Comparative electrophoretic mobility and streaming current study for zeta-potential determination

The main purpose of this work is to compare the xi-potential obtained from streaming current and electrophoretic mobility measurements. The electrokin etic experiments were performed using two anionic polystyrene latexes whose surface charge density and average particle diameter were -9.8 and -3.4 mu C cm (-2) and 0.65 and 1.2 mu m, respectively. For the conversion two theo ries were used, the Levine et al. theory for the streaming current and O' B rien-White for the electrophoretic mobility measurements. This way most of the phenomena taking place at the interface are taken into consideration. T he xi-potentials obtained this way compare well for the largest latex with the lowest: surface, charge. However, there are substantial discrepancies f or the smaller latex sample with the higher surface charge density. These d iscrepancies are discussed in terms of the effect of the surface conductanc e on the electrokinetic signal. (C) 1999 Elsevier Science B.V. All rights r eserved.