Experimental and theoretical evaluation of a newly synthesized quinoline derivative as corrosion inhibitor for iron in 1.0 M hydrochloric acid solution

Detection of paracetamol by a montmorillonite-modified carbon paste sensor: A study combining MC simulation, DFT computation and electrochemical investigations

This study aims to develop a suitable electrochemical electrode through the incorporation of potassium montmorillonite (MMTK10)clay into the carbon matrix for the direct and sensitive determination of paracetamol (PAR) in pharmaceutical formulations. Electrochemical characterization of the electrodes involves the use of techniques such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). The results reveal that the voltammetric response of PAR is linear over a wide concentration range (1.0-15 μM), with a low detection limit of 0.46 μM. Analytically, PAR recovery results were around 94%, indicating that the developed electrode is highly suitable for PAR detection in pharmaceutical formulation. Additionally, density functional theory (DFT) is employed to investigate the reactivity of PAR and explain the interaction process of PAR on the electrode surface at different pH values. A Monte Carlo simulations model is developed to provide a deeper understanding of the adsorption mechanism, particularly to comprehend molecular interactions and preferential orientations of PAR with MMT fractions at the electrode surface. Reduced Density Gradient is calculated and discussed using techniques such as Multiwfn and Visualization of Molecular Dynamics. The developed CPE-MMTK10 sensor provided a simple preparation method, rapid response, high sensitivity, reproducibility, strong selectivity, and extended stability. Moreover, there is a good correlation between most parameters calculated by DFT and experimental results, thereby reinforcing the validity of the theoretical approach in this study.

Cysteine as an Eco-Friendly Anticorrosion Inhibitor for Mild Steel in Various Acidic Solutions: Electrochemical, Adsorption, Surface Analysis, and Quantum Chemical Calculations

The corrosion of iron in acidic environments has a negative impact on global industry. Herewith, the inhibitory effect of cysteine (Cys.) on mild steel (MSL) corrosion in different acidic solutions (1 M HCl, 1 M H2SO4, and 1 M H3PO4) was investigated through weight loss, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy, scanning electron microscopy (SEM), and theoretical calculations. The measurement results indicated that the adsorption of Cys. molecules on the metal surface caused corrosion inhibition. As a result, a protective layer or insoluble compound, or both, is obtained, blocking the active sites, preventing corrosion. The effectiveness (IE %) of the Cys. was enhanced by increasing concentration and lowering temperature. The maximum IE % of inhibition at 1 × 10-2 M of Cys. obtained are 97.3, 89.7, and 84.4% in HCl, H3PO4, and H2SO4 solutions, respectively. At the same inhibitor concentration, the double-layer capacity decreased, and the charge-transfer resistance increased from 17.17 to 188.5, 3.564 to 31.91, and 1.325 to 8.715 Ω cm2 in HCl, H3PO4, and H2SO4 solutions, respectively. Adsorption and PDP studies confirmed that it obeys the Langmuir adsorption isotherm and acts as a mixed-type inhibitor of physicochemical nature. The corresponding thermodynamic and kinetic parameters were also calculated and discussed. Moreover, the inhibitory effect on the surface was inspected by SEM. The findings demonstrated that the order of IE % using Cys as anticorrosion agent for MSL is HCl > H3PO4 > H2SO4 solutions.

Frontiers and advances in N-heterocycle compounds as corrosion inhibitors in acid medium: Recent advances

The acid solution is widely used in chemical cleaning, oil well acidifying, and other fields, which also brings the problem of metal corrosion that cannot be underestimated. However, adding an inhibitor is one of the most convenient and effective ways to slow down metal corrosion. N-heterocyclic compounds with high stability and durability, in line with the strategy of sustainable development, have been widely studied in an acidic environment. Imidazole, pyridine, and quinoline compounds, as the most commonly used corrosion inhibitors, can form a compact protective film via π electron cloud shifting towards the N atoms to generate coordination function. In particular, flexible modifiability makes N-heterocyclic compounds adapt to different corrosion environments readily, conducive to the formation of chemical bonds between compounds with metal surfaces to be better adsorption, so as to avoid the blemish of traditional inhibitors (such as inorganic salt and organic amines inhibitors) due to excessive usage, surface roughness of metal or environmental factor (for instance, temperature, pH and metallic) causing loose bonding between film and metal surface. More importantly, the efficient corrosion inhibition and toxicity of N-heterocyclic compounds have close to do with their own functional groups. Combined with the latest research achievement, the effects of different substituents on the corrosion inhibition and corrosion inhibition mechanisms were systematically reviewed in the acid-corrosive solution of imidazole, pyridine, and quinoline and their derivatives in this review article, respectively. In addition, the application and function of density functional theory in predicting the corrosion inhibition effect of corrosion inhibitors are also discussed. The future development trend was prospected according to the summarized research results.

Synthesis, Characterization, Thermodynamic Analysis and Quantum Chemical Approach of Branched N, N′-bis(p-hydroxybenzoyl)-Based Propanediamine and Triethylenetetramine for Carbon Steel Corrosion Inhibition in Hydrochloric Acid Medium

The influence of branched N, N′-bis(p-hydroxybenzoyl) containing propylenediamine (PDA) and triethylenetetramine (TETA) composites for corrosion inhibition of carbon steel in acidic solution (1 M HCl) was investigated using several quantum chemical, electrochemical impedance spectroscopy and potentiodynamic polarization as electrochemical techniques. The investigated molecules were posteriorly characterized by proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared spectroscopy (FTIR) while the surfaces of carbon steel test coupons were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The obtained results revealed that the two amino compounds, N, N′-bis(p-hydroxybenzoyl) propanediamine (N, N′-HBPDA) and N, N′-bis(p-hydroxybenzoyl) triethylenetetramine (N, N′-HBTETA), have significant efficiency toward steel corrosion attack and its inhibition performance was significantly boosted by increasing concentration of di- and tetramine containing inhibitors. The two inhibitors achieved a maximum corrosion inhibition efficiency of 99.1% as indicated from polarization measurements. The isotherm feature of Langmuir adsorption appeared to be proper factor for associating the experimental gains with an applicable mechanism of inhibition process. The free energy ∆Gads was calculated to be − 27.5, 29.1 kJ/mol based on the adsorption isotherm model, indicating physical adsorption on the carbon steel surface. Further, images of the morphological analysis exhibited various features of attack owing to the aggressive medium and the employed concentration of the inhibitor. These synthesized amines supplied many favorable scores in the fabrication of functional mixed-type inhibitors. The computational studies reveal that N, N′-HBPDA and N, N′-HBTETA molecules could absorb via several lone pairs and π clouds, confirming their ability to be good corrosion inhibitors.

New QSPR model for prediction of corrosion inhibition using conceptual density functional theory

The relationship between structure and corrosion inhibition of a series of twenty-eight quinoline and pyridine derivatives has been established through the investigation of quantum descriptors calculated with PBE/6-311 +  + G** method. A quantitative structure-property relationship (QSPR) model was obtained by examining these descriptors using a genetic algorithm approximation method based on a multiple linear regression analysis. The results indicate that the efficiency of corrosion inhibitors is strongly associated with hardness (η), minimal electrostatic potential (ESP_min), and volume (V) descriptors. Furthermore, the validity of the proposed model is corroborated by an adsorption study on an iron surface Fe(110).