Heteroatoms and π electrons as favorable factors for efficient corrosion protection

Abstract

Six corrosion inhibitors based on dimeric quaternary ammonium salts (gemini surfactants) with a flexible/rigid spacer have been tested for stainless steel in 3 M HCl. Potentiodynamic polarization (linear polarization resistance, Tafel slopes) and electrochemical impedance spectroscopy have been used to determine the corrosion inhibition efficiency of the compounds. The results suggest that inhibitors act as anodic/cathodic inhibitors. The highest corrosion inhibition efficiency has been reached around the values of the critical micellar concentration for each inhibitor. Scanning electron microscopy has been applied to study the surface of the stainless steel samples. Theoretical studies of the inhibitors have been run based on density functional theory.

Theoretical and experimental studies of a new aniline derivative corrosion inhibitor for mild steel in acid medium

“…The R ct values increase when the CPYA concentration increases, leading to a greater number of organic molecules adsorbed on the MS surface, resulting in an efficient metal surface protection. The maximum anticorrosive efficiency of 95.3% was obtained by CPYA at 4.59 mmol/L, corroborating the results from the weight loss method . All data are shown in Table .…”

“…The authors also observed an increase of the E HOMO and E LUMO from the neutral to the protonated form. Furthermore, Δ E is slightly higher for the neutral than the protonated form …”

Caprylamidopropyl Betaine as a highly efficient eco-friendly corrosion inhibitor for API X120 steel in 1 M H2SO4

“…The slope of (∆H * /2.303R) and the intercept of [log (R/Nh) + (∆S * /2.303R)] are used to calculate ∆H * and ∆S * , respectively. The average difference between E a and ∆H * is approximately 2.6 kJ mol −1 for each test, which is almost the value of RT (2.63 kJ mol −1 ) [51][52]. This indicates that the dissolution of API X120 steel in this environment is a unimolecular reaction.…”

New imidazole‐based dimers as potential inhibitors for mild steel corrosion in acidic media: Electrochemical and DFT evaluation

“…The effectiveness of these compounds is attributed to the readily accessible free pairs of electrons on the heteroatoms; which can be in a number of cases coupled with the presence of aromatic characters. Such key electronic properties would facilitate the adsorption scenario on the metal surface . Other factors, such as the nature of substituent groups, molecular orientation, and type of electrolyte media, have been shown to influence the inhibitive performance of these compounds …”

“…Imidazole‐based materials have received greater attention in recent years because they are nontoxic, environment‐friendly, and water‐ and oil‐soluble corrosion inhibitors . The presence of quaternary nitrogen atoms in these molecules significantly enhances their adsorption capabilities through the charge‐donation phenomenon, which facilitates the formation of stable protective layers on the metal surface …”