PREPARATION AND CHARACTERIZATION OF NANO-SILICA DIOXIDE MODIFIED CELLULOSE ACETATE MEMBRANES FOR FORWARD OSMOSIS

Nano-silica dioxide (nano-SiO2) modified cellulose acetate (CA) membranes for forward osmosis (FO) were prepared by phase inversion via immersion precipitation technique. Nano-SiO2 particles were added into the casting solution of CA, 1, 4-dioxane, acetone, lactic acid and methanol to improve the FO membranes performance. Different percentage of nano-SiO2 (2, 4 and 6 wt. %) of CA composite membranes were cast. The modified membranes were characterized by various methods to probe the membranes structure and surface properties. The FO performances were also evaluated for the modified membranes compared to the non nano-SiO2 membranes. The surface hydrophilicity, porosity and tensile strength of nano-SiO2 CA membranes were improved with the increase of the percentage of nano-SiO2 added to the CA. The morphological studies showed that the addition of nano-SiO2 significantly changed the surface properties of the modified CA membranes compared to CA membranes without nano-SiO2. The FO performance was evaluated using 1M NaCl solution asdraw solution and purified water as feed solution. The nano-SiO2 CA membranes showed better water permeability and salt rejection in the range of 2~6 wt. % nano-SiO2 content than original CA membranes. These encouraging results suggested that nano-SiO2 CA membranes displayed potential to be further developed for FO applications.