Chitosan as a green inhibitor for mild steel corrosion: Thermodynamic and electrochemical evaluations

The inhibition performance of Acacia mearnsii bark tannin was investigated as ecofriendly green inhibitor on the corrosion of AA7075-T6 aluminum alloy in 0.1 M HCl solution by potentiodynamic polarization technique, electrochemical impedance spectroscopy (EIS) and scanning electron microcopy (SEM). Polarization curves showed that this tannin acts predominantly as a cathodic inhibitor. High corrosion inhibition performance was achieved with inhibition efficiencies of 95% and 97% at 14 g L −1 as obtained by polarization and EIS electrochemical techniques, respectively. The SEM images revealed that localized attack initiated at intermetallic particles causing local dissolution of the matrix due to potential differences between them. EIS results and SEM images confirmed the protection of AA7075-T6 aluminum alloy by A. mearnsii bark tannin, evidencing the formation of an adsorbed film on the metal surface that attenuate the aluminum dissolution reaction. K E Y W O R D SAcacia mearnsii tannin, aluminum alloy, green corrosion inhibitor

Section: Introductionmentioning

confidence: 99%

Tannin of Acacia mearnsii as green corrosion inhibitor for AA7075‐T6 alluminum alloy in acidic medium

Guedes

Bacca

Lopes

et al. 2019

“…It has been also attributed to the accumulation of the corrosion products or relaxation of the charged species on the working electrode. [ 39 ] In this study, all of the above can be true. High corrosion rates can easily lead to the appearance of corrosion products on the steel surface, and the presence of the

{Cl}_{ads}^{‐}

on the surface is also probable.…”

Section: Resultsmentioning

confidence: 85%

“…An equivalent circuit similar to the system with a surface oxide layer, coating with defects, is often used for metal with ceramics or another type of the nonideal coatings. [ 39 ] The porosity of the coating is a deviation from the ideal coated metal surface and gives consistency for the chosen model. The only difference between the modeled circuits for the heat‐treated sample and the sample with alumina/titania coating is that the latter has a CPE instead of the capacitor.…”

Section: Resultsmentioning

confidence: 99%

Improvement of the corrosion characteristics of 1.4713 ferritic steel in 0.1 M sulfuric acid by heat treatment and Al₂O₃–TiO₂ coating

Stevanović¹,

Dimitrijević

Kamberović

et al. 2020

This study addresses the influence of heat treatment and alumina coating on the corrosion of EN 1.4713 steel in 0.1 mol dm−3 sulfuric acid. The corrosion characteristics of three different samples are examined using the open circuit potential measurements, Tafel extrapolation, linear polarization resistance, weight‐loss method, and electrochemical impedance spectroscopy. The results showed that the application of the weight‐loss method yielded similar values to the electrochemical method in the first 24 h. A decrease in corrosion rate, in a similar manner, was observed for all three samples. The largest deacceleration was obtained for the alumina/titania‐coated sample. It was obtained that the heat treatment significantly increased the corrosion resistance, but only in the first 24 h. The alumina/titania coating decreases the corrosion rate by approximately 30 times at the beginning of the corrosion exposure and by nearly 300 times after 240 h. This coating could have a significant influence on construction design, which uses ferritic stainless steel as the material.

“…The study of iron and mild steel corrosion in an acid medium has received considerable attention. [ 5,6 ] One of the most practical methods to prevent and/or reduce metal corrosion is the use of corrosion inhibitors. The most‐reported inhibitors of metal corrosion are organic compounds with heteroatoms such as oxygen, nitrogen, sulfur, and phosphorous, or compounds containing multiple bonds.…”

Section: Introductionmentioning

confidence: 99%

Effect of substituents on the inhibitive properties of newly synthesized 5‐benzoyl‐4‐methyl‐1,3,4,5‐tetrahydro‐2H‐1,5‐benzodiazepin‐2‐one derivatives against mild steel corrosion in an acidic medium

Al-Fakih

Al-Maqtari

Aziz

et al. 2020

Inhibition performance of three newly synthesized 1,5-benzodiazepine derivatives with 4-methoxybenzoyl (methoxyBBD), 3-methylbenzoyl (methylBBD), and 2-chlorobenzoyl (chloroBBD) groups was investigated against mild steel corrosion in 1 M hydrochloric acid. The potentiodynamic polarization, electrochemical impedance spectroscopy, and adsorption isotherms were used for characterization of the corrosion processes. Surface morphology was studied by scanning electron microscope (SEM). Quantum chemical calculations were carried out to establish the active sites of the inhibitors. The results show that the inhibitors inhibit mild steel corrosion and their inhibition efficiencies (IE) increase with the increase in concentration. The methoxyBBD shows a higher inhibiting effect with IE of 89.13% at 10 −3 M, followed by methylBBD. All three inhibitors act as mixed-type inhibitors with predominant control of cathodic reaction for chloroBBD and their adsorption obeys Langmuir isotherm. The SEM analysis confirms the inhibitors' adsorption on the mild steel surface. The active sites of the inhibitors were effectively established using the density functional theory method on the basis of natural atomic charge, highest occupied molecular orbital, and the lowest unoccupied molecular orbital frontier molecular orbitals. The experimental and quantum results prove the inhibition performance trend of the inhibitors as follows: methoxyBBD > methylBBD > chloroBBD.