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Special Issue "Chemistry of Corrosion Inhibitors"

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Electrochemistry".

Deadline for manuscript submissions: 31 January 2023 | Viewed by 2550

Special Issue Editors

Dr. Lukman Olawale Olasunkanmi
E-Mail Website1 Website2
Guest Editor
Department of Chemistry, Faculty of Science, Obafemi Awolowo University, Ile-Ife 220005, Nigeria
Interests: corrosion prevention; electrochemical corrosion; quantum chemistry; computational chemistry; reaction kinetics and mechanism; chemical thermodynamics
Prof. Dr. Eno E. Ebenso
E-Mail Website
Guest Editor
College of Science, Engineering and Technology, University of South Africa, Johannesburg 1710, South Africa
Interests: corrosion inhibition; quantum chemical studies; theoretical studies; DFT; molecular simulation: electrochemistry; electrocatalysis; cyclic voltammetry

Special Issue Information

Dear Colleagues,

This Special Issue, entitled “Chemistry  of Corrosion Inhibitors”, invites various research papers on corrosion inhibition study—both experimental and theoretical investigations. Studies that present detailed assessment of inhibition potentials and mechanism are particularly encouraged.

The use of appropriate corrosion control practices promises to reduce the global cost of corrosion by a significant extent. The use of corrosion inhibitors is a versatile method of repressing metal corrosion. Corrosion inhibitors are substances that reduce corrosion rate, particularly when added in small concentration to an aggressive solution. Corrosion inhibition is a widely used corrosion prevention technique. This is due to its economic viability, as well as the ease and dynamism of application. From the chromate-based toxic inorganic compounds to triazoles and myriads of organic heterocyles, corrosion chemistry experts continue to explore the research space for more efficient, cost effective, and environmentally friendly corrosion inhibitors. The inhibition efficiency and mechanism vary from one compound to another, and these also depend on several factors, which include the nature of aggressive environment and corroding material.

There are continuous efforts towards better understanding of the chemistry of corrosion inhibitors. There are still more to understand on the adsorption process of inhibitor molecules on metal substrate, as well as inhibitor–metal interactions. Different experimental and theoretical techniques are also being employed in this regard.

Original research papers and review articles that fit into the above description and aim at improving the understanding of the chemistry of corrosion inhibitors are hereby welcomed in this Special Issue.

Dr. Lukman Olawale Olasunkanmi
Prof. Dr. Eno E. Ebenso
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2300 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • metal/alloy corrosion
  • corrosion prevention
  • electrochemical techniques
  • computational studies
  • surface morphology
  • inhibitor/metal adsorption study

Published Papers (5 papers)

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Research

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Article
An Eco-Friendly Quaternary Ammonium Salt as a Corrosion Inhibitor for Carbon Steel in 5 M HCl Solution: Theoretical and Experimental Investigation
Molecules 2022, 27(19), 6414; https://doi.org/10.3390/molecules27196414 - 28 Sep 2022
Viewed by 164
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 (∆= −16.40 kJ.mol1). 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)
Article
Experimental and Quantum Chemical Investigations on the Anticorrosion Efficiency of a Nicotinehydrazide Derivative for Mild Steel in HCl
Molecules 2022, 27(19), 6254; https://doi.org/10.3390/molecules27196254 - 23 Sep 2022
Viewed by 273
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 (Rct) and a decrease in the double-layer capacitance (Cdl). 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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Article
Synthesis of Cyano-Benzylidene Xanthene Synthons Using a Diprotic Brønsted Acid Catalyst, and Their Application as Efficient Inhibitors of Aluminum Corrosion in Alkaline Solutions
Molecules 2022, 27(17), 5733; https://doi.org/10.3390/molecules27175733 - 05 Sep 2022
Viewed by 323
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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Article
Corrosion Inhibition of Mild Steel in Hydrochloric Acid Environment Using Terephthaldehyde Based on Schiff Base: Gravimetric, Thermodynamic, and Computational Studies
Molecules 2022, 27(15), 4857; https://doi.org/10.3390/molecules27154857 - 29 Jul 2022
Cited by 1 | Viewed by 367
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 Gadso  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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Review
A Brief Review on Fruit and Vegetable Extracts as Corrosion Inhibitors in Acidic Environments
Molecules 2022, 27(9), 2991; https://doi.org/10.3390/molecules27092991 - 06 May 2022
Viewed by 900
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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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

 

Title: Experimental and DFT Elucidation of the Adsorption and Protective Mechanism of Lippia javanica Leaf Extract for Aluminium Corrosion

Authors: Tshimangadzo Nesane 1, Ntakadzeni Edwin Madala 2, Mwombeki Mwadham Kabanda 1 and Lutendo C. Murulana 1

Affiliations: 

1. Department of Chemistry, University of Venda, South Africa

2. Department of Biochemistry & Microbiology, University of Venda, South Africa

Abstract: Theoretical calculations are now able to predict the behaviour of corrosion inhibitors on metal surfaces and provide an understanding of their protective efficiency at the atomic level. They can be used in conjunction with experimental work to evaluate the protective effect of corrosion inhibitors. Using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) and gravimetric analysis techniques, Lippia javanica leaf extract was evaluated for its ability to inhibit aluminium (Al) corrosion. As one of the main metabolites identified in the L. javanica extract, the adsorption of verbascoside molecules on the Al surface was studied using the generalized gradient approximation (GGA) of density functional theory (DFT) to identify the most stable adsorption configurations. The DFT calculations were performed on the face centred cubic (FCC) surface plane of the Al surface {Al(111)}, which is one of the most stable planes of the metal. According to EIS, the presence of L. javanica extract in the caustic solution decreased the corrosion current density (icorr) and the double-layer capacitance (Cdl) due to the formation of a protective adsorption layer on the Al surface. PDP curves showed anodic polarization passivation of the Al substrate, which is a well-known property of a highly entropic alloy like Al. Gravimetric results showed that the maximum protective efficacy of the L. javanica extract was 97.22%. Contact angle and Fourier transform infrared spectroscopy (FTIR) were also used in this work to evaluate the protective adsorption film formed on the Al surface. It was discovered that the mechanism of the extract on the Al surface follows the Langmuir adsorption isotherm description process.

Keywords: Verbascoside, Adsorption isotherm, L. javanica, Corrosion inhibitors, DFT calculations, Anodic polarization

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