A comparative electrochemical and quantum chemical calculation study of BTAH and BTAOH as copper corrosion inhibitors in near neutral chloride solution

Preparation and Rheological Properties of the PVA/CMC/Gel Composite for Mining

A composite gel material with an interpenetrating network structure was formed using the chemical cross-linking method. The viscosity, yield stress, and thixotropy of a poly(vinyl alcohol)/carboxymethyl cellulose/gelatin (PVA/CMC/Gel) composite gel slurry with different ratios were tested using a viscometer, and the interaction between the surface of the gelling agent and the cross-linking agent was analyzed by calculating the frontline orbital energy of a single polymer material molecule. The seepage diffusion characteristics of the composite gel in a goaf were then studied through a numerical simulation. The results indicate that the PVA/CMC/Gel composite gel exhibits shear thinning behavior following the power law model and behaves as a pseudoplastic fluid. The optimal ratio for the composite gel at 30 °C is determined as follows: 30 wt % for the gelling agent (PVA/(Gel + CMC) = 20:10), 4 wt % for the cross-linking agent, 3.09 wt % for the carbide slag, 7.5 wt % for the alcohol amine solution, and 0.5% sodium dodecyl sulfonate + 0.1% alkyl glycoside for the foaming agent. Gel exhibits the lowest energy band gap (0.096 eV), indicating strong reaction activity and strong reaction with the cross-linking agent (sodium tetraborate). PVA has the largest energy band gap (0.238 eV), strong molecular stability, and weak reaction with the cross-linking agent (sodium tetraborate). When the dip angle of the goaf is 4° and the injection time is 40 min, the composite gel tends to diffuse more easily along the dip. The investigation into the rheological properties of the PVA/CMC/Gel composite gel holds significant importance in the design of coal mine pipeline transportation and understanding diffusion flow in goaf.

Effect of benzotriazole on the existing pits of copper tube in fire sprinkler system

In this paper, two leaking tubes were investigated among copper tubes injected with 200 and 400 ppm benzotriazole after 8 years of usage. The electrochemical tests were conducted in simulated pit-out and pit-in environments (i.e., regions outside and inside of the pit) to determine the effect of benzotriazole on the propagation of an existing pit. The electrochemical analysis results showed that 200 and 400 ppm benzotriazole exhibit relatively lower inhibition efficiency in an acidic simulated pit-in environment because of the difficulty of forming a protective film and the benzotriazole cationization.

Investigation of Hexylamine Adsorption on Gold in Perchloric Acid

The adsorption of hexylamine at the solution-gold interface in 1 M HClO₄ in the presence of 0.1 M Fe²⁺ and 0.1 Fe³⁺ was studied by potentiodynamic, chronoamperometric and EIS methods. The main kinetic characteristics of the oxidation-reduction reaction iron ions (exchange current density, transfer coefficient, diffusion coefficients of iron ions) were determined. It was shown that the physical adsorption of hexylamine on gold can be described by the Dhar-Flory-Huggins isotherm. The values of the adsorption constant and the Gibbs free adsorption energy were obtained. A comparison of the free adsorption energy at these interfaces with the interaction energies of hexylamine and water molecules, and hexylamine molecules with each other was carried out. It was shown that hexylamine adsorption at all of these interfaces is due mainly to the hydrophobic effect of the interaction of hexylamine and water molecules.

Investigation of the anticorrosion and adsorption properties of two polymer compounds on the corrosion of SABIC iron in 1 M HCl solution by practical and computational approaches

The anticorrosion efficiency of two polymer compounds, namely polystyrene (PS), polybutylene terephthalate (PBT), against the corrosion of SABIC iron (S-Fe) in 1.0 M HCl solution was investigated. The anticorrosion efficiency was estimated by chemical and electrochemical measurements. The anticorrosion efficiency increased with the increase in the concentration of the polymer compounds and reduction in temperature. All the obtained corrosion data confirmed the anticorrosion strength in the presence of PS and PBT compounds, such as the decreasing values of the corrosion current density, capacity of the double layer, and weight reduction, while the values of the charge-transfer resistance increased. Also, the pitting potential values moved in the noble (+) direction. The anticorrosion efficiency of the PBT compound was higher than that of the PS compound, which was 95.98% at 500 ppm concentration for PBT while for PS it was 93.34% according to polarization measurements. The anticorrosion activity occurred by the adsorption of PS and PBT compounds on the surface of S-Fe according to the Langmuir isotherm. The polarization curves indicated that the PS and PBT compounds were mixed-type inhibitors. Density functional theory (DFT) and Monte Carlo simulation (MC) were performed for the two polymer compounds. The computational quantum functions were found to be in agreement with the experimental results.

