Anti-corrosion performance of the synergistic properties of benzenecarbonitrile and 5-bromovanillin on 1018 carbon steel in HCl environment

Abstract

The synergistic properties of the combined admixture of benzenecarbonitrile and 5-bromovanillin (BNV) on the corrosion resistance of 1018 carbon steel in 1 M HCl was analysed with potentiodynamic polarization technique, weight loss method, micro-analytical studies and ATF-FTIR spectroscopy. Results obtained show the admixed organic compound was effective with optimal corrosion inhibition values of 99.33% and 90.34% at 1.25% BNV concentration from both electrochemical methods due to the effective inhibition action and passivation characteristics of the protonated inhibitor molecules in the acid solution. Primary amines, stretch alkyl halides and C-H triple bond functional groups of the molecules were observed to actively adsorb during the corrosion inhibition reaction from ATF-FTIR spectroscopic analysis. Calculations from thermodynamic evaluation confirmed cationic adsorption mechanism to be chemisorption obeying the Langmuir and Frumkin adsorption isotherm. Micro-analytical observations of the inhibited carbon steel morphology significantly contrast the unprotected steel due to visible surface deterioration and presence of micro/macro-pits. The organic derivatives showed mixed type inhibition reactions.

The empirical prediction of weight change and corrosion rate of low-carbon steel

“…Empirical prediction (see Table 5 ) of mild steel degradation rate at 1750 h of the immersion time increases from 0.209 to 0.246 to 0.268 to 0.274 and to 0.290 mm/y with increasing of the NaCl concentration from 0 to 2 to 3 to 4 and to 5% (w/w), respectively. An increase in the NaCl concentration is capable of donating more free Cl − ions to the solution and leads to a failure of the mild steel caused by the surface deterioration and presence of the micro/macro-pits [ 52 ]. The corrosion rate can be influenced by the presence of settled bacteria in the biofilm and by the immersion time [ 53 ].…”

Comparative study of corrosion inhibition by three anionic surfactants in an acidic environment

“…This procedure allowed for the analysis of irreversibly adsorbed films only (while reversibly adsorbed films would be washed off). The weight loss measurements allowed for the CR to be calculated using Equation () (Anand et al, 2012; Loto, 2017): where CR is the corrosion rate, ∆ W is the weight loss (mg), A is the total surface area of the specimen (cm 2 ), ρ is the density of the specimen (g cm −3 ) and t is the time immerged (h). Additionally, the inhibition efficiency was calculated utilizing Equation () (Anand et al, 2012; Loto, 2017): where CR 0 and CR are the corrosion rates of without and with the surfactants under investigation respectively (Anand et al, 2012; Loto, 2017).…”

“…This procedure allowed for the analysis of irreversibly adsorbed films only (while reversibly adsorbed films would be washed off). The weight loss measurements allowed for the CR to be calculated using Equation (1) (Anand et al, 2012;Loto, 2017):…”

“…where CR is the corrosion rate, ΔW is the weight loss (mg), A is the total surface area of the specimen (cm 2 ), ρ is the density of the specimen (g cm À3 ) and t is the time immerged (h). Additionally, the inhibition efficiency was calculated utilizing Equation ( 2) (Anand et al, 2012;Loto, 2017):…”

“…where CR 0 and CR are the corrosion rates of without and with the surfactants under investigation respectively (Anand et al, 2012;Loto, 2017).…”