Potential Corrosion Inhibitor Research Articles

Enhanced corrosion inhibition effect of sodium tartrate on copper in potable water

In this study we have reported sodium tartrate (ST) and Zn2+ as the potential mixed corrosion inhibitors for copper corrosion in drinking water, by using electrochemical impedance and polarization techniques. The results of potentio-dynamic polarization indicated that sodium tartrate could be used as mixed type inhibitor with Zn2+. ST was found to be 92% effective for slowing down both the anodic and cathodic reaction rates. It was additionally found that ST could coat the surface of copper to prevent it from conducting electricity. As the inhibitor concentration increased, the stability of the formed protective layer was also improved. The results obtained from studies like SEM, EDAX, AFM, and water contact angle clearly indicated the development of a barrier by inducing the lotus effect on copper surface. The water contact angle measurement results suggested that the coating formed in the presence of inhibitor was superhydrophobic, and the surface was homogeneous.

New benzisoxazole derivative: A potential corrosion inhibitor for mild steel in 0.5 M hydrochloric acid medium -insights from electrochemical and density functional theory studies

6-fluoro-3-(4-piperidinyl)-1,2-benzisoxazole. HCl (FPBH), a substituted benzisoxazole derivative, was prepared from isonipecotic acid and characterized using various spectroscopic techniques. Using electrochemical examinations such as potentiodynamic polarisation (PDP) and electrochemical impedance spectroscopic (EIS) technique, the corrosion mitigation capabilities of this compound for mild steel (MS) in 0.5 M HCl medium were investigated. Theoretical studies were performed using quantum chemical calculations and density functional theory (DFT). PDP results exhibited the mixed-type behavior of FPBH and showed a maximum efficiency of 94.5 % at 1 × 10−3 M. The development of a protective adsorbed layer of FPBH decreases the corrosion current density (icorr) and corrosion rate (CR). The EIS technique revealed that the rise in the charge transfer resistance (Rct) values and reduction in the thickness of the double-layer capacitance (Cdl) reflected the drop in corrosion rate. The adsorption of FPBH took place through physisorption by conforming Langmuir's isotherm. The DFT method was performed on the optimized structure of FPBH to get additional evidence on the action mode of FPBH with the metal surface.

Experimental investigation of pyrrolidinium-based ionic liquid as shale swelling inhibitor for water-based drilling fluids

This study evaluated the potential of 1-ethyl-1-methylpyrrolidinium bromide (1E1MPyBr) ionic liquid as a shale swelling inhibitor for water-based mud. Firstly, a linear shale swelling test was conducted to evaluate the ionic liquid's ability to inhibit clay hydration. Moreover, a capillary suction time test was performed to determine the fluid absorbance potential. Besides, particle size distribution analysis and zeta potential were evaluated to determine the ionic liquid effect on the base mud's colloidal distribution and surface charge. Furthermore, the rheological and filtration properties of the ionic liquid-mixed drilling mud were investigated. Finally, The X-ray diffraction analysis was conducted to evaluate the inhibition mechanism. The findings of this study revealed that the incorporation of 0.3 wt% of pyrrolidinium-based ionic liquid into the drilling mud resulted in a 20% reduction in shale swelling behaviour compared to conventional bentonite mud. The observed increase in particle size, decrease in zeta potential, and lower capillary suction timer values demonstrated the clay inhibition potential of ionic liquids. Moreover, adding the ionic liquid to bentonite mixed with water-based mud led to higher fluid loss and decreased rheological properties. These effects were attributed to the intercalation of ionic liquids into the clay layers, which inhibited swelling and hydration and reduced the water absorbance capacity of clay. Besides, the tested ionic liquid showed corrosion inhibition potential. Based on these results, the pyrrolidinium-based ionic liquid is proffered as an efficient shale swelling inhibition additive for water-based mud.