Antipsychotic drug waste: A potential corrosion inhibitor for mild steel in the oil and gas industry

In this study, the corrosion inhibition efficiency of thioridazine hydrochloride (TH), an antipsychotic drug, on mild steel (commonly used pipeline material in the oil and gas industry) in 1 M hydrochloric acid (HCl) was evaluated using electrochemical techniques and weight loss method. Electrochemical impedance spectroscopy (EIS) results suggest that TH significantly enhances the polarization resistance (R_p) of mild steel. Similarly, potentiodynamic polarization results showed that the corrosion current density (i_corr) of mild steel decreased significantly with addition of TH. To understand the long-term effect of TH, mild steel was tested for 7 days in 100 ppm TH containing electrolyte. EIS results showed that the R_p did not change significantly after 24 h exposure as compared to 2 h exposure; whereas the R_p increased by 28% after 7-day exposure. Weight loss measurements revealed that the inhibition efficiency of TH is remarkably high (98.8%) after 7-day exposure. The adsorption free energy calculation suggests that at the initial stage (1-day) of mild steel exposure, TH was physically adsorbed onto the surface. However, at a later stage (7- day) the binding of TH was chemical, and hence the corrosion protection increased with increase in the exposure period. As compared to the wide range of corrosion inhibitors reported in the literature, TH has shown to be highly effective for mild steel. Thus, it can be suggested that TH drug waste is a potential corrosion inhibitor for mild steel pipelines in the oil and gas industry.

Chloride-Assisted Corrosion of Copper and Protection by Benzotriazole

The structure and composition of copper surfaces in aqueous solutions of benzotriazole (BTAH) and NaCl was investigated by sum frequency vibrational spectroscopy as a function of concentration and bias during cyclic voltammetry experiments. We found that the protection provided by the BTAH films formed at the copper surface is effective for negative bias voltages below the open circuit potential (OCP) but not at positive voltages where Cl^- displaces BTAH. By measuring the Gibbs adsorption energy of BTAH and Cl^-, we found that a particularly stable Cl^- structure is formed around the OCP, suggesting that electronegative additives that move the OCP to higher negative values can improve BTAH protection, which we confirmed by the addition of a negatively charged sodium dodecyl sulfate surfactant.

Interfacial interaction study of EDTA with the defect structure of Fe3-δ O4 passive film in an aggressive alkaline medium based on the lattice theory of point defects

Despite extensive research on the matter of corrosion inhibition efficiency, the interactions between the defect structure of the passive layer and the inhibitor molecules still remain poorly understood. In this study, the corrosion inhibition mechanism of ethylenediamine-tetraacetic acid as a carboxylate-based organic inhibitor on steel specimens in simulated concrete pore solution was studied. The point defect model was used to describe the response of the passive oxide film on the steel surface to the perturbation caused by the addition of the carboxylate compound. The electrochemical behavior of the steel specimens was evaluated through open circuit potential, electrochemical impedance spectroscopy and potentiodynamic analysis. The reduction in efficiency outside the optimal concentrations was discussed from an electrochemical point of view. We suggest that the performance of the inhibitor is highly dependent on the positively charged entities on the passive layer including anion vacancies and interstitial cations. To further investigate the physicochemical behavior of the organic molecules, density functional theory and adsorption isotherms were applied. The topography and morphology of the surface were analyzed through scanning electron microscopy. To confirm the inhibitive effect of EDTA, the elements and chemical bonds present on the surface were characterized via X-ray photoelectron spectroscopy. The surface analysis confirmed that the addition of EDTA formed a network of chemical bonds, which significantly hindered the corrosion phenomenon.

