Removal of chromate anions by micellar-enhanced ultrafiltration using cationic surfactants

Micellar-enhanced ultrafiltration (MEUF) of chromate anions (CrO42-) from a queous streams has been studied at 30 degreesC using twice cationic surfact ants (cetyltrimethylammonium bromide and cetylpyridinium chloride). The sol ution is processed by ultrafiltration, using a membrane with pore sizes sma ll enough to block the passage of the micelles and adsorbed ions. Rejection coefficients higher than 99% are reached in optimal conditions of pressure , feed concentration in cationic surfactant, and percent filtered volume. T he rejection rate depends on the ionic strength and pH. The increasing of i onic strength decreases the retention of chromate ions and the permeate sur factant concentration. As long as the NaCl feed concentration is less than or equal to 100 mM, more than 88% of hexavalent chromium are retained and s urfactant leakage was reduced.