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This study investigates the dynamic mechanical properties of red sandstone under normal and acidic conditions with varying pH levels using the Split Hopkinson Pressure Bar (SHPB) technique. By integrating fractal theory and energy dissipation theory, the study reveals the changing patterns of fractal dimension and dissipated energy density of red sandstone in acidic environments. The test results indicate that as the impact air pressure increases, the strain rate, compressive strength, and maximum strain of the red sandstone show an upward trend, demonstrating a noticeable hardening effect of the strain rate. The physicochemical effects of acid corrosion lead to a deterioration in the mechanical properties of red sandstone, with a more pronounced deterioration as acidity levels increase. Furthermore, the fractal dimension of crushed red sandstone shows a direct positive relationship with the strain rate, while the average fragmentation block size decreases with increasing strain rate and the fractal dimension increases. Under acid corrosion, the fractal dimension increases, the average fragmentation block size decreases, and the dissipated energy density decreases. These findings offer a scientific foundation for the design and protection of underground geotechnical structures in acid-prone regions. [ABSTRACT FROM AUTHOR]

In this paper, nickel chloride was selected as metal ions and 2,2′-bipyridine (bipy) and benzoic acid (ba) as ligands to synthesize Ni-bipy-ba ternary complex. Its corrosion inhibition effects on the corrosion of P110 carbon steel in 0.5 M HCl were evaluated by weight loss test, electrochemical measurements, surface analyses, and theoretical calculations. The results show that the Ni-bipy-ba ternary complex exhibits excellent corrosion inhibition properties compared with the two ligands, especially at high temperatures, which is supported by the calculation of thermodynamic parameters. Surface analyses indicate that Ni-bipy-ba ternary complex can inhibit corrosion by forming adsorption film on the metal surface. Theoretical calculations show a good correlation with the experimental results. The best corrosion inhibition efficiency of Ni-bipy-ba ternary complex could be ascribed to the synergistic effect of metal ligands and the complex structure with larger dimension and molecular mass. [ABSTRACT FROM AUTHOR]

The concrete composition of different pipelines varies greatly, and a comprehensive analysis of the impact of concrete design on pipeline corrosion is required. Developed an integrated model based on Scikit-Optimize, XGBoost and SHAP to analyze concrete's carbonation and sulfuric acid resistance from five aspects: binder type, supplementary cementitious material (SCM's), aggregate, admixture and w/b. Choose Scikit-Optimize for parameter optimization. As an explanation model, the SHAP model can perform analysis well and explain the analysis basis of the XGBoost training model. The established model can accurately predict the corrosion effect (R2 >0.987) without overfitting. Binder should be maintained at 380 to 400 (kg/m3). Water/binder and coarse aggregate/binder are the two main factors that influence the binder, and they should be maintained at a ratio of around 0.4 to 0.6 and 2.5, respectively. Fly ash (FA) should be SCM's used as at a range of 300 to 350 (kg/m3) to improve corrosion resistance. [ABSTRACT FROM AUTHOR]

The utilization of plant extracts as environmentally friendly corrosion inhibitors has garnered considerable interest in the field of metallic corrosion protection. The primary objective of this study was to explore a new approach for utilizing Dillenia suffruticosa leaves extract (DSLE) to provide corrosion protection for mild steel (MS) in a molar hydrochloric acid solution. The phytocompounds responsible for corrosion prevention were extracted using ethanol with Soxhlet apparatus. The effectiveness of the extract as a corrosion inhibitor was evaluated through gravimetric and electrochemical methods, along with surface analysis of the corroded steel samples. This analysis involved the use of scanning electron microscopy (SEM) and Fourier-transformed infrared spectroscopy (FTIR) to examine the specimens with and without addition of the extract as inhibitor. The findings demonstrate that DSLE exhibits notable efficacy as a corrosion inhibitor for MS in an acidic environment. The inhibition efficiency (IE) demonstrates a positive correlation with the concentration of the extract, ultimately reaching a maximum value of 81.4 % at the optimum concentration of 1000 mg/L of the extract investigated. Potentiodynamic polarization data revealed that the DSLE functions as a mixed-type inhibitor.

This study aimed to investigate the effects of acid corrosion on mechanical properties and fractal characteristics of red sandstone. The mineral composition of red sandstone was analyzed using X-ray diffraction. The mechanical properties and acoustic emission (AE) signals of red sandstone specimens corroded by sulfuric acid solution with pH values of 1, 3, and 5 for 30 days were determined by uniaxial compression test and AE technique. The energy dissipation law and the fractal damage characteristics of red sandstone specimens after acid corrosion were analyzed based on the energy and fractal theories. The results indicated that the compressive strength and elastic modulus of red sandstone specimens corroded by acid solution decreased. In addition, the peak strain increased, the cumulative AE ringing count decreased, and the duration of high-level AE ringing shortened. These phenomena became more pronounced as the acidity of the solution increased. The peak values of the total energy and the elastic strain energy of the acid-solution-corroded red sandstone specimens decreased. The energy absorption capacity and energy storage limit of rock specimens also decreased. The fractal dimension and the degree of fragmentation decreased with the dissipated energy used for fragmentation. This research provides valuable insights into the prevention and control of sub-surface geotechnical hazards in acid rain-prone areas. [ABSTRACT FROM AUTHOR]

