Comparative data on corrosion protection of mild steel in HCl using two new thiazoles

Multi-method evaluation of a 2-(1,3,4-thiadiazole-2-yl)pyrrolidine corrosion inhibitor for mild steel in HCl: combining gravimetric, electrochemical, and DFT approaches

The corrosion inhibition properties of 2-(1,3,4-thiadiazole-2-yl)pyrrolidine (2-TP) on mild steel in a 1 M HCl solution were investigated using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and open circuit potential (OCP) measurements. In addition, DFT calculations were performed on 2-TP. The polarization curves revealed that 2-TP is a mixed-type inhibitor. The results indicate that 2-TP is an effective inhibitor for mild steel corrosion in a 1.0 M HCl solution, with an inhibition efficiency of 94.6% at 0.5 mM 2-TP. The study also examined the impact of temperature, revealing that the inhibition efficiency increases with an increasing concentration of 2-TP and decreases with a rise in temperature. The adsorption of the inhibitor on the mild steel surface followed the Langmuir adsorption isotherm, and the free energy value indicated that the adsorption of 2-TP is a spontaneous process that involves both physical and chemical adsorption mechanisms. The DFT calculations showed that the adsorption of 2-TP on the mild steel surface is mainly through the interaction of the lone pair of electrons on the nitrogen atom of the thiadiazole ring with the metal surface. The results obtained from the weight loss, potentiodynamic polarization, EIS and OCP measurements were in good agreement with each other and confirmed the effectiveness of 2-TP as a corrosion inhibitor for mild steel in 1.0 M HCl solution. Overall, the study demonstrates the potential use of 2-TP as a corrosion inhibitor in acid environments.

Palmitic acid-based amide as a corrosion inhibitor for mild steel in 1M HCl

Due to growing environmental concerns and regulations limiting the use of harmful and toxic synthetic corrosion inhibitors, there is a high demand for sustainable corrosion inhibitors. In this study, a green and rapid technique was used to synthesize amide N-(4-aminobutyl)palmitamide (BAPA) which yielded 91.17% of the product within 2 min, compared to a low yield of 75-80% and a very long 8-10 h reaction time with the conventional thermal condensation method. The chemical structure of BAPA was analyzed by FT-IR, 1HNMR and 13CNMR spectra, as well as CHNS elemental analysis. When applied to mild steel exposed to 1 M HCl, BAPA delayed and reduced corrosion by adsorbing to the steel surface to form a protective layer. The inhibition efficiency increased with increasing amide concentration, and maximal inhibition of 91.5% was observed at 0.5 mM BAPA. The adsorption of BAPA on mild steel in an acidic solution was studied and inhibition performance was correlated with the calculated adsorption-free energy ΔGads, indicating good agreement between the experimental and adsorption findings. Surface morphology of untreated and treated mild steel coupons was evaluated by SEM, and based on density functional theory (DFT) computations and atomic charges analysis, a stronger interaction was observed between BAPA and mild steel surface leading to the formation of a compact protective film on the metallic surface. This protective film is attributed to the presence of nitrogen atoms and carbonyl group in the chemical structure of BAPA.

Computational, Kinetics, and Corrosion Protection Aspects of Electrodeposited Poly(Salicylic Acid) Coatings as a Corrosion Inhibitor for Mild Steel

Poly(salicylic acid) PSA has been electrochemically deposited onto a Pt electrode. The kinetics of the polymerization reaction has been studied. The polymer structure was confirmed and characterized using IR spectroscopy, XRD, SEM, and TGA analysis. The deposited PSA was then collected from the Pt surface and tested as a corrosion inhibitor for a mild steel electrode in an aqueous medium of 1 M sulfuric acid. The corrosion behavior was then evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Corrosion measurements showed that the inhibition efficiency of 20, 50, and 100 ppm of PSA was 33, 57, and 74%, respectively. The inhibition mechanism was proved using adsorption isotherms as well as quantum calculations. The inhibition of the corrosion process was due to the adsorption of PSA on the steel surface, which was found to comply with the Langmuir adsorption isotherm.