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 electrode (<0.1 mg). Unlike traditional methods for measurement of mineral deposition, the EIS allows in situ semicontinuous measurements of overall mineral deposition, and its sensitivity provides means for early detection of mineral deposition.

pH dependent kinetic insights of electrocatalytic arsenite oxidation reactions at Pt surface

“…Note that at pH ̴ 3 and 5, the system exhibited two breakpoints, whereas at pH ̴ 7 and 9, there appeared single notable break point in each case due to large charge transfer resistance. However, in the order of decreasing frequency; two breakpoints correspond time constants 1, and 2, respectively, defining R , Rct and Cdl as follows [39][40][41][42]. It is to denote that the Bode phase plots (Figure 10b (i-iv) Y2 axes) also express the similar significance to those of Bode magnitude plots for the simplified Randle's circuit.…”

“…For an ideal non polarizable system, the circuit comprises a series connection of solution resistance (R ) with a parallel combination of charge transfer resistance (Rct) and a double layer capacitance (Cdl), Warburg element etc , which is known as simplified Randle's circuit (see inset of Fig. 10a)[39][40][41][42]. Irrespective of pH (5 to 9), the complex plane plot(Figure 10(a)) shows that the impedance of faradic process appeared as semicircle at high frequency edge and the diffusion process appears as a diagonal line with a slope of 45° at the low frequency edge at a working potential of 0.5 V. This observation justifies the relevance of occurring of reaction…”

Quantum chemical and experimental investigations on inhibitory behavior of amino–imino tautomeric equilibrium of 2-aminobenzothiazole on steel corrosion in H2SO4 solution

“…The negative values of DG ads indicate that the adsorption of inhibitor molecule on steel surface is a spontaneous process. Generally, values of DG ads up to À20 kJ mol À1 are consistent with the electrostatic interaction between the charged molecules and the charged metal (physical adsorption) while those more negative than À40 kJ mol À1 involve sharing or transfer of electrons from the inhibitor molecules to the metal surface to form a co-ordinate type of bond (chemisorption) [86,87]. The values of standard free energy of adsorption are between these two.…”

A nonlinear Cole–Cole model for large-amplitude electrochemical impedance spectroscopy

“…An open question is the interpretation of the electrical circuitry nonlinear models in terms of the mechanisms underlying the transformations in electrochemical systems (Harrington and Van den Driessche, 2011). Potential applications of the approach can be in the interpretation of mineral deposition (Li et al, 2012), electrochemical devices (Verma et al, 2014), corrosion effects (Sridharan et al, 2013) and ion-exchange membrane systems (Moya, 2013). The results exhibited above also illustrate the complexity of dealing with nonlinear equivalent circuitry to model electrochemical behavior and the involvement to estimate the underlying parameters.…”

“…The involvement of the chemical engineering community in the design of a series of electrochemical processes and devices (e.g., fuel cells, hydrometallurgical and coating processes), has motivated the increasing use of EIS to characterize and monitor electrochemical processes (Lai, 2010;Li et al, 2012;Sridharan et al, 2013;Mechelhoff et al, 2013;Verma et al, 2014, GarciaAnton et al, 2014Ling et al, 2015). The motivation relies in the fact that the technique is relatively inexpensive and can provide on-line fast results.…”