Improving water desalination: Sustainable grafted cellulose acetate reverse osmosis membrane from Egyptian cotton

Abstract

Cellulose diacetate (CDA) and triacetate (CTA) were derived from Egyptian cotton to fabricate reverse osmosis (RO) membranes. The Pphase inversion method was utilized for the production of CDA‐based membranes. Comprehensive characterization of these membranes involved structural, morphologial, and hydrophilic property analyses through techniques such as nuclear magnetic resonance (NMR), infrared spectroscopy, thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle measurements. NMR spectra indicated a degree of substitution of 2.9 for CTA and 2 for CDA. The resulting RO membrane demonstrated a water flux of 6.1 L/m2·h and a salt rejection of 90.3%. Annealing led to an enhanced top layer with reduced defects and macrovoids in the support layer. Moreover, grafting the RO membranes with 15 wt% of 2‐acrylamidopropane‐2‐methyl sulphonic acid improved salt rejection to 96.2% and water flux to 8.7 L/m2.h. These findings underscore the significant performance enhancements achieved through both annealing and grafting processes in RO membranes.