The effect of 3-phenyl-1H-1,2,4-triazole-5-thiol, 24-methyl-5-((4-phenyl-1H-1,2,3-triazol-1-yl)methyl)-4H-1,2,4-triazol-3-thiol, and 4-amino-4H-1,2,4-triazole-3,5-dithiol on the corrosion of C1018 steel in acid media (1 M and 5 M HCl) has been studied by weight loss tests, potentiodynamic polarization and electrochemical impedance spectroscopy. These studies have shown that 4-methyl-5-((4-phenyl-1H-1,2,3-triazol-1-yl)methyl)-4H-1,2,4-triazol-3-thiol is more effective in 1 M HCl, but 4-amino-4H-1,2,4-triazole-3,5-dithiol is better in 5 M HCl. The polarization measurements have shown that all the inhibitors studied are cathodic-type inhibitors in the HCl media in the temperature range of 293-353 K. 3-Phenyl-1H-1,2,4-triazole-5-thiol remained efficient in the temperature range of 293-353 K both in 1 M hydrochloric acid and in 5 M HCl solution due to chemical adsorption of inhibitor molecules on the metal surface. 4-Methyl-5-((4-phenyl-1H-1,2,3-triazol-1-yl)methyl)-4H-1,2,4-triazol-3-thiol and 4-amino-4H-1,2,4-triazole-3,5-dithiol in 5 M HCl solution lose their protective properties with an increase in temperature, which is associated with a change in the nature of adsorption. The nature of adsorption was assessed based on the calculation of the activation energy of the corrosion process in the presence of the compounds studied. Furthermore, the adsorption obeys the Langmuir isotherm at room temperature. The negative standard Gibbs energy of adsorption in the presence of triazoles suggests the chemisorption of its molecules on the steel surface.

(E)-5-{[4-(Dimethylamino)benzylidene]amino}-1,3,4-thiadiazole-2(3H)-thione (DATT) was synthesized and its corrosion inhibitive efficiency on mild steel has been investigated in 1 and 5 mol L-1 HCl medium by gravimetric and electrochemical measurements. The structure of DATT was determined by Nuclear Magnetic Resonance (NMR) spectroscopy and Grimme's GFN2-xTB method. The same calculations determined that there are three most stable DATT protomers among mono, double and triple protonated structures. Fukui functions mapped on the van der Waals (vdW) surfaces of DBT and its protonated forms at the PBE0-D3BJ[C-PCM(Water)]/ma-def2-TZVP level of theory was determined. The polarization measurements and analysis of anodic and cathodic slopes of polarization curves have shown that DATT is a mixed-type inhibitor in HCl media in a broad temperature range. Scanning electron microscopy and surface profilometry confirmed the formation of protective films on mild steel surface. The inhibition efficiency of DATT is associated with the protonation of its molecules and increases with concentration of hydrochloric acid solutions when oxygen, sulfur and nitrogen atoms with their single electron pairs bind more easily to the free 3d orbitals of iron. The degree of steel coverage in 5 M HCl is higher than in 1 M acid, according to electrochemical impedance spectroscopy results. Contact angle measurement detected the hydrophobic nature of the steel surface modified by the inhibitor molecules applied in corrosive solutions. The influence of molecular configuration on the corrosion inhibition behavior of (E)-5-{[4-(dimethylamino)- benzylidene]dmino}-1,3,4-thiadiazole-2(3H)-thione was explored by quantum chemical calculation and MD simulation.