The Blue Tansy Essential Oil–Petra/Osiris/Molinspiration (POM) Analyses and Prediction of Its Corrosion Inhibition Performance Based on Chemical Composition

Sustainable materials encompass a diverse range of substances used in both consumer and industrial domains. These materials are sourced in quantities that safeguard non-renewable resources and environmental equilibrium, with a focus on bio-based alternatives derived from plants. This study investigates the corrosion inhibition potential of two distinct Blue Tansy essential oils (BTES 1 and BTES 2) with varying chemical compositions. Corrosion resistance for mild steel in 1 M HCl environment was assessed using weight loss and Potentiodynamic polarization techniques. The evaluation of BTES 1 and BTES 2 revealed compelling insights. Notably, their inhibition efficiency exhibited an intriguing, damped oscillation pattern with fluctuating concentrations. Remarkably, at 0.5 g/L concentration, BTES 1 achieved an impressive 80% inhibition, while BTES 2 demonstrated a substantial 70% inhibition at 2.5 g/L. This behavior stems from intricate interactions among active compounds, leading to protective film formation and competitive adsorption effects. Importantly, congruence between weight loss measurements and potentiodynamic polarization curves fortified the reliability of outcomes. The study also confirmed BTES as a mixed-type inhibitor, as indicated by polarization curves. Furthermore, Petra/Osiris/Molinspiration (POM) analyses were conducted to unravel molecule interactions, elucidate toxicity risks, and assess bioactivity scores. This comprehensive exploration sheds light on the interplay between sustainable materials, corrosion inhibition efficacy, and complex molecular dynamics, enhancing our understanding of environmentally conscious corrosion prevention strategies.

Valerian extract used as potential corrosion inhibitor for carbon steel in different media

Valerian extract used as potential corrosion inhibitor for carbon steel in different media

Experimental and theoretical investigations of the effect of bis-phenylurea-based aliphatic amine derivative as an efficient green corrosion inhibitor for carbon steel in HCl solution

A novel bis-phenylurea-based aliphatic amine (BPUA) was prepared via a facile synthetic route, and evaluated as a potential green organic corrosion inhibitor for carbon steel in 1.0 M HCl solutions. NMR spectroscopy experiments confirmed the preparation of the targeted structure. The corrosion inhibitory behavior of the prospective green compound was explored experimentally by electrochemical methods and theoretically by DFT-based quantum chemical calculations. Obtained results revealed an outstanding performance of BPUA, with efficiency of 95.1% at the inhibitor concentration of 50 mg L−1 at 25 °C. The novel compound has improved the steel resistivity and noticeably reduced the corrosion rate from 33 to 1.7 mils per year. Furthermore, the adsorption study elucidates that the mechanism of the corrosion inhibition activity obeys Langmuir isotherm with mixed physisorption/chemisorption modes for BPUA derivatives on the steel surface. Calculated Gibb's free energy of the adsorption process ranges from −35 to −37 kJ mol−1.The SEM morphology analysis validates the electrochemical measurements and substantiates the corrosion-inhibiting properties of BPUA. Additionally, the eco-toxicity assessment on human epithelial MCF-10A cells proved the environmental friendliness of the BPUA derivatives. Density functional theory (DFT) calculations correlated the inhibitor's chemical structure with the corresponding inhibitory behavior. Quantum descriptors disclosed the potentiality of BPUA adsorption onto the surface through the heteroatom-based functional groups and aromatic rings.

Trisodium citrate as a potential and eco-friendly corrosion inhibitor of copper in potable water

