The inhibitive impact of both kinds of 5-isothiocyanatomethyl-8-hydroxyquinoline derivatives on the corrosion of carbon steel in acidic electrolyte

Two new 8-hydroxyquinoline derivatives namely 1-((8-hydroxyquinolin-5-yl)methyl)-3-methylthiourea (HQMT) and 5-isothiocyanatomethyl-8-hydroxyquinoline (TCHQ) were synthesized and identified by various spectroscopic methods (IR, NMR and Elemental analysis). The inhibitive action of 5-isothiocyantomethyl-8-hydroxyauinoline derivatives against the corrosion of carbon steel corrosion in 1 M HCl environment was examined using the conventional electrochemical, gravimetric, UV ? visible spectroscopy, SEM observations and theoretical calculation methods. The results finding indicate that the effect of preventing of HQMT is higher compared to TCHQ, and both heterocyclic compounds exhibiting excellent anticorrosive properties of carbon steel in HCl electrolyte reaches approximately 91% at10?3 M of HQMT and 89% achieved by TCHQ. Polarization curves indicate that the both compounds act as mixed type inhibitors. Moreover, the kinetic and thermodynamic parameters for the corrosion reaction were estimated and debated. - 2019 Elsevier B.V.Scopu

An experimental-coupled empirical investigation on the corrosion inhibitory action of 7-alkyl-8-Hydroxyquinolines on C35E steel in HCl electrolyte

International audienceTwo 8-Hydroxyquinoline-based piperazine, 7-((4-(4-chloro phenyl)piperazin-1-yl) methyl) quinolin-8-ol (CPQ) and 7-((4-methyl piperazin-1-yl) methyl)quinolin-8-ol (MPQ) were prepared, identified and investigated as corrosion inhibiting additives of C35E steel in HCl electrolyte using experimental and theoretical tools. All outcomes findings confirm that CPQ and MPQ significantly improved anti-corrosion properties of C35E steel and CPQ performed better than MPQ and their inhibition efficiency depends on the temperature, the amount, and the chemical structure of the inhibitor. The ηmax of CPQ and MPQ reaches as much as 91.5% and 86.3% at 10−3 M, respectively. EIS outcomes revealed that the corrosion of C35E steel is controlled by only one charge transfer mechanism and the adsorbed CPQ and MPQ molecules decreased the steel dissolution by developing a pseudo-capacitive film on the steel surface. Both additives revealed mixed-type inhibitory activity, lowering of cathodic and anodic corrosion reactions rate, as proposed from the polarization investigation. The UV–Visible spectra suggest the existence of strong interaction between iron cations and 7-(4-alkylpiperazinylmethyl)-8-Hydroxyquinolines molecules. The 7-(4-alkylpiperazinylmethyl)-8-Hydroxyquinolines were chemisorbed on the C35E steel surface in accordance with Langmuir adsorption isotherm. Temperature influence studies of CPQ and MPQ adsorption behavior, as well as estimated thermodynamic magnitudes, are consistent with a physisorption process. The computational correlations (DFT, Monte Carlo, and Molecular Dynamic simulations) justify the experimental observations

Performance and computational studies of two soluble pyran derivatives as corrosion inhibitors for mild steel in HCl

The present study is aiming to explore the effect of 4-Hydroxy-6-methyl-3-(3-quinolin-8-yl-acryloyl)-pyran-2-one (HMQP) and 3-[3-(4-Dimethylamino-phenyl)-acryloyl]-4-hydroxy-6-methyl-pyran-2-one (DMPHP) on mild steel (MS) corrosion in acid solution (1 M HCl). The compound was tested at various concentrations (0.001–1 mM) and four temperatures (298, 308, 318, and 328 K) to determine the optimal concentration and temperature range for the best corrosion inhibiting effect. In evaluating the inhibition efficiency, weight loss measurement, potentiodynamic polarization measurement (PDP), electrochemical impedance spectroscopy, SEM/EDS and theoretical methods were used. The inhibition efficiencies increase with increase in concentration and decreases with temperature. The maximum inhibition efficiency was found 90% and 85.4% at 298 K in the presence of 1 mM of DMPHP and HMQP respectively. The experimental adsorption data obeyed the Langmuir isotherm model. The polarization parameters suggest that DMPHP and HMQP are mixed type inhibitors. The results of the EIS study suggest that these compounds inhibit corrosion by adsorption mechanism. A good correlation between theoretical and experimental results was obtained.Scopu

