scholarly journals Experimental and Theoretical Studies of α-Linolenic Acid as Green Corrosion Inhibitor for Carbon Steel in 0.5 M Sulfuric Acid

Molecules ◽  
2021 ◽  
Vol 26 (20) ◽  
pp. 6169
Author(s):  
I.A. Hermoso-Diaz ◽  
R. Lopez-Cecenes ◽  
J.P. Flores-De los Rios ◽  
L.L. Landeros-Martínez ◽  
E. Sarmiento-Bustos ◽  
...  

A component of Salvia hispanica, α-linolenic acid, has been evaluated as a green corrosion inhibitor for 1018 carbon steel in 0.5 M sulfuric acid using weight loss tests, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) measurements. Theoretical calculations using Density Functional Theory (DFT) were used also. The results have shown that this compound is a good corrosion inhibitor, with an efficiency which increased with an increase in its concentration up to 600 ppm, but it decreased with a further increase in the concentration. α-linolenic acid formed protective corrosion products layer because it was chemically adsorbed onto the steel surface according to a Langmuir type of adsorption isotherms. Polarization curves have shown that α-linolenic acid is a good, mixed type of inhibitor with a predominant effect on the cathodic hydrogen evolution reactions. EIS measurements indicated a charge transfer-controlled corrosion process. DFT calculations indicated that α-linolenic acid was more efficient in an acidic environment than in a neutral one because has a high tendency to donate electrons and can be easily protonated. In addition to this, it had the highest EHUMO value, the best chemical reactivity, the greatest tendency to transfer electrons and a greater facility of modifying its electronic configuration in the presence of carbon steel specimens according to its chemical hardness value.

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
E. A. Florez-Frias ◽  
V. Barba ◽  
R. Lopez-Sesenes ◽  
L. L. Landeros-Martínez ◽  
J. P. Flores-De los Ríos ◽  
...  

A tin-containing metallic complex derived from Curcuma longa, bis[1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dionato-κO,κO ′ ]bis(butyl), has been obtained and used as a green corrosion inhibitor for carbon steel in 0.5 M sulfuric acid by using weight loss, electrochemical techniques, and the Density Functional Theory. It was found that the obtained metallic complex greatly decreases the steel corrosion rate by adsorption according to a Frumkin model in a weak, physical type of adsorption. Inhibitor efficiency increased with its concentration, and it acted as a mixed type of inhibitor. Results were supported by quantum-chemical research in order to examine the relationship between structural and electronic properties and the inhibitor efficiency.


Author(s):  
Elyor Berdimurodov ◽  
Abduvali Kholikov ◽  
Khamdam Akbarov ◽  
Lei Guo ◽  
Savaş Kaya ◽  
...  

In this research work, a new and green corrosion inhibitor based on new imidazole derivate (IMD) was introduced for carbon steel in 1 M HCl medium. Its inhibition properties were fully characterised by the gravimetric, electrochemical, surface and quantum chemical analyses. The experimental results confirmed that the inhibition efficiency of IMD was over 99% at 150 mg/L, forming a protective hydrophobic film on the metal surface, which maximally blocked the cathodic and anodic corrosive processes by adsorption. The electrochemical results suggested that the IMD is a mixed-type inhibitor. The adsorption behaviour of IMD was obeyed by Langmuir isotherms. The gravimetric results show that the inhibition efficiency depends on the change of concentration and temperature. The experimental tests were supported by the DFT (density functional theory) measurements, and a good relationship was found among these tests. The observed results of the surface analysis indicated that the metal surface was seriously improved with the presence of IMD.


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