Iron and steel materials are extensively used in many industries due to low cost and availability. We suggested alpha-linolenic acid (ALA) to slow down the corrosion of XC48 steel in H2SO4 solution. We chose ALA because it comprises a carboxylic group and an aliphatic chain containing 17 carbons with three double bonds. This work was conducted by electrochemical measurements (stationary current-voltage curves) and gravimetric measurements (weight loss method) at various temperatures (298-348 K). The findings show that this agent acts as a strong inhibitor in a large concentration range. The inhibition effect is 92% at a concentration of 5 center dot 10-3 M. Adsorption and activation parameters were also evaluated. Conceptual Density Functional Theory calculations and the results of the Molecular Dynamic Simulation Approach are in good agreement with the experimental observations.

Green chemistry becomes in the last decade a tool for the sustainable developments in various sectors, the reorientation of the use of environmentally ecofriendly alternatives is gaining attention in the field of corrosion protection. The use of natural plant extracts as corrosion inhibitors is counted by thousands of papers and industrial patents. Plant extracts contain complex phytochemicals that interact strongly with metallic surface through their electron rich sites. In this context, this review investigates the corrosion inhibitive action of henna (Lawsonia Inermis) leaves extracts on mild steel in various acid media by weight loss measurements (WL) as chemical measurements and by potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) as electrochemical ones. The study indicates that as the acid concentration increases, the corrosion rate increases. The corrosion inhibition efficiency increases with an increase in the concentration of the extract. The results obtained reveal that the henna leaves extract acts as an efficient inhibitor. The adsorption of the henna leaves extracts obeys the Langmuir adsorption isotherm. The calculated thermodynamic parameters indicate that the adsorption is a spontaneous, exothermic process accompanied by an increase in entropy. Cathodic and anodic polarization curves show that the henna leaves extract is a mixed-type inhibitor. The inhibitory action is generally explained as an intermolecular synergistic effect of different components of the natural extract.

The corrosion inhibition of mild steel in 1 M hydrochloric acid solution by some bipyrazole derivatives N,N'-dimethyl-N,N'-bis(1H-pyrazol-1-ylmethyl)ethane-1,2-diamine (3a), 1-{[{2-[[(3carboxy-5-methyl-1H-pyrazol-1-yl)methyl](methyl)amino]ethyl}(methyl)amino]methyl}-5-methyl-1H- pyrazole-3-carboxylic acid (3b) and 1-{[{2-[{[3-(methoxycarbonyl)-1H-pyrazol-1-yl]methyl}(methyl)a mino]ethyl}(methyl)amino]methyl}-1H-pyrazole-3-carboxylic acid (3c) has been studied in relation to the concentration of the inhibitors as well as the temperature using chemical (weight loss) and electrochemical (ac impedance and dc polarisation) techniques. All the methods employed are in reasonable agreement. The protection efficiency increases with increasing inhibitors concentration and with increasing temperature. The thermodynamic functions of dissolution and adsorption processes were calculated from weight loss measurement and the interpretation of the results are given. Adsorption of inhibitor on the carbon steel surface is found to obey the Langmuir adsorption isotherm. (C) 2020 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of The Third International Conference on Materials and Environmental Science.

Some bipyrazole derivatives {N,N'-bis-[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]-N,N'-dimethylethane-1,2-diamine (M1) and N,N '-bis[(3ethylcarboxylate-5-methyl-1H-pyrazol-1-yl)methyl]-N,N'-dimethyl ethane-1,2-diamine (M2)} have been studied as corrosion reduction for mild steel in 1 M HCl acid.Influence of inhibitors concentration as well as the temperature was investigated using chemical (weight loss) and electrochemical techniques.All the techniques employed are in good agreement.The protection efficiency rise with increasing inhibitors concentration and with rise temperature.Weight loss data used for determining the thermodynamic parameters of dissolution and adsorption processes and the interpretation of the results are given.Adsorption of inhibitor on the carbon steel surface is found to obey the Langmuir adsorption isotherm.Quantum chemical parameters calculation such as the energies of highest occupied molecular orbital (EHOMO) and the lowest unoccupied molecular orbital (ELUMO), energy gap (∆Eg) between EHOMO and ELUMO, dipole moment (µ), ionization potential (I), electron affinity (A), global hardness (η), global electrophilicity index (χ), softness (S), back donation energy (∆Eback donation) total energy and effective atomic charges were calculated.In addition, Monte Carlo (molecular dynamics) simulation was used to simulate the adsorption of bipyrazole derivatives on the iron surface in 1 M HCl acid.