Use of a Metallic Complex Derived from Curcuma Longa as Green Corrosion Inhibitor for Carbon Steel in Sulfuric Acid

A tin-containing metallic complex derived from Curcuma longa, bis[1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dionato-κO,κO ${}^{\prime }$ ]bis(butyl), has been obtained and used as a green corrosion inhibitor for carbon steel in 0.5 M sulfuric acid by using weight loss, electrochemical techniques, and the Density Functional Theory. It was found that the obtained metallic complex greatly decreases the steel corrosion rate by adsorption according to a Frumkin model in a weak, physical type of adsorption. Inhibitor efficiency increased with its concentration, and it acted as a mixed type of inhibitor. Results were supported by quantum-chemical research in order to examine the relationship between structural and electronic properties and the inhibitor efficiency.

Cyclic Voltammetry as an Electroanalytical Tool for Analysing the Reaction Mechanisms of Copper in Chloride Solution Containing Different Azole Compounds

Background:

Cyclic voltammetry is widely employed in electroanalytical studies because it provides fast information about the redox potentials of the electroactive species and the influence of the medium on the redox processes. Azole compounds have been found to be effective corrosion inhibitors for copper in chloride-containing solutions. The aim of this work was to investigate in detail the influence of the addition of various azole compounds on the oxidation mechanism of copper in chloride-containing solutions, using cyclic voltammetry.

Methods:

The influence of thirteen azole compounds, at three different concentrations on the electrochemical/ chemical reactions of pure copper immersed in 3 wt.% NaCl solution was studied using cyclic voltammetry at different scan rates. The change of the peak current and potential with the scan rate were investigated. The possible linearity was compared with the theoretically derived mechanism. The possible reaction mechanisms were discussed based on the linearity of these parameters (peak current and potential) with the scan rate compared to theoretically derived models.

Results:

Both the peak current and peak potential of the copper samples immersed in chloridecontaining solutions with additions of the majority of azole compounds showed linearity with the square root of the scan rate, suggesting that copper follows the Müller-Calandra passivation model. The same behavior was also found for copper in chloride-containing solutions without additions of azole compounds. A linear variation of the peak potential with the natural logarithm of the scan rate and linear variation of the peak potential with the square root of the scan rate was observed for the copper samples immersed in chloride-containing solutions with the addition of 10 mM of 2-mercapto-1- methylimidazole, imidazole, or 2-aminobenzimidazole. This suggests that copper follows irreversible redox reactions under a diffusion controlled process. No other linear relations of the peak current and peak potential with the scan rate were found.

Conclusion:

Copper oxidation in chloride-containing solutions is controlled by passivation (following the Müller-Calandra passivation model) upon the addition of the majority of the selected azoles. In the minority of cases, irreversible redox reactions that follow a diffusion-controlled process were identified. None of the systems followed an adsorption-controlled process. Moreover, none of the tested systems underwent reversible redox reactions that followed a diffusion controlled process.

The synthesis and characterization of benzotriazole-based cationic surfactants and the evaluation of their corrosion inhibition efficiency on copper in seawater

This study aims at preparing three cationic surfactants based on benzotriazole and evaluating their efficiencies as corrosion inhibitors for copper electrodes in seawater using different electrochemical techniques (potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM)). FTIR and 1H NMR spectroscopic techniques confirmed the chemical structures of the as-prepared cationic compounds. The inhibition efficiency increased with the increase the concentration of the as-prepared compounds in the solution. The curves of the potentiodynamic polarization and the plots of EIS techniques show that the performance of all investigated compounds as mixed type. The standard free energy values imply that the three as-prepared compounds show physicochemical adsorption and obey the Langmuir adsorption model. AFM technique observed the reduction in the surface roughness due to the protective film formed on the copper surface. Finally, computational calculations show a great correlation with the experimental results due to the electron-donating effect.

