Enhancing PES ultrafiltration membranes with amphiphilic copolymer for improved dye and salt removal in textile wastewater

The development of ultrafiltration membranes with integral sponge-like structures is essential for efficient dyes and salts removal from textile wastewater. However, enhancing antifouling performance while controlling the formation of full sponge-like structures remains challenging. In this study, an amphiphilic copolymer (PVP-PS) was successfully polymerized and blended with PES via a single step phase inversion process, using N -vinylpyrrolidone (NVP) and styrene (St) as additives. Unlike single-monomer modifications that suffer from poor modifier retention or limited structural tunability, this dual-monomer strategy precisely regulates the hydrophilic-hydrophobic balance. By optimizing the ratio of hydrophilic/hydrophobic monomers, an entirely spongy-like membrane morphology was achieved. Scanning electron microscopy (SEM) confirmed the formation of the pore structure, while Fourier transform infrared spectroscopy (FTIR) verified the successful incorporation of the PVP-PS copolymer. The optimized membrane, designated S-M0.5, exhibited a water flux of 711.5 L‧m −2 ‧h −1 and excellent antifouling performance with a FRR exceeding 90%. When applied to separate a dye/salt mixture containing 2.5 g‧L −1 Na 2 SO 4 and 200 ppm Congo red (CR) at 1 bar, S-M0.5 achieved a high CR rejection rate of 98.38% alongside a low Na 2 SO 4 rejection rate of 9.86%, and a stable dye solution permeability of 83.6 L‧m −2 ·h −1 . These results highlight the potential of the developed membrane for practical textile wastewater treatment.