Abstract A novel two tri-thiosemicarbazones derivatives, namely 2,2',2''-((2-Hydroxybenzene-1,3,5-triyl)tris(methanylylidene))tris(N-benzylhydrazine-1-carbothioamide) (HBC) and 2,2',2''-((2-hydroxybenzene-1,3,5-triyl) tris (methanylylidene)) tris (N-allylhydrazine-1-carbothioamide) (HAC), have been synthesized and their chemical structures were determined using different spectroscopic and analytical approaches. Then, utilizing methods including open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy, the inhibitory effect of the synthesized thiosemicarbazones on mild steel (MS) in an acidic environment (0.5 M H2SO4) was thoroughly investigated. Remarkably, raising the concentration of our recently synthesized tri-thiosemicarbazones HBC and HAC increased the inhibitory efficiency values. The η values of the two investigated tri-thiosemicarbazones derivatives (HAC and HBC), at each concentration are extremely high, and the maximum values of the efficiencies are 98.5% with HAC and 98.8% with HBC at the 800 ppm. The inhibitors adsorbed on the mild steel surface and generated a charge and mass movement barrier that protected the metal from hostile ions. According to polarization curves, HBC and HAC act as mixed-type inhibitors. Electrochemical impedance testing revealed a notable rise in charge transfer resistance (Rct) readings to 4930-Ω cm2, alongside a reduction in the Constant Phase Element (CPE) value to 5.81 μF, suggesting increased effectiveness in preventing corrosion. Also, density functional theory (DFT) was applied to investigate the assembled tri-thiosemicarbazones HBC and HAC. Moreover, the adsorption mechanism of HBC and HAC on the mild steel surface was explored using Monte Carlo simulation. Finally, the theoretical outputs were discovered to support the practical outcomes.

Enamel coatings, showing advantages in material durability, aesthetics, hardness, corrosion resistance, and high-temperature tolerance, are widely used for corrosion protection of metallic substrate. Recently, a new type of aluminophosphate-based low temperature enamel (LTE) coating was developed to avoid the strength degradation of steel substrate, which was also applicable to relatively low-melting metal and was more environmentally friendly with reduced energy consumption. LTE coating might suffer the corrosion of acids or alkalis in some special cases like kitchen utensils, petroleum pipelines, and reinforcing bars. In this study, the chemical corrosion behavior of aluminophosphate-based LTE was investigated in H 2 SO 4 and NaOH solutions with varying pHs of 1∼13. Results indicated that after 30 days of immersion, LTE survived at pHs 3–10, but severely deteriorated at pHs 1, 2, 12, and 13, with the corroded layer presenting a loose structure, completely losing mechanical strength, and even peeling off. For pH 11, the color changed slightly whereas the mass loss was negligible. Specially, LTE suffered selective corrosion in strong acid and alkali conditions, that is, H 2 SO 4 corroded the Ca-compounds (Ca 5 (PO 4) 3 F and CaF 2) phases to generate CaSO 4 ·2H 2 O and H 3 PO 4 , whereas NaOH corroded the LTE matrix (AlPO 4) to generate soluble Na 3 PO 4 and NaAlO 2. The findings of this study confirmed the acid and alkali tolerance range of LTE and clarified the corrosion mechanism of LTE under both acid and alkaline environments, which guides the further composition design and application of LTE coatings. [ABSTRACT FROM AUTHOR]

A333 and API 5L steel are typical metals used in oil and gas industries. Techniques of gravimetric method, linear polarization resistance, and EIS measurements have been used to examine the synergistic corrosion inhibition performance of sodium sulfite, SS, and ginger extract, GE, on aforementioned metal dissolution in 0.02 M acidic crude oil in pipelines at various temperatures, fluid velocities which is new parameter in term of corrosion studies and could be considered as novel study, and inhibitor concentrations. Moreover, the combination of SS and GE and using them as a synergistic corrosion inhibitor in the acidic crude oil medium could be considered as a novelty. The results remarkably reveal enchantment of SS-GE inhibitory by mitigating metal attack of anodic area by providing polarization to become cathodic surface. Effect of temperature and fluid velocity on the thermodynamic adsorption equilibrium was evaluated and obeys Freundlich isotherm at all studied temperature. Unsignificant temperature effect can be seen. [ABSTRACT FROM AUTHOR]

The paper presents the results of non‐destructive testing examinations, metallographic tests and risk assessment of degradation related to corrosion of amine regeneration unit in a desulphurisation system. Intensive corrosion resulting from acid gases environment upon water condensation causes perforation of the pipeline. Detailed analysis reveals cracking related to the mechanism of wet H2S. Hydrogen penetration, resulting from the wet H2S process, causes a decrease in mechanical properties of steel and an increase in hydrogen content inside steel. Corrosion results mostly from high stream velocity, the presence of acid gases (with high ammonia content), the presence of amine and low stream temperature. [ABSTRACT FROM AUTHOR]

The corrosion inhibition performance of L(-)- Cystine on copper alloy immersed in 2 M HNO3 solution is investigated using weight loss, potentiodynamic polarisation, electrochemical impedance spectroscopy, and scanning electron microscopy. Potentiodynamic polarization measurements confirmed that L(-)-Cystine behaved as mixed-type inhibitor. The highest corrosion inhibition efficiency was 98.99% at 298 K and decreased with increasing temperature. The Nyquist plots displayed an increase in the capacitive loops with increasing the concentration of the inhibitor. The mechanism of inhibition obeys Langmuir isotherm. SEM images confirm the adsorption of L(-)-Cystine on the surface of the cooper alloy [ABSTRACT FROM AUTHOR]

In this study, the corrosion behavior of 316L stainless steel (SS) in hydrofluoric acid and chloride-containing hydrofluoric acid solutions were investigated. The immersion results show that the addition of chloride ions yields a tremendous improvement in corrosion resistance. The corrosion rate of 316L SS remarkably reduces from 68.80 to 0.48 mm/a while adding 1 M chloride ions into 23 M hydrofluoric acid solution. Through morphology and corrosion composition analysis, the high corrosion resistance in chloride-containing hydrofluoric acid solution is mainly attributed to the interaction between competitive adsorption and selective corrosion. Due to competitive adsorption, chloride ion preferentially adsorbs and dominates corrosion. It shifts the preferentially corroded phase and increases the compactness of the product layer, resulting in a remarkable reduction of the corrosion rate. Additionally, a model has been developed to further elucidate the inhibition effect of chloride ions on the corrosion of 316L SS in hydrofluoric acid solution. [ABSTRACT FROM AUTHOR]

This study assessed concrete durability in pig farm environments, focusing on resistance to organic acid corrosion and physical abrasion. It used supplementary cementitious materials like silica fume (SF), coal fly ash (CFA), and bagasse fly ash (BFA) to improve concrete resilience. The research involved casting and testing concrete samples for compressive strength, acid corrosion resistance, abrasion resistance, and their combined effects. A custom apparatus simulated corrosion and abrasion cycles typical in pig farm flooring. Results showed that a combination of SF, CFA, and BFA significantly enhanced compressive strength, especially with extended curing. Additionally, these materials improved concrete's resistance to acid corrosion, physical abrasion, and their combined effects. The replacement of 30 wt% of cement with CFA and BFA in concrete significantly reduced mass loss due to acid corrosion to less than 10%, whereas the control mix exhibited a mass loss exceeding 24%. Additionally, concrete with 30 wt% CFA or BFA replacement exhibited a minimal combined mass loss, decreasing to less than 2.5% due to acid corrosion and physical abrasion, as opposed to the 16% observed in the control mixture.