Reinforcing steel corrosion behavior in the presence of 2-(thiophen-3-yl) ethanamine (3ET) and 2-(thiophen-2-yl) ethanamine (2ET) was studied using Electrochemical impedance spectroscopy. Both pit growth and corrosion of steel were inhibited with either compound present in the corroding medium. (EIS) measurements permitted the investigation of concentration, immersion time and the applied potential effects. Inhibition efficiencies up to ca. 86.22% and ca. 86.51% were achieved in the presence of 5x10-3M (2ET) and (3ET), respectively.

The corrosion inhibition of mild steel in 1M hydrochloric acid solutions by some new N,N'-bipyrazole piperazine derivatives namely piperazine (P1), N,N'-bis[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]piperazine (P2) and N,N'-bis[(3-ethylcarboxylate-5-methyl-1H-pyrazol-1-yl)methyl]piperazine (P3) was studied using chemical (weight loss) and electrochemical (potentiodynamic and electrochemical impedance spectroscopy, EIS) measurements. These measurements show that the inhibition efficiency obtained by these compounds increased by increasing their concentration to attain 91% for P2 and 92% for P3 since 10(-3)M. The inhibition efficiency follow the order P3>P2>P1. The inhibition efficiency of (P1 and P2) increases with the rise in temperature in the range 298-353K Polarization studies show that these compounds act as mixed type inhibitors in 1M HCl solutions. These inhibitors function through adsorption following Langmuir isotherm.

The focus of this study is to synthesize new calixarene derivatives namely calix[8]arenes (3a) (P1) and (2a) (P2), and to test its performance as corrosion inhibitor of steel in molar HCl at 308K. Polarization and weight loss measurements were used. The inhibition efficiency was found to increase with calixarene derivatives content to attain 95.14% for (P1) and 80% for (P2) at 10-3M. Polarization curves revealed that calixarene derivatives affect both cathodic and anodic domains by decreasing current densities and then it may be classified was mixed type inhibitors. The calixarene derivatives tested is adsorbed on the surface according to the Langmuir adsorption isotherm. Free enthalpy of adsorption reveals that calixarene derivatives act from physisorption onto the steel surface.

Inhibition of the corrosion of mild steel in molar hydrochloric acid by two calixarenes, including the effect of inhibitor concentration and temperature, has been investigated by use of weight loss and electrochemical measurements (polarisation and impedance). The results obtained showed that the rate of corrosion decreased substantially in the presence of the compounds, with maximum inhibition of 98.2 % by one of the compounds at a concentration of 10−3 M. The effect of temperature on corrosion behaviour in the presence of different concentrations of the two new calixarenes was studied in the range 45–75 °C. The efficiency of inhibition by the compounds increased with increasing inhibitor concentration and was independent of temperature. Polarisation curves revealed that the calixarenes are mixed-type inhibitors. Adsorption of the inhibitors by the carbon steel surface obeyed the Langmuir adsorption isotherm. Some thermodynamic data for the dissolution and adsorption processes were also determined.

The inhibition of the corrosion of mild steel 1 M HCl solution by some diamine compounds has been investigated in relation to the concentration of the inhibitor as well as the temperature using weight loss and electrochemical measurements. The effect of the temperature on the corrosion behavior with the addition of different concentrations of new diamine compounds (3-[2-(2-cyano-ethylamino)-methylamino]-propionitrile (P1); 3-[2-(2-cyano-ethylamino)-ethylamino]-propionitrile (P2), and 3-[6-(2-cyano-ethylamino)-hexylamino]-propionitrile (P3), respectively, was studied in the temperature range 40–80 °C. Polarization curves reveal that (P1, P2, and P3) are mixed type inhibitors. The inhibition efficiency of organic compounds is temperature independent, but increases with the inhibitor concentration. Adsorption of inhibitor on the carbon steel surface is found to obey the Langmuir adsorption isotherm. Some thermodynamic functions of dissolution and adsorption processes were also determined. On the other hand, and in order to determine the relationship between the molecular structure of these compounds and inhibition efficiency, quantum chemical parameters were calculated. The theoretically obtained results were found to be consistent with the experimental data.

