Photo-polymerization as a new approach to fabricate the active layer of forward osmosis membrane.

A novel approach is employed to prepare the active layer of the forward osmosis membrane by the photo-polymerization method. The poly (ethylene glycol) phenyl ether acrylate (PPEA) and methacrylic acid (MAA) are used as monomers. The emphasis is given to analysing the effect of monomer concentration on chemical functional groups of active layer, thermal stability, surface morphology, roughness, interfacial free energy, organic fouling tendency and osmotic flux performance. The functional groups of the active layer are characterized by ATR-FTIR. Furthermore, thermal analysis (TGA/DTG) is performed to calculate grafting density and thermal stability of prepared FO membranes. Surface morphology and roughness are characterized by atomic force microscopy (AFM). Unlike control polyamide active layer membrane that suffered from organic fouling (28.14 ± 3.70% flux decline and 95% flux recovery), the photo-polymerized 75/25 active layer FO membrane demonstrated the low fouling propensity (2.77 ± 0.62% flux decline) and high flux recovery (nearly ~100%). The interfacial free energy and low fouling property of 75/25 FO membrane is also reflected in improved osmotic flux performance with 11.20 ± 0.79 L/g (AL-FS) and 8.41 ± 0.22 L/g (AL-DS) reverse solute flux selectivity (RSFS) (J/J) than control polyamide FO membrane (7.94 ± 0.22 L/g (AL-FS) and 7.64 ± 0.54 L/g (AL-DS)).