[Cu2(EDA)2] [Cu (CN)2] 2.H2O] (MOF1) and [H2DB] [Cu4(CN)6] 2.H2O (MOF2) were synthesized and studied as a corrosion inhibitor for aluminium (Al) in 1.0 M HCl solution. The synthesis was done at room temperature via chemical method. The crystals of MOF1 and MOF2 were obtained after filtration and coating with cold H2O. The MOF precipitate was characterized by X-ray diffraction (XRD) techniques. The study aimed to evaluate the corrosion inhibition efficacy of the MOFs using mass loss, potentiodynamic polarization, and EIS electrochemical impedance techniques. Both MOF1 and MOF2 were physically adsorbed on the surface of the aluminium and acted as mixed-type inhibitors affecting metal dissolution and hydrogen evolution reactions. The inhibitors conformed to the Henry adsorption isotherm model, indicating successful adsorption on the aluminium surface. The mass loss analysis (MLA) results were obtained at (298, 308, and 318) K, and for potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS) results were obtained at 298 K. Increasing inhibitor doses led to increased inhibition efficiency (%IE), corresponding to 93 % for MOF2 and 91 % for MOF1 at 2.5x10−4M. The adsorption of inhibitors on Al surfaces has been calculated and discussed by a Henry isotherm. The inhibitors that were created showed great effectiveness, with a noticeable increase in their inhibitory efficiency (%IE) as the dosage was raised and the temperature was lowered. The synthesized inhibitors acted as mixed-type inhibitors based on polarization curves. The surface of Al was coated with a thin film of inhibitors, confirming the protective effect. A scanning electron microscope (SEM) technique was used to study the surface morphology of a sample of aluminium. A cell construction model and electron density map were used as theoretical calculations. The results from mass reduction, potentiodynamic polarization, and EIS electrochemical impedance techniques showed good agreement, validating the effectiveness of the MOFs as corrosion inhibitors.

A novel POEGMA-b-(PMEEU-co-PMAA) (poly(oligo(ethylene glycol) methacrylate)-b-poly((methacrylamidoethyl) ethylene urea)-co-poly(methacrylic acid) block copolymer has been synthesized by RAFT polymerization as a corrosion inhibitor. Structural characterization of the block copolymer was done by FTIR, 13C NMR and 1H NMR spectroscopic techniques. The carboxylic acid and cyclic urea units on the block copolymer exert a synergistic effect on corrosion inhibition through chelating of the metal ions or adsorption to the metal surface. Corrosion inhibition of SAE 1012 carbon steel in a 1 M HCl medium has been investigated in the presence of 5 mM polymer using both experimental (electrochemical impedance spectroscopy, Tafel polarization (TP), weight loss) and theoretical approaches. Also, SAE 1012 carbon steel surface morphology changes were followed by energy dispersive X-ray spectroscopy and scanning electron microscopy. Electrochemical techniques indicated that the presence of PMEEU-co-PMAA segments of the polymer in the acid solution inhibits corrosion of SAE 1012 carbon steel. The inhibition efficiency of the polymer was found to be about 85%. According to TP studies, PMEEU-co-PMAA segment acts as a mixed type corrosion inhibitor. The adsorption of PMEEU-co-PMAA molecules onto the metal surface follows Langmuir adsorption isotherm. The Kads value calculated from the equilibrium constant of the adsorption process reflects a strong interaction. SEM and EDAX studies provide evidence of PMEEU-co-PMAA adsorption on the metal surface. [ABSTRACT FROM AUTHOR]

The current study investigates the adsorption properties of a novel heterocyclic compound, 13-(4-chlorophenyl)-3, 3-dimethyl-3, 4-dihydro-1H-indazolo[1,2-b] phthalazine 1,6,11(2H,13H)-trione (DDIP), as an inhibitor against the oxidation of brass in hydrochloric acid solution. The experimental investigation included several methods, including EIS and PDP. The inhibition efficiency of the compound followed the order of 90.0%. The adsorption process of this inhibitor on the brass substrate followed the Langmuir adsorption model. SEM/EDS and XRD techniques were utilized to analyze surfaces, revealing the presence of a protective film overlaying the brass substrate. In addition, the results of DFT calculations of the DDIP compound revealed the existence of many active sites on the brass surface, facilitating the adsorption of our inhibitor. [ABSTRACT FROM AUTHOR]

The kinetics of the cathodic reduction of hydrogen on low-carbon steel in a sulfuric acid solution containing a mixture of quaternary ammonium salts (QASs) (catamine AB) and 3-substituted 1,2,4-triazole (IFKhAN-92 inhibitor) are studied. The main rate constants of the stages of evolution of gaseous hydrogen and the introduction of hydrogen atoms into the metal are determined. It is shown that these substances reduce the reaction rate of the discharge of H+ ions, change the ratio between the concentrations of H atoms on the surface and in the phase of the metal, and, as a result, reduce the amount of hydrogen absorbed by steel. The most effective inhibitor of corrosion and hydrogenation of steel is IFKhAN-92, due to the formation of a polymolecular protective layer of the inhibitor on the metal surface. The data of X-ray photoelectron spectroscopy of the steel surface show that the protective layer has a thickness of not more than 4 nm and consists of IFKhAN-92 molecules associated with the steel surface by chemical interaction; and inside the layer, by physical interaction. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central South University is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Refractory negative thermal expansion (NTE) materials can reduce stress when subjected to drastic temperature changes and therefore have potential applications in fire-fighting field. However, NTE ceramics are susceptible to impact damage due to their poor mechanical properties. We have found that treatment of a ceramic with hydrofluoric acid (HF) generated floral microstructures that enhanced the ceramic's impact resistance. Specifically, pellets of a refractory NTE ceramic, Zr 2 P 2 WO 12 (ZWP) ceramics, containing various doping ratios of MgO) are fabricated and then treated with hydrofluoric acid (HF) to induce the formation of flower-like microstructures. Structural analyses show that the concentration of MgO in the ZWP pellets affects the morphology of the microstructures. The crystal orientation of ZWP appears after HF acid corrosion, and the formation of floral particles corresponded to the content of MgO. This investigation demonstrates that HF treatment can alter the microstructure of a refractory NTE ceramic and may have wide application for enhancing such ceramics' mechanical properties. [Display omitted] [ABSTRACT FROM AUTHOR]

