Interfacial electrochemistry study of particle–wall interaction using electrochemical impedance spectroscopy

Particulate fouling by corrosion products reduces the efficiency of heat transport systems. This paper examines particle–wall interactions during the course of deposition. Electrochemical impedance spectroscopy was employed to evaluate the interaction of submicron magnetite and hematite particles with a platinum electrode at acidic, near-neutral and alkaline conditions. It was observed that changes in double-layer capacitance on the platinum surface could be used to detect deposition at different conditions. It was observed from impedance data that double layer capacitance at pH = 3 did not change with particle mass loading. Modeling suggests that strong electrostatic repulsion at this pH keeps particles above the surface at equilibrium distances large enough that EIS cannot detect them. Significant changes in the double layer capacitance at pH = 10 were ascribed to surface blockage by particles. At pH = 5, a cathodic potential of −1 V vs. Ag/AgCl was utilized for particle detection.

► EIS is used to study iron oxide particle–wall interaction in pH = 3, 5 and 10.
► Double-layer capacitance is a measure of electrode particle loading.
► A model of particle–wall interaction was employed to interpret the EIS data.