Inhibition effect of natural polysaccharide composite on hydrogen evolution and P110 steel corrosion in 3.5 wt% NaCl solution saturated with CO2: Combination of experimental and surface analysis

For the analysis of corrosion and hydrogen production inhibition, we have synthesized Guar gum and methylmethacrylate (GG-MMA) composite. The synthesized composite was used as an eco-friendly corrosion inhibitor for P110 steel in 3.5% NaCl solution saturated with carbon dioxide at 50 °C. The primary corrosion techniques like weight loss, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) was used to analyze the corrosion inhibition process. EIS study reveals the kinetically controlled corrosion inhibition process. The results of PDP proposed that GG-MMA composite is the cathodic type of inhibitor. The corrosion inhibition performance of GG-MMA alone is 90% at 400 mg/L, and that of formulation with KI (5 mM) + GG-MMA (300 mg/L) is 96.8%. The adsorption of GG-MMA over P110 steel is spontaneous and mixed type i.e., both physical and chemical. The conformation of GG-MMA molecule adsorption was done using a scanning electron microscope (SEM), Contact angle measurement, Atomic force microscopy (AFM), Scanning Electrochemical Microscopy (SECM) and X-ray photoelectron spectroscopy studies.     

Insight of corrosion mitigation performance of SABIC iron in 0.5 M HCl solution by tryptophan and histidine: Experimental and computational approaches

The inhibitory strength of two amino acids namely, tryptophan (Tryp) and histidine (Hist) on the corrosion of SABIC iron (SABIC Fe) in a 0.5 M HCl solution was examined utilizing mass loss (MS), electrochemical (PDP and EIS) and theoretical studies. Density functional theory (DFT) and Monte Carlo (MC) simulation were inspected for Tryp and Hist inhibitors. All the corrosion parameters and theoretical data obtained from these studies confirm the inhibiting impact of the two amino acids. The efficacy of inhibition augment with augmentation the concentration of two amino acids from 100 to 500 ppm and reducing at elevated temperature. The effectiveness of the inhibition depends on the presence of some active centers that accelerate the adsorption process and the molar mass of the inhibitors. The inhibition efficacy of Tryp is greater than that of Hist reaching 92.09% at a concentration of 500 ppm while in the presence of Hist it is 89.37% using PDP measurements. Inhibition was demonstrated by spontaneous adsorption of Hist and Tryp on the surface of SABIC Fe according to the Langmuir adsorption isotherm. PDP curves clarified that the Tryp and Hist compounds acted as mixed type inhibitors. A variety of thermodynamic and kinetics parameters were computed and explained. SEM images demonstrate that the protective layer constructed on the surface of S– Fe in the presence of both amino acids. The results obtained from DFT are in complete agreement with the experimental work. Tryp and Hist compounds are adsorbed horizontally onto the surface of Fe (110).     

Inhibition effect of newly synthesized benzoxanthonesderivative on hydrogen evolution and Q235 steelcorrosion in 15% HCl under hydrodynamic condition: Combination of experimental,surface and computational study

The investigation of this study deals with the synthesis using green synthetic approach, characterization and application of benzoxanthones derivative namely 9,9-Dimethyl-12-p-tolyl-8, 9,10, 12-tetrahydrobenzo[a]xanthen-1-one (TBX) for the inhibition of Q235 steel corrosion in 15% HCl under dynamic condition. The results of EIS confirmed towards the increment in R_ct values with rise in concentration. Additionally, results of PDP reveals that TBX is cathodic type inhibitor. The maximum inhibitive excellency of TBX was given at 200 mg/L with the value of 92.3%. The increasing temperature tends to increase in corrosion rate. Langmuir adsorption isotherm provides the excellent fitting. The surface morphology and adsorption of TBX molecules were confirmed using scanning electron microscopy (SEM) and X-photo electron microscopy (XPS). Density functional theory (DFT) and Molecular dynamic simulation (MD) confirmed that corrosion inhibition efficiency ranking obtained for studied molecules is TBXH⁺> TBX.     