In this work, the mixture of trisodium cittrate and Zn2+ was used as binary (hetero type) inhibitor for corrosion inhibition of copper metal in potable water. The binary inhibitor system (Zn2+ and trisodium citrate) was used to form hydrophobic surfaces on copper submerged in potable water. Water contact angle (WCA) was found to be 155°4° when the inhibitor was present, whereas it was 84°2° when there was no inhibitor. These observations suggested the development of superhydrophobic layer on the surface of copper in drinkable water. Electrochemical impedance spectroscopy (EIS – AC mode), and potentiodynamic polarization (DC mode) experiments conveyed that the copper surface could be protected by utilizing the mixture of trisodium citrate and Zn2+ in potable water. The morphological studies including SEM (coupled with EDX), AFM, and WCA were evidenced the formulation of a hetero-type inhibitor for the corrosion inhibition of copper in potable water. In this study, the decline in the double-layer capacitance and the rise in the charge transfer resistance were due to the adsorption of inhibitor confirming the development of protective layer, which EIS, SEM, EDX, AFM, and WCA studies also supported. Thus, there was a synergism observed between TSC and Zn2+, and the formulation consisting of TSC and Zn2+ provided 83% of inhibition efficiency (IEp). So, it was suggested that the approach reported in this study could be a simple method for obtaining the superhydrophobic copper surface.

Data-driven investigation to model the corrosion inhibition efficiency of Pyrimidine-Pyrazole hybrid corrosion inhibitors

This paper proposes a quantitative structure–property relationship model (QSPR) based on machine learning (ML) for a pyrimidine-pyrazole hybrid as a corrosion inhibitor. Based on the metric values of the coefficient of determination (R2) and root mean square error (RMSE), the extreme gradient boosting (XGBoost) model was found to be the best predictive model for the N-heterocyclic dataset and its respective non-aggregated dataset. When the XGBoost model was applied to three additional pyrimidine-pyrazole hybrid derivatives, this consistency was also seen, and high corrosion inhibition efficiency (CIE) values were obtained ranging from 82.09% to 95.26%. According to the CIE trends found from the ML predictions, DFT calculations for these derivatives also reveal a strong and suitable adsorption energy trend ranging from −1.40 to −1.52 eV. Also supported by the compatibility of the energy gap trend with the CIE trend of the inhibitor molecule. This innovative method can elucidate the characteristics of potential organic corrosion inhibitors before conducting experimental research, which can speed up the preparation of fresh and strong organic corrosion inhibitors.

Environmentally Friendly Amino Acid-Based Polishing Slurry with Reduced Galvanic Corrosion at Copper/Cobalt Interface for Advanced Cu Interconnect Applications

Chemical mechanical planarization (CMP) is an integral part in semiconductor processing including the back-end-of-line (BEOL) step. A goal of CMP is to uniformly polish the metal interconnects and the liner/barrier materials while minimizing CMP-related defects such as pitting, dissolution, and galvanic corrosion. A variety of azoles are used as corrosion inhibitors such as benzotriazole (BTA) to prevent corrosion defects during polishing. [1,2] These azoles work together with particles in the slurries to polish the overplated metal forming the interconnects. However, azoles are very poorly biodegradable during wastewater treatment and highly toxic to the nitrification process, which requires expensive wastewater treatment challenges.[3,4] Also, it is known that the use of BTA leads to contamination of Cu films by forming undesirable hydrophobic organic residues (e.g., BTA and Cu-BTA complexes),[5] making their removal very difficult during cleaning. To address these challenges aliphatic amino acids were examined as potential corrosion inhibitors to replace problematic azoles in CMP slurries.Three amino acids were considered in a model CMP slurry. These three were chosen for their unique functional groups: methionine, containing a sulfur group, glutamic acid, having an extra carboxylic acid group, and leucine, having a branched hydrocarbon chain. A representative polishing slurry with 35 nm colloidal silica abrasives, 1 wt% hydrogen peroxide as an oxidizer, 0.5wt% arginine as a complexing agent, at pH 8 was used. Three experimental aims were considered (1) corrosion characterization of the three amino acid and BTA electrolytes with linear sweep voltammetry; (2) comparison of the Co and Cu metal removal rate (MRR) in polishing experiments with a proto-type CMP polisher with 8” wafers, and (3) oxidation of the amino acids and BTA in a Fenton assisted electrooxidation reaction. Methionine was most effective in controlling the galvanic corrosion of the Cu-Co couple. The Co and Cu MRR decreased in the presence of three amino acids and showed comparable removal selectivity. The forced degradation of the amino acids under the Fenton-assisted electrooxidation confirmed that they were more readily degraded compared to BTA. Acknowledgments: This work was supported by the Semiconductor Research Corporation grant (Task 3100.001) under the Global Research Collaboration program. References Seo, J., A review on chemical and mechanical phenomena at the wafer interface during chemical mechanical planarization. Journal of Materials Research 2021, 1-23.C. Peethala, H. P. Amanapu, U. Lagudu, and S.V. Babu, J. Electrochem. Soc, 159(6), H582-H588, 2012.D.E. Speed, Chapter 11, Advances in chemical mechanical planarization (CMP) 2nd edition, Babu, S. V., Ed. 2021.G. Li et al. / Chemosphere 241 (2020) 1249932.Seo, J.; Vegi, S. S. R. K. H.; Babu, S.V. ECS Journal of Solid State Science and Technology 2019, 8 (8), P379–P387.