Some aspects of mild steel corrosion in 1 M hydrochloric acid with addition of 1,3-DPTA in the corrosive system were studied by weight loss and electrochemical methods (potentiodynamic polarization measurements and electrochemical impedance spectroscopy) and also by contact angle and surface tension measurements. N-(1,3-dithiolan-2-ylidene)-5-phenyl-1,3,4-thiadiazole-2-amine (1,3-DPTA) has high inhibitory effect on the cathodic and anodic reactions on steel in HCl solutions. To determine the mechanism of inhibition of 1,3-DPTA, different adsorption isotherms including Langmuir, Freundlich, Temkin and Redlich-Peterson model were studied. The adsorption of 1,3-DPTA is described as a complex process of interaction of inhibitor molecules with the steel surface linearized in the coordinates ln(0/(1-0))=f(lnC). The corrosion rate decreased with the addition of 1,3-DPTA due to the formation of a hydrophobic film. This process is proven by measuring the contact angles of water after the samples are immersed in aggressive media with inhibitor for 24 hours. The hydrophobization of the steel surface increases with increase in the inhibitor concentration.

Triazole derivatives (4,5-diphenyl-4H-1,2,4-triazole-3-thiol (4,5-PhTAT) and 3,4-diphenyl-5-(prop-2-yn-1-ylthio)-4H-1,2,4-triazole (3,4-PhPTTA) have been researched as corrosion inhibitors for mild steel in 0.1 N sulfuric acid solution. Electrochemical methods were used to estimate the corrosion rate and the inhibition efficiency: potentiodynamic polarization and impedance spectroscopy. The semi-empirical GFN2-xTB method, taking into account their implicit solvation in water using the ALPB method in the XTB program have been used for Geometry optimization of the structures of individual compounds and protomers in solution. Quantum chemical calculations suppose predominantly protonated structure for 3,4-PHPTTA molecules and neutral form of molecules for 4,5-PhTAT. According to electrochemical measurements the best inhibition efficiency for 4,5-PhTAT achieved at 50 mg∙l-1and 200 mg∙l-1 for 3,4-PhPTTA. 4,5-PhTAT and 3,4-PHPTTA are the mix-type inhibitors in 0.1 N sulfuric acid solution, but rate of cathodic process is decreased more than anodic. Contact angle measurements were carried out by the sessile drop method. Hydrophobization of the steel surface occurs in the blank acid and inhibited solution. The contact angle measurements by two test liquids (water and diethylene glycol) after corrosion with presents 4,5-Pstat and 3,4-PHPTTA show that the protective film formed in inhibited solution.

The paper presents the results of a study of thiadiazole derivatives as corrosion inhibitors of mild steel in a solution of 1 M hydrochloric acid. 2-Amino-5-styryl-1,3,4-thiadiazole and 2-amino-5-heptyl-1,3,4-thiadiazole were studied. The semi-empirical GFN2-xTB Grimme method was used to calculate the protonation of the studied molecules in hydrochloric acid medium. Weight loss tests were carried out on C1018 steel at a temperature of 293 K, the exposure time of the samples was 24 h. The polarization curves in the temperature range of 293-353 K were recorded in the potentiodynamic mode in a three-electrode cell from the cathodic to the anodic potentials at a potential sweep rate of 0.5 mV/s, using a SOLARTRON 1280C electrochemical measuring complex. The case of the greatest inhibitory effect by the studied compounds was not distinguished, since at a concentration equal to or more than 100 mg/L, they all exhibit the same protective effect, taking into account the statistical error. A similar degree of protection of the metal surface by the studied inhibitors is associated with the same order of protonation of molecules in acidic solutions. Using the potentiodynamic polarization method, it was found that the studied compounds are inhibitors of the mixed (2-amino-5-styryl-1,3,4-thiadiazole) and cathodic (2-amino-5-heptyl-1,3,4-thiadiazole) types. The preservation of a high protective effect for inhibitors over the entire temperature range under study is associated with the process of chemical adsorption of inhibitor molecules on the metal surface, this fact is confirmed by the calculation of the activation energy of the corrosion process. The degrees of surface coverage of the steel with triazole molecules were calculated based on the results of electrochemical impedance spectroscopy at the corrosion potential. It was found that the adsorption process obeys the Freundlich equation for an energetically inhomogeneous surface. The results of this work point to the prospects of searching for potential inhibitors of acid corrosion in the series of thiadiazole derivatives.

