Effects of surface modification on antifouling and performance properties of reverse osmosis membranes

The effects of surface modification of commercial reverse osmosis (RO) poly amide membranes were studied in terms of flux/rejection and surface propert ies. Selected RO membranes, spanning ultra-low pressure to seawater membran es, were modified by in-situ graft polymerization using redox generation of monomer radicals. Modification of the membrane significantly reduced both receding and advancing contact angles of some of the membranes as measured by a modified Wilhelmy plate method. Lower contact angles indicate more hyd rophilic membranes and such membranes will potentially show better resistan ce to fouling by hydrophobic foulants. This was confirmed by adsorption mea surements carried out on modified and unmodified membranes with a highly fo uling surface water. Modified membranes adsorbed less organic material and were more easily cleaned than unmodified membranes. Specific fluxes were no t changed by more than 0-25% and NaCl rejection was unchanged or increased slightly.