Chemical treatment of commercial reverse osmosis membranes for use in FO Original Research Article

Commercially available reverse osmosis (RO) membranes – SW30HR, BW30, and AG – were chemically treated for use in forward osmosis (FO). Nitric acid, phosphoric acid, sulfuric acid, ethanol, and ethanol–acid–water ternary solutions were employed for the treatment. All three membranes, after treatment by nitric acid, ethanol, and ethanol–acid–water solutions, demonstrated significant flux enhancement (as much as 40 times higher) compared to their untreated counterparts. The SW30HR membrane treated by ethanol showed the lowest reverse salt flux among the treated membranes. Extensive changes to the barrier layer of the SW30HR membrane after ethanol treatment were observed using ATR-FTIR, XPS, and contact angle measurements. It appears that the PVA coating of the SW30HR membrane was either partially or totally removed. The reduction/removal of the PVA layer in conjunction with higher wettability of the substrate induced by ethanol treatment appears responsible for the improved flux.