Removal of pesticides by reverse osmosis

Two types of reverse osmosis membranes, i.e., cellulose acetate (CA) and cross linked polyethylenimine, designated as NS 100 by OSW, were evaluated for their removal of a wide variety of pesticides, including chlorinated hydrocarbons, organophosphorus, and miscellaneous pesticides. With each membrane the rejection of pesticides was better than 99%. A considerable amount of pesticide was adsorbed onto the membrane materials. The extent of adsorption is governed by the van der Waals London forces and hydrophobic bonding between pesticide molecules and the polymeric membrane materials. Membrane rejection of the pesticides is in turn governed by the polarity of the solute molecules in aqueous solution, which is in accord with the theory advanced by Sourirajan.