Green synthesis of copper oxide nanoparticles from Murraya koenigii and its corrosion resistivity on Ti-6Al-4V dental alloy

The present work describes green-mediated copper oxide nanoparticles as a potential corrosion inhibitor for the dental alloy Ti-6Al-4V. The salt of copper was reduced to metal nanoparticles using Murraya koenigii leaves, which helps with the agglomeration and nanocluster formation through a reduction mechanism. The current synthesis is a single-step process and is cost-effective. The synthesized nanoparticle was characterized using UV, FTIR, XRD, Zeta potential and Particle size analyzer, SEM, and EDX. The particles were then electrodeposited on Ti-6Al-4V alloy, and the corrosion resistivity in the dental medium was analyzed using Electrochemical parameters such as Corrosion current, Corrosion potential, and anodic and cathodic intercepts through the Tafel and Nyquist plots. The synthesized nanoparticles showed characteristic absorbance at 359 nm. FTIR peaks confirm the phytochemical constituents present in the Murraya koenigii that accounts for the formation of nanoparticles. The XRD predicts the crystalline nature, which is further studied using SEM and EDX. The Zeta potential and Particle size analyzer confirms the negative-negative interactive nature of the synthesized CuO NPs. The NPs showed explicit corrosion inhibition properties with an overall inhibition efficiency of 58.15% and 25.6%, respectively. The study confirms the advantage of using Copper Oxide nanoparticles as a potential coating agent in dental implant alloys in increasing its corrosion efficiency.

Mapping the frontier orbital energies of imidazolium-based cations using machine learning.

The knowledge of the frontier orbital, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), energies is vital for studying chemical and electrochemical stability of compounds, their corrosion inhibition potential, reactivity, etc. Density functional theory (DFT) calculations provide a direct route to estimate these energies either in the gas-phase or condensed phase. However, the application of DFT methods becomes computationally intensive when hundreds of thousands of compounds are to be screened. Such is the case when all the isomers for the 1-alkyl-3-alkylimidazolium cation [CnCmim]+ (n = 1-10, m = 1-10) are considered. Enumerating the isomer space of [CnCmim]+ yields close to 386 000 cation structures. Calculating frontier orbital energies for each would be computationally very expensive and time-consuming using DFT. In this article, we develop a machine learning model based on the extreme gradient boosting method using a small subset of the isomer space and predict the HOMO and LUMO energies. Using the model, the HOMO energies are predicted with a mean absolute error (MAE) of 0.4eV and the LUMO energies are predicted with a MAE of 0.2eV. Inferences are also drawn on the type of the descriptors deemed important for the HOMO and LUMO energy estimates. Application of the machine learning model results in a drastic reduction in computational time required for such calculations.