As a case study in the practical problem of how to solve the issue of waste medicine more reasonably, furazolidone (FZD) was investigated as an acidizing corrosion inhibitor and bactericide for oilfield water treatment. Gravimetric results indicate that FZD exhibits high inhibitory efficiency under acidic conditions. In addition, the corrosion inhibition performance decreases as the temperature increases. The adsorption of FZD on the surface of steel has been studied, and the experimental results indicate that the material exhibits the characteristics of a Langmuir‐type adsorption isotherm. The thermodynamic results demonstrate that the adsorption behavior of FZD on the steel surface is that of an exothermic, spontaneous, entropy‐decreasing process. Finally, the bactericidal activity of FZD was investigated. This work provides a simple and beneficial way to utilize a particular waste drug. [ABSTRACT FROM AUTHOR]

The inhibition effect of 4-[(benzylidene)-amino]-antipyrine (BAAP) on corrosion behaviour of mild steel in 1 M HCl solution was studied by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. Polarization measurements indicate that BAAP acts as mixed type of inhibitor. The adsorption of BAAP on the mild steel surface follows Langmuir adsorption isotherm model. The thermodynamic parameters governing the adsorption process were determined and discussed. Also, quantum chemical parameters were calculated to provide further insight into the mechanism of inhibition action of BAAP.

In southwest China, carbonate rocks are widely distributed. It has unique dissolution features which bring a lot of resistance to engineering constructions. In order to explore the dissolution damage regular of layered carbonate rocks in acidic water, a self-made flow dissolution system was used to conduct laboratory dissolution tests on limestone cores under four different conditions. The mass loss, the change of p-wave velocity, the mass concentration of Ca2+ and Mg2+ and the morphology of the core surface were obtained. Mass loss rate after dissolution of layered limestone was used to define the damage variation. Through multivariate statistical regression analysis, the relationship between four different arguments (bedding dip Angle, pH, velocity of flow, dissolution time) and dissolution damage variation was established. The results show that the dissolution damage of layered limestone has a good mathematical relationship between the four different arguments. The following conclusions can be drawn from the analysis: The time has a significant effect on the dissolution damage of bedded limestone, followed by the velocity and pH. Under the same acidic environment, the dissolution effect shows a rule of 90° >0° >45° >30° >75° >15° >60° for limestone with different bedding inclination angles. The bedded angle has less effect on the dissolution of limestone than other factors, but plays a decisive role in the surface dissolution morphology of rock samples. The results of this study can provide some reference for engineering practice and geological disaster control in limestone areas.

Rock mass subjected to acidic groundwater corrosion may cause great property alteration. In this work, the effects of microstructure on change of the pore structure and mechanical property under acid corrosion were investigated. Two types of limestone, which are microstructurally different but have almost same mineral compositions, were corroded in HCl and Na2SO4 mixed solutions with different pH values (pH = 3, 4, 5, 6, and 7). A series of approaches including uniaxial compression, Brazilian splitting, and nuclear magnetic resonance (NMR) tests were carried out to examine the strength, brittle index, porosity, and pore distribution. The mechanical properties (uniaxial compressive strength, elastic modulus, tensile strength, and brittleness index) decreased as the pH value decreased. In addition, the larger the initial microstructure, the faster the degradation rate of mechanical parameters except for the brittleness index. Moreover, NMR results revealed that the porosity increment of Group 2 (large initial microstructure) was larger than that of Group 1 (small initial microstructure). Under acid corrosion, the reason for the increasing porosity in Group 1 was the increased proportion of the internanopore, while it was transition from the supernanopore to the submicropore for Group 2. Furthermore, the brittleness index decreased as porosity increased and the proportion of the internanopore decreased. Finally, the degradation mechanisms of pore and mechanical properties were discussed. [ABSTRACT FROM AUTHOR]

The etching of iron alloy items in a H3PO4 solution is used in various human activities (gas and oil production, metalworking, transport, utilities, etc.). The etching of iron alloys is associated with significant material losses due to their corrosion. It has been found that an efficient way to prevent the corrosion of iron alloys in a H3PO4 solution involves the formation of thin complex compound films consisting of the corrosion inhibitor molecules of a triazole derivative (TrzD) on their surface. It has been shown that the protection of iron alloys with a mixture of TrzD + KNCS in a H3PO4 solution is accompanied by the formation of a thin film of coordination polymer compounds thicker than 4 nm consisting of TrzD molecules, Fe2+ cations and NCS−. The layer of the complex compound immediately adjacent to the iron alloy surface is chemisorbed on it. The efficiency of this composition as an inhibitor of iron alloy corrosion and hydrogen bulk sorption by iron alloys is determined by its ability to form a coordination polymer compound layer, as experimentally confirmed by electrochemical, AFM and XPS data. The efficiency values of inhibitor compositions 5 mM TrzD + 0.5 mM KNCS and 5 mM TrzD + 0.5 mM KNCS + 200 mM C6H12N4 at a temperature of 20 ± 1 °C are 97% and 98%, respectively. The kinetic parameters of the limiting processes of hydrogen evolution and permeation into an iron alloy in a H3PO4 solution were determined. A significant decrease in both the reaction rate of hydrogen evolution and the rate of hydrogen permeation into the iron alloy by the TrzD and its mixtures in question was noted. The inhibitor compositions 5 mM TrzD + 0.5 mM KNCS and 5 mM TrzD + 0.5 mM KNCS + 200 mM C6H12N4 decreased the total hydrogen concentration in the iron alloy up to 9.3- and 11-fold, respectively. The preservation of the iron alloy plasticity in the corrosive environment containing the inhibitor under study was determined by a decrease in the hydrogen content in the alloy bulk. [ABSTRACT FROM AUTHOR]

