Potential of Borage flower aqueous extract as an environmentally sustainable corrosion inhibitor for acid corrosion of mild steel: Electrochemical and theoretical studies

A Review on Plants and Biomass Wastes as Organic Green Corrosion Inhibitors for Mild Steel in Acidic Environment

Acid corrosion is a problem pertaining to corrosion that involves an acid solution. It is important to treat metal to preserve its integrity. Thus, acids are utilized to clean and treat metal surfaces. In return, this may lead to over-etching and metal degradation. Corrosion inhibitors were introduced as a solution for the issue. However, there are some problems associated with the usage of conventional corrosion inhibitors. Traces of nitrites and chromates that are present in the inhibitors may lead to serious health and environmental issues. As a solution, organic green corrosion inhibitors have been studied to replace the conventional corrosion inhibitors. These inhibitor molecules form a protective layer on top of the metal surface to suppress metal dissolution when added to the acid solution. This process prevents direct contact between the metal surfaces and the acid environment. This study explores the usage of natural resources and biomass wastes as the basis for organic green corrosion inhibitors. This study also provides some suggestions for new biomass wastes that can be studied as new organic corrosion inhibitors, and it is aimed at opening the perspective of researchers on exploring new organic inhibitors by using natural resources and biomass wastes.

Nitrogen and sulfur Co-doped carbon dots as ecofriendly and effective corrosion inhibitors for Q235 carbon steel in 1 M HCl solution

Novel nitrogen and sulfur co-doped carbon dots (N,S-CDs) were synthesized via a hydrothermal procedure using citric acid (CA) and thiourea (TU) as precursors, and the corresponding corrosion protection performance was first investigated for Q235 carbon steel in 1 M HCl solution. Experimental results indicated that N,S-CDs as mixed-type corrosion inhibitors could effectively prevent Q235 carbon steel from corrosion in 1 M HCl solution, and the corrosion inhibition efficiency was improved with the increase in N,S-CD concentration. The maximum value was achieved at 400 ppm of N,S-CDs at 25 °C, which was approximately 96.6%, 94.6% and 90.55%, according to the potentiodynamic polarization curves, EIS results and weight loss measurement, respectively. Additionally, with the temperature ranging from 25 to 55 °C, the inhibition efficiency obtained from the weight loss measurement was enhanced from 90.55% to 94.04%. Such superior inhibition effect was assigned to the physisorption and chemisorption of N,S-CDs on the Q235 carbon steel surface, which was also be confirmed by XPS analysis. The adsorption of N,S-CDs onto a steel substrate conformed to the Langmuir adsorption isotherm.

Effective Corrosion Inhibition of Carbon Steel in Hydrochloric Acid by Dopamine-Produced Carbon Dots

In present study, novel nitrogen doped carbon dots (NCDs) are synthesized using a green material-dopamine-as a precursor and studied as corrosion inhibitors for Q235 carbon steel in 1 M HCl solution. According to the electrochemical results, it is found that NCDs acting as a mixed-type corrosion inhibitor can effectively retard the acid corrosion of carbon steel, and their inhibition efficiency increases with the concentration increasing from 50 to 400 ppm. The highest inhibition efficiency is 96.1% in the presence of 400 ppm NCDs at room temperature. Additionally, the adsorption of NCDs obeys the Langmuir adsorption isotherm. In addition, weight loss results show that the inhibition efficiency in the presence of 400 ppm NCDs increases with prolonged exposure time and rising temperature (298-328 K), owing to the strong adsorption of NCDs on the steel surface, and the η value is 92.2% at 60 h of immersion and 86.2%, 89.1%, 90.6% and 92.9% at 298, 308, 318 and 328 K, respectively. Surface analysis by scanning electron microscope (SEM), laser scanning confocal microscope (LSCM) and X-ray photoelectron spectroscopy (XPS) further proves the formation of a protective NCD film on the steel surface.

Corrosion inhibiting effect of a green formulation based on Opuntia Dillenii seed oil for iron in acid rain solution

This study examines the development of a new green and eco-friendly formulation derived from Opuntia dillenii seed oil (labeled as FOD) and its application as a corrosion inhibitor to protect iron which is subject to corrosion phenomena that become important especially in acidic environments as acid rain.

Physicochemical properties and fatty acid analysis of Opuntia dillenii seed oil were performed and they demonstrated that the oil is a major source of unsaturated fatty acids, in particular linoleic acid, with a percentage of 73.388%.

