Inhibitive action of Cystine on the corrosion of low alloy steel ASTM A213 grade T22 in sulfamic acid solutions

AbstractThe effect of Cystine on the corrosion behavior of low alloy steel ASTM A213 grade T22 in 0.5M sulfamic acid solutions have been investigated by various electrochemical techniques. The study was performed using electrochemical impedance spectroscopy (EIS) and the recent technique electrochemical frequency modulation (EFM). The results of the investigation show that the inhibition efficiency increased with increasing inhibitor concentration, but decreased with increasing the solution temperature and stirring velocity. All the collected results from the two techniques are in good agreements, which confirm the ability of EFM technique for monitoring the corrosion inhibition under the studied conditions

Adsorption and inhibitive properties of Tryptophan on low alloy steel corrosion in acidic media

AbstractThe inhibition efficiency of Tryptophan (Trp) has been studied for the corrosion of low alloy steel ASTM A213 grade T22 in sulfamic (HSO3NH2) and hydrochloric (HCl) acid solutions.Corrosion inhibition was studied using electrochemical methods (electrochemical impedance spectroscopy; EIS and the new technique electrochemical frequency modulation; EFM) and weight loss measurements. The influence of inhibitor concentration, solution temperature, and immersion time on the corrosion resistance of low alloy steel (LAS) has been investigated. Trp proved to be a very good inhibitor for low alloy steel acid corrosion. EFM measurements showed that Trp is a mixed type inhibitor. Trp behaved better in 0.6M HCl than in 0.6M HSO3NH2. Moreover, it was found that the inhibition efficiency increased with increasing inhibitor concentration, while a decrease was detected with the rise of temperature and immersion time. The associated activation energy (Ea) has been determined. The values of Ea indicate that the type of adsorption of Trp on the steel surface in both acids belongs to physical adsorption. The adsorption process was tested using Temkin adsorption isotherm