The Corrosion Inhibition of AA6082 Aluminium Alloy by Certain Azoles in Chloride Solution: Electrochemistry and Surface Analysis

The corrosion inhibition effect of five azole compounds on the corrosion of an AA6082 aluminium alloy in 5 wt.% NaCl solution at 25 and 50 °C was investigated using weight loss and electrochemical measurements. Only 2-mercaptobenzothiazole (MBT) showed a corrosion inhibition effect at both temperatures and was further studied in detail, including with the addition of potassium iodide as a possible intensifier. Surface analysis of the MBT surface layer was performed by means of attenuated total reflectance Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry techniques. The hydrophobicity of the MBT surface layer was also investigated.

Adsorption Behavior of Organic Molecules: A Study of Benzotriazole on Cu(111) with Spectroscopic and Theoretical Methods

The adsorption of organic molecules on solid substrates is important to applications in fields such as catalysis, photovoltaics, corrosion inhibition, adhesion, and sensors. The molecular level description of the surface-molecule interaction and of the adsorption structures in these complex systems is crucial to understand their properties and function. Here, we present an investigation of one such system, benzotriazole (BTAH) on single-crystal Cu(111) in vacuum conditions. BTAH is the most widely used corrosion inhibitor for copper and thus a molecule of great industrial relevance. We show that the co-application of a wide range of spectroscopic techniques with theoretical methods provides unique insight in the description of the atomistic details of the adsorbed structures. Specifically, spectroscopic photoemission, absorption, and standing wave experiments combined with ab initio computational modeling allowed us to identify that benzotriazole forms overlayers of intact BTAH when deposited at low temperature, and it dissociates into BTA and H at room temperature and above. The dissociated molecule then forms complex structures of mixed chains and dimers of BTA bound to copper adatoms. Our work also reveals that copper adatoms at low concentrations, such as the theoretically predicted superstructures, cannot be resolved by means of current X-ray photoelectron spectroscopy as the modeled Cu 2p spectra are practically indistinguishable from those for a Cu surface without adatoms. Overall this study significantly deepens understanding of BTAH on Cu, a system studied for more than 50 years, and it highlights the benefits of combining spectroscopic and computational methods to obtain a complete picture of a complex adsorption system.

Discoloration Resistance of Electrolytic Copper Foil Following 1,2,3-Benzotriazole Surface Treatment with Sodium Molybdate

The copper which an important component in the electronics industry, can suffer from discoloration and corrosion. The electrolytic copper foil was treated by 1,2,3-benzo-triazole (BTA) for an environmentally friendly non-chromate surface treatment. It was designed to prevent discoloration and improve corrosion resistance, consisted of BTA and inorganic sodium molybdate (Na2MoO4). Also the ratio of the constituent compounds and the deposition time were varied. Electrochemical corrosion of the Cu-BTA was evaluated using potentiodynamic polarization. Discoloration was analyzed after humidity and heat resistance conditioning. Surface characteristics were evaluated using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Increasing corrosion potential and decreasing current density were observed with increasing Na2MoO4 content. A denser protective coating formed as the deposition time increased. Although chromate treatment under severe humidity (80% humidity, 80 °C, 100 h) provided the highest humidity resistance, surface treatment with Na2MoO4 had better heat discoloration inhibition under severe heat-resistant conditions (180 °C, 10 min). When BTA reacts with Cu to form the Cu-BTA-type insoluble protective film, Na2MoO4 accelerates the film formation without being itself adsorbed onto the film. Therefore, the addition of Na2MoO4 increased anticorrosive efficiency through direct/indirect action.

Sugar based N,N'-didodecyl-N,N'digluconamideethylenediamine gemini surfactant as corrosion inhibitor for mild steel in 3.5% NaCl solution-effect of synergistic KI additive

