Effects of Zeta Potential and Electrolyt (1)

This study investigates the relative motion of colloidal particles loosely deposited on an electrode subjected to alternating current (ac) polarization. The objective is to understand how parameters such as zeta potential, electrolyte composition, electrolyte concentration, and frequency affect particle interactions. Experimental methodologies involved varying these parameters in solutions of sodium bicarbonate, sodium chloride, and sodium hydroxide at frequencies of 100 Hz and 1000 Hz. Results indicate that at low frequency, particles aggregated in bicarbonate and chloride solutions but separated in hydroxide solutions. Conversely, at high frequency, particles exhibited separation in both bicarbonate and hydroxide solutions, with the relative velocity being slower for hydroxide solutions at higher frequencies. Notably, zeta potential had a negligible effect on interparticle motion, suggesting a dominance of convective mechanisms. Additionally, electrolyte concentration did not significantly influence particle dynamics. These findings align with electrohydrodynamic theory predictions based on space charge interactions near the electrode surface under electric fields, showcasing a good qualitative agreement, particularly for sodium hydroxide at 100 Hz, despite some discrepancies at higher frequencies.