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Purpose The purpose of this paper is to minimize corrosion-related pollution in the environment. From the lemongrass extract (LGE), the authors selected one of the best green inhibitors. Design/methodology/approach The corrosion and inhibition of mild steel in traditional acidification solutions were estimated by electrochemical measurements. The corrosion appearance was observed with scanning electron microscopy, atomic force microscopy micrographs and attenuated total reflectance infrared spectroscopy spectrum. The correlation was formed between the gained inhibition efficiency (IE)% from electrochemical measurements and certain quantum chemical parameters. Findings The results displayed that the IE was up to 90% when the LGE concentration was 300 ppm. The results confirmed that the theoretical experiments are very similar to the experimental observations. Originality/value For the first time, LGE was used as a cheap and safe corrosion inhibitor for mild steel corrosion in the acidification process. The mechanism of mild steel corrosion and anti-corrosion in acid solution has been suggested.

The inhibition performance of 5-methyl-3-phenylisoxazole-4-carboxylic acid (MPC) alone and in combination with potassium iodide (KI) for low carbon steel in 1.0 M HCl and H2SO4 solutions is studied...

Experimentally proved by the method of polarization resistance formation of protective layers during inhibition steel corrosion by Sulfanilamide in aqueous solutions of hydrochloric acid with different pH. It is shown the difference due to the predominance of the protonated or unprotonated form of the molecule. It was found that at predominance of protonated forms of molecules (pH £2,4) formed dense protective films and predominance of unprotonated forms of molecules (pH ³2,4) are formed layers that do not inhibit diffusion processes. Sulfanilamide provides high and stable inhibition efficiency (

Secondary and tertiary amines of the acetylene series of various structures (14 compounds) were synthesized based on propargylamine. The possibility of a significant inhibition with these substances of low-carbon steel corrosion in hot solutions of hydrochloric acid has been established. The protective effect of acetylenic amines rises with an increase in their content in an aggressive environment and with an increase in its temperature. The maximum protection effect is provided by tertiary amines containing 2,3-epoxypropyl or 2,3-epithiopropyl as a substituent. The presence of chemically active epoxy and epithio groups in the structure of these acetylenic compounds promotes the stimulation of their polymerization on the steel surface through the opening of C≡C bonds, which leads to the rapid formation of a protective polymer film on it.

Synergistic effect of KI on the corrosion inhibition efficiency of methylene bis [(2-hydroxy-5, 1-phenylene) bismethylene] tetraphosphonic acid (TPA) on corrosion of copper in 0.5 M HCl have been t...

The effect of poly acryl amide in the 15% HCl solution of carbon steel (class L-80) was studied using weight loss method , the efficiency of inhibitor increased by increasing inhibitor concentration and decreasing temperatures. Inhibition attributed to insoluble complex adsorbed on the coupon (L-80) carbon steel surface. The iron complex was identified by FTIR. And the mechanism of inhibition was explained as Langmuir adsorption isotherm. The thermodynamic parameters of adsorption operation was calculated and explained

The adducts were synthesized by means of diene condensation reaction of levopimaric acid with acrylic acid, and through carrying out the free radical addition of ethandithiol to levopimaric acid. The composition and structure of these adducts were identified through data of the elemental analysis, IR and PMR spectroscopy. The efficiency of the synthesized diacids as corrosion inhibitors was determined by means of the gravimetric method (on mass losses of a sample of steel plate of mark C-3) in an acidic medium (solutions of 1H and 5H of sulfuric acid). The influence of the medium temperature and concentration of the used compounds on the degree of protection and corrosion inhibition coefficient was analyzed. It found that rise in temperature results in the increase of protective effect of the inhibitor. Note that the increase of the inhibitor concentration, raising the degree of protection though, is not so noticeable.

The article presents the results of a study of individual representatives of oxazolidin-2-ones as inhibitors of acid corrosion of steel. The influence of temperature and inhibitor concentration on the degree of protection was evaluated by a complete two-factor experiment. The results of electrochemical tests of steel are presented. Oxazolidin-2-ones can be attributed to a group of promising inhibitors of acid corrosion of steel and continue research.

The inhibition of (3ar,6ar)-3a,6a-di-p-tolyltetrahydroimidazo[4,5-d]imidazole-2,5(1 h,3h)-dithione (TTHIIDT) for carbon steel was full characterized in a 1 M hydrochloride acid environment at various inhibitor concentrations and temperatures by the gravimetric, electrochemical, surface and quantum chemical analyses. The obtained results confirmed that the inhibition efficiency of TTHIIDT was over 95–97% and nearly stable in the rise of temperature and concentration; TTHIIDT was mixed type inhibitor and effectively influenced both anodic and cathodic corrosion reactions; a protective hydrophobic thin layer of this inhibitor on the carbon steel surface is more stable and non soluble in 1 M HCl medium; this inhibitor adsorbed endothermically on the carbon steel surface by the chemical and physical adsorption processes. The quantum chemical calculations supported the experimental results and showed that the inhibition efficiency is depends on the structure of inhibitor.

