Polyamide composite membranes for enhanced organic solvent nanofiltration performance by metal ions assisted interfacial polymerization method

Abstract Herein, thin‐film composite membranes consisting of poly(m‐phenyleneisophthalamide) substrate and polyamide active layer were constructed by transition metal ion‐assisted interfacial polymerization method. As compared to the traditional polyamide membranes, a much thinner polyamide layer (33 vs. 200 nm) can be synthesized with higher permeance (3.2 vs. 0.62 L m −2 h −1 bar −1 ) in the organic solvent nanofiltration. Similarly, the prepared membranes maintained a high rejection (>99%) for various dyes. Optimal membranes prepared by using Co 2+ exhibited strong tolerance to various organic solvents with good long‐term stability. Positron annihilation spectroscopy and other characterization methods were used to investigate the relationships between the membrane microstructures and the enhanced separation performance. Based on molecular dynamics simulation, it was found that the diffusion coefficient of polyethyleneimine monomer decreased by about 18 times after adding Co 2+ to the aqueous solution (forming coordination interaction). This procedure has great potential and sustainability for practical organic solvent nanofiltration applications.