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15 pages, 4468 KiB

Open AccessArticle

Smart Inhibition Action of Amino Acid-Modified Layered Double Hydroxide and Its Application on Carbon Steel

by Elena Messina, Marianna Pascucci, Cristina Riccucci, Francesca Boccaccini, Maria Teresa Blanco-Valera, Ines Garcia-Lodeiro, Gabriel Maria Ingo and Gabriella Di Carlo

Molecules 2023, 28(15), 5863; https://doi.org/10.3390/molecules28155863 - 3 Aug 2023

Cited by 2 | Viewed by 1411

Abstract

Surface impregnation of concrete structures with a migrating corrosion inhibitor is a promising and non-invasive technique for increasing the lifetime of existing structures that already show signs of corrosion attack. The main requirement for inhibitors is their ability to diffuse the rebar at [...] Read more.

Surface impregnation of concrete structures with a migrating corrosion inhibitor is a promising and non-invasive technique for increasing the lifetime of existing structures that already show signs of corrosion attack. The main requirement for inhibitors is their ability to diffuse the rebar at a sufficient rate to protect steel. The use of smart nanocontainers such as layered double hydroxides (LDH) to store corrosion inhibitors significantly increases efficiency by providing an active protection from chloride-induced corrosion. The addition of LDH to reinforced mortar can also improve the compactness and mechanical properties of this matrix. Here, we report the synthesis of a magnesium–aluminum LDH storing glutamine amino acid as a green inhibitor (labeled as Mg–Al–Gln), which can be used as a migrating inhibitor on mortar specimens. The corrosion behavior of the specimens was determined via electrochemical techniques based on measurements of corrosion potential and electrochemical impedance spectroscopy. A cell containing a 3.5% NaCl solution was applied to the mortar surface to promote the corrosion of embedded rebars. The specimens treated with Mg–Al–Gln presented an improved corrosion protection performance, exhibiting an increase in polarization resistance (Rp) compared to the reference specimens without an inhibitor (NO INH). This effect is a consequence of a double mechanism of protection/stimuli-responsive release of glutamine and the removal of corrosive chloride species from the medium. Full article

(This article belongs to the Special Issue Chemistry of Corrosion Inhibitors)

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18 pages, 3081 KiB

Open AccessArticle

Investigation of Hexylamine Adsorption on Gold in Perchloric Acid

by Gennady I. Ostapenko and Nina A. Kalashnikova

Molecules 2023, 28(13), 5070; https://doi.org/10.3390/molecules28135070 - 28 Jun 2023

Cited by 2 | Viewed by 1160

Abstract

The adsorption of hexylamine at the solution–gold interface in 1 M HClO₄ in the presence of 0.1 M Fe²⁺ and 0.1 Fe³⁺ was studied by potentiodynamic, chronoamperometric and EIS methods. The main kinetic characteristics of the oxidation-reduction reaction iron ions [...] Read more.

The adsorption of hexylamine at the solution–gold interface in 1 M HClO₄ in the presence of 0.1 M Fe²⁺ and 0.1 Fe³⁺ was studied by potentiodynamic, chronoamperometric and EIS methods. The main kinetic characteristics of the oxidation-reduction reaction iron ions (exchange current density, transfer coefficient, diffusion coefficients of iron ions) were determined. It was shown that the physical adsorption of hexylamine on gold can be described by the Dhar–Flory–Huggins isotherm. The values of the adsorption constant and the Gibbs free adsorption energy were obtained. A comparison of the free adsorption energy at these interfaces with the interaction energies of hexylamine and water molecules, and hexylamine molecules with each other was carried out. It was shown that hexylamine adsorption at all of these interfaces is due mainly to the hydrophobic effect of the interaction of hexylamine and water molecules. Full article

(This article belongs to the Special Issue Chemistry of Corrosion Inhibitors)

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20 pages, 5107 KiB

Open AccessArticle

Corrosion Inhibition Effect of Pyridine-2-Thiol for Brass in An Acidic Environment

by Darshan Jayasinghe Karunarathne, Alireza Aminifazl, Tori E. Abel, Karen L. Quepons and Teresa D. Golden

Molecules 2022, 27(19), 6550; https://doi.org/10.3390/molecules27196550 - 3 Oct 2022

Cited by 2 | Viewed by 2461

Abstract

In this study, the inhibitive performance of pyridine-2-thiol added to a corrosive solution was investigated for brass using potentiodynamic polarization, electrochemical impedance spectroscopy, and X-ray photoelectron spectroscopy. Electrochemical experiments were performed with different inhibitor concentrations in 0.5 M H₂SO₄ as [...] Read more.

