Electrochemical Impedance Spectroscopy (EIS) Based Characterization of Mineral Deposition from Precipitation Reactions

Abstract

An accurate and convenient approach for monitoring the rate of mineral deposition on metals in real time was developed and involves use of an electrochemical cell employing the metallic collecting surface as a working electrode (WE). The WE serves as both the surface for mineral deposition and a sensor for probing subtle changes attributable to the growth of mineral deposits at the metal–mineral–water interface. The interfacial capacitance obtained from electrochemical impedance spectroscopy (EIS) was used as a measure of surface coverage by the mineral scale. Results show that a constant-phase element (CPE) capacitance correlated very well with the mass of mineral deposits accumulated on the metal surface. Moreover, the characteristics of different minerals evaluated in this study, i.e., calcium carbonate, calcium sulfate, and calcium phosphate, did not affect the CPE capacitance measurement significantly. Rather, the CPE capacitance was sensitive to small changes in the mineral mass deposited on the ele...