Enhancement of corrosion resistance of the cooling systems in desalination plants by green inhibitor

Zingiber officinale Roscoe extract, Raphanus sativus L. extract, Rheum palmatum extract, Coptis chinensis extract, Glycyrrhiza uralensis extract (GUE), Potentilla discolor extract (PDE) and Taraxacum officinale extract (TOE) were screened for the green corrosion inhibitors of AZ91 alloy in saline environment. The experiment results demonstrated that GUE, PDE and TOE can significantly enhance the corrosion resistance of AZ91 alloy by 73.4, 87.6 and 84.6%, respectively. Surface characterization using FTIR, UV–Vis and XPS revealed that the organic compounds of GUE, PDE and TOE can interact with the alloy surface to form a protective physisorbed film, effectively mitigating the corrosion process of AZ91 alloy. The present results may be helpful to discover the new green inhibitors with high inhibition efficiency for AZ91 alloy.

Corrosion behavior of mild steel in 1 M HCl with Cyclotrichium niveum as a green inhibitor

In this work, Henna leaves extract (HLE) and its principal derivatives of Lawsone and Gallic acid are examined as green corrosion inhibitors. Our contribution is to quantify the effectiveness of HLE, Lawsone and Gallic acid on the corrosion inhibition of steel in simulated concrete pore solution (SCPS) containing 0.5 M NaCl, using electrochemical methods as open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy. In addition, environmental scanning electron microscopy, coupled to the energy dispersive X-ray microanalysis, was performed to investigate the morphology of the steel surface immersed in SCPS containing green inhibitors. Results highlight a synergistic effect with the formation of a protective layer on the steel surface by forming inhibitor-metal complexes. The HLE and Gallic acid act as anodic corrosion inhibitors and Lawsone behaves as a mixed type. These inhibitors are adsorbed on the steel surface by chemisorption according to the adsorption isotherm of Langmuir. The maximal inhibition efficiency is about 93% obtained at 0.2 g/L of HLE, which represents the higher effectiveness compared to Lawsone and Gallic acid.

Corrosion inhibition of copper alloy of archaeological artifacts in chloride salt solution using Aloe vera green inhibitor

The present work evaluates two different inhibitors, hexane and methanol extracts obtained of Curcuma longa (C. longa), as green corrosion inhibitors for 1018 carbon steel immersed in chloride solution 3% using electrochemical techniques. The Inhibition Efficiency (IE) was obtained from Potentiodynamic Polarization Curves (PPC) and Electrochemical Impedance Spectroscopy (EIS). Corrosion rate, inhibition efficiency, and adsorption isotherms were obtained for the better green inhibitor. The C. longa methanol green inhibitor reached 93.68% of IE obtained by EIS and reduced in two orders of magnitude corrosion rate. It acts as mixed-type inhibitor. It was concluded that C. longa has a potential of application as green corrosion inhibitor for steel in media chloride.

Exploitation of a new green inhibitor against mild steel corrosion in HCl: Experimental, DFT and MD simulation approach