In this study, the inhibitive performance of pyridine-2-thiol added to a corrosive solution was investigated for brass using potentiodynamic polarization, electrochemical impedance spectroscopy, and X-ray photoelectron spectroscopy. Electrochemical experiments were performed with different inhibitor concentrations in 0.5 M H₂SO₄ as the corrosive medium. For potentiodynamic polarization, i_corr values decreased significantly for the inhibited solutions in contrast with the uninhibited solution. Pyridine-2-thiol had an optimum inhibition concentration of 0.25 mM, giving an i_corr value of 1.8 µA/cm² compared to 26 µA/cm² for the blank solution. EIS data indicated that R_p and R_ct values increased substantially after the addition of the corrosion inhibitor and corrosion inhibition efficiencies of more than 85% was achieved for the majority of the inhibited solutions. Scanning electron microscopy showed defect free and less scale formation for the inhibited surface but the bare brass surface had larger amounts of scale formation. X-ray photoelectron spectroscopy and UV-vis spectroscopy was used to investigate surface chemical composition and inhibitor structural changes over time. Full article

(This article belongs to the Special Issue Chemistry of Corrosion Inhibitors)

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21 pages, 4475 KiB

Open AccessArticle

An Eco-Friendly Quaternary Ammonium Salt as a Corrosion Inhibitor for Carbon Steel in 5 M HCl Solution: Theoretical and Experimental Investigation

by Rem Jalab, Mohammed A. Saad, Mostafa H. Sliem, Aboubakr M. Abdullah and Ibnelwaleed A. Hussein

Molecules 2022, 27(19), 6414; https://doi.org/10.3390/molecules27196414 - 28 Sep 2022

Cited by 13 | Viewed by 2621

Abstract

The corrosion of industrial material is a costly problem associated with global economic losses reaching trillions of US dollars in the repair of failures. Injecting corrosion inhibitors is the most practically promising method for decelerating corrosion reactions and protecting surfaces. Recent investigations have [...] Read more.

The corrosion of industrial material is a costly problem associated with global economic losses reaching trillions of US dollars in the repair of failures. Injecting corrosion inhibitors is the most practically promising method for decelerating corrosion reactions and protecting surfaces. Recent investigations have focused on surfactants as corrosion inhibitors due to their amphiphilic nature, low cost, and simple chemical preparation procedures. This study aims to investigate the performance of an environment-friendly Quaternium-22 (Q-22) surfactant which is widely used in cosmetics for C-steel corrosion inhibition in a 5 M HCl medium. Weight loss experiments were performed at different concentrations and immersion times, presenting a maximum efficiency at 2.22 mmol·L⁻¹. The influence of Q-22 on the corrosion behavior of C-steel was elucidated using non-destructive electrochemical measurements. The overall results revealed that adding varied concentrations of Q-22 significantly decreases the corrosion rate of C-steel. The results revealed the physisorption nature of Q-22 onto the C-steel surface, with adsorption following the Freundlich isotherm (∆

H_{ads}

= −16.40 kJ·mol⁻¹). The relative inhibition performance of Q-22 was also evaluated by SEM and AFM analyses. Lastly, quantum chemical calculations based on density functional theory (DFT) demonstrated that Q-22 has promising molecular features concerning the anticorrosive mechanism. Full article

(This article belongs to the Special Issue Chemistry of Corrosion Inhibitors)

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16 pages, 5821 KiB

Open AccessArticle

Experimental and Quantum Chemical Investigations on the Anticorrosion Efficiency of a Nicotinehydrazide Derivative for Mild Steel in HCl

by Nadia Betti, Ahmed A. Al-Amiery and Waleed Khalid Al-Azzawi

Molecules 2022, 27(19), 6254; https://doi.org/10.3390/molecules27196254 - 23 Sep 2022

Cited by 14 | Viewed by 1902

Abstract

A corrosion inhibitor namely N′-(4-hydroxy-3-methoxybenzylidene) nicotinohydrazide was synthesized and the inhibition efficiency of the investigated inhibitor toward the mild steel corrosion in 1 M HCl was studied. The anticorrosion effect has been investigated by weight loss (WL) techniques and electrochemical analysis includes potentiodynamic [...] Read more.