The microstructure transformation of ternary Ti-Cr-V alloys after introduction of hydrogen has been analyzed for a long time. Assessment of the impact of vanadium concentration and ratio of Ti and V concentrations on composition stability has been carried out. Investigated alloys system corresponds to relation (TiCr1.8)100–xVx. The atomic ratio Ti/Cr is constant. Vanadium content changes with the step 20 at.%. The hydrogen charging has been carried out in a thermostatic three-electrode electrochemical cell using 1M KOH electrolyte (ic = 10–30 mA/cm2) at 293 K for three hours. It was established that the hydrogen introduction leads to sur-face migration of alloy components. Their distribution oscillates as time passed. This is due to the fact that hydrogen interacts differently with titanium and vanadium. The electrolytic hydrogen introduction initiates deformation of the crystal lattice and self-diffusion of alloy atoms. The statistically nonuniform distribution of electrolytic hydrogen increases the intensity of the process. The relaxation of internal stresses leads to fur-ther redistribution of components. The observed changes depend on the vanadium content in the alloys and have a different character inside the grain and near grain boundaries. A significant change has been estab-lished for (TiCr1.8)60V40.

The article presents the results of studies on triazole and thiadiazole derivatives as corrosion inhibitors for mild steel in 5 M hydrochloric acid solution. 2-Amino-1,3,4-thiadiazole with tall oil fragments, namely, 3,4-diphenyl-5-(prop-2-yn-1-ylthio)-4H-1,2,4-triazole, and 2-(3,5diphenyl-4,5-dihydro-1H-pyrazole-1-yl)-5-phenyl-1,3,4-thiadiazole, were studied. The protonation of the studied molecules in hydrochloric acid medium was calculated using semi empirical GFN2-xTB Grimme's method. Weight loss measurements were carried out on C1018 steel at a temperature of 293 K and 24 h exposure time. Polarization curves were recorded in the temperature range of 293-353 K in potentiodynamic mode in a three-electrode cell from cathodic to anodic potentials at a potential sweep rate of 0.5 mV/s using a SOLARTRON 1280 C electrochemical measuring complex. It was found that 2-(3,5-diphenyl-4,5-dihydro-1H- pyrazole-1-yl)-5-phenyl-1,3,4-thiadiazole had the maximal inhibition effect in 5 M HCl solution (similar to 97% at concentrations >50 mg/L). 3,4-Diphenyl-5-(prop-2-yn-1-ylthio)-4H-1,2,4-triazole had the minimum protective properties among the compounds studied, as its inhibition effect reached 80-90% in the concentration range studied. The compounds studied are mixed-type (2amino-1,3,4-thiadiazole with a tall oil fragment and 2-(3,5-diphenyl-4,5-dihydro-1H-pyrazole-1-yl)-5-phenyl-1,3,4-thiadiazole) or cathodic-type inhibitors (3,4-diphenyl-5-(prop-2-yn-1ylthio)-4H-1,2,4-triazole). The results of weight loss and electrochemical measurements agree both qualitatively and quantitatively. 2-(3,5-Diphenyl-4,5-dihydro-1H-pyrazole-1-yl)-5-phenyl-1,3,4-thiadiazole retains its high protective effect at elevated temperatures because its molecule has significantly more conjugated electron clouds. Addition of the inhibitors to a corrosive medium increases the effective activation energy of the corrosion process. This fact indicates physical adsorption of the inhibitor molecules on the electrode surface. The degrees of surface coverage of steel with triazole molecules were estimated from the results of electrochemical impedance spectroscopy at the corrosion potential. The adsorption process was found to obey the Langmuir equation. The results show that it is promising to search for potential acid corrosion inhibitors among a number of triazole and thiadiazole derivatives.