The surfactant sodium dodecyl sulfate (SDS) has been investigated for aluminum (Al) corrosion inhibition in 0.2-0.4M hydrochloric acid (HCl) employing mass loss (ML), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) techniques. The inhibition efficiency (IE) of SDS was found to be concentration-dependent, with a maximum of 97% at 8mM, which was attributed to the presence of long-chain groups. Notably, the highest inhibition efficiencies were recorded at an inhibitor concentration of 8mM in a 0.2M HCl solution at 303K, achieving 97.76% via the gravimetric method, 97.30% through PDP, and 93.72% using EIS analysis. The temperature variation from 303 to 333K showed that higher SDS concentrations improved the degree of inhibition, whereas higher temperatures reduced the degree of effectiveness. Polarization measurements indicated that SDS exhibited a cathodic inhibition mechanism. A double-layer capacitance (Cdl) was added to an equivalent circuit model for evaluating the electrochemical impedance spectroscopy data. SDS adsorption behaviour followed the Langmuir and Freundlich isotherms as well as the kinetic thermodynamic model. SEM (scanning electron microscopy), EDX (energy-dispersive X-ray spectroscopy), and AFM (atomic force microscopy) proved the protective adsorbed layer of the Al surface. Corrosion resistance of aluminum in SDS-acidic environments was investigated using PDP and EIS methods. Experiments utilized a three-electrode system in which only a 1-mm2 area of the aluminum sample was exposed, with measurements carried out in 0.2M HCl solutions (with and without SDS) under controlled conditions, including OCP stabilization, PDP, and EIS with repeated trials to ensure data reliability. The study assessed Al corrosion by measuring weight loss under varying SDS concentrations, immersion times, and temperatures, using precise weighing and standardized calculation methods for inhibition efficiency. Additionally, surface analysis after immersion in corrosive media was carried out using SEM, EDX, and AFM to observe morphological and elemental changes. The Gaussian 09 W software utilizes density functional theory (DFT) for computational studies in this research, applying the B3LYP functional with the 6-311 + + G (d,p) basis set and conducting a natural bond orbital analysis of sodium dodecyl sulfate (SDS) in both gas and aqueous environments. To enhance the precision, the polarizable continuum model (PCM) was employed, using water as the solvent. The computational tasks were run on a PC with results visualized through Gaussian View 5.0.9, with a focus on parameters such as the HOMO energy, LUMO energy, band gap, and electrophilicity. For the Monte Carlo (MC) and molecular dynamics (MD) simulations, Material Studio 7.0 was used to model interactions between the aluminum surface and an inhibitor molecule in corrosion simulations. The simulations were carried out via an Al (1 1 0) model under periodic boundary conditions, with a simulation box containing ions and molecules in a 0.2M HCl solution. Multiple cycles of simulated annealing and MD simulations were performed at temperatures ranging from 303 to 333K, with the COMPASS III force field employed for accurate interaction analysis, including calculating the radial distribution function (RDF).

A novel organic-inorganic hybrid complex based on Cissus quadrangularis plant extract and zirconium acetate as a green inhibitor for mild steel in 1 M HCl solution

This study investigates the potential of Taraxacum officinale (TO) root extract as an environmentally friendly corrosion inhibitor for two types of steel, TH-550 and TS-275, in an acidic environment. The corrosion inhibition was assessed by monitoring the weight loss of steel samples over a 72-hour immersion period in four different solutions: blank 4% HCl solution and 4% HCl solutions containing 0.5, 1.0, and 1.5 g/L of TO extract. The inhibitor efficiency, calculated from weight loss data, ranged from 70% to 89%. Surface analysis of the steel samples, conducted after 24 hours of immersion, revealed the formation of a uniform protective film on the steel exposed to the inhibited solutions, while samples in the blank acidic solution showed significant corrosion. Fourier-transform infrared spectroscopy analysis identified key metal-complexing functional groups in the TO extract, including aromatic C-H, C-O, C=O, and O-H, which are likely responsible for the interaction with the steel surface. Potentiodynamic polarization measurements indicated that TO extract acts as an anodic corrosion inhibitor, with the ability to cover up to 88% of the steel surface. Electrochemical impedance spectroscopy, in combination with polarization and weight loss results, demonstrated that the inhibitor efficiency of TO extract increases with concentration.