Corrosion inhibitive action of glutathione reduced (Gth), an eco-friendly inhibitor of aluminium alloy 6061 (AA6061) was investigated in a 0.5 M HCl medium. Experiments were conducted using weight loss and potentiodynamic polarization (PDP) methods. The inhibition efficiency of Gth increases with increasing its concentration and decreases with increasing temperature. Gth demonstrated reasonably good inhibition performance (87 % at 0.7 mM at 303 K) by acting as a mixed inhibitor. The measurement of activation and thermodynamic parameters regulating the inhibition behavior of Gth shows the mixed adsorption of Gth on the alloy surface, which follows the Langmuir isotherm model. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) was used to conduct the surface morphological examination of corroded and inhibited alloy specimens.

Alumina ceramics are widely used because of chemical corrosion resistance. Although alumina ceramics can resist many strong acids and organic acids, be corroded easily by HF due to silicon components in raw materials. This work aimed to reveal the effect of La2O3 on HF/HCl resistance of the alumina ceramic containing SiO2. The X-ray diffractometer (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), were used to study the microstructure and mechanism, acid solubility and bulk density were tested. It was discovered that La caused the enrichment of Ca and Si, and the enrichment degree of Si was higher, which led to generation more CaAl2Si2O8 in the ceramic. Moreover, La3+ could replace Ca2+ to form solid solutions with CaAl2Si2O8. The acid solubility of the solid solutions and La0.85Al11.55O18.6 and the effect of them on the corrosion resistance of this alumina ceramic were studied. Results showed that a proper addition of La2O3 was beneficial to the acid resistance of alumina ceramic for long time corrosion, while bulk density increased. The mechanism of corrosion resistance has been discussed.

The detection and identification of cigarette ash in fire debris can be meaningful in fire investigations caused by burning cigarettes. In this work, a novel analytical method based on negative chemical ionization time-of-flight mass spectrometry (NCI/TOFMS) combined with a phosphoric-acid-enhanced evaporation strategy has been developed for the discrimination of cigarette ash samples (CAs) and common household decoration material ash samples (CHDMAs). A series of characteristic ions representing the acidified products HNCO and formic acid in the CAs were achieved, whose signal responses were enhanced with the help of mechanical agitation operation. To account for both the signal responses of the characteristic ions and acid corrosion of the ion source, the dynamic-purge gas was chosen to be 200 mL/min. The whole time for analysis was only 5 min, which is suitable for high-throughput measurements of large quantities of fire debris. As a result, a preliminary discrimination was achieved between the CAs and CHDMAs by virtue of the chemometric tool of principal components analysis (PCA) based on intensity differences of the characteristic ions. The results are encouraging and highlight the potential of NCI/TOFMS without complicated sample preparation steps for the accurate and high-throughput identification of cigarette ash on substrates in fire debris.

Herein, An examination into the corrosion inhibition of mild steel (MS) in 1.0 M HCl by the Chicoriumintybus extract as a green inhibitor had been achieved via chemical, electrochemical and morphological measurements. The effect of KI additives on corrosion inhibition efficiency was carried out using a weight loss method. The results reveal that the Chicoriumintybus extract inhibited the corrosion reaction by adsorption onto the metal/solution interface. Inhibition efficiency, increased with the Chicoriumintybus concentration and synergistically increased with the presence of KI. The addition of iodide ions to the Chicoriumintybus extract raises inhibition efficiency of 74 to 99%. Polarization data suggest that the Chicoriumintybus extract acts as a mixed inhibition-mechanism. This observation was further corroborated by the fit of experimental adsorption data to the Temkin isotherm. The results were confirmed by AFM, SEM images and ATR-IR for the surface morphology.

Se utilizaron extractos de Endocarpio y pericarpio de cactus Cereus fricii para inhibir la corrosion del acero al carbono en soluciones de HCl y NaCl mediante ensayos gravimetricos. Los extractos fueron obtenidos mecanicamente, las concentraciones fueron fijadas y caracterizadas por pruebas fitoquimicas y analisis FTIR y la naturaleza de la inhibicion fue determinada por calculo de Gibbs Free Energy. Se establecio que los extractos tienen la presencia de taninos, saponinas y compuestos antioxidantes, lo que fue corroborado por el analisis FTIR, mostrando picos de absorbancia correspondientes a los grupos OH y COOH, siendo el extracto de endocarpio el de mayor proporcion. Los extractos de endocarpio con una concentracion del 5% mostraron un mejor rendimiento en la inhibicion de la corrosion que los extractos obtenidos del epicarpio, con porcentajes del 97,71 al inhibir el HCl y del 73,91% al inhibir el NaCl. La presencia de taninos, saponinas y compuestos antioxidantes en los extractos del endocarpio y del epicarpio favorecen la inhibicion de la corrosion metalica.