The inhibitory behaviour of non-ionic sugar based N,N'-didodecyl-N,N'-digluconamideethylenediamine gemini surfactant, designated as Glu(12)-2-Glu(12) on mild steel (MS) corrosion in 3.5% NaCl at 30-60 °C was explored using weight loss, PDP, EIS and SEM/EDAX/AFM techniques. The compound inhibited the corrosion of mild steel in 3.5% NaCl and the extent of inhibition was dependent on concentration and temperature. The inhibiting action of Glu(12)-2-Glu(12) is synergistically enhanced on addition of potassium iodide (KI) at all concentrations and temperatures. The inhibiting formulation comprising of 2.5 × 10-3 mM of Glu(12)-2-Glu(12) and 10 mM of KI exhibits an inhibition efficiency of 96.9% at 60 °C. Quantum chemical calculations and MD simulation were applied to analyze the experimental data and elucidate the adsorption behaviour and inhibition mechanism of inhibitors. MD simulation showed a nearly parallel or flat disposition for Glu(12)-2-Glu(12) molecules on the MS surface providing larger blocking area to prevent the metal surface from corrosion.

Surface analysis of 2-mercapto-1-methylimidazole adsorbed on copper by X-ray photoelectron spectroscopy

A detailed analysis using X-ray photoelectron spectroscopy (XPS) is presented for the system of 2-mercapto-1-methylimidazole (MMeI) adsorbed on Cu in 3wt% NaCl solution. High-resolution and survey XPS spectra and XPS-excited Auger L₃M_4,5M_4,5 spectra were analysed in detail. Surface analysis revealed that the MMeI molecules do not lie flat on the surface via π-d interactions, but adsorb on the surface through an N-S-bridge configuration. Moreover, the characteristic Cu(I)-MMeI connection fingerprint, which is usually observed for these kinds of molecules, was not observed. Tougaard thickness analysis showed that a relatively thin MMeI surface layer (0.3-0.6nm) is formed on the Cu substrate after 1h of immersion. Herein, MMeI is considered as a Cu corrosion inhibitor for chloride solution for short-term immersion periods. Based on the XPS analysis, an explanation of why MMeI is not effective for longer-term immersion periods, compared with similar compounds, is given.

Corrosion inhibition of copper in aqueous chloride solution by 1H-1,2,3-triazole and 1,2,4-triazole and their combinations: electrochemical, Raman and theoretical studies

Triazoles are well-known organic corrosion inhibitors of copper. 1H-1,2,3-Triazole and 1,2,4-triazole, two very simple molecules with the only difference being the positions of the nitrogen atoms in the triazole ring, were studied in this work as corrosion inhibitors of copper in 50 mM NaCl solution using a set of electrochemical and analytical techniques. The results of electrochemical tests indicate that 1H-1,2,3-triazole exhibited superior inhibitor properties but could not suppress anodic copper dissolution at moderate anodic potentials (>+300 mV SCE), while 1,2,4-triazole, although it exhibited higher anodic currents, suppressed anodic copper dissolution at very anodic potentials. Density functional theory calculations were also performed to interpret the measured data and trends observed in the electrochemical studies. The computational studies considered either the inhibitors isolated in the gaseous phase or adsorbed onto Cu(111) surface models. From the calculations, the mechanisms of the inhibitive effects of both triazoles were established and plausible mechanisms of formation of the protective films on the Cu surface were proposed. The results of this study hold positive implications for research in the areas of catalysis, and copper content control in water purification systems.

Experimental and theoretical investigation on corrosion inhibitive properties of steel rebar by a newly designed environmentally friendly inhibitor formula

In order to mitigate the corrosion of steel rebar in concrete, a new environmentally friendly corrosion inhibitor formula (WKI) was designed and the corrosion inhibitive effects of WKI on steel rebar were studied by gravimetric method, electrochemical impendence spectroscopy (EIS), potentiodynamic polarization and Mott–Schottky scanning in simulated concrete pore solution. Furthermore, surface analysis and quantum chemical calculations were conducted in order to illustrate the corrosion inhibitive mechanism. The results indicate that WKI exhibits excellent corrosion inhibitive activities on steel rebar in simulated concrete pore solution. By the presence of WKI, local corrosion was significantly suppressed and no pitting could be detected during the whole experimental period. The total corrosion resistance was increased from 5469 Ω cm² to 64 440 Ω cm² and the corrosion current density was reduced from 3.23 μA cm⁻² to 0.21 μA cm⁻² for the sample immersed in the corrosion medium for 7 d with WKI. The corrosion potential of the steel rebar electrode moved to a higher level and the charge transfer resistance increased, indicating that the anti-corrosion properties of the steel rebar were enhanced. The corrosion inhibitive mechanism of WKI can be attributed to the fact that it can promote the formation of a passive film and reduce its defect concentration via its adsorption and interaction with the metal surface, consequently inhibiting the corrosion of steel rebar caused by chloride ions.