The inhibition effect of series of thiadiazole derivatives against the corrosion of mild steel in 15 % HCl was studied by weight-loss method and electrochemical measurements. The experiments were performed on steel St3 at 293 K, the exposure time of the samples in solution for weight-loss measurements was 24 h. Potentiodynamic polarization curves were obtained in a typical three electrode cell with the help of electrochemical measuring complex SOLARTRON 1280 C. A scan rate was 1 mV⋅s-1 and a measurement point was taken every 0.2 s. 2-aminothiazole, 5-amino-1,3,4-thiadiazole-2-thiol, 2-amino-1,3,4-thiadiazole, 2-amino-5-(furan-2-yl)- 1,3,4-thiadiazole, 1,3,4-thiadiazole-2-ylamide of acetic acid were studied as potential inhibitors. The maximal inhibition efficiency was obtained at concentration 0.10-0.20 g⋅L−1. The best result was demonstrated by 5-amino-1,3,4-thiadiazole-2-thiol (inhibition effect was more than 90 %). The minimal inhibition effect had 1,3,4-thiadiazole-2-ylamide acetic acid. The corrosion inhibition effect calculated from data of the corrosion current density and from the weight-loss measurements were in sufficiently good agreement. The effective activation energy of the corrosion of St3 increased significantly due the presence of the inhibitors (from 3.3 to 94.8 kJ⋅mol-1). The results point to promising of investigating of series of thiadiazole derivatives and inhibitory compositions based on thiadiazole as potential acid corrosion inhibitors.

The article presents the results of studies on triazole derivatives as corrosion inhibitors for mild steel in hydrochloric acid solutions of various concentrations, namely, 1 M and 5 M. 5-Heptyl1,2,4-triazole-3,4-diamine and 4,5-diphenyl-4H-1,2,4-triazole-3-thiol were studied. Grimme ' s semi-empirical GFN2-xTB method was used to calculate the protonation of the investigated molecules in hydrochloric acid media. Weight loss tests were carried out on steel C1018 at a temperature of 293 K with an exposure time of 24 h. The polarization curves in the temperature range of 293-353 K were recorded in the potentiodynamic mode in a three-electrode cell from the cathodic to the anodic potentials at a potential sweep rate of 0.5 mV/s, using a SOLARTRON 1280C electrochemical measuring complex. It was found that 5-heptyl-1,2,4triazole-3,4-diamine at a concentration of 200 mg/L has the greatest inhibition effect in 1 M HCl, whereas 4,5-diphenyl-4H-1,2,4-triazole-3-thiol is most efficient in 5 M HCl at the same concentration. It was determined by the potentiodynamic polarization method that the investigated compounds are cathodic-type inhibitors. The effective activation energy of the corrosion process in the presence of 4,5-diphenyl-4H-1,2,4-triazole-3-thiol decreases, which indicates that chemosorption on the electrode surface occurs. The degrees of surface coverage of the steel with triazole molecules were calculated based on the results of electrochemical impedance spectroscopy at the corrosion potential. It was found that the adsorption process obeys the Freundlich equation for an energetically inhomogeneous surface.

According to the estimates of the World Health Organization, the share of medications based on medicinal plant materials is increasing from year to year. Along with industrial drugs, the population widely uses medicinal plants harvested on their own. However, medicinal plants growing in unfavorable environmental conditions can cause serious harm to health. Thus, it is necessary not only to control raw materials but also to study the areas where harvested medicinal plants grow, which in most cases are located in the immediate vicinity of industrial facilities. The purpose of this work was a comprehensive study of the ecological state of Zakurye Island in the town of Chusovoy and its plant communities. When planning the research work, the study area was zoned in accordance with the distance from the alleged source of pollution. In the process of work, we used standard methods of preparation and drying of medicinal plant materials, sampling of soil and water. Chemical analysis was carried out with the use of generally accepted and approved methods. A conclusion is made about a significant degree of pollution with pollutant metals of the surface and deep layers of the Chusovaya River, as well as of soil and medicinal plants near Zakurye Island. Most likely, environmental pollution is associated with poorly maintained dumps of blast-furnace slag from the Chusovoy Metallurgical Plant, located along the river bank.

