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The purpose of this paper is to investigate the mechanisms of low alloyed medium-carbon steel (LAMCS) corrosion in 0.5 M H₂SO₄ inhibited by seeds oils of rubber (SOR), Neem (SON) and Jatropha (SOJ) containing varying degree of free fatty acid (FFA).

Specific gravity, acid values and FFA compositions of oils were determined. Potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and X-ray diffraction (XRD) are techniques used to investigate the corrosion inhibition mechanisms with evaluated Gibbs free energy of adsorption.

Corrosion inhibition efficiencies of oils reached values >99% as obtained from PDP and EIS. Protective oxide layer was formed on LAMCS consequent on containment of carbonyl and hydroxyl groups in the FFA of SOR, SON and SOJ, respectively. The SOR and SOJ are found to be mixed inhibitors, whereas SON behaved as anodic inhibitor. Mechanism of adsorption of SOR was synergistic between physisorption and chemisorption, while SON and SOJ exhibited physisorption. SEM micrographs images showed that uninhibited sample exhibited thicker mass of corrosion products. Formation of protective oxide layer was confirmed by XRD diffractograms.

This study has shown that the need for modification of vegetable seed oils containing FFA is unnecessary as the hydroxyl and carbonyl groups of the FFA contained in the respective oil were found to be the center of adsorption of the oils on the steel surface. Hence, cost and by-products associated with modification of oils used as corrosion inhibitors are eliminated.

SOR, which has the highest percentage FFA, was found to be the most influential on the corrosion inhibition mechanism of LAMCS, specifically within 0.01–0.02 g/mL concentration. FFA contained in the respective seed oil aided formation of protective oxide layer at interface between H₂SO₄ and LAMCS, relative to amount composed.

This work has been motivated by the authors' long‐term research on odor‐sensing systems using acoustic wave‐based sensors and pattern recognition techniques. The sensors should be fabricated in such a way that they mimic performance of the olfactory receptors. In these terms, the purpose of this paper is to test a simple method for fabrication of quartz crystal microbalance (QCM) sensors by using nanocomposites and amphiphilic gas chromatography (GC) materials. The obtained sensors were intended to be highly sensitive to odorants at low concentrations and in high‐humidity conditions, as well as contributing to discrimination among odorant samples.

The proposed fabrication process consists of four stages: formation of all‐lipopolymeric layer on surface of the QCM sensor; preparation of lipopolymeric nanocomposites by means of chemisorption of lipopolymers onto nano‐Au; precipitation of the nanocomposites onto the lipopolymer‐coated QCM surface; and physisorption of amphiphilic GC materials onto the lipopolymer‐nanocomposite matrix. The fabricated sensors have been evaluated in the experiments of exposure to vapors of odorants at various concentrations and humidity levels.

The authors found that sensitivity of the sensors fabricated using the proposed method was much superior to that recorded for the sensors with all‐lipopolymeric and all‐amphiphilic films. The novel sensors' performance showed robustness against humidity and capability to discriminate among odorant samples at relatively low‐concentration levels.

The sensors fabricated using the proposed method can be useful in recognition of the odorant samples at ppb‐level under high humidity. Their performance has not been deteriorated even under high humidity.

The paper presents application of a relatively simple chemi‐/physisorption processes to form an odor‐interactive coating, with high sensitivity and robustness against humidity. To the best of the authors' knowledge, the method proposed here has not been presented by other groups.

This paper aims to investigate the influence of temperature and lignin concentration on the inhibition of carbon steel corrosion in 1 M HCl.

Weight loss corrosion tests were performed at different temperatures in the range of 30-70°C (303-343 K).

It was found that the corrosion inhibition efficiency (IE) of lignin on the carbon steel decreased when the temperature was increased from 60 to 70°C. However, at lower temperatures ranging from 30 to 50°C, the IE improved, due to occurrence of lignin adsorption on the surface of metal specimens. The IE was higher with increasing lignin concentration, thus reducing the weight loss of the carbon steel. The adsorption phenomenon involved exothermic processes because the value of enthalpy of adsorption (ΔH°_ads) < 0 and Gibbs free energy of adsorption (ΔG°_ads) were less negative with increase in temperature. The entropy of adsorption (ΔS°_ads) had negative values, representing the decrease in disorder of adsorption. The adsorption of lignin on the carbon steel surface in 1 M HCl was comprehensive, as deduced from kinetic and thermodynamic parameters. However, physisorption was the major contributor in the inhibition mechanism. The inhibitive features of carbon steel surfaces showed less damage once the steel was treated in lignin, as evident from macroscopy images.

The use of lignin as an acid corrosion inhibitor at high temperature is practical in metal surface treatment process.

The use of organic compounds gives an advantage to the environment, universal health and save cost, as the compounds can be found in nature.

Lignin can act as a flexible corrosion inhibitor within the temperature range of 30-70°C in 1 M HCl because it exhibits comprehensive adsorption (i.e. a combination of both physisorption and chemisorption) at specific concentrations.

