Electrochemical Investigation of C-Steel Corrosion Inhibition, In Silico, and Sulfate-Reducing Bacteria Investigations Using Pyrazole Derivatives.

The inhibitory impact of the two synthesized pyrazole derivatives (3 and 4) toward metallic and microbial corrosion was investigated. Using open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy, it was possible to determine their ability to prevent the corrosion of C-steel in 1 M HCl, which was significantly enhanced with increasing concentration (ex. 93%). They act as mixed-type inhibitors, according to polarization curves. The compounds under investigation were adsorbed on a C-steel surface in 1 M HCl following the Langmuir isotherm model. The double-layer capacitance was decreased, and the charge transfer resistance (Rct) was raised due to the examined inhibitors' adsorption. Investigating changes in the surface morphology and confirming the corrosion inhibition mechanism are done using scanning electron microscopy. Density functional theory calculations and Monte Carlo simulations were also conducted to show the adsorption affinity of the understudied compounds over the steel substrate in neutral and protonated forms. Furthermore, the antimicrobial performance of the two synthesized pyrazoles against sulfate-reducing bacteria was evaluated, and the recorded inhibition efficiency was 100%. The current research shows important developments in producing highly effective anticorrosion and antimicrobial pyrazole derivatives.

Electrochemical, surface analysis, computational and anticorrosive studies of novel di-imine Schiff base on X65 steel surface.

The inhibitory effect of di-imine-SB namely ((N1Z, N4E)-N1, N4-bis (4 (dimethylamino) benzylidene) butane 1,4-diamine) on X65-steel in 1 M HCl has been investigated experimentally and theoretically. The electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and weight loss outcomes display the anticorrosion properties of "di-imine- SB". The inhibitory efficiency exceeds 90% at the optimal concentration of 1 × 10-3 M "di-imine- SB". The metal surface was examined further using scanning electron microscope (SEM) and energy dispersive X-ray (EDX). The effectiveness of the di-imine-SB is returned into its adsorption on X65-steel surface and found in agreement with Langmuir adsorption isotherm. According to the standard Gibbs free energy of adsorption [Formula: see text], di-imine-SB adsorption tends to be chemical rather than physical, it increases the activation energy ([Formula: see text]) of metal dissolution reaction and makes it hard to occur. The PDP data suggested anodic and cathodic type of the di-imine-SB inhibitor. Meanwhile, increasing the resistance of X65-steel to 301 Ω cm2 after adding 1 mM of di-imine-SB confirms its protective effect. Whereas, the positive value of the fraction of electron transference (ΔN, 0.746), confirms the affinity of di-imine-SB to share electrons to the partially filed 3d-orbital of Fe forming strong protective film over X65-steel surface. Aided by Monte Carlo (MC) simulation, the calculated adsorption energy (Eads) suggests excessive adsorption affinity of di-imine-SB on metal surface over the corrosive chlorides and hydronium ions. A good correlation between the theoretical hypothesis and the experimental inhibition efficiency has been achieved. The comparative study showed the superior of the di-imine-SB as potential corrosion inhibitor compared with those reported before. Finally, global reactivity descriptors; electron affinity (A), ionization potential (I), electronegativity (χ), dipole moment (µ), global hardness ([Formula: see text]), electrophilicity index and, Fukui indices were also calculated and found well correlated to the reactivity of di-imine-SB.

Corrosion Inhibition of Carbon Steel in Hydrochloric Acid Solution Using Ethoxylated Nonionic Surfactants Based on Schiff Base: Electrochemical and Computational Investigations.

Two ethoxylated nonionic surfactants (L400 and L600) based on Schiff base are prepared from polyoxyethylene, glyoxalic acid, and phenylenediamine. They are evaluated electrochemically as carbon steel corrosion inhibitors in 1 M HCl by electrochemical impedance spectroscopy (EIS) and Tafel techniques and complemented with microscopic analysis methods. The obtained Tafel data indicate the mixed-type behavior of the inhibitor used. The inhibition efficiency touches the peak at 1 × 10-4 M, exhibiting 92 and 94% for L400 and L600, respectively. The presence of the tested inhibitors decreases corrosion current density (i corr) and double-layer capacitance (C dl) due to the formation of a protective adsorption layer in place of the already adsorbed water and aggressive Cl- ions. Both L400 and L600 adsorption modes follow Langmuir adsorption isotherm. The density functional theory (DFT) calculated indices (ΔE gap and E HOMO) indicate the superiority of L600 over the L400 counterpart as a reactive compound. Adsorption of L600 and L400 over the Fe(1 1 0) in simulated acidic medium is investigated by Monte Carlo (MC) simulation to verify their inhibition performance and are matched with adsorption free energy ΔG ads calculated values. Both experimental and theoretical data are in agreement.

Adsorption characteristics and inhibition effect of two Schiff base compounds on corrosion of mild steel in 0.5 M HCl solution: experimental, DFT studies, and Monte Carlo simulation.

In this work, we report the synthesis of two Schiff bases of substituted gallic acid derivatives via amidation reaction and their characterization using 1H-NMR spectroscopy to study their inhibition performance on the aggressive attack of HCl on mild steel (MS). The inhibitive performance was examined using chemical (weight loss) and electrochemical (Tafel and EIS) test methods. The results indicate that these derivatives significantly suppress the dissolution rate of mild steel via adsorption phenomena, which correlates to the Langmuir adsorption model. Tafel data display the mixed-type properties of these compounds and EIS results show that increasing Schiff base concentration not only leads to delaying the charge transfer (R ct) of iron from 26.4 ohm cm-2 to 227.7 ohm cm-2 but also decreases the capacitance of the adsorbed double layer (C dl) from 8.58 (F cm-2) × 10-5 to 2.55 (F cm-2) × 10-5. The inhibition efficiency percentage reaches the peak (90%) at optimum concentration of 250 ppm. The Monte Carlo simulations confirm the adsorption ability of the as-prepared compounds on the Fe (1 1 0) crystal. The SEM/EDX results revealed the presence of a protective film on the mild steel sample.