Rejection of heavy metal ions in water by zeolite forward osmosis membrane

Water treatment of heavy metals using zeolite membranes in forward osmosis was demonstrated. A continuous Na-ZSM-5, aluminosilicate zeolite, crystal layer was synthesized on the outer surface of a porous tubular α-alumina support and used as the forward osmosis membrane. The rejection performances and fouling resistances of Na-ZSM-5 membrane were studied. Na-ZSM-5 membrane exhibited a high rejection performance of 99 % for various metal species (As(III), As(V), Se(IV), Se(VI), Cr(VI)). This superior rejection performance was achieved by combining the molecular sieving effect and electrostatic repulsion between the anions and the anionic framework of the zeolite. Na-ZSM-5 membrane exhibited a stable water flux in the presence of model foulants such as sodium alginate, humic acid, bovine serum albumin, and silica particles, suggesting that the membrane had excellent antifouling properties against both organic and inorganic foulants.