Thermal and surface studies on the corrosion inhibition of petroleum pipeline by aqueous extract of Allium cepa skin under acidic condition

In this study, the temperature effect on the inhibitory action of the cheap, eco-friendly and sustainable hot water extract of onion skin (HWEOS) on the corrosion of C-steel petroleum pipeline in 1 M hydrochloric acid solution was investigated using weight loss technique. Generally, the inhibition was found to increase with inhibitor concentration but decreased with the increase in temperature. The presence of protective inhibitor film on metal surface was confirmed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analyses. The thermodynamic activation parameters were evaluated, suggesting a physical adsorption, the corrosion process was suggested to be a unimolecular reaction, the enthalpies reflected the endothermic nature of the steel dissolution process. Large and negative values of entropies showed that the activated complex in the rate determining step represented an association rather than a dissociation step. HWEOS adsorbed on the metal surface according to the Langmuir isotherm at all the studied temperatures. The compounds responsible for the inhibitory action of HWEOS were proved to be flavonoids including quercetin and a suggested mechanism of corrosion inhibition was elucidated.     

Analysis of corrosion inhibition of Kleinhovia hospita plant extract aided by quantification of hydrogen evolution using a GLCM/SVM method

During a corrosion inhibition test, a combination of common electrochemical corrosion test methods with an in-situ quantification of H₂ evolution could provide a comprehensive analysis of the effectiveness of an organic inhibitor. This work analyzes the corrosion inhibition efficiency of Kleinhovia hospita plant extract on carbon steel specimens polarized in 1 M HCl, based on acquired H₂ bubbles images, by using gray level co-occurrence matrix (GLCM) and support vector machine (SVM) classification. A conformity was established between the classified-algorithm models and the corrosion test results obtained by potentiodynamic polarization test and electrochemical impedance spectroscopy. Hydrogen rate and corrosion rate show the same lowest trends at the addition of 3000 mg/L of KH extract. The inhibitor addition led to 99% of maximum inhibition efficiency. Based on the polarization data, KH extract is a mixed type inhibitor. Supported by Langmuir calculation for adsorption isotherm, a physisorption is stated as the main inhibition mechanism. The feature extraction using GLCM was able to distinguish changes in H₂ bubbles characteristics where the addition of inhibitor affected the corrosion rate. The GLCM/SVM method applied as a linear kernel function and showed 88% accuracy with d = 5 for image data testing. Remarkable changes in H₂ gas bubbles characteristic were observed in the specimen immersed in the solution with 3000 mg/L inhibitor addition, signified by 99% inhibition efficiency.     

Corrosion inhibition performance of 4-(prop-2-ynyl)- [1,4]-benzothiazin-3-one against mild steel in 1 M HCl solution: Experimental and theoretical studies

4-(prop-2-ynyl)-2H [1,4]-benzothiazin-3(4H)-one (PBO) was synthesized and evaluated on corrosion resistance for mild steel (MS) in1 M HCl environment. The molecular and crystal structure of PBO has been determined by single-crystal X-ray crystallography, Hirshfeld surface (HS) analysis was carried out by using Crystal Explorer 17.5. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques were used to find corrosion rate (CR) and corrosion inhibition efficiency (η) in the presence and absence of PBO. These techniques were supported with energy dispersive X-ray (EDX) and scanning electron microscope (SEM). Molecular Dynamics Simulation (MDS) and Frontier Molecular Orbital (FMO) are realized by means of the Density Functional Theory (DFT) method. The results show that PBO could offer an inhibition efficiency of 92% at 303 K. The type of inhibition mechanism of PBO was mixed-type. The Langmuir isotherm proved the highest compliance with experimental data, representing the generation of protective mono-layer of inhibitors on the MS substrate. The SEM pictures displayed a metallic substrate covered with a highly compact protective layer covered. The theoretical findings suggested by electronic/atomic computer simulations supported the inhibitive chemicals interfacial adsorption through reactive centres.     

Influence of 2-(4-chlorophenyl)-2-oxoethyl benzoate on the hydrogen evolution and corrosion inhibition of 18 Ni 250 grade weld aged maraging steel in 1.0 M sulfuric acid medium

Electrochemical corrosion behavior and hydrogen evolution reaction of weld aged maraging steel have been investigated, in 1.0 M sulfuric acid solution containing different concentrations of 2-(4-chlorophenyl)-2-oxoethyl benzoate (CPOB). The data obtained from polarization technique showed that the corrosion current density (i_corr) and the hydrogen evolution rate decrease, indicating a decrease in the corrosion rate of weld aged maraging steel as well as an increase in the inhibition efficiency (η%) with the increase in inhibitor concentration. Changes in impedance parameters were indicative of adsorption of CPOB on the metal surface, leading to the formation of protective film. Both activation (E_a) and thermodynamic parameters (ΔG_ads⁰, ΔH_ads⁰ and ΔS_ads⁰) were calculated and discussed. The adsorption of CPOB on the weld aged maraging steel surface obeyed the Langmuir adsorption isotherm model. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) study confirmed the formation of an adsorbed protective film on the metal surface.     

