Measurement of the Zeta Potential of Pla

This study describes a method for measuring the zeta potential of disks by combining hydrodynamic properties of a rotating disk with the solution of Laplace’s equation for electrokinetic potential. The objective is to derive an equation that connects the zeta potential of the disk to the surrounding streaming potential. The proposed methodology involves placing one reference electrode on the disk's axis and another remotely, measuring the streaming potential of silicon oxide and indium tin oxide in potassium chloride solution to verify theoretical predictions. Results indicate a cubic relationship between the streaming potential and the rotation rate, consistent with theoretical expectations. The calculated zeta potentials aligned well with previously published values, confirming the validity of the approach. Furthermore, the optimal measurement conditions are established, highlighting the importance of measuring the potential near the disk's axis to avoid errors near the edge. This technique provides a straightforward means of assessing the zeta potential of planar solids, thereby enhancing our understanding of their electrochemical properties.