A NOVEL THIN FILM COMPOSITE REVERSE OSMOSIS MEMBRANE MODIFIED BY IONIC LIQUID

摘要

ABSTRACT Thin Film Composite Reverse Osmosis (TFC RO) membranes have undergone significant changes since inception; particularly the top polyamide layer has been tuned for optimal performance. The present paper demonstrates the novel approach to alter the polyamide membrane performance by subjecting it to ionic liquids. Ionic liquids 1-Butyl-3-Methylimidazolium Chloride [BMIM][Cl], 1-Methyl-3-Octylimidazolium Chloride [C8MIM][Cl] and 1-Butyl-3-Methylimidazolium Bromide [BMIM][Br] were used to alter the membrane performance. About a 6.5% increase in MgSO4 rejection and about an 87% increase in water-flux were noted when the membrane was subjected to 3000 mg/L [BMIM][Cl] after 2000 mg/L sodium hypochlorite each for 2 hours. Also, the decline in contact angle from 52.86o to 43.12o by this treatment demonstrated higher hydrophilicity. Atomic force microscope images showed a decline in surface roughness with the treatment. Scanning electron micrographs were taken to understand the changes in morphology of thin film composite reverse osmosis membranes with ionic liquid treatment. Attenuated total reflectance, infrared spectroscopy and nuclear magnetic resonance analysis were done to evaluate the changes in chemical structure and it was found that the treatment resulted in chemical structural modification of thin film composite reverse osmosis membranes with ionic liquid treatment.