Thermodynamic Study and Characterization by Electrochemical Technique of Pyrazole Derivatives as Corrosion Inhibitors for C38 Steel in Molar Hydrochloric Acid

Abstract

The effect of synthesized 1,1'-propane-1,3-diylbis[3-(chloromethyl)-5-methyl-1Hpyrazole], dimethyl 1,1'-butane-1,4-diylbis(5-methyl-1H-pyrazole-3-carboxylate) and 1,1'-butane-1,4-diylbis[3-(chloromethyl)-5-methyl-1H-pyrazole] on corrosion of C38 steel in hydrochloric acid solution has been investigated in the temperature range from 298 K to 328 K by weight loss, potentiodynamic polarization method and modelled with an equivalent electric circuit. All the compounds exhibited more than 90% anticorrosion activity, the highest is 96 % by 1,1'-butane-1,4-diylbis[3-(chloromethyl)-5-methyl-1H-pyrazole], and it has been shown that the inhibition efficiencies increased with the concentration of the inhibitors, remaining almost constant in a wide temperature range. Potentiodynamic polarization studies suggested that it is a predominance cathodic type. Nyquist plots showed depressed semicircles with their centre below the real axis. The adsorption on the C38 steel surface followed the Langmuir adsorption isotherm. The thermodynamic parameters for dissolution were investigated at different concentrations and temperature. The theoretical study by modelling the molecules of these inhibitors has been performed by considering the Density Functional Theory (DFT) using the Gaussian 03W suite of programs that can calculate the different quantum parameters such as E HOMO , E LUMO, ∆ E HOMO , E LUMO , and µ dipolar moment, allowing us to confirm the results found by the gravimetric and electrochemical methods.

Corrosion Inhibition of Carbon Steel in Hydrochloric Acid Solution by Mentha Pulegium Extract

“…Addition of plant extracts at 33% in 1 M HCl decreases the activation energy from 92.41 to 89.32 kJ mol -1 . This diminution may be attributed to the change in the mechanism of the corrosion process in the presence of adsorbed inhibitor molecules [28,29]. The lower value of the activation energy of the process in the inhibitor's presence when compared to that in its absence is attributed to its chemisorptions [30][31][32].…”

Benzyl Nicotinate as an Efficient Corrosion Inhibitor for Cold Rolled Steel in a 1 M HCl Solution

“…It is observed that Ea -ΔH * = RT is indicative of uni-molecular adsorption of BN molecules [31]. The value of ΔS * increases with an increase in the concentrations of inhibitor, showing that the free energy of reactants is converted into an activated complex [32]. The adsorption of BN on CRS reduces the disorder of the system, thus producing an ordered arrangement of BN.…”

Synthesis and comparative study between two pyrazoles in inhibition against the corrosion of steel in 1 M hydrochloric acid

“…On the other hand, there is a very important number of substituted pyrazoles which have a broad spectrum at the industrial activities [12], especially in the corrosion inhibitors for steel in acidic media [13][14][15][16][17]. Bibliography results directed us towards the synthesis of new pyrazole derivatives.…”