A corrosion inhibitor namely N′-(4-hydroxy-3-methoxybenzylidene) nicotinohydrazide was synthesized and the inhibition efficiency of the investigated inhibitor toward the mild steel corrosion in 1 M HCl was studied. The anticorrosion effect has been investigated by weight loss (WL) techniques and electrochemical analysis includes potentiodynamic polarization (PDP) studies and electrochemical impedance spectroscopy (EIS). The current investigation has demonstrated that the tested inhibitor is suitable in corrosive environment and the inhibitive efficacy up to 97% in 1 M HCl. PDP measurements showed that the nicotinohydrazide is a mixed type inhibitor. EIS measurements showed that an increase in the inhibitory concentration leads to an increase in the charge transfer resistance (

R_{c t}

) and a decrease in the double-layer capacitance (

C_{d l}

). Experimental results for the inhibitory performance of WL methods and electrochemical techniques (PDP and EIS) are in good agreement. The tested inhibitor molecules adsorbed on the surface of mild steel in a hydrochloric acid solution followed Langmuir’s isothermal adsorption. Quantum chemical parameters based on density function theory (DFT) techniques were conducted on oxygen/nitrogen-bearing heterocyclic molecule employed as a corrosion inhibitor for mild steel in HCl to evaluate the correlation between the inhibitor structure and inhibitory performance. The parameters including the energy gap (ΔE), dipole moment (μ), electronegativity (χ), electron affinity (A), global hardness (η), softness (σ), ionization potential (I), the fraction of electrons transferred (ΔN), the highest occupied molecular orbital energy (EHOMO), and the lowest unoccupied molecular orbital energy (ELUMO) were also calculated and were in good agreement with the experimental results. Full article

(This article belongs to the Special Issue Chemistry of Corrosion Inhibitors)

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16 pages, 5100 KiB

Open AccessArticle

Synthesis of Cyano-Benzylidene Xanthene Synthons Using a Diprotic Brønsted Acid Catalyst, and Their Application as Efficient Inhibitors of Aluminum Corrosion in Alkaline Solutions

by Mohammed A. Amin, Gaber A. M. Mersal, Morad M. El-Hendawy, Abdallah A. Shaltout, Ali Badawi, Johan Boman, Adil A. Gobouri, Murat Saracoglu, Fatma Kandemirli, Rabah Boukherroub, Jacek Ryl and Mohamed E. Khalifa

Molecules 2022, 27(17), 5733; https://doi.org/10.3390/molecules27175733 - 5 Sep 2022

Cited by 4 | Viewed by 2218

Abstract

Novel cyano-benzylidene xanthene derivatives were synthesized using one-pot and condensation reactions. A diprotic Brønsted acid (i.e., oxalic acid) was used as an effective catalyst for the promotion of the synthesis process of the new starting xanthene–aldehyde compound. Different xanthene concentrations (ca. 0.1–2.0 mM) [...] Read more.

Novel cyano-benzylidene xanthene derivatives were synthesized using one-pot and condensation reactions. A diprotic Brønsted acid (i.e., oxalic acid) was used as an effective catalyst for the promotion of the synthesis process of the new starting xanthene–aldehyde compound. Different xanthene concentrations (ca. 0.1–2.0 mM) were applied as corrosion inhibitors to control the alkaline uniform corrosion of aluminum. Measurements were conducted in 1.0 M NaOH solution using Tafel extrapolation and linear polarization resistance (LPR) methods. The investigated xanthenes acted as mixed-type inhibitors that primarily affect the anodic process. Their inhibition efficiency values were enhanced with inhibitor concentration, and varied according to their chemical structures. At a concentration of 2.0 mM, the best-performing studied xanthene derivative recorded maximum inhibition efficiency values of 98.9% (calculated via the Tafel extrapolation method) and 98.4% (estimated via the LPR method). Scanning electron microscopy (SEM) was used to examine the morphology of the corroded and inhibited aluminum surfaces, revealing strong inhibitory action of each studied compound. High-resolution X-ray photoelectron spectroscopy (XPS) profiles validated the inhibitor compounds’ adsorption on the Al surface. Density functional theory (DFT) and Monte Carlo simulations were applied to investigate the distinction of the anticorrosive behavior among the studied xanthenes toward the Al (111) surface. The non-planarity of xanthenes and the presence of the nitrile group were the key players in the adsorption process. A match between the experimental and theoretical findings was evidenced. Full article

(This article belongs to the Special Issue Chemistry of Corrosion Inhibitors)

