Experimental and theoretical investigation on the effect of N-substituent position on the inhibition performance of l -l
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Experimental and theoretical investigation on the effect of N‑substituent position on the inhibition performance of l‑lysine derivatives for carbon steel in H2SO4 solution Lin Zhu1 · Xingwen Zheng1,2 · Xianguang Zeng2,3 · Min Gong3 · Lei Guo4 Received: 1 March 2020 / Accepted: 3 October 2020 © Springer Nature B.V. 2020
Abstract The inhibitive effect and inhibition mechanism of l-lysine derivatives, namely α-Nbenzyloxycarbonyl-l-lysine (α-NL) and ε-N-benzyloxycarbonyl-l-lysine (ε-NL), on the corrosion of carbon steel in 0.5 M H2SO4 solution were investigated by electrochemical technique, weightlessness test, scanning electron microscope, atomic force microscope, infrared attenuated reflectance spectroscopy and quantum chemical calculation. The results showed that α-NL and ε-NL as moderate cathodic inhibitors mainly inhibited the cathodic reaction of carbon steel in 0.5 M H 2SO4 solution, and the terminal substituted ε-NL showed better corrosion inhibition than the α-N-benzyloxycarbonyl protected α-NL. Their inhibition efficiencies increased with the increase in inhibitor concentration, and the inhibition efficiency of α-NL and ε-NL with concentration of 10 mmol can reach 53.4% and 61.5%, respectively, but decreased with rising temperature. The adsorption of investigated inhibitors on the surface of carbon steel obeyed the modified Langmuir isotherm and El-Awady thermodynamic-kinetic model, and the thermodynamic and kinetic parameters were determined to discuss the mechanism of inhibition of α-NL and ε-NL. Moreover, Quantum chemical calculation gave further insight into the inhibition mechanism of α-NL and ε-NL and was employed to reveal the reasons for their differences in inhibition performance. Keywords l-lysine derivatives · Carbon steel · Corrosion inhibitor · Adsorption · Quantum chemical calculation
* Xingwen Zheng [email protected] * Xianguang Zeng [email protected] Extended author information available on the last page of the article
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Introduction Corrosion, as an inevitable natural phenomenon, is an important destructive factor in industrial production, and causes serious economic losses [1, 2]. Among anti-corrosion technology, adding inhibitor is a convenient, economic and effective way to inhibit the corrosion of metal materials in corrosive solution, which is widely used in acid pickling, oil and gas exploitation and processing and cooling system and so on [3, 4]. More often than not, corrosion inhibitor is an organic compound containing unsaturated bond and heteroatom such as oxygen, nitrogen, sulfur and phosphorus, which can be adsorbed onto the metal surface through these active centers to form a protective film, thus inhibiting the corrosion of metal [5–7]. However, most organic inhibitors are expensive and hazardous to environment. With the improvement of environmental awareness and the requirement of sustainable development, developing environment-friendly inhibitor has become a growing demand. Amino acids, containing functional groups with pote
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