Water purification through nanofiltration membranes holds immense potential, yet challenges like fouling and limited hydrophilicity often hinder their performance. In this study, we crafted mixed-matrix nanofiltration membranes using polyethersulfone (PES) as the base material, employing the phase inversion method. To enhance the membrane’s properties, we incorporated functionalized activated carbon-chitosan (AC-CS) nanoparticles at ultra-low concentrations ranging from 0.001 to 0.1 wt%. Both the nanoparticles and membranes underwent thorough characterization through techniques such as SEM, FTIR, EDX, contact angle measurements, porosity tests, water flux, salt rejection, and antifouling assessments. The results were striking: our modified membranes showed a remarkable increase in water flux and improved salt rejection, rising from 55% in the unmodified membrane to over 71% for sodium sulfate at optimal nanoparticle loadings (0.001 and 0.01 wt%). Hydrophilicity also saw a dramatic boost, with the water contact angle dropping from 50° to just 14°. Among the tested samples, the membrane with 0.001 wt% activated carbon-co-chitosan nanoparticles stood out, delivering an exceptional balance of permeability, selectivity, and antifouling performance (FRR > 98%). This work highlights a cost-effective and innovative approach to optimizing nanoparticle concentrations for designing high-performance nanofiltration membranes, paving the way for sustainable water treatment solutions.