In this paper, we compared the corrosion inhibiting effect of two essential oils on mild steel in 1 M HCl. The essential oils are extracted from natural plants harvested in Morocco and prepared through distillation. To carry out this work, we used gravimetric and electrochemical methods, including current-potential plots and impedance spectroscopy. The results obtained show that both essential oils are a good corrosion inhibitor and that the inhibition efficiency of wormwood essential oil reaches a value of more than 80 % at 298 K. To learn the fundamentals of how inhibitors interact with metal surfaces, wormwood essential oil adsorption on a mild steel surface was also investigated. The Langmuir isotherm model is revealed to be how the essential oils adsorb on the metal surface. The effect of temperature on the performance of mild steel in 1 M HCl with wormwood essential oil was examined in the temperature range of 313 to 353 K. Additionally, calculations and discussions are made to provide some thermodynamic data for the adsorption processes. This work enters the framework for the use of non-toxic products in green chemistry. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology & Engineering Geology / Shuiwendizhi Gongchengdizhi is the property of Hydrogeology & Engineering Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sustainable materials encompass a diverse range of substances used in both consumer and industrial domains. These materials are sourced in quantities that safeguard non-renewable resources and environmental equilibrium, with a focus on bio-based alternatives derived from plants. This study investigates the corrosion inhibition potential of two distinct Blue Tansy essential oils (BTES 1 and BTES 2) with varying chemical compositions. Corrosion resistance for mild steel in 1 M HCl environment was assessed using weight loss and Potentiodynamic polarization techniques. The evaluation of BTES 1 and BTES 2 revealed compelling insights. Notably, their inhibition efficiency exhibited an intriguing, damped oscillation pattern with fluctuating concentrations. Remarkably, at 0.5 g/L concentration, BTES 1 achieved an impressive 80% inhibition, while BTES 2 demonstrated a substantial 70% inhibition at 2.5 g/L. This behavior stems from intricate interactions among active compounds, leading to protective film formation and competitive adsorption effects. Importantly, congruence between weight loss measurements and potentiodynamic polarization curves fortified the reliability of outcomes. The study also confirmed BTES as a mixed-type inhibitor, as indicated by polarization curves. Furthermore, Petra/Osiris/Molinspiration (POM) analyses were conducted to unravel molecule interactions, elucidate toxicity risks, and assess bioactivity scores. This comprehensive exploration sheds light on the interplay between sustainable materials, corrosion inhibition efficacy, and complex molecular dynamics, enhancing our understanding of environmentally conscious corrosion prevention strategies. [ABSTRACT FROM AUTHOR]

The corrosion behaviour of 6061Al-15 % (v) SiC (P) composite was investigated in a 0.5 M HCl medium using electrochemical techniques. A water-soluble inhibitor, N-(1-morpholinobenzyl) semicarbazide (NMSc), was synthesised to test its corrosion inhibition activity on 6061Al-15 % (v) SiC (P) composite. The inhibitor showed cathodic-type behaviour and 95.42 % inhibition efficiency at 2.56 mM concentration and 303 K temperature. The thermodynamic results revealed the inhibitor's physisorption, which followed Langmuir's isotherm model. A drastic reduction in corrosion current density in the inhibited medium indicates that the inhibitor effectively controls the deterioration of the composite in the HCl medium. A significant rise in polarisation resistance on increasing inhibitor concentration offers greater resistance for the charge transfer process, ensuring better control over the composite corrosion. The surface analysis by scanning electron microscopy (SEM) and atomic force microscopy (AFM) confirms the inhibitor film formation on the composite. The quantum chemical theoretical calculations supported the electrochemical results. [ABSTRACT FROM AUTHOR]

Aluminium is preferred over iron for various uses as it is lighter, rust-proof and has an exceptional strength-to-weight ratio. Aluminium is more reactive than iron because of its higher standard reduction potential but it forms a self-protective layer of Al2O3 due to its higher reducing potential. Still, aluminium is corroded in acidic and alkaline media. The present research paper reports the corrosion behaviour of aluminium in 0.1 M NaOH solution with Alizarin Red S (ARS) or Xylenol Orange (XO) as an inhibitor. Corrosion potential, Corrosion current, Tafel slopes (βc) and (βa) for aluminium corrosion have been potentiodynamically investigated. The weight loss method has also been used to calculate the inhibition efficiencies of these additives. The corroded surfaces have been characterized by SEM images. It is found that corrosion potential values change significantly towards the anodic direction in the presence of ARS but they are sifted towards a cathodic direction at a high concentration of XO. While ARS shows a corrosion inhibition effect, XO shows a reverse effect. The inhibition efficiency values of ARS and XO calculated from corrosion current in potentiodynamic polarization studies tally with those calculated from weight loss studies. Studies on a laboratory model of aluminium-air batteries in 0.1 M NaOH containing these organic additives show that the discharge curve of the cell is improved in the presence of ARS and XO in combination. The results are explained in terms of the formation of well-known Al+3.3ARS− and Al+3-XO6− complexes. At room temperature, 1.0 × 10−3 M solution of ARS is found effective in inhibiting the corrosion of aluminium while the same concentration of XO is acting as a corrosion accelerator. This interesting study can be very vital in the field of corrosion science.