Experimental studies and computational exploration on the 2-amino-5-(2-methoxyphenyl)-1,3,4-thiadiazole as novel corrosion inhibitor for mild steel in acidic environment

International audienceIn the present research, a new 1,3,4-thiadiazole derivative, namely the 2-amino-5-(2-methoxyphenyl)-1,3,4-thiadiazole (5-AMT) was synthesized and investigated as corrosion inhibitor for mild steel (M-steel) in molar hydrochloric acid medium. The experimental studies such as weight loss, potentiodynamic polarization (PDP), Linear polarization resistance (LPR) technique and electrochemical impedance spectroscopy (EIS) were performed in order to evaluate the corrosion protection performance of the tested compound. Based on the experimental outcomes, a protection degree of approximately 98 % was achieved exploiting 5 × 10−4 M of 5-AMT after 1 h of immersion at temperature 303 K. Additionally, PDP study highlighted that the investigated 1,3,4-thiadiazole is of mixed-kind inhibitor. Thermodynamic data from adsorption isotherms and activation energies were determined and discussed. It was shown that the adsorption of 5-AMT molecules fits Langmuir isotherm model. Furthermore, in order to characterize the M-steel surface and to comprehend the adsorption mechanism of 5-AMT, XPS analyses were accomplished. Computational studies by DFT and MD simulation were also conducted to correlate the protection properties and quantum chemical parameters of the investigated inhibitor

Experimental, DFT studies and molecular dynamic simulation on the corrosion inhibition of carbon steel in 1 M HCl by two newly synthesized 8-hydroxyquinoline derivatives

International audienceIn the present work, two new 8-hydroxyquinoline derivatives namely, 5-(((2-hydroxybenzylidene)amino)methyl) 8-hydroxyquinoline [HBMQ] and 5-(((4-chlorobenzylidene)amino)methyl) 8-hydroxyquinoline [CBMQ] were synthesized and investigated as corrosion inhibitors against the dissolution of carbon steel (C38 steel) in 1 M HCl. These compounds were obtained with high yield, and their structures were characterized by nuclear magnetic resonance spectroscopy (NMR) and elemental analysis. Gravimetric, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and surface morphology analyses utilizing scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) were used to quantify inhibitory performance. The adsorption process of inhibitory compounds was then demonstrated using quantum mechanics approaches such as Density Functional Theory (DFT) and Molecular Dynamic Simulation (MD). Based on EIS results, the investigated derivatives effectively inhibit the degradation of C38 steel over the entire concentration range with a maximum efficiency of 91.9% and 88.0% for [CBMQ] and [HBMQ], respectively, at 10−3 M. In addition, the PDP studies revealed that [HBMQ] and [CBMQ] compounds acted according to a mixed-type mechanism. Moreover, the adsorption mechanism follows the Langmuir isotherm model. The quantum theoretical study by DFT and MD simulation confirmed the experimental results

Synthesis and characterization of novel Cu (II) and Zn (II) complexes of 5-{[(2-Hydroxyethyl) sulfanyl] methyl}-8-hydroxyquinoline as effective acid corrosion inhibitor by experimental and computational testings

International audienceTwo new complexes were synthesized, characterized and tested as inhibitors for mild steel corrosion in 1.0 M HCl. The anticorrosive effect has been studied using the potentiodynamic polarization (PDP) and impedance spectroscopy (EIS). The inhibitory efficiency increases with increasing concentration to reach 96.0% for Q-Cu and 94.6% for Q-Zn at 10−3 M. The two inhibitors are mixed type and follows the Langmuir isotherm adsorption. The surface of the mild steel has been examined by SEM/EDS and the corrosive solution by ICP-OES. DFT calculations and molecular dynamic simulation (MD) show a good correlation with the experimental results for both complexes