The essential oil from aerial parts of Mentha spicata L. an aromatic member of the Lamiaceae family, collected from "Tazouka" (Errachidia-Morocco), was obtained by hydrodistillation using Clevenger apparatus and analyzed by GC and GC/MS. The constituents were identified by their Mass spectra and Retention indices. Forty one compounds consisting 91.90% of the total components were identified from the oil obtained. Among those, Carvone (29.00%) and Trans carveol (14.00%) were the major oil components. The inhibitory effect of this oil was estimated on the corrosion of steel in 1M hydrochloric acid using electrochemical polarisation and weight loss measurements. The corrosion rate of steel is decreased in the presence of natural oil. The inhibition efficiency was found to increase with oil content to attain 97% at 2.00 g/l. Polarisation curves revealed that this natural oil act as mixed type inhibitor. The temperature effect on the corrosion behaviour of steel in 1M HCl without and with the inhibitor at 2.00 g/l was studied in the temperature range from 303 and 333 K, the associated activation energy have been determined. The adsorption of oil on the steel surface was found to obey Langmuir's adsorption isotherm. EIS measurements show that the increase of the transfer resistance with the inhibitor concentration.

2-Allyl-p-mentha-6,8-dien-2-ols P1−P3 synthesized from carvone P are tested as corrosion inhibitors of steel in 1M HCl using weight loss measurements, potentiodynamic polarisation and impedance spectroscopy (EIS) methods. The addition of 2-allyl-p-mentha-6,8-dien-2-ols reduced the corrosion rate. Potentiodynamic polarisation studies clearly reveal that the presence of inhibitors does not change the mechanism of hydrogen evolution and that they act essentially as cathodic inhibitors. 2-Allyl-p-mentha-6,8-dien-2-ols tested adsorb on the steel surface according to Langmuir isotherm. From the adsorption isotherm some thermodynamic data for the adsorption process are calculated and discussed. EIS measurements show the increase of the charge-transfer resistance with the inhibitor concentration. The highest inhibition efficiency (92%) is obtained for P1 at 3g/L. The corrosion rate decreases with the rise of temperature. The corresponding activation energies are determined.

Rosmarinus of ficinalis essential oil obtained by hydrodistillation was tested as corrosion inhibitor of steel in 0.5 M H2SO4 using weight loss measurements, and electrochemical polarisation methods. Results obtained indicate that the corrosion rate is reduced and R. of ficinalis oil adsorbs on the metal surface and then inhibits corrosion process. Its inhibition efficiency increases with oil increasing content to reach 61% at 1 g/L. Polarisation curves indicate that RO acts as a cathodic inhibitor. The inhibition efficiency of naturally oil remains slightly constant with the rise of temperature. Chemical analysis of R. of ficinalis essential oil was carried out using capillary GC and GC/MS. The oil composition was characterized by high amount of oxygenated monoterpene (77%) with 1,8-cineol (52.1%) as main component. Discussion of adsorption was investigated on the basis of essential oil composition. Finally, the isotherm adsorption of essential oil on the steel has been also reported.

Essential oil from Artemisia herba alba (Art) was hydrodistilled and tested as corrosion inhibitor of steel in 0.5M H2SO4 using weight loss measurements and electrochemical polarization methods. Results gathered show that this natural oil reduced the corrosion rate by the cathodic action. Its inhibition efficiency attains the maximum (74%) at 1 g/L. The inhibition efficiency of Arm oil increases with the rise of temperature. The adsorption isotherm of natural product on the steel has been determined. A. herba alba essential oil was obtained by hydrodistillation and its chemical composition oil was investigated by capillary GC and GC/MS. The major components were chrysanthenone (30.6%) and camphor (24.4%).

The focus of this study is to synthesize a new calixarene derivative namely calix[6]arene (C21) and to test its performance as corrosion inhibitor of C38 steel in molar HCl at 308 K. Polarization and weight loss measurements were used. Weight loss tests show that C21 retards until to stop corrosion phenomenon at 5 × 10-5M . C21 is an excellent inhibitor and its inhibition efficiency increases with its concentration to reach 100% since 5 × 10-5M . Polarization curves revealed that C21 affects both cathodic and anodic domains by decreasing current densities and then it may be classified as a mixed type inhibitor. The calixarene tested is adsorbed on the surface according to the Langmuir adsorption isotherm. Free enthalpy of adsorption reveals that C21 acts from chemisorption onto the steel surface.