Abstract Red sandstone was selected for the study and specimens were prepared at 0°, 30°, 45° and 60° fracture inclinations and maintained in an acid solution at pH = 2. The specimens were subjected to uniaxial compression tests before and after maintenance to obtain the mechanical parameters and to observe the damage properties of the specimens. Based on the Lemaitre strain equivalence principle, a macroscopic fracture model for single-fissure rock masses and a statistical damage model for the Weibull distribution of micro-fissures were combined to derive macro-and micro-coupled damage variables for the specimens. The damage variables after acid solution corrosion are considered to derive the constitutive model for fractured red sandstone containing fractures after acid corrosion. The theoretical damage constitutive curves were compared with the experimental curves to analyse the applicability of the constitutive equation. The results show that the peak stress, peak strain and elastic modulus of the fractured specimens all vary regularly with the inclination angle, first decreasing and then increasing with the increase in the inclination angle; the peak compressive strength and elastic modulus of the fractured sandstone all tend to decrease and the peak strain tends to increase after corrosion by acid solution; the damage characteristics of the fractured sandstone are more influenced by the inclination angle and less influenced by acid corrosion; by comparing the theoretical curve with the experimental curve, the established damage constitutive model is in good agreement at the elastic deformation and plastic yielding stages. The mechanical properties of rock masses with different inclinations of fracture are quantified on the basis of the test results. The damage characteristics of rock masses with different fracture inclinations under normal and acid corrosion conditions are studied. The macro- and micro-coupled damage variables of fractured rock masses under acid corrosion are derived and validated.

Aiming at the problem of temperature-mechanics-chemical (T-M-C) action encountered by rocks in underground engineering, sandstone was selected as the sample for acid corrosion treatment at pH 1, 3, 5 and 7, the acid corrosion treated samples were then subjected to high-temperature experiments at 25, 300, 600, and 900 °C, and triaxial compression experiments were conducted in the laboratory. The experimental results show that the superposition of chemical damage and thermal damage has a significant impact on the quality, wave velocity, porosity and compression failure characteristics of the rock. Based on the Lemaitre strain equivalent hypothesis theory, the damage degree of rock material was described by introducing damage variables, and the spatial mobilized plane (SMP) criterion was adopted. The damage constitutive model can well reflect the stress-strain characteristics of the rock triaxial compression process, which verified the rationality and reliability of the model parameters. The experiment and constitutive model analyzed the change law of mechanical properties of rock after chemical corrosion and high temperature thermal damage, which had certain practical significance for rock engineering construction.

To study the effect of area-to-volume ratio on the dissolution and deterioration characteristics of sandstone in the static acid-rock reaction system, the HCl and H2SO4 solutions with pH=2 and 5 are selected as corrosion environments, and the different area-to-volume ratios are set by changing surface areas of sandstone. The effects of area-to-volume ratios on the physicochemical and mechanical properties of sandstone are studied. According to the acid-rock reaction theory, the effect of the area-to-volume ratio on the diffusion-dissolution mechanism during sandstone corrosion is analyzed. The results show that the sandstone mass loss rate and amount of substance of total cations are all related to the corrosion time as a power function. The area-to-volume is positively correlated with the dissolution rate constant and has little effect on the reaction order. The reaction order is less than one in different environments, indicating that the sandstone corrosion rate decreases gradually with soaking time. In the pH=2、5 HCl solution and pH=2 H2SO4 solution, the amount of substance of cation shows N(Ca2+) > N(Na+) > N(Mg2+) > N(K+), and in the pH=5 H2SO4 solution, it is N(Na+) > N(Ca2+) > N(Mg2+) ≈N(K+). The acid-rock reaction can be summarized as two mechanisms: diffusion control and chemical reaction control. The two control parameters are negatively correlated with the area-to-volume ratio and positively with the pH value of solutions. The parameter values in the H2SO4 solutions are slightly larger than the corresponding values in the HCl solutions. The interaction between sandstone and acid in different conditions is dominated by the chemical reaction. The area-to-volume ratio significantly influences diffusion more than the chemical reaction. The mechanical properties of sandstone are weakened after acid corrosion. The damage of sandstone under uniaxial compression can be divided into four stages: compaction, elastic deformation, plastic yielding and post-peak. The peak strength and elastic modulus decrease, the peak strain increases, the brittleness declines, and the ductility is enhanced. The larger the area-to-volume ratio, the more severe the sandstone deterioration is. Overall, the smaller the pH value of solutions, the more prominent the effects of the area-to-volume ratio on the dissolution characteristics and mechanical properties of sandstone are, which is more obvious in the HCl solutions than in the H2SO4 solutions. The finding can provide theoretical references for the safety assessment and disaster prevention of rock mass engineering under an acidic environment.

Cemented gangue backfill technology is beneficial to the reuse of solid waste and sustainable economic development. However, mine water has a great impact on the strength and deformation of cemented gangue backfill (CGB). In this study, the CGB specimens under load were placed in simulated acid mine water (H2SO4 solution). The changes in deformation, resistivity, and ultrasonic pulse velocity (UPV) of CGB were monitored. On the 360th day, the stress–strain curve and acoustic emission (AE) energy of the specimen during loading were recorded. The degradation mechanism of CGB was discussed by scanning electron microscope (SEM) and X-ray diffraction (XRD). The results showed that the deformation of CGB increased with time. The effect of H2SO4 solution concentration on the deformation was different in the early and late stages. Applying an 80% stress-strength ratio (SSR) reduced the strength and increased the deformation. The UPV and resistivity had different characteristics at different corrosion ages, which could be used for long-term stability monitoring of CGB. The CGB showed the strongest AE energy characteristics near the peak stress. The AE energy decreased with the increase of pH value in the pore compaction stage, and the AE activity of the CGB under 80% SSR was much greater than that of the CGB under 40% SSR. The erosion of the H2SO4 solution on the CGB was inhibited by applying a small load. Excessive load aggravated the erosion deterioration of CGB due to initial plastic damage. The research results can provide a reference for the durability design of CGB. [ABSTRACT FROM AUTHOR]

