenged by the trade-off between permeability and selectivity, along with issues of irreversible compaction and inadequate control over the interfacial polymerization (IP) process. To overcome these challenges, we engineered a high-performance solvent desalination nanofiltration (SDNF) membrane through the construction of a carboxylated microporous polymer (cPIM-1)/polyimide (PI) composite substrate, interfacial self-assembly of a cucurbit[6]uril-based host-guest selective layer, and a solvent-phase amination for enhanced rejection. The rigid skeleton of cPIM-1 significantly enhanced the compressive resistance of the composite membrane, resulting in a 10% reduction in flux decline. The abundant surface carboxyl groups promoted the adsorption of aqueous amine monomers through electrostatic interactions, enabling precise control over the IP process. This resulted in a selective layer with smaller pores (r p = 0.16 nm) and high negative surface charge (Zeta potential = -9.54 mV). The membrane demonstrated a MgSO 4 retention rate of 91.3% in a 30wt% N-methylpyrrolidone (NMP)/H 2 O solution, representing an approximately 30% improvement over the PI membrane without cPIM-1 doping. This study introduces a novel material design strategy for high-performance SDNF membranes, offering significant potential for the recovery of high-value components from electronic industrial waste streams.