Investigation of two triazine derivatives as potential eco-friendly corrosion inhibitors for copper in artificial seawater

The inhibiting action of 6-N,N-bis(6-methylheptyl)amine-1,3,5-triazine-2,4-dithiolmono-sodium, (iso-DON) and 6-dibutylamino-1,3,5-triazine-2,4-dithiol monosodium (DBN) on the corrosion of copper in artificial seawater (3.5 wt% NaCl solution) has been investigated using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) methods and scanning electron microscopy (SEM) techniques. The results from weight loss and electrochemical measurements consistently identify that both iso-DON and DBN exhibit good performance as inhibitor for copper corrosion in 3.5 wt% NaCl solution and the inhibition efficiency increases with the increase in inhibitor concentration. Potentiodynamic polarization measurements reveal that the studied triazine dithiol derivatives act as mix-type inhibitors, and the maximum value of the inhibition efficiency was obtained (93 % for iso-DON and 95 % for DBN) when the inhibitor concentration reaches 1.5 mM. EIS imply that the corrosion of copper in NaCl solution is influenced by charge transfer. The adsorption of iso-DON and DBN molecules on copper surface was found to obey the Langmuir adsorption isotherm. Parameters for adsorption indicate a strong interaction between inhibitor molecules and copper surface, and the negative values of ΔGθ reveal the spontaneous adsorption of iso-DON and DBN on copper surface.

Investigasi Model Machine Learning Berbasis QSPR pada Inhibitor Korosi Pirimidin

Since corrosion causes considerable losses in many fields, including the economy, environment, society, industry, security, and safety, it is a major concern for the industrial and academic sectors. Damage control of materials based on organic compounds is currently a field of great interest. Because it is non-toxic, affordable, and effective in a variety of corrosive situations, pyrimidine has potential as a corrosion inhibitor. It takes a lot of time and resources to carry out experimental investigations in the exploration of potential corrosion inhibitor candidates. In this study, we evaluate the gradient boosting regressor (GBR), support vector regression (SVR), and k-nearest neighbor (KNN) algorithms as predictive models for corrosion inhibition efficiency using a machine learning (ML) approach based on the quantitative structure-property relationship model (QSPR). Based on the metric coefficient of determination (R2) and root mean square error (RMSE), we found that the GBR model had the best predictive performance compared to the SVR and KNN models as well as models from the literature for pyrimidine compound datasets. Overall, our study offers a new perspective on the ability of ML models to predict corrosion inhibition of iron surfaces

Computational insights into the corrosion inhibition potential of some pyridine derivatives: A DFT approach

In the present investigation, the corrosion inhibition potency of five pyridine derivatives was computationally simulated and investigated by utilizing the Density Functional Theory (DFT) technique using a basis set of B3LYP/6-31++G (d,p). The predicted corrosion inhibition capacity was shown to improve in the order of 6-(trifluoromethyl) nicotinic acid > 4-(trifluoromethyl) nicotinic acid > N-methyl-4-chloropyridine-2-carboxamide > 2-chloro-6-trifluoromethylnicotinic acid > methyl 2-aminopyridine-4-carboxylate. Anticorrosion potentials were predicted using quantum chemical variables such as energy gap (∆E) i.e. HOMO-LUMO, ionization potential (I), electron affinity (A), proportion of electrons transmitted (∆N), hardness (η), softness (σ) and electronegativity (χ) of chemical species. It was often observed that the corrosion inhibiting rate improved with enhancement of EHOMO, σ, and reduced ELUMO, ∆E and η. Additionally, the electrostatic potential (ESP) mapping revealed that the heteroatoms, including the oxygen and nitrogen atoms, were the regions of anticipated electrophilic attack. This meant that atoms of oxygen and nitrogen could form bonds between the metallic substrate atoms and the investigated inhibitors. With the findings obtained, 4-methyl-2-aminopyridine-4-carboxylate showed the highest EHOMO (-0.23167 eV), softness (12.40694 eV-1) and the lowest ELUMO (-0.7047 eV), energy gap (0.1612 eV) and hardness (0.15107 eV), therefore revealed the excellent corrosion inhibiting attribution for several crucial metals and alloys, including aluminum, mild steel, stainless steel, zinc, brass, copper, etc.

