Phenolic fraction of Ammi visnaga extract as environmentally friendly antioxidant and corrosion inhibitor for mild steel in acidic medium

Theoretical Exploration of Enhanced Antioxidant Activity in Copper Complexes of Tetrahydroxystilbenes: Insights into Mechanisms and Molecular Interactions

A theoretical investigation was conducted using DFT/PW91/TZP/DMSO calculations on a complete set of exhaustive lists of 18 compounds resulting from the complexation of trans-2,4,3',5'-tetrahydroxystilbene (T-OXY) and cis-2,4,1',3'-tetrahydroxystilbene (C-OXY) with copper metal cations (Cu+ and Cu2+). The ligand-binding sites are the critical points of Quantum Theory of Atoms in Molecules (QTAIM) analysis on neutral and deprotonated ligands. Various mechanisms, including hydrogen atom transfer (HAT), sequential proton loss electron transfer (SPLET), single electron transfer followed by proton transfer (SET-PT), and bond dissociation energy (BDE(E0)) calculations, were employed to quantify the antioxidant activity. The BDE(E0) mechanism emerged as the most suitable approach for such analyses to evaluate the departure of hydrogen atoms since the results show the HAT mechanism is the most likely occurring. Particularly intriguing were the anionic Cu+ complexes with ligands adopting trans configurations and deprotonated conformations, displaying superior antioxidant activity compared to their counterparts. Remarkably, a single ligand within the Cu+ complex exhibited exceptional antioxidant prowess, yielding a BDE(E0) value of 91.47 kcal/mol. Furthermore, a complex involving two deprotonated ligands demonstrated antioxidant activity of 31.12 kcal/mol, signifying its potential as a potent antiradical agent, surpassing T-OXY by a factor of 3.91 and even surpassing the antioxidant efficiency of Vitamin C.

Eco-Friendly Methanolic Myrrh Extract Corrosion Inhibitor for Aluminum in 1 M HCl

Aluminum corrosion was inhibited by myrrh extract when it was placed in a solution of 1 M HCl. Several procedures were used for these tests, including weight loss WL, potential dynamic polarization PL, and electrochemical impedance EIS in addition to theoretical calculations like density functional theory (DFT), Fukui functions, and Monte Carlo simulation. Fourier transform infrared spectroscopy was used to analyze the compositional surface of Al. Scanning electron microscopy was used to determine the shape of the Al surface. The inhibition rate of Al corrosion in HCl with varying myrrh extract contents at 25-45 °C was studied. An analysis of the PL curves indicates that myrrh extract is an inhibitor of mixed type. Upon increasing the concentration of myrrh, the inhibition efficiency increased. Moreover, rising temperatures decrease inhibition efficiency. It was discovered that the inhibition process follows the Langmuir isotherm, demonstrating that a monolayer has formed on the surface of aluminum. Theoretical and practical studies proved the validity of the conclusions.

Antioxidant activity, analgesic activity, and phytochemical analysis of Ammi majus (L.) extracts

Ammi majus (L.) is commonly used to cure many diseases in Moroccan folk medicine, especially vitiligo. This research tries to evaluate the phytochemical constituents of two aqueous extracts (E1; Maceration; 48 h) and (E2: Infusion; 1h) and three organic fractions (F1: Cyclohexane), (F2: Ethyl acetate (EtOAc)) and (F3: Ethanolic (EtOH)) of A. majus (L.) seeds, as well as to study the antioxidant and analgesic activity of the species. Phytochemical analysis, antioxidant activity (DPPH, FRAP, ABTS, and TAC tests), and analgesic activity (writhing and tail immersion were induced by Acetic acid tests) were analyzed according to the literature. A quantitative phytochemical study indicate that the E1 had the highest content of total polyphenols (26.95 ± 0.53 mg GAE/g extract) and flavonoids (37.92 ± 0.46 mg QE/g extract), while F3 showed a promising flavonol content (24.26±0.08 mg QE/g extract). Tannins were found to be high in F1 (59.27 ± 0.16 mg CE/g extract) and F2 (57.65 ± 1.18 mg CE/g extract). Antioxidant results reveals that DPPH (IC50 = 179.68 ± 0.47 μg/mL) and FRAP (EC50 = 367.03 ± 0.12 μg/mL) show to E1 a high antioxidant activity. Regarding the analgesic activity of the different studied extracts, it was found that E1 has a high peripheral analgesic effect with 62.32 % and a high central analgesic potential throughout the experimentation at 500 mg/kg. Our studies demonstrated for the first time that A. majus seeds extracts have high antioxidant and analgesic activities through different analysis techniques.

