(387e) Fabrication and Positron Annihilation Spectroscopy (PAS) Characterization of Cellulose Triacetate Membranes for Forward Osmosis

Cellulose triacetate (CTA) has been extensively used as membrane material for reverse osmosis (RO) and forward osmosis (FO) applications. Membranes fabrication from CTA is easy and straightforward as compared to that of many other types of membranes such as thin-film composite (TFC) membranes. Its excellent hydrophilicity and selectivity properties make CTA a very popular candidate as membrane material for water treatment. Furthermore, its excellent resistance towards chlorine attack makes CTA ideal as a membrane material since most water treatment processes undergo chlorine treatment. As cellulose acetate (CA) is notoriously famous for its susceptibility towards hydrolysis and bacteria attack, CTA is a good substitute for CA for the FO applications as CTA shows a better tolerance towards bacteria attack and hydrolysis under higher pH range. The fundamental engineering and science of CTA membrane formation were explored by casting the membranes from different solvent systems and characterizing the membranes’ morphology using advanced tools such as positron annihilation spectroscopy (PAS). N-methyl-2-pyrrolidone (NMP) and dioxane were used as the solvents for CTA in the membrane fabrication process. It was found that the choice of solvents for membrane fabrication significantly affects the morphology of as-cast membranes and their FO performance.