Candle soot derived carbon dots as potential corrosion inhibitor for stainless steel in HCl medium

Candle soot derived carbon dots as potential corrosion inhibitor for stainless steel in HCl medium

Electrochemical, surface analysis, computational and anticorrosive studies of novel di-imine Schiff base on X65 steel surface

The inhibitory effect of di-imine-SB namely ((N1Z, N4E)-N1, N4-bis (4 (dimethylamino) benzylidene) butane 1,4-diamine) on X65-steel in 1 M HCl has been investigated experimentally and theoretically. The electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and weight loss outcomes display the anticorrosion properties of “di-imine- SB”. The inhibitory efficiency exceeds 90% at the optimal concentration of 1 × 10–3 M “di-imine- SB”. The metal surface was examined further using scanning electron microscope (SEM) and energy dispersive X-ray (EDX). The effectiveness of the di-imine-SB is returned into its adsorption on X65-steel surface and found in agreement with Langmuir adsorption isotherm. According to the standard Gibbs free energy of adsorption ({Delta G}_{ads}^{^circ }), di-imine-SB adsorption tends to be chemical rather than physical, it increases the activation energy ({mathrm{E}}_{a}) of metal dissolution reaction and makes it hard to occur. The PDP data suggested anodic and cathodic type of the di-imine-SB inhibitor. Meanwhile, increasing the resistance of X65-steel to 301 Ω cm2 after adding 1 mM of di-imine-SB confirms its protective effect. Whereas, the positive value of the fraction of electron transference (ΔN, 0.746), confirms the affinity of di-imine-SB to share electrons to the partially filed 3d-orbital of Fe forming strong protective film over X65-steel surface. Aided by Monte Carlo (MC) simulation, the calculated adsorption energy (Eads) suggests excessive adsorption affinity of di-imine-SB on metal surface over the corrosive chlorides and hydronium ions. A good correlation between the theoretical hypothesis and the experimental inhibition efficiency has been achieved. The comparative study showed the superior of the di-imine-SB as potential corrosion inhibitor compared with those reported before. Finally, global reactivity descriptors; electron affinity (A), ionization potential (I), electronegativity (χ), dipole moment (µ), global hardness (eta), electrophilicity index and, Fukui indices were also calculated and found well correlated to the reactivity of di-imine-SB.

Investigation of triazole derivatives as corrosion inhibitors on Q235 steel in NaCl solution: Experimental and theoretical studies

Triazole derivatives were synthesised as a new eco-friendly corrosion inhibitor, called C207, which was used in NaCl solutions to protect Q235 steel from corrosion. Electrochemical measurements verified its excellent performance. It was an anode corrosion inhibitor and maintained over 96 % (50 mg/L) inhibition within 48 h. Surface morphology and structure analysis showed that coordination bonds were formed between C207 and Q235 steel. As a result, C207 strongly adsorbed on the surface of steel and made it smooth. Quantum chemical calculations and molecular dynamics simulations confirmed these experimental studies. It was suggested that C207 could be a potential corrosion inhibitor for applications in harsh seawater environments.

Theoretical and experimental insights into the C-steel aqueous corrosion inhibition at elevated temperatures in 1.0 M HCl via multi-carbonyl Gemini cationic surfactants

Abstract Despite corrosion being an inevitable process, researchers strive to control corrosion. In this study, our goal was to prepare two amido Gemini cationic surfactants, LAPG and MAPG, each with different alkyl chains and multiple carbonyl groups as rich electronic rich centers. We aimed to evaluate these surfactants as potential corrosion inhibitors for carbon steel (CS) in 1 M HCl at temperatures of 25–55 ± 0.1 °C. In theoretical investigations, DFT parameters and Mont Carlo simulation were run to predict the adsorption affinity and reactive sites of the LAPG and MAPG molecules. Their efficacy was investigated experimentally considering weight loss and electrochemical techniques. The Tafel polarization revealed that at 0.1 mM of LAPG and MAPG, the corrosion current density (i corr) of CS was reduced to the lowest extent (75.56 and 53.82 μA cm−2) compared to 529.3 μA cm−2 in the absence of the inhibitors. EIS data suggests the enhancement of the thickness of the adsorbed layers of the studied compounds from the decrease of the double-layer capacitance C dl values. The Langmuir isotherm explained the adoption phenomena of these compounds at 25–55 ± 0.1 °C. Activation and adsorption thermodynamic parameters predicted the chemisorption behavior of these molecules onto the steel surface. AFM and XPS tools confirm the CS surface protection due to these inhibitors’ adsorbed layer. A parallel study showed the superiority of these corrosion inhibitors in HCl compared with those reported earlier, making these compounds highly promising corrosion inhibitors, especially in high-temperature acidic environments.