Computational, Kinetics, and Corrosion Protection Aspects of Electrodeposited Poly(Salicylic Acid) Coatings as a Corrosion Inhibitor for Mild Steel

Poly(salicylic acid) PSA has been electrochemically deposited onto a Pt electrode. The kinetics of the polymerization reaction has been studied. The polymer structure was confirmed and characterized using IR spectroscopy, XRD, SEM, and TGA analysis. The deposited PSA was then collected from the Pt surface and tested as a corrosion inhibitor for a mild steel electrode in an aqueous medium of 1 M sulfuric acid. The corrosion behavior was then evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Corrosion measurements showed that the inhibition efficiency of 20, 50, and 100 ppm of PSA was 33, 57, and 74%, respectively. The inhibition mechanism was proved using adsorption isotherms as well as quantum calculations. The inhibition of the corrosion process was due to the adsorption of PSA on the steel surface, which was found to comply with the Langmuir adsorption isotherm.

Ethyl ester/acyl hydrazide-based aromatic sulfonamides: facile synthesis, structural characterization, electrochemical measurements and theoretical studies as effective corrosion inhibitors for mild steel in 1.0 M HCl

In this research paper, aromatic sulfonamide-derived ethyl ester (p-TSAE) and its acyl hydrazide (p-TSAH) were directly synthesized, characterized, and employed for the first time as prospective anticorrosive agents to protect mild steel in 1.0 M HCl conditions. The corrosion efficiency was probed by electrochemical methods including polarization, impedance, and frequency modulation measurements. Optimal efficiencies of 94% and 92% were detected for the hydrazide and ester, respectively, revealing excellent corrosion inhibition. Moreover, both the hydrazide and ester molecules combat the cathodic and anodic reactions correspondingly in a mixed-type manner. The electron transfer (ET) at the inhibitor/metal interface was evaluated using DFT at the B3LYP/6-31g(d,p) level. Natural bond orbital analysis (NBO) and frontier molecular orbital analysis (FMO) calculations showed superior capabilities of the synthesized inhibitors to easily reallocate charge into the metal surface. However, the hydrazide molecules showed slightly better inhibition efficiency than the ester due to the strong interaction between the lone pairs of the nitrogen atoms and the d-orbitals of the metal. The chemical hardness of the hydrazide and ester are 2.507 and 2.511 eV, respectively, in good accordance with the recorded electrochemical inhibition efficiencies for both molecules. Good and straightforward correlations between the experiments and calculations are obtained.

Environmentally benign cinchonain IIa from Uncaria laevigata for corrosion inhibition of Q235 steel in HCl corrosive medium: Experimental and theoretical investigation

Traditional corrosion inhibitors make great contribution to metal protection, but also cause environmental pollution. To solve the problem, plant extracts as green corrosion inhibitors have attracted much attention in recent years. Plants are good raw materials for corrosion inhibitors and also meet the requirements of industry. However, they have not been successfully applied in industry due to the unknown composition of the effective corrosion inhibitors and large dosage thereof. Therefore, cinchonain IIa was separated from Uncaria laevigata with abundant sources and low cost from nature in this work. Here we hypothesized that cinchonain IIa could show good corrosion inhibition performance for Q235 steel in the acidic medium. Through experiments and theoretical calculation, we studied the corrosion inhibition effect of cinchonain IIa on Q235 in 1 M HCl solution at 298 K for 48 h. Electrochemical experiments revealed that the inhibition efficiency of 200 mg/L cinchonain IIa in 1 M HCl for Q235 steel was 94.08% for 48 h. It even showed over 93% corrosion inhibition efficiency and durable protection performance to 28 d. Surface observations indicated that cinchonain IIa were firmly attached to the steel surface by forming a protective film. Moreover, quantum chemical calculation and molecular dynamics simulation revealed the inhibition mechanism at molecular and atomic level. Compared with some plant extracts, here we demonstrate that the outstanding advantages of cinchonain IIa include sustained protective effect, small dosage, and low toxicity. Accordingly, it may be used as a green industrial corrosion inhibitor with great potential in oilfield acidification and acid pickling.

