CHANGES IN THE ZETA-POTENTIAL OF COLLOIDAL TITANIUM-DIOXIDE AFTER EXPOSURE TO A RADIO-FREQUENCY ELECTRIC-FIELD USING A CIRCULATING SAMPLE

The effect of exposure to a 44 MHz, 60 V peak-to-peak electric held on the zeta potential of colloidal titanium dioxide is investigated for samples at a variety of different pHs using a circulating sample. The zeta potential, as measured by a Brookhaven ZetaPlus apparatus, is obs erved to be diminished after held exposure across a broad range of pHs . The field effect is also investigated as a function of ionic strengt h and exposure time for samples in KCl at natural pH. The effect is ob served to be most pronounced for short exposure times and modest salt concentrations. The data is in qualitative agreement with the proton d esorption process proposed earlier [E. Chibowski, S. Gopalakrishnan, M .A. Busch and K.W. Busch, J. Colloid Interface Sci., 139 (1990) 43]. ( C) 1998 Elsevier Science B.V.