Theoretical aspects of low-carbon steel corrosion in H3PO4 solutions containing FePO4 are considered. In the system under study, reactions of iron with the acid solution and Fe(III) salt are thermodynamically allowed. The oxidizing power of this medium, characterized by the Fe(III)/Fe(II) couple redox potential, is mainly determined by its anionic composition. Phosphate anions of a corrosive medium bind Fe(III) cations into complex compounds, reducing their oxidizing ability. In H3PO4 solutions containing FePO4 and Fe3(PO4)2, the dependence of the system's redox potential on the Fe(III) and Fe(II) cation relative content is poorly described by the Nernst equation, which is due to the nonequivalent complex formation of these cations with phosphate anions. Analysis of the effect of the studied media convection on the low-carbon steel electrode reactions allowed revealing some of their features. In a FePO4-containing H3PO4 solution, kinetically controlled partial reactions of iron anodic ionization and H+ cathodic reduction, as well as diffusion-controlled Fe(III) cation cathodic reduction, occur on the steel. The FePO4 accelerating effect on the steel corrosion in H3PO4 solution is due only to the Fe(III) reduction but does not affect the H+ reduction and the iron ionization. The value of the Fe(III)-cation diffusion coefficient in the studied corrosive medium was experimentally determined from the data of cyclic voltammetry of the Pt electrode therein and the results of the studying of the cathodic reaction of a steel disk electrode at different rotation velocities. The data on the low-carbon steel corrosion in the flow of the studied media, obtained from the metal samples mass loss, are in full agreement with the results of the study of the electrode partial reactions. An accelerating effect of FePO4 on the steel corrosion in H3PO4 solutions is observed. In this environment, steel corrosion is determined by the convective factor, which is typical of processes with diffusion control. The empirical dependence of the steel corrosion rate on the medium flow intensity is described by the linear dependence k = kst + λw1/2, where kst is the steel corrosion rate in a static medium, w is the rotation velocity of the propeller stirrer that creates the medium flow, λ is the empirical coefficient. [ABSTRACT FROM AUTHOR]

Currently, the use of synthetic inhibitors in preventing corrosion is destructive to the environment; therefore, natural inhibitors might be an alternative and innovative solution to this challenge, owing to their sustainability. Herein, wasted avocado seed extract was examined as a sustainable and green inhibitor for API 5L X65 pipeline steel at an ambient temperature using the gravimetric analysis, the potentiodynamic polarization curve, and linear polarization resistance techniques. The inhibitor's chemical characterization was carried out with Fourier-transform infrared spectroscopy (FTIR), and the morphological characterization was carried out by detailed scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM/EDX). The result showed that the extract decreased the corrosion rate by retarding the cathodic and anodic electrochemical reactions, with a maximum efficiency of 88% at 5 g/L. The extract was adsorbed physically onto the X 65 steel following the Langmuir adsorption isotherms. The electrochemical studies showed that the agro-waste was a mixed-type inhibitor. The SEM image of the X65 steel with the extract showed thin film formation on the steel surface. The extract can be substituted for synthetic inhibitors, which are toxic, scarce, and costly. [ABSTRACT FROM AUTHOR]

Etching of steel items in sulfuric acid solution is used in various human activities (oil and gas industry, metal production, utilities, transport, etc.). This operation is associated with significant material costs due to corrosion losses of the metal. It has been found that an efficient way to prevent corrosion of steel in sulfuric acid solution involves the formation of thin protective films consisting of corrosion inhibitor molecules of triazole class on its surface. It has been shown that the protection of steels with a 3-substituted 1,2,4-triazole (3ST) in H2SO4 solution is accompanied by the formation of a polymolecular layer up to 4 nm thick. The 3ST layer immediately adjacent to the steel surface is chemisorbed on it. The efficiency of this compound as an inhibitor of corrosion and hydrogen absorption by steel is determined by its ability to form a protective organic layer, as experimentally confirmed by XPS and AFM data. The kinetic constants of the main stages of hydrogen evolution and permeation into steel in the H2SO4 solution were determined. A significant decrease in both the reaction rate of cathodic hydrogen evolution and the rate of hydrogen permeation into steel by the triazole in question was noted. It has been shown that the preservation of the metal plasticity in the acid medium containing the triazole under study is due to a decrease in the hydrogen concentration in the metal bulk. [ABSTRACT FROM AUTHOR]

Inhibitive performance of 1,3 dimethyl imidazolium dimethyl phosphate (DIDP) towards the corrosion of 6061‐Al (10 vol.%) SiC(P) composite (Al‐CM) and base alloy in 0.1 M HCl medium was studied using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques at different temperatures. Optimization of inhibitor concentration was done to get maximum inhibition efficiency. Thermodynamic parameters were calculated by fitting the results into a suitable adsorption isotherm. Scanning electron microscope (SEM), energy‐dispersive X‐ray (EDX), and atomic force microscope (AFM) analyses were performed to understand surface morphology, elemental mapping, and surface roughness before and after the addition of DIDP. UV–visible and X‐ray diffraction (XRD) tests were performed to confirm the adsorption of inhibitor on the surfaces of materials. Studies revealed an increased rate of corrosion for Al‐CM than for the base alloy. The maximum inhibition efficiency for the base alloy was found to be 80.48% for the addition of 1000 ppm, and for Al‐CM, it was found to be 87.38% for the addition of 1400 ppm at 303 K. As the temperature increased, the inhibition efficiency decreased. The inhibitor was adsorbed physically on the surface of the metal by obeying the Freundlich adsorption isotherm. Surface studies confirmed the adsorption of DIDP on the surfaces of both Al‐CM and the base alloy. [ABSTRACT FROM AUTHOR]

Fluoride (F−) impurity at 20 mg L−1 in the zinc sulphate electrolyte increased by 73% and 98% the corrosion rate of Al-1050 and Al-1070 alloys, respectively, which are used as cathode in zinc electrowinning process. The addition of aluminium ions, Al3+, to the electrolyte reduced the corrosion rate by about 21% for the Al-1050 alloy and about 28% for the Al-1070 alloy. The effect was ascribed to the formation of AlF2+ and AlF2+ complexes, thus decreasing fluoride activity. Electrochemical impedance spectroscopy demonstrated that the corrosion resistance of Al alloys is increased in the presence of Al3+. Scanning electron microscopy indicated uniform corrosion of the Al surface, the degree of which depends on fluoride concentration. The higher corrosion resistance of Al-1050 was related to its coarser microstructure, which is less susceptible to corrosion in a non-passivating media. The selection of effective complexing agent for fluoride ion and the consequent reduction in the corrosion rate of aluminum cathodes are relevant in scenario of increasing co-processing of secondary zinc sources.

