Phosphonates and Phosphonic Acids: New Promising Corrosion Inhibitors

In this chapter we present our published research results concerning the use of phosphonates and phosphonic acids synthesized in our laboratory as corrosion inhibitors. Firstly, the corresponding synthetic pathways used to prepare this type of inhibitors have been illustrated. Also, the different experimental methods used to evaluate the inhibition activities of these derivatives have been presented in this chapter such as weight loss measurements, polarization curves, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), atomic force microscopy (AFM), etc. On the other hand, the theoretical approaches such as Density Functional Theory (DFT) and Molecular Dynamic Simulations (MDS) are also implanted in this chapter in order to determine correlations between the experimental efficiencies and some calculated structural and electronic properties

Molecular dynamic simulation and DFT computational studies on the adsorption performances of methylene blue in aqueous solutions by orange peel-modified phosphoric acid

International audienceAdsorptive removal of methylene blue dye (MB) from aqueous medium using orange peels treated with phosphoric acid (OP-H3PO4) was examined. The OP-H3PO4 was characterized using Fourier transform Infra-red spectroscopy, X-ray diffraction, scanning electron microscopy, Energy Dispersive X-ray Spectroscopy, and thermogravimetric analysis. The effect of different process parameters, namely contact time, initial dye concentration, initial solutions pH, and temperature effect were examined. Equilibrium experimental data were fitted by Langmuir, Freundlich, Redlich-Peterson (R-P) and Sips isotherm models. For the two-parameter models, the data fitted well with the Langmuir isotherm model suggesting a monolayer adsorption of the dye onto the homogeneous adsorbent surface. However, regarding the three-parameter models, for the whole temperature range, both the sips and the Redlich-Peterson models showed high correlation factors, indicating that calculated data were close to those found experimentally and suggesting that MB adsorption occurs on both homogeneous and heterogeneous surfaces of OP-H3PO4 The present study revealed that OP-H3PO4 is an effective and efficient adsorbent for the removal of basic dyes from aqueous solution. In addition, quantum chemical calculations realized with density functional theory (DFT) method were successfully considered to correlate the experimental results. Moreover, the molecular dynamics simulations (MDS) were used to simulate the interactions between the MB molecule and the OP-H3PO4 (110) surface, indicating that the MB molecule adsorbs onto the OP-H3PO4 (110) surface in a nearby horizontal position. (C) 2019 Elsevier B.V. All rights reserved

Synergistic corrosion inhibitor of carbon steel by dihydroxy benzyl phosphonic acid -Zn2+ system in O.5 M H2SO4: Experimental and theoretical studies

402-411The synergistic effect of dihydroxy benzyl phosphonic acid (DAP) and zinc sulfate ZnSO4 (Zn2+) system in 0.5 M H2SO4 solution on carbon steel X48 has been evaluated using potentiodynamic polarization measurements, electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), and quantum methods (DFT). The combination of DPA and Zn2+ has been demonstrated to have remarkable inhibitory efficiency (96%). DPA/Zn2+ formulation operate as a mixed inhibitor, inhibiting both the anodic and cathodic reactions to the same amount, according to polarization studies. The diameter of the semicircles increases with the addition of DPA/Zn2+ formulation. Furthermore, the double layer capacitance Cdl decreases and Rt values increase with this combination of DPA and Zn2+, confirming the significant adsorption on the surface steel. The adsorption isotherm of Langmuir is approached by the adsorption on the metal surface. The nature of the protective coating is also determined using surface characterization techniques (FTIR and SEM). The molecular orbital (HOMO and LUMO) energies, energy gap (ΔEgap), dipole moment (μ), global hardness (η), global softness (σ), electrophilicity index (ω), absolute electronegativity (χ) and the fraction of transferred electrons (ΔN) have been determined as supporting evidence

Corrosion Protection of Mild Steel by a New Phosphonated Pyridines Inhibitor System in HCl Solution

International audienceThe adsorption behavior and inhibition mechanism of (1, 4, 7-Tris [hydrogen (6-methylpyridin-2-yl) phosphonate] -1, 4, 7-triazacyclononane) (TPP) on the corrosion of mild steel in 1 M HCl were investigated by weight loss technique, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) methods for different concentrations at 25°C. The results show that the inhibition efficiency values depend on the amount of immersion times and the concentration. A 90% efficiency is found at the highest concentration of the studied compound according to weight loss measurements. The adsorption of the investigated inhibitor on the mild steel surface was well supported using an AFM study. For the assignment of the absorption sites, we performed quantum chemical calculations with (DFT) method. The interaction between the inhibitor and iron surface were performed by molecular dynamic (MD) simulations. In this paper, experimental methods and results used to assess the efficiency of the studied compound are presented

Development of new benzil-hydrazone derivatives as anticholinesterase inhibitors: synthesis, X-ray analysis, DFT study and <i>in vitro</i>/<i>in silico</i> evaluation

Alzheimer’s disease (AD) is a complex neurodegenerative disorder affecting the central nervous system. Current drugs for AD have limited effectiveness and often come with side effects. Consequently, there is a pressing need to develop new, safe, and more effective treatments for Alzheimer’s disease. In this work, two novel benzil-hydrazone compounds, abbreviated 2-ClMHB and 2-ClBHB, were synthesized for the first time by refluxing the benzil with 2-Chloro phenyl hydrazine and they have been tested for their in vitro anti-cholinesterase activities and in silico acetyl and butyryl enzymes inhibition. The resulting products were characterized using UV-Vis and IR spectroscopy, while the single-crystal X-ray diffraction investigation was successful in establishing the structures of these compounds. DFT calculations have been successfully made to correlate the experimental data. According to biological studies, the synthesized hydrazones significantly inhibited both butyrylcholinesterase (2-ClMHB: 20.95 ± 1.29 µM and 2-ClBHB: 31.21 ± 1.50 µM) and acetylcholinesterase (2-ClMHB: 21.80 ± 1.10 µM and 2-ClBHB: 10.38 ± 1.27 µM). Moreover, molecular docking was also employed to locate the molecule with the optimum interaction and stability as well as to explain the experimental findings. The compound’s dynamic nature, binding interaction, and protein-ligand stability were investigated using molecular dynamics (MD) simulations. Analyzing parameters such as RMSD and RMSF indicated that the compound remained stable throughout the 100 ns MD simulation. Finally, the drugs displayed high oral bioavailability, as per projected ADME and pharmacokinetic parameters. Communicated by Ramaswamy H. Sarma</p