Tuning the pore features of cellulose acetate/cellulose triacetate membranes via post-casting solvent treatment for forward osmosis.

In this study, solvent exchange method was applied as a post-casting solvent treatment to tune the porosity and improve the performance of cellulose acetate/cellulose triacetate forward osmosis (CA/CTA FO) membrane. Ethanol and n-hexane were both used for this treatment as the first and second solvent, respectively. Pristine and treated CA/CTA FO membranes with different thicknesses were characterized using FESEM and adsorption/desorption analysis and also evaluated in terms of the intrinsic transport properties and structural parameter, and performance. The results showed that the treated membranes contained more micropores and mesopores than the pristine membranes. Moreover, the treatment was able to increase reverse salt flux and pure water flux by 65 and 20 %, respectively. These improvements were due to the increase in selectivity (55 %) and the reduction in structural parameter (40 %). Hence, the proposed post-casting solvent treatment has been introduced as a method for improvement of the CA/CTA FO membranes performance.