The first run of continuous hydrothermal leaching of lithium-ion battery cathode materials, LiCoO2, was performed using citric acid as the leachant at 200 °C. The flow system was specially designed and customized. Prior to the hydrothermal leaching experiments, a three-layer model was used to predict the flow state in this flow system, and a cold flow test using two kinds of flow lines was performed to determine the conditions in the preliminary experiments. Finally, the pulp density of the slurry and the flow rate were set to 10 g L−1 and 30 ml min−1, respectively, for the continuous hydrothermal leaching experiments. At 60 min after the start of slurry feeding, the leaching efficiency of Li and Co reached 81.3% and 92.7%, respectively, and can continue to increase with the extension of time. The successful run indicated that the process of hydrothermal leaching is feasible and promising to be applied in practice. Meanwhile, a problem of acid corrosion caused by the use of citric acid during this process was revealed and is expected to be resolved using inner coating materials with high acid corrosion resistance or organic acids with low or no acid corrosion as the leachant.

Imidazoline obtained from the essential oil contained in Pouteria sapota seed was tested as an environmentally-friendly corrosion inhibitor of 1018 carbon steel in CO2 saturated 3.5 % NaCl solution using electrochemical techniques. This imidazoline contains fatty acids with the presence of long hydrophobic chains, with 52.73 % of unsaturated (oleic and linolenic acids) and 40 % of saturated (palmitic and myristic acids) compounds. Polarization curves revealed that this inhibitor is highly efficient mixed-type of inhibitor with the inhibitor efficiency of 99.9 % reached at 25 ppm. Also, the lowest pitting potential value was observed at 25 ppm of inhibitor, making the carbon steel highly susceptible to the pitting type of corrosion. Corrosion current density value decreased by nearly four orders of magnitude, and a passive film formation was induced for inhibitor concen­tra­tions higher than 5 ppm. Accordingly, polarization resistance values were increased from 100 W cm2 up to about 106 W cm2 at 25 ppm of inhibitor. The inhibitor forms a protective film of corrosion products adsorbed on the metal surface in a very strong chemical way, following a Langmuir type of adsorption isotherm. This was supported by electrochemical impedance spectra that showed two relaxation processes ascribed to electrode interface and film regions. In agre­ement with polarization resistance data, the total electrode resistance determined by inter­facial charge transfer and film resistance, increased up to 8.2 ´ 105 W cm2 in presence of 25 ppm of inhibitor. SEM images additionally showed that type of corrosion was fully changed from uniform to a localized type when 25 ppm of inhibitor was added into the solution.

The anticorrosive potential of Ficus hispida leaf extract (FHLE) as a corrosion inhibitor in 1 M HCl was investigated using weight loss measurement as well as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Stigmasterol as the major constituent of F. hispida was confirmed by Gas Chromatography–Mass Spectrometry (GC–MS). Inhibition efficiency of 90% was achieved with 250 ppm of FHLE at 308 K. Temperature studies revealed an increase in inhibition efficiency with decrease in temperature and activation energies increased in the presence of the extract. Cathodic and anodic polarization curves revealed that FHLE acts as mixed type inhibitor, but cathodic effect was more pronounced. Impedance diagrams showed that increasing FHLE concentration, increased charge transfer resistance and decreased double layer capacitance. The adsorption of FHLE on mild steel surface obeyed Langmuir adsorption isotherm. The morphology of the surface was examined by scanning electron microscopy (SEM) and the surface composition was evaluated using energy-dispersive X-ray (EDX) spectroscopy to verify the presence of inhibitor on the mild steel surface. The adsorbed film on the mild steel surface containing the FHLE inhibitor was also characterized by diffuse reflectance Fourier transform infrared spectroscopy (DRFT-IR) and X-ray diffraction (XRD) studies. Keywords: Acid corrosion, Mild steel, Polarization, SEM, Adsorption

This study investigated the feasibility of H2 production by acid corrosion, employing a by-product from the fertilizer industry (Hexafluorsilic acid - H2SiF6) and waste iron sources. Different masses of metal from three different sources: iron powder (waste from metal workshops), steel wool and rebar (construction waste), were reacted with various proportions of H2SiF6 with HCl. The influence of the variables was evaluated by factorial design, verifying greater production of H2 for materials with higher contact areas. The lowest production was observed for construction industry waste (rebar) probably due to the presence of protective films and lower contact area. The gas produced was analyzed by gas chromatography and was found to consist only of H2 (up to 99%) and air. The results indicate a promising application of H2SiF6, which is generated in large quantities during phosphate fertilizer production and has few commercial applications. The method proposed is promising, it does not emit toxic or polluting gases, contributing to the sustainable generation of H2.