The work presents the results of the study of some thiadiazole derivatives as corrosion inhibitors for mild steel in 5-20% H2SO4. Gravimetric tests and electrochemical studies were performed on low-carbon steel St3 at ambient temperature. The exposure time of the samples was 24 h. Polarization curves were obtained by potentiodynamic method (v = 1 mV/s) in a three-electrode cell, using the SOLARTRON 1280 C electrochemical measuring complex. The following thiadiazole derivatives were studied: (E)-N,N-dimethyl-4-{[(5-phenyl-1,3,4-thiadiazol-2-yl)imino]methyl}aniline, (E)-5-{[4-(dimethylamino)benzylidene]amino}-1,3,4-thiadiazol-2-thiol, (E)-4-{[(5-(furan-2-yl)-1,3,4-thiadiazol-2-yl)imino]methyl}-N,N-dimethylaniline, N-(1,3,4-thiadiazol-2-yl)acetamide. It was established that the studied compounds at a concentration of 0.1 – 0.2 g/l show a good protective effect. The best result is given by (E)-5-{[4- (dimethylamino)benzylidene]amino}-1,3,4-thiadiazol-2-thiol with a protective effect Z more than 90%. The introduction of the benzene ring and the furan fragment into the molecules of the compounds under study leads to a decrease in their protective action as compared with the thiol group. With the help of electrochemical studies it was shown that the compounds studied are inhibitors of a mixed (cathodic-anodic) type, but to a greater extent they reduced the rate of the cathodic process. The results of the work indicate the promise of searching for potential acid corrosion inhibitors in a series of thiadiazole derivatives and the development of inhibiting compositions based on them.

The article presents the results of a study of the protective effect on low-carbon steel in solutions of 5% hydrochloric acid of the synthesized potential inhibitors from a group of thiazoles and thiadiazoles. The mechanism of the protective action of the investigated compounds was evaluated by the method of polarization curves, and their influence on the kinetics of partial electrode reactions was studied.

The protective action of imidazoline-based corrosion inhibitors for low-carbon steel tending to absorb hydrogen in acidic media is studied using impedance spectroscopy and breaking tests. It is shown that commercial inhibitors FLEK-IK 201 A and FLEK-IK 201 B reduce corrosion and the hydrogen-absorption rate, having an St3 steel-protection degree above 80%, and lower the strength-loss coefficient of steel-wire samples in acidic H2S-containing media to 1.3-4.3%.

Results of investigation of electrical and kinetic properties of inhibitors "FLEK" are presented. The influence of particles size as well as of their charge on the inhibitive effect on mild steel in a neutral media containing hydrogen sulfide was estimated zeta-potential of steel surface in solutions under study was determined.

In given paper the results of study of influence of inhibitory compositions on the base of imidazoles on corrosion-electrochemical behavior of steel 3 were given for acid solutions containing hydrogen sulfide and free from it for the temperature range of 293-333 K. Studies were carried out with the gravimetric and polarized methods. The activation energy of corrosion process was determined.

The results of investigation of influence of some inhibitive compositions on electrochemical and corrosion behavior of steel St3 in acidic and neutral media by means of weight-loss, polarization and impedance methods are presented. Impedance spectra were described by equivalent circuits taking into consideration the inhibitive films on electrode surface. It has been shown that the investigated compositions are more effective in acidic media as compared with neutral media.

Effect of the pH of the medium on colloidal-chemical characteristics of reagents from the N-(2-hydroxyethyl)alkylamine series and the effect of these reagents on the corrosion behavior of 0.5 KP steel in 1 M HCl were studied. The corrosion inhibition mechanism was found.