Furosemide drug as a corrosion inhibitor for carbon steel in 1.0 M hydrochloric acid.

Furosemide (4-chloro-2-furan-2-ylmethylamino-5-sulfamoylbenzoic acid) was examined as an inhibitor for the corrosion of carbon steel (CS) in 1.0 M HCl. The investigation included mass loss (ML) and electrochemical techniques: potentiodynamic polarization (PP), electrochemical impedance spectroscopy (EIS), and electrochemical frequency modulation (EFM). The efficiency of inhibition rises with increasing Furosemide concentration and temperature. This compound follows the Temkin isotherm with good fit. The presence of varying quantities influences both anodic metal dissolution and cathodic hydrogen evolution. Scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR) were used to detect the effect of the compound on the CS surface. The molecular inhibitory effect of Furosemide was demonstrated using quantum chemical calculations, and the molecular simulation results demonstrated the adsorption on the carbon steel surface.

Expression of concern: Effectiveness of some novel heterocyclic compounds as corrosion inhibitors for carbon steel in 1 M HCl using practical and theoretical methods.

Expression of concern for 'Effectiveness of some novel heterocyclic compounds as corrosion inhibitors for carbon steel in 1 M HCl using practical and theoretical methods' by Abd El-Aziz S. Fouda et al., RSC Adv., 2021, 11, 19294-19309, https://doi.org/10.1039/D1RA03083C.

Expression of concern: Experimental and surface morphological studies of corrosion inhibition on carbon steel in HCl solution using some new hydrazide derivatives.

Expression of concern for 'Experimental and surface morphological studies of corrosion inhibition on carbon steel in HCl solution using some new hydrazide derivatives' by Abd El-Aziz S. Fouda et al., RSC Adv., 2021, 11, 13497-13512, https://doi.org/10.1039/d1ra01405f.

The Role of Some Cationic Surfactants Based on Thiazine as Corrosion Inhibitors in Petroleum Applications: Experimental and Theoretical Approach.

Two cationic surfactants based on thiazine, dodecyl thiazin bromide (DTB) and hexyl thiazin bromide (HTB), were synthesized, characterized, and investigated as corrosion inhibitors for API X-65 type steel in oil wells' formation water under an H2S environment. Various spectroscopic techniques such as FTIR and 1H NMR were used to confirm the DTB and HTB chemical structures. The corrosion inhibition efficiency of the selected compounds was investigated using both potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The innovation of the current study is the existence of a long chain in the inhibitor molecule, which leads to an increase in the performance of the surfactant as a corrosion inhibitor, due to the increase in the surface area per molecule. It was found that these surfactants act as mixed-type inhibitors, leading to suppression of both the cathodic and the anodic processes by its adsorption on the electrode surface according to the Langmuir adsorption isotherm. Carbon steel's inhibitory mechanism was studied using an analogous circuit. The scanning electron microscope technique was used as a suitable analysis tool to show the nature of the layer designed on carbon steel. Quantum chemical calculations and Monte Carlo simulation techniques were used to support the obtained experimental results. Finally, a suitable mechanism for the inhibition process was proposed and discussed.

Experimental and surface morphological studies of corrosion inhibition on carbon steel in HCl solution using some new hydrazide derivatives.

The corrosion inhibition of C-steel in 1 M HCl was assessed using three newly synthesized hydrazide derivatives (H1, H2 and H3) using weight loss (WL), potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) techniques. Also, the adsorption of these compounds was confirmed using several techniques such as atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). High inhibition efficiencies were obtained resulting from the constitution of the protective layer on the C-steel surface, which increased with increasing concentration and temperature and reached 91.7 to 96.5% as obtained from the chemical method at 20 × 10-6 M at 45 °C. The polarization curves refer to these derivatives belonging to mixed-type inhibitors. The adsorption of (H1, H2 and H3)on the CS surface follows the Temkin adsorption isotherm. Inhibition influence of hydrazide derivatives at the molecular level was greatly proven using quantum chemical calculations and Monte Carlo simulation methods. Furthermore, the molecular simulation results evidenced the adsorption of these derivatives on the carbon steel surface.

Effectiveness of some novel heterocyclic compounds as corrosion inhibitors for carbon steel in 1 M HCl using practical and theoretical methods.

Corrosion of carbon steel is a major problem that destroys assists of industries and world steel installations; the importance of this work is to introduce new heterocyclic compounds as effective and low-cost corrosion inhibitors. Three compounds of carbohydrazide derivatives, namely: 5-amino-N'-((2-methoxynaphthalen-1-yl)methylene)isoxazole-4-carbohydrazide (H4), 2,4-diamino-N'-((2-methoxy-naphthalene-1-yl)methylene) pyrimidine-5-carbohydrazide (H5) and N'-((2-methoxynaphthalen-1-yl)methylene)-7,7-dimethyl-2,5-dioxo-4a,5,6,7,8,8a-hexahydro-2H-chromene-3-carbohydrazide (H6) were used to examine the efficacy of corrosion of carbon steel in 1 M hydrochloric acid solution. This corrosion efficacy was detected by utilizing various methods including electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), weight loss measurements (WL), surface morphology analyses by atomic force microscopy (AFM), quantum chemical computations based on density functional theory (DFT) and molecular dynamics (MD) simulation. The results indicated that these compounds act as mixed type inhibitors i.e. reduce the corrosion rate of carbon steel due to the formation of a stable protective film on the metal surface and reduce the cathodic hydrogen evolution reaction. As confirmed from impedance, carbohydrazide derivatives molecules are adsorbed physically on metal surface with higher corrosion efficacy reached to (81.5-95.2%) at 20 × 10-6 M concentration at room temperature. Temkin isotherm model is the most acceptable one to describe the carbohydrazide derivative molecules adsorption on the surface of carbon steel. Protection mechanism was supported by quantum chemical analyses and Monte Carlo modeling techniques. The theoretical calculations support the experimental results obtained. This proves the use of carbohydrazide derivatives as a very effective inhibitors against the corrosion of carbon steel in acidic media.

Micellization and Solvation Properties of Newly Synthesized Imidazolium- and Aminium-Based Surfactants.

This work aimed to study the solvation properties of newly synthesized cationic surfactants: 1-hexyl-1-methyl-1H-imidazol-1-ium bromide (R6Im), 1-dodecyl-1-methyl-1H-imidazol-1-ium bromide (R12Im), N,N,N-tributylhexan-1-aminium bromide (R6N4), and N,N,N-tributyldodecan-1-aminium bromide (R12N4) in water and ethanol-water solvents with a 0.237 mole fraction of ethanol at 298.15 K using conductivity, refractive index, surface tension, and density measurements. Critical micelle concentration (CMC) for the synthesized surfactants was determined and discussed. Thermodynamic parameters including association constant, molal volume, and polarizability were calculated and discussed. Some surface properties of surfactants including excess surface concentration and minimum area per molecule were also calculated and discussed. A good agreement was found between the CMC values obtained from different techniques, such as conductivity, refractive index, and surface tension. Imidazolium surfactants had been proved to decrease the CMC and increase the association constant with the increase of ethanol mole fraction, while tributylamine had been proved to increase the CMC and decrease the association constant with the increase of ethanol mole fraction. Also, imidazolium surfactants had been proved to have higher CMC than tributylamine, which may be related to higher solvation of imidazolium surfactants than that of tributylamine. Both surfactants (R12Im) and (R12N4) were proved to have lesser CMC.