Effect of some tripodal bipyrazolic compounds on C38 steel corrosion in hydrochloric acid solution

Abstract

The corrosion inhibition of C38 steel in molar HCl by N,N-bis[2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl]buthylamine (P1) and 5-{N,N-bis[2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl] amino} pentanol (P2) has been investigated at 308 K using electrochemical and weight loss measurements. Measurements show that these compounds act as good inhibitors without changing the mechanism of the corrosion process. Moreover, the inhibiting efficiency increases with the increase in concentration of the studied inhibitors. Compound P2 showed better protection properties even at relatively higher temperatures when compared to P1. The associated activation corrosion and free adsorption energies have been determined. P1 and P2 are adsorbed on the C38 steel surface according to a Langmuir isotherm adsorption model.

The Corrosion Inhibition of Mild Steel in Sulphuric Acid Solution by Adsorption of African Perquetina Leaves Extract

“…This indicates that the activated complex in the rate of determining step represents an association rather than dissociation meaning that a decrease in disordering takes place on going from reactants to activated complex. Similar observations have been reported in the literature for mild steel dissolution in the absence and presence of inhibitors in H 2 SO 4 solution [27,35]. Also the ∆S values tend to more negative values as the extract concentration increases showing more ordered behavior leading to increase inhibition efficiency.…”

“…This observation further supports the proposed physisorption mechanism as reported by [34] The values of ∆H and ∆S are given in Table 7. The positive values of ∆H both in the absence of additives reflect the endothermic nature of the steel dissolution process and it indicates that the dissolution of steel is difficult [35]. It is also seen in Table 7 that E a and ∆H vary in the same manner but however, the values of ∆H are lower than that of Ea.…”

Inhibitory Properties of Neomycin Thin Film Formed on Carbon Steel in Sulfuric Acid Solution. Electrochemical and AFM Investigation

“…From Fig. 1a, it can be seen that the addition of NMS leads to: (i) the shifting of curves to higher potential values for all NMS concentrations, which entails the increase of the corrosion potential (Ecorr) in proportion to the increase in drug concentration; (ii) the movement of the polarization curves in lower current areas highlights the decrease in corrosion current density (icorr) with the NMS concentration increase; (iii) the addition of NMS in 1.0 M H2SO4, solution affects more the anodic process than the cathodic one and consequently, NMS acts as a mixed inhibitor, predominantly anodic, indicating the occurrence of a protective film [20] on the carbon steel surface that leads to the decrease of the corrosion current density. The main electrochemical parameters were calculated using VoltaMaster 4 software and these are listed in Table 1.…”

“…Also, Table 1 shows the inhibition efficiency (IE) calculated as a function of (icorr) and (Rct), as shown the Equation 6 and 7 [20,[23][24][25]. (7) where: i o corr and R o ct are the corrosion current density and charge-transfer resistance, respectively computed for the carbon steel corroded in 1.0 M H2SO4 blank solution, icorr and Rct represent the corrosion current density and charge-transfer resistance, respectively, computed for carbon steel corroded in 1.0 M H2SO4 solution containing various NMS concentrations.…”

“…The fitting of the degree of surface coverage (θ) values with the maximum regression coefficient (R 2 ) enables the accurate determination of the adsorption-desorption equilibrium constant (K) and then the calculation of the standard adsorption free energy (ΔG o ads) [20][21][22][23][24][25][26][27][28].…”