SOLUBILIZATION AND MICELLAR-ENHANCED ULTRAFILTRATION OF O-CRESOL BY SODIUM DODECYL-SULFATE MICELLES

The solubilization and the micellar-enhanced ultrafiltration (MEUF) of o-cresol were investigated by using an anionic surfactant, sodium dod ecyl sulfate (SDS). In order to study the solubilization behaviour of the solute, the semiequilibrium dialysis (SED) method was employed and stirred-cell ultrafiltration experiments were performed for the test of MEUF. The analysis of the results supported that approximately two surfactant molecules provide a location for the solubilized solute wit hin micelle. In the removal of o-cresol by MEUF, as long as high SDS c oncentrations in the retentate (>0.2 M) are avoided, relatively good r ejection of o-cresol (85 %) could be obtained under the conditions use d (initial concentration ratio:[o-cresol]/[SDS]=0.2 and 0.6). Furtherm ore, the ultrafiltration processes were nearly at equilibrium, so that the permeate concentrations of o-cresol could be predicted from the S ED results. The separation efficiency was greater at lower o-cresol co ncentrations when the SDS concentrations were fixed in the feed, while the rejection increased with increasing the SDS concentrations at con stant intramicellar mole fraction of the solute Xc. In addition, as th e o-cresol loading of retentate increased, the less SDS in the retenta te permeated through ultrafiltration membranes. On the other hand, the higher o-cresol loadings reduced the fluxes of MEUF runs.