Effect of hydrophilic polymer modification of reverse osmosis membrane surfaces on organic adsorption and biofouling behavior

Abstract

Abstract Biofouling in reverse osmosis (RO) membranes is a serious problem, owing to the inherent membrane performance and lifetime; therefore, there have been attempts on various surface modifications of RO membrane surfaces using hydrophilic polymers. This study evaluates the effect of hydrophilic polymers modified on RO membrane surfaces on the adsorption of organic foulants causing biofouling and resulting in biofouling behavior. Polyamide RO membrane surfaces modified by three types of hydrophilic polymers, namely, 2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (MEDSAH), 2-hydroxyethyl methacrylate (HEMA), and poly(ethylene glycol) methyl ether methacrylate (PEGMA), were fabricated via an interfacial polymerization method and surface-initiated atom transfer radical polymerization (SI-ATRP). The hydrophilic property of each polymer is attributed to different functional groups: a zwitterionic group, hydroxyl group, and PEG group, respectively. To evaluate the anti-biofouling properties, the adsorption properties against bacteria, proteins and polysaccharides were quantified using a fluorescent-labelling method, and the biofouling behavior was evaluated during the filtration test. Fluorescently labelled alginate was synthesized for the adsorption test. Each hydrophilic polymer showed different adsorption properties against each organic foulant; none of the hydrophilic polymers was effective in the prevention of polysaccharide adsorption. The biofouling test showed that the zwitterionic polymer, MEDSAH, had superior anti-biofouling properties compared to the other hydrophilic polymers because of its high anti-adsorption property against bacteria.