A new corrosion inhibitor formula was designed and the inhibitive mechanism was analyzed based on HSAB theory and the PDM model.

4,6-Dimethyl-2-mercaptopyrimidine as a potential leveler for microvia filling with electroplating copper

Filling performance of microvia was defined as following equation: η = (A/B) × 100%.

The first electrochemical and surface analysis of 2-aminobenzimidazole as a corrosion inhibitor for copper in chloride solution

High corrosion inhibition effectiveness of 2-aminobenzimidazole is proven after a long-term immersion period in 3 wt% NaCl solution.

Metal Complexes of New Bioactive Pyrazolone Phenylhydrazones; Crystal Structure of 4-Acetyl-3-methyl-1-phenyl-2-pyrazoline-5-one phenylhydrazone Ampp-Ph

The condensation reaction of phenylhydrazine and dinitrophenylhydrazine with 4-acetyl and 4-benzoyl pyrazolone precipitated air-stable acetyldinitrophenylhydrazone Ampp-Dh, benzoylphenylhydrazone Bmpp-Ph and benzoyldinitrophenylhydrazone Bmpp-Dh in their keto imine form; a study inspired by the burning interest for the development of new bioactive materials with novel properties that may become alternative therapeutic agents. Elemental analysis, FTIR, ¹H, and ¹³C NMR, and mass spectroscopy have been used to justify their proposed chemical structures, which were in agreement with the single crystal structure of Bmpp-Dh earlier reported according to X-ray crystallography. The single crystal structure of 4-acetyl-3-methyl-1-phenyl--pyrazoline-5-one phenylhydrazone Ampp-Ph, which crystallizes in a triclinic crystal system with a P-1 (No. 2) space group is presented. Octahedral Mn(II), Ni(II), Co(II), and Cu(II) complexes of these respective ligands with two molecules each of the bidentate Schiff base, coordinating to the metal ion through the azomethine nitrogen C=N and the keto oxygen C=O, which were afforded by the reaction of aqueous solutions of the corresponding metal salts with the ligands are also reported. Their identity and proposed structures were according to elemental analysis, FTIR spectroscopy, UV-VIS spectrophotometry (electronic spectra) and Bohr magnetic moments, as well as thermogravimetric analysis (TGA) results. A look at the antibacterial and antioxidant activities of synthesized compounds using the methods of the disc diffusion against some selected bacterial isolates and 1,1-diphenyl-2-picryl-hydrazil (DPPH) respectively, showed biological activities in relation to employed standard medicinal drugs.

Synthesis and spectral characterization of bis(4-amino-5-mercapto-1,2,4-triazol-3-yl)propane

Bis(4-amino-5-mercapto-1,2,4-triazol-3-yl)propane (BAMTP) was synthesized and characterized by FT-IR and FT-Raman spectra. Gas phase structure of BAMTP was examined under density functional theory B3LYP/6-311++G(d, p) level of basis set, wherein the molecule was subjected to conformational analysis. Thus the identified stable structure utilized for the calculations such as geometry optimization, vibrational behavior, hyperpolarizability analysis, natural bond orbital analysis, band gap, chemical hard/softness and stability. Geometry of BAMTP has been discussed elaborately with related crystal data. The results found from experimental and theoretical methods were reported herewith.

Synthesis and evaluation of novel series of Schiff base cationic surfactants as corrosion inhibitors for carbon steel in acidic/chloride media: experimental and theoretical investigations

A new family of Schiff base cationic surfactants (CSSB) having various alkyl chain lengths were prepared and their chemical structure was elucidated by using different spectroscopic techniques (FTIR, ¹³C-NMR and ¹H-NMR).