Highly porous cellulosic nanocomposite membranes with enhanced performance for forward osmosis desalination

Abstract

Novel highly porous cellulose triacetate (CTA)/cellulose acetate (CA) blends were fabricated as flat sheet membranes, for water desalination using the forward osmosis (FO) procedure. Maleic acid (MA) was used as a pore-forming additive and as a polymeric modifier in combined casting. The aluminum oxide nanoparticles (Al2O3) (NPs) were used for the modification of MA/CTA/CA membrane performances. The synthesized FO membranes are characterized by FTIR spectroscope, contact angle measurement, membrane porosity, SEM, AFM, and mechanical properties. The Al2O3/MA/CTA/CA nanocomposite (NC) modified membrane showed a higher water flux of 27.1 L/m2 h, reverse solute flux of 10.3 g/m2 h, and lower salt rejection of 99.15% using 1 M NH4Cl water solution as the draw solution and 0.1 M NaCl as feed solution. The Al2O3/MA/CTA/CA nanocomposite modified membrane shows a higher porosity (60.3 ± 2), a lower contact angle (55°), and its reduced structural parameter (S) to 0.87 mm. The results revealed that the Al2O3/MA/CTA/CA nanocomposite modified membrane showed the highest water flux using 1 M of the KCl and NH4Cl (20 L/m2 h); followed by (NH4)2SO4 (19.7 L/m2 h) and K2HPO4 (17.6 L/m2 h) as draw solutions (DS) under the FO approach and using natural groundwater sample collected from Al-Zafer village, Sidi Barrani Area, north-western coast of Egypt with salinity of 8536 mg/L as feed solution (FS). It was revealed that the synthesized Al2O3/MA/CTA/CA nanocomposite modified membrane has great potential for application of FO process in brackish water desalination. The current cost per m2 of an Al2O3/MA/CTA/CA nanocomposite modified membrane is AU$ 32/m2 when compared with the commercial FO membrane (AU$ 188/m2).