GO/PVA-integrated TFN RO membrane: Exploring the effect of orientation switching between PA and GO/PVA and evaluating the GO loading impact

In this work, a new membrane fabrication strategy is proposed to overcome the challenges of conventional nanofillers deposition and to develop novel thin film nanocomposite (TFN) membrane with enhanced performance for reverse osmosis (RO) application. Using polyvinyl alcohol (PVA) as adhesive for the hydrophilic graphene oxide (GO), TFN membranes with two different GO/PVA orientations (atop polyamide (PA) or between PA and substrate) at varying GO loading (0-0.02 wt/v%) were fabricated and characterized to evaluate their effects on membrane physicochemical properties and performances. Evidently, the membrane pure water flux (PWF) is significantly enhanced upon the incorporation of GO/PVA layer regardless of the orientations. Compared to the membrane without GO incorporation, the PWF of the membrane with GO/PVA atop PA layer and GO/PVA sandwiched between PA and substrate at optimum GO loading (0.015 wt/v%) was improved by 50.94% and 91.93%, respectively, mainly attributed to the improved surface hydrophilicity and altered structural properties. Besides exhibiting comparable separation efficiency (similar to 98% NaCl rejection), the membrane with GO/PVA atop PA layer also showed better antifouling property (100% flux recovery, 5-h filtration using 1000 mg/L organic solutions) than the self-synthesized TFC and commercial RO membranes with negligible nanofillers leaching.