Stirred cell ultrafiltration of aqueous micellar TX-100 solutions

Cellulose membranes with different molecular weight cut-offs (MWCO, 5–100 kDa) were used for the filtration of aqueous micellar TX-100 solutions. The experiments were performed in a stirred cell and surfactant concentration and pressure were varied. The gel-polarization model was employed and showed a gel concentration for TX-100 in the range of 150–300 g/L. Ultrafiltration was also carried out with dimethyl itaconate (DMI) and diethyl itaconate (DEI) as dissolved organic compounds and we found that the solute retention was directly associated to the hydrophobicity of the compounds. The flux was not affected as long as the solution appears homogeneous and the formation of a second phase with higher organic content was avoided. In order to use micellar enhanced ultrafiltration (MEUF) for the recovery of hydrophobic catalysts dissolved in aqueous micellar reaction media, a low MWCO membrane, low surfactant concentrations and hydrophilic reactants should be preferred.