Rust Conversion of Proanthocyanidins to Archaeological Steel: A Case Study of Lingzhao Xuan in the Forbidden City

This work was focused on the rust conversion of proanthocyanidins (PC) for goethite (α-FeOOH), akaganeite (β-FeOOH) and lepidocrocite (γ-FeOOH), trying to show the potential of PC as an eco-friendly corrosion inhibitor and rust converter for archaeological steel conservation. The experiment used a rusted steel screw from Lingzhao Xuan of the Forbidden City in the Qing Dynasty and three kinds of pure iron oxyhydroxides as research samples. By means of micro-Raman, FTIR, XRD, XPS, SEM and EIS, PC had the ability to chemically react with iron oxyhydroxides in the rust, forming amorphous PC-FeOOH with a marked signal about 1384 cm^-1 as phenolic-Fe in infrared properties. The original relatively stable iron oxides were not induced to phase transformation and still remained. The converted rust layer could be more stable in the corrosive medium and increased the corrosion potential more effectively. Both the rust layer resistance and the charge transfer resistance of the archaeological samples were improved by at least 3 times with 5.0 g/L of PC, which could reasonably stabilize the archaeological rust and hindered external corrosive penetration into the core. It was a mild protection material that showed satisfactory performance for archaeological steel cultural heritage and has a good application prospect.

Corrosion Inhibition and Rust Conversion of Catechin on Archaeological Iron of Nanhai I

This work took the iron objects from the Nanhai No. 1 shipwreck in the Southern Song Dynasty of China as the sample to test and analyze the application potential of catechin, an environmentally friendly corrosion inhibitor and rust converter. The article used metallographic microscopy to clarify that the structure of the iron artifact was hypereutectic white iron. By means of micro-Raman, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), potentiodynamic polarization and electrochemical impedance spectroscopy, catechin had the ability to react with iron oxyhydroxides such as goethite, akaganeite and lepidocrocite in the rust, forming an amorphous substance with a marked signal about 1380 cm−1 as phenolic-Fe in infrared properties. The new products could make the original rust layer form a laminated dense structure. After the archaeological iron was soaked in 3.0 g/L catechin, the corrosion current density decreased by 37.13% and the corrosion potential shifted positively by 32.67 mV. The anode reaction was more inhibited than the cathode in the polarization curve. The rust resistance in electrochemical impedance increased to 3.75 times and the ion diffusion resistance increased to 6.33 times. The corrosion inhibition efficiency was 21.75% and the rust conversion efficiency was 73.26%. After 36 h of accelerated corrosion, the protection effect of the newly transformed rust layer was still better than that of the original state. Catechin was a mild protection material which showed satisfactory performance for archaeological iron and has a good application prospect.

Evaluation of Tannins as Potential Green Corrosion Inhibitors of Aluminium Alloy Used in Aeronautical Industry

In this work some organic natural products were studied, namely tannic acid, gallic acid, mimosa tannin and chestnut tannin, as potential green corrosion inhibitors of the aluminium alloy AA2024-T3. The anodizing treatment was performed in a solution of the referred organic compounds in diluted sulfuric acid. The electrochemical impedance spectroscopy and the potentiodynamic polarization were performed to assess sealing quality and corrosion protection granted by the anodic films. To understand the green inhibitors; interaction with the metal surface, FTIR spectra of anodizing and anodizing and sealed samples of AA2023-T3 were recorded, and the shifts in the position of the major bands confirmed that the green inhibitor interacts with the metal surface. Images of the morphology of the coatings were provided by Scanning Electron Microscopy. From the results obtained through the various techniques that were used to carry out this study it is possible to conclude that the formed anodic films can be a good contribution for the prevention of corrosion in the aluminium alloy AA2024-T3.

Organic Compounds as Corrosion Inhibitors for Carbon Steel in HCl Solution: A Comprehensive Review

Most studies on the corrosion inhibition performance of organic molecules and (nano)materials were conducted within “carbon steel/1.0 M HCl” solution system using similar experimental and theoretical methods. As such, the numerous research findings in this system are sufficient to conduct comparative studies to select the best-suited inhibitor type that generally refers to a type of inhibitor with low concentration/high inhibition efficiency, nontoxic properties, and a simple and cost-economic synthesis process. Before data collection, to help readers have a clear understanding of some crucial elements for the evaluation of corrosion inhibition performance, we introduced the mainstay of corrosion inhibitors studies involved, including the corrosion and inhibition mechanism of carbon steel/HCl solution systems, evaluation methods of corrosion inhibition efficiency, adsorption isotherm models, adsorption thermodynamic parameters QC calculations, MD/MC simulations, and the main characterization techniques used. In the classification and statistical analysis section, organic compounds or (nano)materials as corrosion inhibitors were classified into six types according to their molecular structural characteristics, molecular size, and compound source, including drug molecules, ionic liquids, surfactants, plant extracts, polymers, and polymeric nanoparticles. We outlined the important conclusions obtained from recent literature and listed the evaluation methods, characterization techniques, and contrastable experimental data of these types of inhibitors when used for carbon steel corrosion in 1.0 M HCl solution. Finally, statistical analysis was only performed based on these data from carbon steel/1.0 M HCl solution system, from which some conclusions can contribute to reducing the workload of the acquisition of useful information and provide some reference directions for the development of new corrosion inhibitors.