Hydrogen generation during the corrosion of carbon steel in crotonic acid and using some organic surfactants to control hydrogen evolution

The purpose of this paper is to describe and evaluate the corrosion of carbon steel in crotonic acid for hydrogen production and using polysorbate 20 (NS), dioctyl sodium sulfosuccinate (AS) and benzalkonium chloride (CS) to control hydrogen evolution. Measurements were conducted in tested solutions using hydrogen evolution and electrochemical impedance spectroscopy (EIS) measurements and complemented by scan electron microscope (SEM) and energy dispersive X-ray (EDX) investigations. It is shown that the hydrogen generation rate obtained during the corrosion of carbon steel in crotonic acid increased with increase in acid concentration, temperature and immersion time. The addition of organic surfactants inhibits the hydrogen generation rate. The inhibition occurs through adsorption of organic surfactants on the metal surface. Adsorption processes followed the Langmuir isotherm. The order of effectiveness of the surfactants was AS > NS > CS. The values of activation energy (E_a) and heat of adsorption (Q_ads) were calculated and discussed.     

Recycling of some domestic wastes to produce green corrosion inhibitors and biocides for sulfate reducing bacteria

Egypt suffers from a huge amount of domestic wastes which causes a lot of economic and environmental problems. This work investigated the possibility of recycling of some of these wastes into green corrosion inhibitors and biocides. The studied aqueous extracts of outer brown peels of onion (A), outer peels of garlic (B), orange (C), and mandarin (D) peels reduced markedly the corrosion rate of carbon steel alloy in 1.0 M HCl and behaved as mixed inhibitors. The inhibition efficiency decreased in the following order: C > B > A > D and generally increased with the increase of the extract concentration. The inhibition mechanism and adsorption isotherms were discussed to describe the adsorption characteristics of the extracts on the carbon steel surface. The extracts of orange and mandarin peels expressed biocidal effect on sulfate reducing bacteria (SRB). However, those of onion and garlic peels did not express any biocidal activity against SRB.     

Inhibitive effect of onion mesocarp extract-nickel nanoparticles composite on simultaneous hydrogen production and pipework corrosion in 1 M HCl

Nanoscale nickel is prepared from ethanol extracts of Allium cepa and characterized. Zerovalent face centred cubic (fcc) nickel nanoparticles oriented mainly at Ni (111) plane formed rapidly within 30–45 min. The nanoparticles are stabilized by negative surface potential, non-agglomerated, monodispersed, round-shaped and distributed between sizes of 39.5–53.1 nm. The nanoparticles are used to simultaneously regulate the rates of hydrogen gas production and X80 steel corrosion in 1 M HCl solution for the first time. The nanoparticles efficiently inhibit hydrogen gas evolution and X80 steel corrosion rates especially at increased concentration. Inhibition efficiency increases as temperature increases from 303 to 323 K, remains fairly constant from 323 to 343 K and decreases drastically from 343 to 363 K. By means of O–H, N–H and C=C sites, the nanoparticles are spontaneously physically adsorbed on X80 steel surface and act as mixed type corrosion inhibitor with dominant influence on cathodic reaction involving hydrogen gas evolution. In the presence of the nanoparticles, surface roughness (measured by AFM) reduces by 76.0% and heights of peaks from the mean plane reduces by 58.2%. Comparatively, even 100 ppm of the nanoparticles showed higher inhibition efficiency at all temperatures than 1000 ppm concentration of the crude extract.     

Influence of cerium (III) ions on corrosion and hydrogen evolution of carbon steel in acid solutions

This paper intended to investigate the influence of rare earth Ce(III) ions on the corrosion behavior of carbon steel in two acid solutions (0.5 M HCl and 0.25 M H₂SO₄) in order to control the rate of hydrogen evolution in those systems. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests were used for corrosion rate and electrochemical impedance evaluation. SEM was used to examine the sample surfaces immersed in acid solutions containing the optimal threshold Ce(III) concentration (0.1 mM). All results reveal that the corrosion resistance of carbon steel in HCl is superior to that in H₂SO₄ due to the higher rate of hydrogen production in the latter. A model for the corrosion process mechanism and inhibition by Ce(III) salt for carbon steel in the two tested media is proposed.     

