Eco‐engineered cellulose triacetate/cellulose nanocrystal membranes for sustainable ultrafiltration of proteins and heavy metals

Abstract Background Cellulose nanocrystals (CNCs) have emerged as promising, renewable nanofillers for ultrafiltration (UF) membranes due to their low cost, hydrophilicity, and capacity to enhance mechanical properties. This study investigates the fabrication of cellulose triacetate (CTA) nanocomposite membranes using the eco‐friendly solvent dimethyl sulfoxide (DMSO), with poly (vinyl pyrrolidone). The goal was to evaluate the impact of CNC incorporation on membrane performance for the removal of bovine serum albumin (BSA) and heavy metals (cobalt and copper). Results A series of membranes with varying CNC content (0.5, 1, and 2 wt%) were fabricated via phase inversion. The incorporation of CNCs led to a more homogeneous surface and enhanced membrane hydrophilicity, which resulted in a substantial and consistent increase in pure water flux. The effect on solute retention, however, was dependent on the CNC loading and the target solute. While heavy metal (Co and Cu) retention improved, BSA retention exhibited a complex relationship, initially improving or remaining stable at lower CNC loadings but decreasing at the highest loading (2%), indicating a potential trade‐off between high permeability and selectivity for larger molecules. Conclusion The use of CNCs as nanofillers in CTA membranes significantly enhances hydrophilicity and water flux. However, the optimization of CNC concentration is critical, as excessive loading can compromise the retention of specific solutes like proteins. These findings underscore the potential of CNCs in sustainable membrane technology while highlighting the need for careful, application‐specific formulation to balance permeability and selectivity. © 2025 Society of Chemical Industry (SCI).