Integrated approach to elevating PES membrane performance with a dynamic silica and chitosan additive duo

Abstract

Membrane fouling, low permeate flux, and the trade-off between flux and solute rejection remain pressing challenges in ultrafiltration processes, often compromising efficiency and selectivity. In this work, we highlight a novel dual-additive approach by combining silica and chitosan to enhance the performance of polyethersulfone (PES) ultrafiltration membranes. Membranes were fabricated via Non-Solvent Induced Phase Separation (NIPS) in which the modification was performed by blending technique using different combinations of these additives. The prepared membranes were characterized for their morphological structure, surface chemistry, porosity, hydrophilicity, tensile strength, pure water flux, solute rejection, and fouling resistance. The results demonstrate that the combined addition of silica and chitosan significantly improves membrane properties. Compared to single-additive modifications reported in recent studies, membranes modified with both additives showed an increase in porosity by up to 49.34 %, reducing the water contact angle to 61°, indicating enhanced hydrophilicity due to the enriched presence of hydroxyl groups. The modified membranes exhibited a remarkable 25-fold improvement in pure water flux (up to 57.8 L/m²·h) compared to the unmodified PES membrane, while maintaining a high solute rejection of 81 %. The flux recovery ratio of nearly 80 % highlights the enhanced fouling resistance. Overall, this dual-additive strategy offers a robust approach to tackle fouling and achieve a better balance between flux and selectivity, paving the way for more efficient ultrafiltration processes.