Corrosion inhibition, hydrogen evolution and antibacterial properties of newly synthesized organic inhibitors on 316L stainless steel alloy in acid medium

Electrochemical corrosion behavior and hydrogen evolution reaction of 316L stainless steel has been investigated, in 0.5 M sulfuric acid solution containing four novel organic inhibitors as derivatives from one family, using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) measurements and surface examination via scanning electron microscope (SEM) technique. The effect of corrosion inhibitors on the hydrogen evolution reaction was related to the chemical composition, concentration and structure of the inhibitor. The inhibition efficiency, for active centers of the four used compounds, was found to increase in the order: -Cl < -Br < -CH₃ < -OCH₃. The corrosion rate and hydrogen evolution using the compound with methoxy group as a novel compound was found to increase with either increasing temperature or decreasing its concentration as observed by polarization technique and confirmed by EIS measurements. The compound with methoxy group (newly synthesized) has very good inhibition efficiency (IE) in 0.5 M sulfuric acid (98.3% for 1.0 mM concentration). EIS results were confirmed by surface examination. Also, antibacterial activity of these organic inhibitors was studied. The results showed that the highest inhibition efficiency was observed for the compound that posses the highest antibacterial activity.     

Effect of conducting composite polypyrrole/polyaniline coatings on the corrosion resistance of type 304 stainless steel for bipolar plates of proton-exchange membrane fuel cells

A bilayer conducting polymer coating composed of an inner layer of polypyrrole (Ppy) with large dodecylsulfate ionic groups obtained by galvanostatic deposition, and an external polyaniline (Pani) layer with small SO₄²⁻ groups obtained by cyclic voltammetric deposition was prepared to protect type 304 stainless steel used for bipolar plates of a proton-exchange membrane fuel cell. The corrosion performance of the bare and coated steel in 0.3 M HCl was examined by electrochemical impedance spectroscopy, polarization and open-circuit potential measurements. The experimental results indicated that both the composite Ppy/Pani coatings and the single Ppy coatings increased the corrosion potential of the bare steel by more than 400 mV (saturated calomel electrode), and increased the pitting corrosion potential by more than 500 mV (saturated calomel electrode). The bilayer coatings could reduce the corrosion of the alloy much more effectively than the single Ppy coatings, serving as a physical barrier and providing passivity protection, with acceptable contact resistance.     

Inhibitive action of ferricyanide complex anion on both corrosion and passivation of zinc and zinc-nickel alloy in the alkaline solution

The corrosion of zinc and Zn-0.5Ni alloy in strong alkaline solution (7 M KOH) in the absence and presence of [Fe(CN)₆]³⁻ complex anion (1 × 10⁻³-1 × 10⁻² M) as inhibitor has been studied. Tafel plot, potentiodynamic, potentiostatic and electrochemical impedance spectroscopy (EIS) techniques were used, and complementary by EDX and SEM investigation. It is observed that, the corrosion current density (I_corr) decreases, and the inhibition efficiency (IE%) increases as the concentration of inhibitor is increased. The shift of breakdown potential to less positive direction, indicating that the reduction of oxide layer on the alloy surface occurs somewhat easier in the presence of [Fe(CN)₆]³⁻ complex anion. The impedance measurements have shown that the increase of the inhibitor concentration in the alkaline solution reduces the corrosion rate in the active region. Accordingly, addition of [Fe(CN)₆]³⁻ complex anion to KOH solution can be considered as an important criteria for a good battery anodes. This behavior is due to its high negative open-circuit potential, less corrosion rate and higher self-catalysis in the passive region compared with those in its absence.     

Micro-mechanism study on the effect of O2 poisoned ZrCo surface on hydrogen absorption performance

Hydrogen storage alloys are usually susceptible to poisoning by O₂, CO, CO₂, etc., which decreases the hydrogen storage property sharply. In this paper, the adsorption characteristics of oxygen on the ZrCo(110) surface were investigated, and the effect of oxygen occupying an active site on the surface on the hydrogen adsorption behavior was discussed. The results show that the dissociation barrier of H₂ is increased by more than 26% after O occupies the active sites on the ZrCo(110) surface, and the probability of H₂ adsorption and dissociation decreases significantly. The adsorption energy of H atoms on the O–ZrCo(110) surface decreased by 18–56%, and the adsorption stability of H decreased. In addition, H atom diffusion on the surface and into bulk are prevented with higher reaction energetic barriers by O occupying active sites. Eventually, the ability of the ZrCo surface to adsorb hydrogen is seriously reduced.     

Inhibition effect of newly synthesized heterocyclic organic molecules on corrosion of steel in alkaline medium containing chloride

Two new organic compounds were tested experimentally as inhibitors for mild steel in NaOH in presence of NaCl by electrochemical and hydrogen evolution techniques. Results demonstrated that the two inhibitors show an adsorption on steel surface according to Langmuir adsorption isotherm. The inhibition efficiency increases with increasing inhibitor concentrations to attain a maximum value at 1.0 mM for compound I and at 6.0 mM for compound II, respectively. The results were confirmed by surface examination via scanning electron microscope.     