Plant development and use as green corrosion inhibitors are already recognized as one of the most environmentally friendly and effective protocols. In recent years, efforts have been made to find green corrosion inhibitors as an alternative to synthetic inhibitors for metals in acid medium. This paper aims to report the investigation of use of aqueous extracts of Tamarindus Indica as green inhibitors for corrosion of metals within different circumstances.

The use of Tamarindus Indica extracts (leaves, stem, fruit pulp and fruit husk) as corrosion inhibitors for mild steel and aluminum in different mediums (HCl, H2SO4, formic acid and citric acid) at different temperatures was investigated.

The inhibitory efficiency of Tamarindus Indica extracts increases with increasing concentration and decreases with increasing temperature. Langmuir is the adsorption isotherm, and the extract (inhibitor) is a mixed-type inhibitor (physisorption and chemisorption).

Tamarindus extracts (leaves, stem, fruit pulp and fruit husk) are effective inhibitors and can be used to protect metals from corrosion at different circumstances.

To the best of the authors’ knowledge, this is the first review that discusses the use of Tamarindus Indica extracts as corrosion inhibitors for metals.

This paper aims to investigate the corrosion inhibition efficiency of Landolphia heudelotii (LH) on mild steel in 1 M HCl and 0.5 M H₂SO₄ using weight loss and potentiodynamic polarization techniques.

Water extract of LH was used as corrosion inhibitor on mild steel in acidic media at room temperature and elevated temperatures (30-60°C). Various concentrations of the plant extract were prepared from the stock solution obtained after solvent extraction. The inhibition efficiency of LH extract was evaluated and mechanism of adsorption was deduced.

LH extract showed significant corrosion inhibition on mild steel in both acidic media, with inhibition efficiency increasing with extract concentration. Potentiodynamic polarization measurements revealed mixed inhibition mechanism. Optimum inhibition efficiency was recorded at 2500 mg/L after 288 h. Mechanism of adsorption was mainly of physisorption. The inhibitor exhibited good inhibition efficiency even at elevated temperature.

This study provides new data on the anticorrosion characteristics of LH extract under the specified conditions. Further studies could expand the experimental variables and use advanced surface probe techniques.

The developed inhibitor provides an alternative method of inhibiting corrosion on mild steel using eco-friendly materials from natural products which are less toxic, safer, cost-effective and readily available.

The method used was effective and the inhibitor developed can be incorporated in surface coatings where mild steel is used as construction materials, as tube sheets, rods and bars.

The purpose of this paper is to study the corrosion inhibition tendency of cigarette waste (water extracts of cigarette butts, WECB) on an iron surface in an acid medium.

The electrochemical impedance spectroscopy and polarization techniques were used to analyze the performance of WECB on the iron working electrode. Electrochemical polarization curves were used to determine the intensity of the metal corrosion, specifically to see the effectiveness of the anodic and cathodic reactions in the corrosive medium having WECB. Moreover, the electrochemical impedance of WECB with electrode was analyzed qualitatively. The electrochemical data that relate isotherm adsorption of WECB with iron were analyzed; furthermore, the scanning electron microscope was used to analyze morphology change during the corrosion inhibition.

After analyzing the impedance data, it is seen that there exists a single capacitive semicircle at the higher frequency range corresponding to a one-time constant in the Bode-phase plot. In the polarization curves studies (Tafel slopes), the current densities of both cathodic and anodic branches are greatly affected in the presence of WECB in the corrosive medium, suggesting that WECB performs as a mixed inhibitor. The free energy data and Temkin adsorption isotherm process show that the adsorption process of WECB on the metal surface follows a physisorption. Furthermore, the WECB-coated metal surface analyzed by scanning electron microscopy confirms the corrosion inhibition of WECB in the acid medium.

An in-depth characterization of the corroded scales is recommended to endorse the results of this study.

There may be some people who may challenge that the research may encourage smoking; however, if taken positively, the research offers a very cost-effective and eco-friendly solution to tackle the cigarette waste.

Idea of the present work is to reuse the WECB as corrosion inhibitors for the metal surface, as this waste contains large amount of nicotine, which exhibits corrosion inhibition properties. The present work deals with the study of corrosion inhibition properties of WECB on the iron surface in acid medium. The findings of this study can be very useful from scientific, as well as industrial application point of view. Moreover, the research is important as there is no proper recycling process for this waste so as to maintain a clean environment.

The aim of this paper is to appraise the inhibiting potential of hydroxypropyl methylcellulose (HPMC) on the corrosion of mild steel and aluminium in sulphuric and hydrochloric acid solutions.

The effects of two different corrodents on the dissolution of mild steel and aluminium were examined. Corrosion rates were determined using the weight loss technique. Inhibition efficiency was estimated by comparing the corrosion rates in absence and presence of the additive. The kinetics and mechanism of HPMC adsorption were investigated by impedance study while the anodic and cathodic partial reactions were studied by polarization measurements.

