An induced current method for measuring zeta potential of electrolyte solution–air interface

•An induced current method is developed to measure the zeta potential of electrolyte solution–air interface.•The measured electric signal depends only on the zeta potential at the electrolyte solution–air interface.•A correlation curve can be used to predict the zeta potential with the measured voltage signal.

This paper reports a novel and very simple method for measuring the zeta potential of electrolyte solution–air interface. When a measuring electrode contacts the electrolyte solution–air interface, an electrical current will be generated due to the potential difference between the electrode–air surface and the electrolyte solution–air interface. The amplitude of the measured electric signal is linearly proportional to this potential difference; and depends only on the zeta potential at the electrolyte solution–air interface, regardless of the types and concentrations of the electrolyte. A correlation between the zeta potential and the measured voltage signal is obtained based on the experimental data. Using this equation, the zeta potential of any electrolyte solution–air interface can be evaluated quickly and easily by inserting an electrode through the electrolyte solution–air interface and measuring the electrical signal amplitude. This method was verified by comparing the obtained results of NaCl, MgCl2 and CaCl2 solutions of different pH values and concentrations with the zeta potential data reported in the published journal papers.

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