Spent Coffee Grounds as Eco-Friendly Additives for Aluminum-Air Batteries

A new approach to the recycling of spent coffee grounds is described in which lignin, a chemical component of spent coffee, is used as an electrolyte additive in aluminum-air batteries. The effect of lignin on the performance of aluminum-air batteries has been investigated by weight loss measurement, galvanostatic discharge test, and electrochemical impedance spectroscopy (EIS). The corrosion inhibition efficiency is improved up to 37.3% and fuel efficiency up to 21.7% at 500 ppm of lignin molecules. The chemisorption of lignin molecules on the aluminum surface improves battery performance. Adsorption of lignin molecules onto the aluminum surface is driven by the electrostatic interaction between the lignin's hydroxyl group and the aluminum surface. The mechanism for the performance improvement is explained by the chemisorption behavior of lignin molecules. The adsorption behavior has been investigated by scanning electronic microscopy with energy-dispersive spectroscopy (SEM-EDS), laser scanning microscopy (LSM), atomic force microscopy (AFM), Freundlich adsorption isotherm, Fourier-transform infrared (FT-IR) spectroscopy, and the computational calculation of adsorption energies based on the density functional theory (DFT).

Corrosion resistance and antibacterial activity of procyanidin B2 as a novel environment-friendly inhibitor for Q235 steel in 1 M HCl solution

Flavonoids, alkaloids, glucosides and tannins with good corrosion inhibition are the main natural components in plants. In this work, procyanidin B2 (PCB2), a natural flavonoid, was firstly isolated from Uncaria laevigata. Corrosion inhibition, chemical reactivity and adsorption of PCB2 on Q235 carbon steel were described by experimental and theoretical studies. The inhibition performance of PCB2 as a green corrosion inhibitor was evaluated by electrochemical and gravimetric tests. The binding active sites and activities thereof on the steel surface were illustrated by quantum chemistry, and the equilibrium configuration was predicted by molecular dynamics simulation. PCB2 exhibits good corrosion inhibition on Q235 steel over a wide temperature range. The electrochemical results show that PCB2 is a mixed inhibitor, and its inhibition efficiency increases with the addition of PCB2 concentration. Moreover, the protective film is formed on the steel and the active corrosion sites are blocked significantly by surface analysis. Additionally, the theoretical calculation proves a strong interaction between PCB2 molecule and carbon steel. Besides, the antimicrobial activity was also preliminarily studied. This suggests that PCB2 exhibits better antimicrobial activity against many Gram-positive and Gram-negative bacteria. As a novel green corrosion inhibitor and antimicrobial agent, PCB2 is worthy of further exploitation.

Synergetic Effect between Phenolic Extracts of Ammi visnaga and Zea mays Formulation on the Corrosion of Mild Steel in 1 M HCl Solution

The synergetic effects between hydroethanolic extracts of A. visnaga HE (AV) and Z. mays hairs HE (ZM) on corrosion of mild steel in 1 M HCl solution was investigated at 298 K by two techniques: potentiodynamic polarization (PP) methods (Tafel and Stern & Geary) and electrochemical impedance spectroscopy (EIS). The mixture of HE (AV)/HE (ZM) acted as an efficient corrosion inhibitor and its inhibition efficiency increased with concentration up to 96.55% at 0.01 gL−1 HE (AV)/0.2 gL−1 HE (ZM). The polarization curves revealed that the mixture acted as a mixed-type inhibitor, with anodic predominant action. The EIS studies were fitted by the (Rs + CPEdl)/(Rct + CPEf/Rf) equivalent circuit model. The kinetic parameters were in favor of a physisorption character of adsorption of HE (AV)/HE (ZM) components onto the mild steel surface. The influence of exposure time on the efficiency of mixture extract was investigated. Scanning electron microscopy (SEM/EDX) analyses confirmed the formation of a protective adsorbed film upon the mild steel surface.