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.

Applied Sciences 11(20), 9431 (2021). doi:10.3390/app11209431 special issue: "Special Issue "Effects of Temperature on Rock and Rock Masses" / Special Issue Editor: Prof. Dr. Roberto Tom��s, Guest Editor", Published by MDPI, Basel

The inhibitory action of three imine-chalcones on carbon steel corrosion in HCl was investigated by theoretical and experimental methods. Quantum descriptors were calculated at the conductor-like polarizable continuum model (CPCM)-Becke-3 Parameter-Lee-Yang-Parr (B3LYP)‑D3/def2-TZVPP level allowing the prediction of efficiency inhibition ranking. Electrochemical techniques and mass loss experiments were employed to determine inhibition efficiencies and related experimental parameters. Scanning electron microscopy was employed for metal surface analysis. The N-[(1Z,2E)-1,3-diphenylprop-2-in-1-ylidene]-1-phenethylamine (IM‑F) was pointed out as the most efficient inhibitor in this group, with 96% of corrosion inhibition. Moreover, theoretical results obtained from periodic calculations for the adsorption on the Fe(110) surface corroborated the highest efficacy of IM‑F.

This paper describes a staged acid corrosion inhibition concept for application in matrix acidizing treatments. The approach optimizes the performance of acid corrosion inhibitor (ACI) formulations used to protect coiled tubing (CT) and downhole casing during acid injection and flowback. The concept relies on polymerizable ACI chemistry. Matrix acidizing formulations are currently designed with a fixed ACI dosage throughout acid injection. The staged approach uses a higher ACI dosage (first stage) to establish a persistent inhibitor film followed by a lower ACI dosage (second stage) to maintain that film. The persistence of the first stage inhibitor film relies on polymerizable ACI chemistry. Staged performance was evaluated by weight loss and electrochemical testing on CT and casing steels in 15% hydrochloric acid at temperatures in the range 60 to 121°C. Rotating cylinder electrodes (RCEs) were used to compare performance under laminar and realistic turbulent flow conditions. An electrochemical flow cell (EFC) was used to quantify performance when the ACI dosage was changed during flow. The ACI dosage used in the second stage can be at least one order of magnitude lower than that in the first stage. Staged treatments can be designed for enhanced corrosion protection using a lower total quantity of inhibitor relative to conventional treatments. Optimum first and second stage ACI dosages depend on temperature and metal type. For CT in 15% hydrochloric acid, typical stage 1 and stage 2 dosages are 0.2 and 0.01 %, respectively, at temperatures ranging 77 to 99°C; these dosages increase to 1.0 and 0.05–0.1 % at 121°C. RCE testing showed robust performance under realistic dynamic flow conditions, and EFC testing showed good performance when the ACI dosage was changed during flow. The staged ACI concept achieves enhanced corrosion protection of CT and wellbore casing using a lower total quantity of inhibitor relative to conventional treatments. The next step is to evaluate the performance of staged ACI treatments in field experiments.

Acid corrosion is a problem pertaining to corrosion that involves an acid solution. It is important to treat metal to preserve its integrity. Thus, acids are utilized to clean and treat metal surfaces. In return, this may lead to over-etching and metal degradation. Corrosion inhibitors were introduced as a solution for the issue. However, there are some problems associated with the usage of conventional corrosion inhibitors. Traces of nitrites and chromates that are present in the inhibitors may lead to serious health and environmental issues. As a solution, organic green corrosion inhibitors have been studied to replace the conventional corrosion inhibitors. These inhibitor molecules form a protective layer on top of the metal surface to suppress metal dissolution when added to the acid solution. This process prevents direct contact between the metal surfaces and the acid environment. This study explores the usage of natural resources and biomass wastes as the basis for organic green corrosion inhibitors. This study also provides some suggestions for new biomass wastes that can be studied as new organic corrosion inhibitors, and it is aimed at opening the perspective of researchers on exploring new organic inhibitors by using natural resources and biomass wastes.

In the present investigation, thin layer activation technique has been employed to study the effectiveness of an amine derivative compound, namely hexamethylene tetramine (HMTA) for corrosion inhibition of carbon steel in acid solution. The corrosion studies have been performed in 1 mol dm−3 HCl containing different concentrations of inhibitors. Inhibition efficiency of HMTA at different experimental conditions has been estimated. It was observed that at ambient condition, 500 ppm HMTA effectively inhibits acid corrosion of carbon steel with an inhibition efficiency of 89.8%. The inhibition efficiency was found to be altered by increase in the temperature of corrosive solution.