Corrosion inhibition effect of FOD was studied by gravimetric methods, electrochemical measurements, and scanning electron microscopy coupled with elemental analysis (SEM/EDX). Obtained results confirmed that FOD behaves as a good mixed corrosion inhibitor with predominant anodic activity. Inhibition efficiency of FOD is more important when the concentration of FOD and the immersion time increase, reaching values up to 99%. FOD forms a barrier layer on the surface of the iron, and thereby minimizes the contact area between the metal surface and the corrosive solution. The adsorption behavior of FOD on iron surface obeys Langmuir adsorption isotherm with chemisorption and physisorption mechanism.

Effect of phosphonate functional group on corrosion inhibition of imidazoline derivatives in acidic environment

In the present study, ({2-[2-(7-Isopropyl-1,4-dimethyl-9,10-octahydro-phenanthren-1-yl)-4,5-dihydro-1-yl]-ethylamino}-methyl)-phosphonicimidazole (GSIM) was synthesized by introducing phosphonate (-PH₂O₃) group into imidazoline derivatives and its corrosion inhibition performance was studied for Q345 steel in acidic medium along with SIM using potentiodynamic polarization, EIS and SECM analysis. Surface analysis of steel samples was also performed by optical microscopy and SEM-EDS analysis after polarization tests. XPS was used to detect chemical composition of the surface passive films. It was observed that introducing -PH₂O₃ group not only improved the adsorption capacity on the metal surface by coordinating with iron ions, but also inhibited the interference of hydrogen bond formed by -NH₂ group and water molecules on the adsorption. GSIM not only inhibited intercrystalline corrosion and pitting corrosion, but also reduced uniform corrosion. Thermodynamics studies demonstrated that GSIM followed the Langmuir adsorption isotherm and had a larger adsorption equilibrium constant than SIM, which indicated that it had a stronger adsorption capacity. XPS and UV confirmed that the coordination between GSIM and Fe³⁺ and hydrogen bonding between SIM and water molecules. The quantum chemical study further clarified that the site and strength of hydrogen bond between SIM and H₂O and the dominant configuration and coordination stability of GSIM with Fe³⁺.

Adlay seed hull polysaccharide as a green corrosion inhibitor for mild steel in acid solution: surface analyses and theoretical calculations

Adlay seed hull polysaccharide was developed here as a green corrosion inhibitor for mild steel in 1 M HCl solution, and its inhibition effect was studied with electrochemical experiments, theoretical calculations, etc.

Plant Extracts as Green Corrosion Inhibitors for Different Metal Surfaces and Corrosive Media: A Review

Natural extracts have been widely used to protect metal materials from corrosion. The efficiency of these extracts as corrosion inhibitors is commonly evaluated through electrochemical tests, which include techniques such as potentiodynamic polarization, electrochemical impedance spectroscopy, and weight loss measurement. The inhibition efficiency of different extract concentrations is a valuable indicator to obtain a clear outlook to choose an extract for a particular purpose. A complementary vision of the effectiveness of green extracts to inhibit the corrosion of metals is obtained by means of surface characterizations; atomic force microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy analysis are experimental techniques widely used for this purpose. Moreover, theoretical studies are usually addressed to elucidate the nature of the corrosion inhibitor—metal surface interactions. In addition, calculations have been employed to predict how other organic substances behave on metal surfaces and to provide experimental work with fresh proposals. This work reports a broad overview of the current state of the art research on the study of new extracts as corrosion inhibitors on metal surfaces in corrosive media. Most constituents obtained from plant extracts are adsorbed on the metal, following the Langmuir adsorption model. Electron-rich regions and heteroatoms have been found to be responsible for chemisorption on the metal surface, whereas physisorption is due to the polar regions of the inhibitor molecules. The plant extracts compiled in this work obtained corrosion inhibition efficiencies above 60%, most of them around 80–90%. The effect of concentration, extraction solvent, temperature, and immersion time were studied as well. Additional studies regarding plant extracts as corrosion inhibitors on metals are needed to produce solutions for industrial purposes.

Review on Corrosion Inhibitors for Oil and Gas Corrosion Issues

The pipeline system in the oil and gas industry is the heart for transportation of crude and refined petroleum. Nevertheless, continuous exposure of the pipeline surfaces to impurities and sources of corrosion such as sulfur and chromate is totally unavoidable. Vast employment of commercial corrosion inhibitors to minimize the corrosion is being restrained due to toxicity towards the environment. The emergence of “green” chemistry has led to the use of plant extracts and fruit wastes which have proven to be good corrosion inhibitors. This paper aims to provide insight into carrying out further investigation under this research theme for accurate inhibition efficiency measurement.