Immersion corrosion behavior,electrochemical performance and corrosion mechanism of subsonic flame sprayed FeCoCrMoSi amorphous coating in 3.5% NaCl solution

A FeCoCrMoSi amorphous coating (AC) was fabricated on Ti6Al4V alloy (TA) by subsonic flame spraying (SFS) technique, which was used to improve its corrosion resistance. The morphology, element distribution and chemical composition of obtained coating were analyzed using a scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X–ray Fluorescence (XRF), respectively, and its amorphous structure was confirmed by X–ray diffraction (XRD). The immersion corrosion behavior and electrochemical performance of FeCoCrMoSi AC immersed in 3.5% NaCl solution for the different days were systematically investigated, and the corrosion mechanism of amorphous structure was also discussed by the model of passive film. The results show that the FeCoCrMoSi AC exhibits the dense amorphous structure, which is beneficial to improving the anti–corrosion performance of TA. The potentiodynamic polarization curve (PPC) and electrochemical impedance spectroscopy (EIS) indicate that the FeCoCrMoSi AC with the lowest i_corr of 1.479 × 10^?6 A·cm^?2 immersed for 60 days has the largest capacitor loop diameter of 7.53 × 10⁵ and charge transfer resistance R_ct of 4.31 × 10⁴ Ω, showing the highest comprehensive corrosion resistance. The mechanism of corrosion resistance is contributed to the Cr–rich passive film, which is further stabilized by the addition of Mo.     

Improvement on the corrosion protection of conductive polymers in pemfc environmets by adhesives

The corrosion protection of polypirrol (PPY) and polyaniline (PANI) coatings electrochemically deposited with and without polyvinil alcohol (PVA) as adhesive onto 304 type stainless steel has been evaluated using electrochemical techniques. Environment included 0.5 M H₂SO₄ at 60 °C whereas employed techniques included pothentiodynamic polarization curves (PC), linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) measurements. Results showed that the free corrosion potential, of the substrate, E_corr, was made more noble up to 500 mV with the polymeric coatings. The corrosion rate was lowered by using the polymers, but with the addition of PVA, it was decreased further, one order of magnitude for PPY and up to three orders of magnitude for PANI. Impedance spectra showed that the corrosion mechanism is under a Warburgh-type diffussional process of the electrolyte throughout the coating, and that the uptake of the environment causes the eventual failure of the coating corroding the substrate.     

The stability of hydrogen evolution activity and corrosion behavior of NiCu coatings with long-term electrolysis in alkaline solution

In this study, NiCu composite coating was electrochemically deposited on a copper electrode (Cu/NiCu) and tested for hydrogen evolution reaction (HER) in 1 M KOH solution for long-term electrolysis with the help of cathodic current–potential curves and electrochemical impedance spectroscopy (EIS) techniques. The bulk and surface composition of the coating was determined using atomic absorption spectroscopy (AAS) and energy dispersive X-ray (EDX) analysis. The surface morphology was investigated by scanning electron microscopy (SEM). The effect of electrolysis on the corrosion behavior of the Cu/NiCu electrode was also reported. It was found that the NiCu coating had a compact and porous structure with good time stability. The HER activity of the coating was stable over 120 h electrolysis and the HER mechanism was not modified during the operation. The corrosion tests showed that the corrosion resistance of the Cu/NiCu electrode changed when a cathodic current was applied to the electrolysis system.     

Propagation behaviour of general and localised corrosion of carbon steel in simulated groundwater under aerobic conditions

Abstract

Carbon steel is one of the candidate overpack materials for geological disposal of high-level radioactive waste in Japan. Corrosion of carbon steel is classified into two types: general corrosion and localised corrosion. In this study, propagation of general and localised corrosion (pitting corrosion and crevice corrosion) were investigated by immersion tests of carbon steel under the aerobic conditions. The results of the immersion tests showed that the corrosion growth rate was strongly dependent on the environmental conditions and type of steel. However, the upper limit of the pitting factor, the ratio between the maximum corrosion depth and the average corrosion depth, was determined approximately using only average corrosion depth. Based on the experimental and literature data, an empirical model that predicts the maximum corrosion depth of an overpack from average corrosion depth was developed by applying the extreme value statistical analysis using the Gumbel distribution function.