Effective inhibition of mild steel corrosion by 6-bromo-(2,4-dimethoxyphenyl)methylidene]imidazo [1,2-a]pyridine-2-carbohydrazide in 0.5 M HCl: Insights from experimental and computational study

Investigating the effectiveness of an imidazopyridine-based compound as an anti-corrosive additive for mild steel in molar hydrochloric acid solutions: a mutual multi-facet experimental and computational approach

The use of effective, environmentally friendly inhibitors is a promising strategy to mitigate metallic corrosion. This work involved the development of a new imidazopyridine-based compound (i.e., MPPIP) and an assessment of its effectiveness as an anti-corrosive entity for the mild steel metal (MS) in 1.00 M hydrochloric acid medium. The compound's performance was evaluated using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS), which demonstrated that MPPIP achieves 98% inhibition efficiency with 10-3 M concentration at room temperature. The electrochemical analysis confirmed that MPPIP acts as a mixed-type inhibitor, reducing both anodic and cathodic reactions. Thermodynamic analyses revealed that MPPIP adsorption follows Langmuir's isotherm, involving a combination of physisorption and chemisorption mechanisms. Additional validation was performed using UV-Vis spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX), which revealed a uniform protective film on the steel surface, preventing metal dissolution. Computational approaches, including density functional theory (DFT) and Monte Carlo simulations, highlighted the molecule's high electron-donating ability and strong adsorption energy, confirming its strong interaction with the metal surface. These findings demonstrate that MPPIP is a promising and efficient corrosion inhibitor for mild steel in acidic environments with inexpensive and easily synthesized route characteristics.

Exploring the synthesis, characterization, and corrosion inhibition of new tris-thiosemicarbazone derivatives for acidic steel settings using computational and experimental studies

A novel two tri-thiosemicarbazones derivatives, namely 2,2',2''-((2-Hydroxybenzene-1,3,5-triyl)tris(methanylylidene))tris(N-benzylhydrazine-1-carbothioamide) (HBC) and 2,2',2''-((2-hydroxybenzene-1,3,5-triyl) tris (methanylylidene)) tris (N-allylhydrazine-1-carbothioamide) (HAC), have been synthesized and their chemical structures were determined using different spectroscopic and analytical approaches. Then, utilizing methods including open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy, the inhibitory effect of the synthesized thiosemicarbazones on mild steel (MS) in an acidic environment (0.5 M H2SO4) was thoroughly investigated. Remarkably, raising the concentration of our recently synthesized tri-thiosemicarbazones HBC and HAC increased the inhibitory efficiency values. The η values of the two investigated tri-thiosemicarbazones derivatives (HAC and HBC), at each concentration are extremely high, and the maximum values of the efficiencies are 98.5% with HAC and 98.8% with HBC at the 800 ppm. The inhibitors adsorbed on the mild steel surface and generated a charge and mass movement barrier that protected the metal from hostile ions. According to polarization curves, HBC and HAC act as mixed-type inhibitors. Electrochemical impedance testing revealed a notable rise in charge transfer resistance (Rct) readings to 4930-Ω cm2, alongside a reduction in the Constant Phase Element (CPE) value to 5.81 μF, suggesting increased effectiveness in preventing corrosion. Also, density functional theory (DFT) was applied to investigate the assembled tri-thiosemicarbazones HBC and HAC. Moreover, the adsorption mechanism of HBC and HAC on the mild steel surface was explored using Monte Carlo simulation. Finally, the theoretical outputs were discovered to support the practical outcomes.

Synthesis and applications of novel Schiff base derivatives as corrosion inhibitors and additives for improvement of reinforced concrete

The studied Schiff-base compounds in this work are multitasked investigated as corrosion inhibitors and also, to improve the physical and mechanical properties of reinforced concrete. The efficiency inhibition of the two novel Schiff-base compounds named (DHSiMF) and (DHSiB) for corrosion of carbon-steel in aqueous media of 1 M HCl was assessed via electrochemical methods and loss in weight. FT-IR, 1H-NMR spectra and elemental analysis were used to confirm the structure of such compounds. It was found to have successful inhibition even at low concentrations in tested media, as an increase in inhibitor concentration led to an improvement in the inhibition efficiency. The weight loss results clearly demonstrate that DHSiMF of C-steel in 1 M HCl has a higher inhibition efficiency than DHSiB, with a maximum inhibition efficiency (85%) attained at 1 × 10-2 M from DHSiMF. Electrochemical experiments likewise revealed the same order, but with a maximal inhibitory efficiency of 98.1%. The addition of inhibitors to the corrosive media dramatically changed the anodic Tafel constants (βa) and cathodic Tafel constants (βc), indicating a mixed type nature. Electrochemical polarization curves illustrated the functions of mixed-type inhibition and the action of adsorption matching with the Langmuir adsorption isotherm. The ∆Gads values for DHSiMF and DHSiB at temperatures (ranging from 303 to 333 K) are - 34.42 kilojoule/mole to - 37.51 kilojoule/mole. These values indicate that the compounds' adsorption types are chemo-physical adsorption. X-ray diffraction (XRD) and Scanning electron microscopy (SEM) experiments were used to check the existence of the protection layer on the surface of carbon steel by analyzing the morphologies of the corrosion effects and the formed chemical compositions of the corrosion outcomes. For the concrete, the findings suggest that the chemical reaction that takes place between the DHSiMF and DHSiB and the concrete mix will result in an increase in the flexural strength, the compressive strength, and the indirect tensile strength of the concrete that is made of the gravel and dolomite aggregate.

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.

Effective Inhibition of Carbon Steel Corrosion by Waterborne Polyurethane Based on N-tert-Butyl Diethanolamine in 2M HCl: Experimental and Computational Findings

The efficiency of corrosion inhibition for waterborne polyurethane based on N-tert-butyl diethanolamine (tB-WPU) is investigated using different techniques. Corrosion weight loss, open circuit potential experiments, electrochemical impedance spectroscopy, and potentiodynamic polarization measurements show that both a commercial reagent and a polyurethane-based inhibitor prevent corrosion at increasing temperature to 50 °C. At 75 °C, the activity of both reagents is reduced. In stirring conditions, the effectiveness of acid corrosion inhibition (25 °C, 500 ppm) drops abruptly from 89.5% to 60.7%, which is related presumably to the complexity of binding the polymer molecules to the metal surface. As follows from thermodynamic calculations, the adsorption of tB-WPU on the metal surface in 2M HCl can be treated as a physisorption. Model quantum–chemical calculations support the experimental studies and elucidate the nature of steel surface–inhibitor molecule chemical bond, which is realized mainly by carboxyl and amino groups. It is concluded that WPUs can be considered as a perspective alternative to commercial oilfield reagents due to their versatility.