Calixarenes CA1–CA4 containing one to four 4-imidazolylethylamidocarbonyl groups were synthesized and tested as inhibitors for the corrosion of mild steel in 1 M HCl at 308 K. The study was made using Tafel polarisation and weight-loss methods. In contrast to CA1, calixarenes CA2–CA4 were good inhibitors, reaching inhibition efficiencies (E%) of 94 to 100% at 10−4 M. The values of the inhibition efficiency calculated by the two techniques were in acceptable agreement. E% increased with the number of 4-imidazolylethylamidocarbonyl groups attached to the calixarene. Polarisation curves showed that CA2–CA4 act as mixed-type inhibitors. Their adsorption on the steel surface followed a Langmuir isotherm. Thermodynamic parameters of adsorption were also deduced.

The inhibitive action of pulegone and pulegone oxide toward acid corrosion of steel in molar hydrochloric acid was studied by weight loss measurements, potentiodynamic polarization, and impedance spectroscopy (EIS) methods. The pulegone is extracted starting from oil of Pennyroyal Mint (Mentha pulegium). The natural compound was found to delay the corrosion rate. The pulegone oxide is prepared by oxidation of pulegone. The inhibition efficiency was found to increase with the inhibitor content to attain 81 and 75% at 5 g dm−3 for pulegone and pulegone oxide. The increase in temperature leads to an increase in the inhibition efficiency of the natural compared.

This paper describes the use of the electrochemical impedance spectroscopy technique (EIS) in order to study the corrosion inhibition process of steel in 0.5M H2SO4 solution at the open circuit potential (OCP). Diethyl pyrazine-2,3-dicarboxylate (Prz) as a non-ionic surfactant (NS) inhibitor has been examined. The Nyquist diagrams consisted of a capacitive semicircle at high frequencies followed by a well-defined inductive loop at low frequency values. The impedance measurements were interpreted according to suitable equivalent circuits. The results obtained showed that the Prz is a good inhibitor. The inhibition efficiency increases with an increase in the surfactant concentration to attain 80% at the 5×10−3M. Prz is adsorbed on the steel surface according to a Langmuir isotherm adsorption model.

The effect of natural occurring extract of artemisia on the corrosion of steel in 0.5 M H2SO4 in the temperature range 298 - 353 K is studied by weight loss method, electrochemical polarisation and linear polarisation R-p measurements. Results obtained reveal that extract reduces the corrosion rate. The inhibition efficiency increases with the increase of artemisia content at 10 g/L to reach 95% and 99% at 298 and 353 K, respectively. Results obtained by gravimetric and electrochemical polarisation are in good agreement. Polarisation studies clearly reveal that the presence of the natural artemisia does not change the mechanism of the hydrogen evolution reaction and acts as a mixed type inhibitor. The inhibition efficiency increases with temperature. The adsorption of artemisia on the steel follows Langmuir adsorption isotherm.

The corrosion rates in the presence of 2,5-bis(4-methoxyphenyl)-1,3,4-oxadiazole (4-MOX) as a steel corrosion inhibitor in 0.5M sulfuric acid, were measured by the weight loss method, in the range of temperatures from 303 to 343K. Results obtained revealed that 4-MOX performed excellently as a corrosion inhibitor for mild steel in sulfuric acid media and its efficiency attains more than 96.19% at 8×10−4M at 333K. The inhibition was assumed to occur via adsorption of the oxadiazole molecules on the metal surface. The Langmuir adsorption isotherm was tested for their fit to the experimental data. The apparent activation energies, enthalpies and entropies of the dissolution process and the free energies and enthalpies for the adsorption process were determined and discussed. The fundamental thermodynamic functions were used to glean important information about 4-MOX inhibitory behaviour.

The influence of 5-(2-chlorobenzyl)-6-methylpyridazine-3(2H)-thione (P1) and 5-(4-chlorobenzyl)-6-methylpyridazine-3(2H)-thione (P2) on the corrosion of steel in 0.5M H2SO4 solution has been studied using weight loss measurements at various temperature. The inhibiting action is more pronounced with P1 than P2. The inhibition efficiency increases with P1 concentration to attain the maximum value of 100% at 5×10−4 M. P1 adsorbs on the surface of steel according to the Langmuir isotherm model. The thermodynamic data of activation and adsorption are determined.