Exploration of procyanidin C1 from Uncaria laevigata as a green corrosion inhibitor in industry: Electrochemical assessment, theoretical simulation, and environmental safety

Traditional corrosion inhibitors have made great contributions to equipment cleaning, metal industry and oil well pipelines, but also cause serious environmental pollution. Therefore, green corrosion inhibitors are gradually explored. Unfortunately, their environmental toxicities have not been experimentally proved, and few of them can be applied in industry. Herein, procyanidin C1 (PCC1), isolated from the abandoned crop Uncaria laevigata, is expected to become a potential green corrosion inhibitor. The corrosion inhibition performance of PCC1 in HCl medium is investigated by electrochemical tests and theoretical calculation. Then the effects of PCC1 on the acute toxicity, antioxidant defense system and apoptosis gene expression of zebrafish are comprehensively explored and analyzed. The electrochemical test confirms that 160 mg/L PCC1 shows a high corrosion inhibition efficiency of 97.70% for Q235 steel exposed to 1 M HCl for 120 h, performing a sustainable and excellent corrosion inhibition performance. The morphology analysis, molecular dynamics and quantum chemistry proves that the protective film is firmly adsorbed on the steel surface like octopuses, together with many active adsorption centers. The acute toxicity tests reveal that PCC1 is a non-toxic corrosion inhibitor. The antioxidant enzyme activity experiment also shows that PCC1 have no obvious damage and neurotoxicity to zebrafish antioxidant system. Apoptosis experiments further demonstrates that PCC1 exhibits no significant effect on the level of apoptosis-related genes under high concentration and long-term exposure. As a proven green corrosion inhibitor, PCC1 may display great potential in industry.

Corrosion inhibiting properties of polysaccharide extracted from Lepidium meyenii root for mild steel in acidic medium: Experimental, density functional theory, and Monte Carlo simulation studies

A polysaccharide obtained from maca (Lepidium meyenii) root extract (MREP) was evaluated as a novel, inexpensive, biocompatible corrosion inhibitor for mild steel (MS) in 1 M HCl. Fourier transform infrared (FTIR) and nuclear magnetic resonance studies were conducted to characterize the inhibitor. Gravimetric, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) techniques were applied to assess the corrosion inhibition potential of the inhibitor. Gravimetric studies were conducted over the temperature range of 30–60 °C. The inhibition efficiency of MREP increased with the concentration and temperature. The maximum inhibition efficiency of MREP was 94.78% at 700 ppm and 60 °C. EIS analysis showed that as the MREP concentration increased, the Rp value obtained from the Nyquist plot increased due to the formation of MREP barrier film at the MS/solution interface. PDP analysis showed that MREP had a mixed type inhibition mechanism. The inhibition efficiencies calculated based on gravimetric, EIS, and PDP analyses were similar. Ultraviolet–visible, FTIR, X-ray photoelectron spectroscopy, atomic force microscopy, and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDAX) analyses demonstrated the formation of a protective film on the MS surface. MREP adsorbed on MS according to the Langmuir adsorption isotherm. The calculated density functional theory parameters indicated the formation of a strong bond between MREP and the unoccupied d-orbital of iron atoms in MS. By contrast, Monte Carlo simulations indicated the adsorption of the MREP inhibitor on the MS surface at the atomic level.