AgNP-doped cellulose acetate-based nanofiltration membrane for enhancing antifouling performance and separation of dye and salt

In this work, an antimicrobial cellulose acetate composite nanofiltration membrane was successfully prepared via in-situ hybridization by anchoring silver nanoparticles (AgNPs) onto the surface of the cellulose acetate nanofiltration membranes for water treatment. DETA monomer was used as a reducing agent to reduce Ag⁺ in AgNO₃ to AgNPs, while the primary amine group of Diethylenetriamine (DETA) monomer can react with 1,3,5-Trimesoyl chloride (TMC) to form a polyamides layer. As a result, the cellulose acetate nanofiltration membranes modified by AgNPs exhibited smoother surfaces and improved hydrophilicity, which resulted in enhanced permeability and resistance to fouling. The flux of the membrane increased from 12 to 37.7 L/m²h, and the FRR values of the membrane increased from 98.4 to 100% respectively in 3.5 cycles. Owing to robust electrostatic interaction between AgNPs and carboxyl groups of the cellulose acetate support, the membranes showed stable separation performance. Over extended operational periods, the membrane retained 37.7 L/m²h of flux and 92% of Na₂SO₄ retention rate. Benefiting from the broad-spectrum antibacterial properties of silver, the membranes showed an excellent bactericidal rate of E. coli and S. aureus (> 99%). This work provided a new method for preparing cellulose acetate nanofiltration membranes with excellent antibacterial and separation performance. It also paved a new avenue to water treatment.