The current research reports the performance of 1-butyl-3-methylimidazolium methane sulfonate ([C4MIM][OMs](IL)) as effective corrosion inhibitor for mild steel in 1 M H2SO4 electrolyte. For proper evaluation, weight loss, electrochemical study, theoretical modeling and optimization techniques were used. Weight loss and electrochemical methods shows that the inhibition performance of [C4MIM][OMs] on the metal surface strengthens as the concentration increases. Maximum inhibition efficiency of 85.71%, 92.5% and 91.1% at 0.8 g L-1 concentration of [C4MIM][OMs] were obtained from the weight loss, polarization and impedance studies, respectively. In addition, response surface methodology (RSM) a statistical tool was used for modeling and optimization of the empirical data. The RSM model validates the empirical findings. Also, DFT/MD-simulation investigations evidenced that [C4MIM][OMs] forms a barrier film on the mild steel surface. The result shows that the synthesized [C4MIM][OMs] could open up opportunities in corrosion and materials protection for sustainability.

During the mandatory acidification process in the oil and gas industry, carbon steel unfortunately suffers significant corrosion damage. From this perspective, for the first time a new ionic liquid called 1-(2-(4-bromophenyl)-2-oxoethyl)-4-(tert-butyl)pyridin-1-ium bromide (ILB) has been used as an effective inhibitor for the carbon steel corrosion in aggressive HCl solution (15%) at 298 K. The experiments were managed with a number of different chemical and electrochemical techniques including weight loss, potentiodynamic polarization (PDP), and impedance spectroscopy (EIS). ILB has good inhibitory performance as an acidizing corrosion inhibitor for carbon steel even at low dosing levels of 1 × 10−3 M. The findings were promising as an inhibition efficiency of about 97% was achieved when ILB was added at low concentrations to the corrosive media. EIS results showed a significant rise in charge transfer resistance (Rct) values with increasing doses of ILB. PDP studies confirmed that ILB is a mixed type and obey Langmuir adsorption isotherm with chemical nature. The metal surface morphologies were inspected using a Scanning Electron Microscope (SEM) and an Atomic Force Microscope (AFM). Additionally, Density Functional Theory (DFT) and Molecular Dynamic Simulation (MDS) indicates that ILB molecules function as inhibitors more successfully. There is a high degree of concordance between practical and theoretical studies. [ABSTRACT FROM AUTHOR]

The authors study the corrosion of low-carbon steel in solutions of H2SO4 containing Fe2(SO4)3 with and without additives of individual and mixed corrosion inhibitors. It is established that the oxidizing capacity of the given system (in which the reactions between iron, an acid solution, and Fe(III) salts are thermodynamically allowed), characterized by the redox potential of an Fe(III)/Fe(II) pair, is largely determined by its anionic composition: sulfate anions of a corrosive medium bind Fe(III) cations into complex compounds, reducing their oxidizing ability. Partial reactions of the anodic ionization of iron and the cathodic reduction of H+ and Fe(III) cations are revealed in analyzing the effect convection of the medium has on the electrode reactions of low-carbon steel. The first two reactions are characterized by kinetic control; the third, by diffusion. It is shown that the accelerating effect Fe2(SO4)3 has on the corrosion of steel in a solution with H2SO4 is mainly due to the reduction of Fe(III). In contrast, the accelerating action of Fe(III) cations affects all partial reactions of steel in an inhibited acid. There is a large drop in the apparent coefficient of diffusion of Fe(III) cations (DFe(III)) in inhibited solutions, relative to an uninhibited medium. Data on the corrosion of low-carbon steel in the given media, obtained from the mass loss of metal samples, are in full agreement with results from studying partial electrode reactions. Consideration is given to the accelerating effect Fe2(SO4)3 has on the corrosion of steel in solutions of H2SO4 with and without inhibitors. In these environments, the corrosion of steel is determined by the convective factor, which is typical of processes with diffusion control. The empirical dependence of the rate of steel corrosion on the intensity of the medium's flow is described by linear dependence k = kst + λw1/2, where kst is the rate of the corrosion of steel in a static environment, w is the rotational speed of the propeller agitator creating the flow of the medium, and λ is an empirical coefficient. [ABSTRACT FROM AUTHOR]

Current approaches to creating mixed inhibitors of metal corrosion in acid solutions and possible pathways of their action on the corrosion process are reviewed. Quantitative approaches to assessing the mutual effect of the components of mixed inhibitors are analyzed, and criteria for the synergism of their action are discussed. The high efficiency of ternary mixed inhibitors based on triazole derivatives in the protection of different steels in high-temperature acid solutions (t = 100–180°C) and solutions of acid mixtures containing Fe(III) salts is shown. Important practical advantages and disadvantages of the different groups of inhibitors of metal corrosion in acidic media are discussed. Data on protecting metals in acidic media with so-called green inhibitors are summarized, and the prospects and discrepancies associated with their practical application are discussed. The need to search for technologies allowing the use of inhibited acid solutions that meet the environmental requirements of current production while simultaneously allowing for the hazard of solutions of the acids is shown. [ABSTRACT FROM AUTHOR]

The creep characteristics of rock have an important effect on the long-term stability of rock engineering. Especially under the action of acid rain and other water chemistry, the rock microstructure is destroyed, and the creep characteristics and deformation are more significant. With the red sandstone of the Erfo Temple in Chongqing as the research object, the creep characteristics of sandstone under acid corrosion are studied by triaxial compression creep test. The results show that the porosity of sandstone increases with acid corrosion and immersion, which leads to the large instantaneous strain and creep of sandstone under the first stage load, and then the instantaneous strain and creep increase with the increase in stress. The creep strength is 76% of the compressive strength, and the long-term strength is only 54% of the compressive strength. To describe the whole creep process, a damage creep model is established to fit the test data, and its applicability is verified, which provides a reference for geotechnical engineering construction.