For mild steel (MS), Vachellia nilotica leaf extract (VNL) was used as a corrosion inhibitor in 1M HCl. Mass loss (ML) and electrochemical methods were used in the inquiry. Increasing the VNL concentration and decreasing the temperature will increase the inhibition efficiency. Electrochemical techniques, including potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS), revealed that VNL effectively inhibited both cathodic and anodic corrosion reactions. With a good fit, VNL follows the Langmuir isotherm. At 150 ppm, the inhibition efficiency of the VNL inhibitor reaches 91.8% at 298K. However, it decreased with elevating temperatures and prolonged exposure. A high activation energy (55.1kJ/mol) for the inhibited solution than that of the blank solution (29.5kJ/mol) and the free energy of adsorption (-19.3 to -18.4kJ mol-1) provides evidence for physical adsorption mechanisms in the interaction of the VNL inhibitor with the steel surface. The efficiency of the extract improved with concentration, achieving optimal values of 93.9% (POD) and 92.2% (EIS) at 150 ppm. Furthermore, the negative free energy values confirm the spontaneous nature of this adsorption process. To find out how the VNL inhibitor affected the MS surface, researchers employed Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM), which confirmed the formation of a protective film on the metal surface. Optimized molecular structures of phytochemicals confirmed their inhibitory properties via Quantum chemical calculations (DFT), which showed the molecular inhibitory action of VNL.

The aim of this work is to investigate the effectiveness of oak galls extract (OGE) as a green corrosion inhibitor from natural resources to prevent the corrosion of archaeological iron artifacts in atmospheric environments. The inhibition efficiency has been evaluated by measuring the weight loss of the treated coupons after exposure to 85% RH in a humidity chamber, Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Also, the morphology of an adsorbed film on the surface was investigated by scanning electron microscopy and optical microscope. The influence of OGE on changing the original appearance of the surface was also evaluated using visual examination and colorimetric measurements. The measurements results revealed that OGE gave high inhibition efficiency reaching approximately 95% of 6% concentration. Based on the study results, OGE can be proposed as an efficient green inhibitor for iron artifacts.

In this study, we evaluated the potential of Anthocleista grandiflora leaf (AGL) plant extract as an environmentally friendly and cost-effective corrosion inhibitor for carbon steel in seawater. We employed various experimental methods, including gravimetric analysis, potentiodynamic polarization, electrochemical impedance spectroscopy, scanning electron microscopy (SEM) and Fourier transform infrared spectrophotometry (FTIR). Our findings indicate that increasing the concentrations of the AGL extract results in higher charge transfer resistance (Rct ) and reduced double-layer capacitance (Cdl ), suggesting the effective adsorption of AGL extract on the surface of carbon steel. The inhibition efficiencies were notably high, 98.7%, 92.40%, and 90.7% determined with gravimetric analysis, potentiodynamic polarization, and electrochemical impedance spectroscopy, respectively. Polarization analysis revealed that the AGL extract acted as a mixed-type inhibitor. Moreover, the results obtained from different techniques exhibited a consistent agreement. The SEM images revealed that the surface layer formed by the AGL extract on the mild steel surface further devoids the surface from pitting as the extract concentration increases. Comparative analysis with similar bio-based inhibitors suggested that the tested AGL extract holds a significant promise as a corrosion inhibitor for carbon steel in seawater. Therefore, our findings support the recommendation of utilizing this AGL extract as an effective anti-corrosion agent in marine industries, owing to its green, low-cost, and efficient characteristics.

The inhibition effect of three green inhibitors, Argan Oil (AO), Cosmetic Argan Oil (CAO) and Argan Hulls Extract (AHE), against copper corrosion in 2 M H3PO4 containing 3·10 M NaCl solutions were evaluated using conventional weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy. The weight loss results showed that all the three green inhibitors are excellent corrosion inhibitors, electrochemical polarizations data discovered the mixed mode of inhibition and the results of electrochemical impedance spectroscopy have shown that the change in the impedance parameters, charge transfer resistance and double layer capacitance, with the change in concentration of the inhibitors employed is due to the adsorption of the molecule leading to the formation of a protective layer on the surface of copper. The values of the inhibition efficiency calculated from these techniques are in reasonably good agreement.

Anticorrosion effect of a green sustainable inhibitor on mild steel in hydrochloric acid

Novel gossypol–indole modification as a green corrosion inhibitor for low–carbon steel in aggressive alkaline–saline solution