Adsorption behavior and corrosion inhibition mechanism of a polyacrylamide on C–steel in 0.5 M H2SO4: Electrochemical assessments and molecular dynamic simulation

Zwitterions and betaines as highly soluble materials for sustainable corrosion protection: Interfacial chemistry and bonding with metal surfaces

The primary requirements for interfacial adsorption and corrosion inhibition are solubility and the existence of polar functional groups, particularly charges. Traditional organic inhibitors have a solubility issue due to the hydrophobic moieties they incorporate. Most documented organic inhibitors have aromatic rings, hydrocarbon chains, and a few functional groups. The excellent solubility and high efficacy of zwitterions and betaines make them the perfect replacements for insoluble corrosion inhibitors. Zwitterions and betaines are more easily soluble because of interactions between their positive and negative charges (-COO-, -PO3-, -NH3, -NHR2, -NH2R, -SO3- etc.) and the polar solvents. The positive and negative charges also aid these molecules' physical and chemical adsorption at the metal-electrolyte interfaces. They develop a corrosion-inhibiting layer through their adsorption. After becoming adsorbed at the metal-electrolyte interface, they act as mixed-type inhibitors, slowing both cathodic and anodic processes. They usually adsorb according to the Langmuir adsorption isotherm. In this article, the corrosion inhibition potential of zwitterions and betaines in the aqueous phase, as well as their mode of action, are reviewed. This article details the advantages and disadvantages of utilizing zwitterions and betaines for sustainable corrosion protection.

Anticorrosive performance of newly synthesized dipyridine based ionic liquids by experimental and theoretical approaches

Two newly synthetic nontoxic dipyridine-based ionic liquids (PILs) with the same chain lengths and different polar groups were investigated: bispyridine-1-ium tetrafluoroborate (BPHP, TFPHP) with terminal polar groups Br and CF3, respectively, on Carbon steel (CS) in 8M H3PO4 as corrosion inhibitors. Their chemical structure was verified by performing 1HNMR and 13CNMR. Their corrosion inhibition was investigated by electrochemical tests, especially as mass transfer with several characterizations: Scanning electron microscope/Energy dispersive X-ray spectroscopy (SEM-EDX), UV-visible, Atomic force microscope, Atomic absorbance spectroscopy, X-ray Photoelectron Spectroscopy and Gloss value. Theoretical calculation using density functional theory by calculating several parameters, molecular electrostatic potential, Fukui Indices, and Local Dual Descriptors were performed to demonstrate the reactivity behavior and the reactive sites of two molecules with a concentration range (1.25-37.5 × 10-5 M) and temperature (293-318 K). The maximum inhibition efficiency (76.19%) and uniform coverage were sufficient for BPHP at an optimum concentration of 37.5 × 10-5 M with the lowest temperature of 293 K. TFPHP recorded 71.43% at the same conditions. Two PILs were adsorbed following the El-Awady adsorption isotherm, including physicochemical adsorption. The computational findings agree with Electrochemical measurements and thus confirm CS's corrosion protection in an aggressive environment.

Novel Polyepoxysuccinic Acid-Grafted Polyacrylamide as a Green Corrosion Inhibitor for Carbon Steel in Acidic Solution

Utilizing green corrosion inhibitors has been classified among the most efficient and economical mitigation practices against metallic degradation and failure. This study aims to integrate the features of green and complementary properties of polyepoxysuccinic acid (PESA) and polyacrylamide (PAM) for steel corrosion inhibition. A novel PESA-grafted-PAM (PESAPAM) has been first-ever synthesized in this research study and deployed as a corrosion inhibitor for C-steel in 1.0 M HCl solution. Eco-toxicity prediction confirmed the environmentally friendly properties acquired by the synthesized inhibitor. Electrochemical, kinetics, and surface microscopic studies were carried out to gain a holistic view of C-steel corrosion behavior with the PESAPAM. Furthermore, the performance of PESAPAM was compared with that of the pure PESA under the same testing conditions. Results revealed predominant inhibitive properties of PESAPAM with an inhibition efficiency (IE) reaching 90% at 500 mg·L^-1 at 25 °C. Grafting PAM onto the PESA chain showed an overall performance improvement of 109% from IE% of 43 to 90%. Electrochemical measurements revealed a charge transfer-controlled corrosion mechanism and the formation of a thick double layer on the steel surface. The potentiodynamic study classified PESAPAM as a mixed-type inhibitor. Furthermore, the investigation of C-steel corrosion kinetics with the presence of PESAPAM predicted an activation energy of 85 kJ·mol^-1, correlated with a physical adsorption behavior. Finally, performed scanning electron microscopy and energy-dispersive X-ray analyses confirmed the adsorption of PESA and PESAPAM, with superior coverage of PESAPAM onto the steel surface.

A Study of the Synthesis and Characterization of New Acrylamide Derivatives for Use as Corrosion Inhibitors in Nitric Acid Solutions of Copper

The objective of this research was to explore the impact of corrosion inhibition of some synthetic acrylamide derivatives 2-cyano-N-(4-hydroxyphenyl)-3-(4-methoxyphenyl)acrylamide (ACR-2) and 2-cyano-N-(4-hydroxyphenyl)-3-phenylacrylamide (ACR-3) on copper in 1.0 M nitric acid solution using chemical and electrochemical methods, including mass loss as a chemical method and electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PP) as electrochemical methods. By Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1HNMR), and mass spectroscopy (MS) methods, the two compounds were verified and characterized. There is evidence that both compounds were effective corrosion inhibitors for copper in 1.0 M nitric acid (HNO₃) solutions, as indicated by the PP curves, which show that these compounds may be considered mixed-type inhibitors. With the two compounds added, the value of the double-layer capacitance was reduced. In the case of 20 × 10^-5 M, they reached maximum efficiencies of 84.5% and 86.1%, respectively. Having studied its behavior during adsorption on copper, it was concluded that it follows chemical adsorption and Langmuir isotherm. The theoretical computations and the experimental findings were compared using density functional theory (DFT) and Monte Carlo simulations (MC).

Investigation of the anticorrosion and adsorption properties of two polymer compounds on the corrosion of SABIC iron in 1 M HCl solution by practical and computational approaches

The anticorrosion efficiency of two polymer compounds, namely polystyrene (PS), polybutylene terephthalate (PBT), against the corrosion of SABIC iron (S-Fe) in 1.0 M HCl solution was investigated. The anticorrosion efficiency was estimated by chemical and electrochemical measurements. The anticorrosion efficiency increased with the increase in the concentration of the polymer compounds and reduction in temperature. All the obtained corrosion data confirmed the anticorrosion strength in the presence of PS and PBT compounds, such as the decreasing values of the corrosion current density, capacity of the double layer, and weight reduction, while the values of the charge-transfer resistance increased. Also, the pitting potential values moved in the noble (+) direction. The anticorrosion efficiency of the PBT compound was higher than that of the PS compound, which was 95.98% at 500 ppm concentration for PBT while for PS it was 93.34% according to polarization measurements. The anticorrosion activity occurred by the adsorption of PS and PBT compounds on the surface of S-Fe according to the Langmuir isotherm. The polarization curves indicated that the PS and PBT compounds were mixed-type inhibitors. Density functional theory (DFT) and Monte Carlo simulation (MC) were performed for the two polymer compounds. The computational quantum functions were found to be in agreement with the experimental results.

Top and side views for adsorption of the two dimers over Fe (110) surface.