Synthesis of ZnO-NPs Using a Convolvulus arvensis Leaf Extract and Proving its Efficiency as an Inhibitor of Carbon Steel Corrosion

This paper studies the use of zinc oxide nanoparticles (ZnO-NPs) synthesized using an extract of Convolvulus arvensis leaf and expired ZnCl₂, as efficient inhibitors of carbon steel corrosion in a 1 M HCl solution. The synthesized ZnO-NPs were characterized by Fourier-transform infrared (FTIR) and UV-Vis spectroscopy analysis. The corrosion inhibition of carbon steel in 1 M HCl was also investigated through potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and the determination of weight loss. The results show that the efficiency of the prevention increased when the concentration of ZnO-NPs was increased to 91%, and that the inhibition efficiency was still high (more than 89%) despite decreasing at high temperatures, acting as a mixed-type inhibitor. A sample of carbon steel with a protective layer of inhibitor on top was observed during immersion in 1 M HCl for 20 h; an increase in the charge transfer resistance (R_ct) and stability of the inhibitor could be observed after 6 h. Adsorption isotherm models demonstrated that the inhibitor adsorption mechanism on the carbon steel surface followed Langmuir rather than Freundlich and Temkin behaviors. The thermodynamic parameters showed that the adsorption process is one of mixed, spontaneous, and exothermic adsorption. The results illustrate that the ZnO-NPs were a strong inhibitor of carbon steel corrosion in acid medium. The results of scanning electron microscopy (SEM) images showed that the ZnO-NPs formed a good protective film on the carbon steel surface.

Production of an environmentally stable anti-corrosion film based on Esfand seed extract molecules-metal cations: Integrated experimental and computer modeling approaches

This study aims at finding a suitable alternative for traditional and hazardous organic/inorganic corrosion inhibitors. In this study, the aqueous extract of Esfand seed (ESE) was used as a unique green source of nitrogen-based organic compound with great capability of the steel corrosion inhibition in a saline solution. Surface and electrochemical analyses were carried out by Ultraviolet-visible spectroscopy (UV), Fourier-transform infrared spectroscopy (FT-IR), Grazing incidence X-ray diffraction (GIXRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), electrochemical impedance spectroscopy (EIS), and polarization methods. Furthermore, the adsorption of inhibitors on the steel surface was explored by Monte Carlo (MC), molecular dynamics (MD) and quantum mechanics (QM) methods. The electrochemical studies established the effectiveness of the zinc cations addition to the ESE containing solution on its inhibition efficiency. The sample inhibited by 300 ppm ESE + 700 ppm Zn showed the highest anti-corrosion properties. The inhibition efficiency of this sample was reached 98.8% after 264 h which is much higher than those reported in the previous studies. QM computations proved the formation of complexes via donor-acceptor action. MC and MD simulations supported the inhibitors adsorption on the steel.

A high-efficiency corrosion inhibitor of N-doped citric acid-based carbon dots for mild steel in hydrochloric acid environment

Novel N-doped carbon dots (CDs) were obtained through pyrolysis of ammonium citrate at 180 °C for 1, 2 and 3 h, and their corrosion inhibition effect on Q235 steel in 1 M HCl solution were evaluated through electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (Tafel), scanning vibrating electrode technique (SVET) analysis. The changes of corrosion current density and impedance modulus of Q235 steel in inhibitor solutions showed that the as-prepared carbon dots presented a valid protective effect on steel in 1 M HCl solution. Meanwhile, the inhibition efficiency of three carbon dots exceeded 90% at 200 mg/L and the highest inhibitive efficiency was found for the carbon dots prepared at the reaction time of 2 h. The adsorption mechanism of all as-prepared carbon dots complied with the Langmuir adsorption model, containing chemical and physical adsorptions, which was also confirmed by X-ray photoelectronic spectroscopy (XPS) analysis.

Carbon steel corrosion controlled by vegetable polyol phosphate, in medium containing chloride and glyoxal: influence of phosphate content and CO2

Glyoxal is a potential sequestrant of H₂S in the pre-salt exploration. However, the mixture containing packer fluid and glyoxal is corrosive. The addition of an eco-friendly polyol phosphate acts as corrosion inhibitor of the AISI 1020 in this environment. The objective of the present work was to study the influence of phosphate content in the inhibitor formulation, as well as its action in packer fluid and glyoxal solution in the presence of dissolved CO₂, by means of surface analysis and electrochemical measurements. The results demonstrated that the inhibition efficiency increases as the phosphate content increases. In the beginning of the tests, the polarization resistance increases from 2.2 kΩ cm² (2.5 % phosphate) to 11.2 kΩ cm² (10 % phosphate). In CO₂ - containing medium, 500 ppm dosage of polyol phosphate increases the polarization resistance (from 0.35 kΩ cm² to 5.9 kΩ cm²) and decreases both the capacitance (from 111.5 μF cm^-2 to 10.2 μF cm^-2) and the corrosion current (in 67%). Polyol phosphate is effective as corrosion inhibitor in the presence of CO₂ due to its adsorption on the metal surface or on the film of the previously formed oxide.