MEASUREMENTS OF ZETA POTENTIAL ON THE SURFACE OF HOLLOW-FIBLE MEMBRANE BY USING STREAMING POTENTIAL METHOD

According to the relationship between streaming potential and zeta potential, an apparatus for measuring zeta potential of hollow-fible microfiltration membrane was developed. The surface streaming potential measurements of polypropylene membrane were carried out in three electrolyte solutions (NaCl,KCl,CaCl2).The results show that: the charge of PP membrane is negative in neutral condition; The pore size of membranes and the method of measurement can affect membrane zeta potentials obviously. The higher the pore size is, the smaller the absolute value of zeta potential is. The absolute value of zeta potential with pressure downward mode is higher than that of pressure upward mode. The zeta potentials are also related to the electrolyte concentrations and species. The higher the electrolyte concentration is, the higher the zeta potential is. The zeta potential of membrane depends strongly on the valence of cations.