Eco-friendly and cost-effective modification strategy for high-performance polyamide membranes: Synergistic regulation of interfacial tension reduction and diffusion inhibition

The eco-friendly and cost-effective regulation of interface polymerization (IP) reaction is an effective strategy to enhance the energy efficiency of nanofiltration (NF). In this work, a novel polyamide (PA) NF membrane was prepared by introducing glycerol-doped sugarcane cellulose nanofibers as a biomass composite interlayer. The optimized interlayer could modulate the water-organic interfacial tension and regulate piperazine (PIP) diffusion, thereby enabling a more controlled IP reaction. The optimized membrane (TFC-8) featured a more homogeneous and integrity PA separation layer with the thickness of only 25 nm. Compared to the control membrane, TFC-8 exhibited a lower zeta potential, reduced pore size, a narrower pore size distribution, and a high pure water permeance of 45.78 LMH/bar. Additionally, TFC-8 achieved a high monovalent/divalent anion selectivity of 160.38 in the treatment of dyeing wastewater and showed great potential in the removal of organic micropollutants. Molecular dynamics simulations and interfacial tension confirmed that the composite interlayer greatly improved the tension at the water-organic interface, promoting a more uniform trans -interfacial mass transfer process of PIP. Overall, this work represents a novel eco-friendly modification method for the preparation of homogeneous and structurally intact PA NF membranes for efficient separation of inorganic salts from wastewater.