THE INFLUENCE OF NONIONIC AND IONIC SURFACTANTS ON HYDROPHOBIC AND HYDROPHILIC ULTRAFILTRATION MEMBRANES

The influence of different types of surfactants on ultrafiltration membranes has been investigated. A basic approach to membrane-surfactant interactions is also presented. A nonionic (Triton X-100), two anionic (potassium oleate and sodium dodecylbenzenesulphonate) and a cationic (hexadecyltrimethylammonium bromide) surfactant were investigated. The effects on commercial membranes of polysulphone, poly(vinylidene fluoride) and cellulose acetate were studied. The flux reductions of the hydrophobic membranes were found to be much more pronounced than the flux variations of the hydrophilic membranes. Both the material and the molecular weight cut-off were found to influence the performance of the hydrophobic membranes. A drastic influence of hydrophobic impurities was demonstrated. The retention of the nonionic surfactant was low at concentrations below the critical micelle concentration. The retention of the ionic surfactants was quite high, even at low concentrations.