The results reveal that corrosion rate of mild steel and aluminium decreased with addition of HPMC. The corrosion rate and inhibition efficiency were found to depend on the concentration of the inhibitor. The polarization data indicated that the inhibitor was of mixed-type, with predominant effect on the cathodic partial reaction. electrochemical impedance spectroscopy confirms that corrosion inhibition was by adsorption on the metal surface following Freundlich adsorption isotherm via physisorption mechanism.

Hydroxypropyl methylcellulose has been studied for the first time as an inhibitor of mild steel and aluminium corrosion and the results suggest that the inhibitor could find practical applications in corrosion control in HCl and H₂SO₄ acid media. The findings are particularly useful, considering the fact that HPMC is a good film former and viscosity enhancer which could also be used in paint formulation.

This study aims to investigate the inhibition effect of a newly synthesized1,2,3-triazole containing a carbohydrate and imidazole substituents, namely, 1-((1-((2,2,7,7-tetramethyltetrahydro-5H-bis([1,3]dioxolo)[4,5-b:4′,5′-d]pyran-5-yl)methyl)-1H-1,2,3-triazol-4-yl)methyl)-1H-benzo[d]imidazole (TTB) on the corrosion of mild steel in aerated 1 M H₂SO₄.

The authors have used weight loss measurement, potentiodynamic polarization, electrochemical impedance spectroscopy, FT-IR studies, scanning electron microscopy analysis and energy dispersive X-ray (EDX) spectroscopy techniques.

It is found that, in the working range of 298-328 K, the inhibition efficiency of TTB increases with increasing concentration to attain the highest value (92 per cent) at 2.5 × 10⁻³ M. Both chemisorption and physisorption of TTB take place on the mild steel, resulting in the formation of an inhibiting film. Computational methods point to the imidazole and phenyl ring as the main structural parts responsible of adsorption by electron-donating to the steel surface, while the triazol ring is responsible for the electron accepting. Such strong donating–accepting interactions lead to higher inhibition efficiency of TTB in the aqueous working system.

This work is original with the aim of finding new acid corrosion inhibitors.

The purpose of this paper is to study the adsorption properties of a proven traditional medicine of West Africa origin, Alstonia boonei with an attempt to evaluate its application in the corrosion protection of mild steel in 5 M H₂SO₄ and 5 M HCl.

Phytochemical screening and Fourier transform infrared spectroscopy analysis were used to characterize the methanolic extract of the plant. Gravimetry, gasometry and electrochemical techniques were used in the corrosion inhibition studies of the extract and computational studies were used to describe the electronic and adsorption properties of eugenol, the most abundant phytochemical in Alstonia boonei.

The extract acted as a mixed-type inhibitor in both acidic solutions, with improved inhibition efficiency achieved with increasing concentration. While the efficiency increased with temperature for the HCl system, it decreased for the H₂SO₄ system. The mechanism of adsorption proposed for Alstonia boonei was chemisorption in the HCl system and physisorption in the H₂SO₄ system, and the adsorptions obeyed Langmuir isotherm at low temperatures. Computational parameters showed that eugenol, being a representative of Alstonia boonei, possesses excellent adsorption properties and has the potential to compete with other established plant-based corrosion inhibitors.

As opposed to pure compounds with distinctive corrosion effects, plant extracts are generally composed of a myriad of phytoconstituents that competitively promote or inhibit the corrosion process and their net effect is evident as inhibition efficiencies. This is, therefore, the main research limitation associated with the corrosion inhibition study of Alstonia boonei.

Being very rich in antioxidant properties by its proven curative and preventive effects for diseases, the interest was stimulated towards the attractive results that abound from its corrosion protection of metals via its anti-oxidation route.

As an example of structure-efficiency relationship study, this paper aims to evaluate the corrosion inhibition effect of two cationic surfactants, cetyl-trimethyl ammonium chloride (CTAC) and cetyl-dimethyl-hydroxyethyl ammonium chloride (CDHAC), and to discuss the effect of structure on the performance by thermodynamics methods.

The effect of the two cationic surfactants, CTAC and CDHAC, on the corrosion of the mild steel in HCl solution was investigated by using weight loss measurements, and the activation energies of CTAC and CDHAC involved in the corrosion inhibition were calculated and discussed.

The weight loss measurements showed that the corrosion inhibition efficiency of CDHAC was higher than that of CTAC in any case. The effects of the structure on performance were discussed, and the following data are available from the results, all of ΔS are positive, the values of ΔG are both close to −40 kJ·mol-1 and the values of ΔH are 10.960 and 36.996 kJ·mol-1, which indicate that the surfactant molecules are spontaneously adsorbed on the surface of the steel surface, and the adsorption on the steel plate is endothermic chemical adsorption.

The available data show that most organic inhibitors undergo physisorption on the metal surface, while in the presence of non-bonded and p-electrons, the inhibitor molecules may undergo chemisorption. This work showed that the two surfactant molecules are spontaneously adsorbed on the surface of the steel surface, and the adsorption on the steel plate is endothermic chemical adsorption.