A New Approach to Provide High Water Permeable Polyethersulfone based Nanofiltration Membrane by Air Plasma Treatment

In this study, polyethersulfone based nanofiltration membranes were modified by air plasma generated through dielectric barrier discharge to increase the membrane hydrophilicity aiming to improve the separation and antifouling characteristics. The effect of plasma time on the physico-chemical and separation properties of membrane was investigated. The PES nanofiltration membranes were fabricated by the solution casting technique associated with phase inversion method. The FTIR spectra showed formation of imine and amine functional groups on the membrane surface. The water contact angle decreased form 58 ° to 31 ° by plasma treatment which produces more hydrophilic surface. SEM and SOM images demonstrated that the surface morphology was changed due to ions collision with membrane surface bombardment. AFM results indicated that membrane roughness was initially enhanced by plasma treatment up to 1 minute, and then decreased again by a further increase of treatment time. Membrane water flux increased from 10.05 (L/m2.h) to 35.17 (L/m2.h) remarkably by plasma treatment up to 1 minute and then decreased again at longer treatment times. An opposite trend was observed for the salt rejection of membranes. The water flux was enhanced ~270% for the modified membrane at 2 min plasma treatment whereas rejection declined less than 18%.