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19 pages, 5376 KiB

Open AccessArticle

Corrosion Inhibition of Mild Steel in Hydrochloric Acid Environment Using Terephthaldehyde Based on Schiff Base: Gravimetric, Thermodynamic, and Computational Studies

by Bahaa Sami Mahdi, Muna Khethier Abbass, Mustafa Khudhair Mohsin, Waleed Khalid Al-azzawi, Mahdi M. Hanoon, Mohammed Hliyil Hafiz Al-kaabi, Lina M. Shaker, Ahmed A. Al-amiery, Wan Nor Roslam Wan Isahak, Abdul Amir H. Kadhum and Mohd S. Takriff

Molecules 2022, 27(15), 4857; https://doi.org/10.3390/molecules27154857 - 29 Jul 2022

Cited by 53 | Viewed by 3283

Abstract

Using traditional weight-loss tests, as well as different electrochemical techniques (potentiodynamic polarization and electrochemical impedance spectroscopy), we investigated the corrosion-inhibition performance of 2,2′-(1,4-phenylenebis(methanylylidene)) bis(N-(3-methoxyphenyl) hydrazinecarbothioamide) (PMBMH) as an inhibitor for mild steel in a 1 M hydrochloric acid solution. The maximum protection efficacy [...] Read more.

Using traditional weight-loss tests, as well as different electrochemical techniques (potentiodynamic polarization and electrochemical impedance spectroscopy), we investigated the corrosion-inhibition performance of 2,2′-(1,4-phenylenebis(methanylylidene)) bis(N-(3-methoxyphenyl) hydrazinecarbothioamide) (PMBMH) as an inhibitor for mild steel in a 1 M hydrochloric acid solution. The maximum protection efficacy of 0.0005 M of PMBMH was 95%. Due to the creation of a protective adsorption layer instead of the adsorbed H₂O molecules and acidic chloride ions, the existence of the investigated inhibitor reduced the corrosion rate and increased the inhibitory efficacy. The inhibition efficiency increased as the inhibitor concentration increased, but it decreased as the temperature increased. The PMBMH adsorption mode followed the Langmuir adsorption isotherm, with high adsorption-inhibition activity. Furthermore, the value of the

∆ G_{a d s}^{o}

indicated that PMBMH contributed to the physical and chemical adsorption onto the mild-steel surface. Moreover, density functional theory (DFT) helped in the calculation of the quantum chemical parameters for finding the correlation between the inhibition activity and the molecular structure. The experimental and theoretical findings in this investigation are in good agreement. Full article

(This article belongs to the Special Issue Chemistry of Corrosion Inhibitors)

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Review

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18 pages, 10521 KiB

Open AccessReview

A Brief Review on Fruit and Vegetable Extracts as Corrosion Inhibitors in Acidic Environments

by Nnabuk Okon Eddy, Udo John Ibok, Rajni Garg, Rishav Garg, Amjad Iqbal, Muhammad Amin, Faisal Mustafa, Mehmet Egilmez and Ahmed M. Galal

Molecules 2022, 27(9), 2991; https://doi.org/10.3390/molecules27092991 - 6 May 2022

Cited by 30 | Viewed by 4139

Abstract

The corrosion of metals, i.e., the initiation and acceleration of the surface deterioration of metals through an electrochemical reaction with the surrounding intrusive environment, is a global concern because of the economic and environmental impacts. Corrosion inhibitors are considered the most practical choice [...] Read more.

The corrosion of metals, i.e., the initiation and acceleration of the surface deterioration of metals through an electrochemical reaction with the surrounding intrusive environment, is a global concern because of the economic and environmental impacts. Corrosion inhibitors are considered the most practical choice among the available corrosion protection techniques due to their effectiveness in terms of functionality and cost. The use of traditional and toxic corrosion inhibitors has led to environmental issues, arousing the need for green counterparts that are environmentally friendly, easily accessible, biodegradable, and cost-effective. In this review, the utilization of green corrosion inhibitors purely acquired from renewable sources is explored, with an in-depth focus on the recent advancements in the use of fruit and vegetable extracts as green corrosion inhibitors. In particular, fruits and vegetables are natural sources of various phytochemicals that exhibit key potential in corrosion inhibition. To shed light on the true potential of such extracts in the protection of steel in acidic environments, the experimental techniques involved in corrosion inhibition and the mechanism of corrosion inhibition are discussed in detail. The study highlights the potential of fruit and vegetable extracts as non-toxic, economical, and effective corrosion inhibitors in the pursuit of green chemistry. In addition to discussing and outlining the current status and opportunities for employing fruit and vegetable extracts as corrosion inhibitors, the current review outlines the challenges involved in the utilization of such extracts in corrosion inhibition. Full article

(This article belongs to the Special Issue Chemistry of Corrosion Inhibitors)

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