Frequency Dispersion of the Interfacial Impedance at Mild Steel Corrosion in Acid Media in the Presence of Benzimidazole Derivatives

Abstract

Measurements of the complex impedance of the interface between mild steel and deaerated 1 M HCl solutions without and with the addition of different inhibitors, derivatives of benzimidazole, have been made in the frequency range of (0.1−9.5) × 104 Hz. Adequate structure models of the interfaces as well as some data on the kinetics of the partial processes are offered. It is found that the double-layer capacity as well as the adsorption capacity can not be presented by a frequency independent lumped element. The experimental data show a frequency distribution and therefore a modeling element with frequency dispersion behavior; a constant phase element has been used. At high inhibitor concentrations a second time constant is clearly observed in the impedance spectra. It is most probably connected with the adsorption process. Two time constants determined by the charge transfer and the adsorption of the inhibitor, respectively, can be readily outlined.

Investigations on the corrosion of constructional steels in different aqueous and simulated atmospheric environments

“…The shapes of the curves are quite similar and mainly consist of a large capacitive loop at higher frequencies. Similar impedance plots have been reported in the literature for the corrosion of iron [24][25][26][27][28][29][30].…”

“…The impedance spectra were recorded and displayed as Nyquist plots ( Figure 7). As can be seen, the impedance diagrams show semicircles, indicating that the corrosion process is mainly charge transfer controlled [24,25] The depressed semicircles of the Nyquist plots suggest the distribution of capacitance is due to inhomogeneous metal surface [26][27][28][29][30]. The shapes of the curves are quite similar and mainly consist of a large capacitive loop at higher frequencies.…”

Electrochemical and Quantum Chemical Studies of 1, 2, 3-Benzotriazole as Inhibitor for Copper and Steel in Simulated Tap Water

“…Figure 4 shows the Nyquist plots that were obtained for (a) steel and (b) copper in the simulated tap water with different BTAH concentrations. The roughness and nonhomogeneity of the specimen surface can affect the variance of the pure capacitive loops [20][21][22] . Figure 4 shows that the increase of the BTAH concentration increases the radius of the capacitive loops as well as the inhibition ef ciencies in all cases.…”

Determination Of Inhibition Effects Of Ascorbic Acid On The Corrosion Behavior Of Copper In Chloride Medium (pH=7.0)

“…Elektrokimyasal yöntemlerle belirlenen korozyon akımları değerlendirilerek Eşitlik 5'de verilen bağıntı ile inhibisyon etkinliği hesaplanabilir. Aynı zamanda, elektrokimyasal impedans spektroskopisi kullanılarak belirlenen polarizasyon dirençleriyle de Eşitlik 6'da verilen bağıntı yardımıyla inhibisyon etkinliği hesaplanabilir (Lipkowski et al, 1992;Popova et al, 1996). Eşitlik 6 ile hesaplanarak bulunan inhibisyon etkinlikleri Tablo 1'de verilmiştir.…”