Corrosion Inhibition Of Mild Steel Research Articles

Inhibition of Mild Steel Corrosion by New Epoxy Resin in 1 M HCl: Synthesis, Characterization, Experimental Study and Theoretical Approach

Inhibition of Mild Steel Corrosion by New Epoxy Resin in 1 M HCl: Synthesis, Characterization, Experimental Study and Theoretical Approach

Bio-based ionic liquid as a corrosion inhibitor for mild steel in 5% HCl solution: Experimental and theoretical investigation

In pickling conditions, corrosion inhibitors are commonly used to mitigate the corrosive effects of the acidic environment on metal surfaces. Green corrosion inhibitors are substances that provide corrosion protection while being environmentally friendly, often derived from renewable resources or having minimal environmental impact. Ionic liquids are a class of green corrosion inhibitors that have gained attention for their potential in corrosion protection due to their unique properties. In this study, we synthesized a bio-based choline hexanoate ionic liquid (referred to as ChH) and used FT-IR and 1H NMR spectroscopy to elucidate its structure. Further the effectiveness of ChH IL was examined in preventing MS corrosion in 5% HCl at 20–80 °C. The corrosion behavior of MS was examined using weight loss, potentiodynamic polarization, and EIS measurements. Increasing inhibitor concentration and temperatures improved the inhibition performance. The highest efficiency i.e., 98.16% was observed at 3.3 × 10−3 M of ChH at 60 °C. To verify the adsorption of ChH on the MS further investigations were done using FT-IR, Raman, and XPS analysis.

Experimental and theoretical insights into Artemisia Stems aqueous extract as a sustainable and eco-friendly corrosion inhibitor for mild steel in 1M HCl environment.

The present research demonstrates an innovative investigation of environmentally friendly mild steel (M-steel) corrosion inhibition using the artemisia stems aqueous extract (ASAEx) as an inhibitor in hydrochloric acid 1M. The standard extraction technique of hydrodistillation was used for producing the aqueous solutions of ASAEx. To assess the ratios of the chemical components, phytochemical screening was used to identify the stems of this plant. We used a variety of methods and techniques in our research on corrosion inhibition, including weight loss measures, surface analysis methods like XPS and SEM/EDS, electrochemical testing like PDP and EIS, as well as computational lead compound evaluation. Maximum inhibitory efficacy was achieved with 400mg/L ASAEx in 1M HCl at 303K, i.e. 90%. The PDP investigation verified the mixed-kind inhibitor status of the ASAEx extract. To describe the surface of M-steel, fitting and synthetic data were used to identify a constant phase element (CPE). SEM surface analysis was also used to detect the ASAEx effect on the surface of M-steel. X-ray photoelectron spectroscopy (XPS) analysis shows the presence of trace molecules of ASAEx on M-steel surface characterizing the bands in Maj-ASAEx (major compound of ASAEx). Density functional theory (DFT) and molecular dynamics simulations (MDs) were used in computational chemistry to clarify the adsorption mechanism and inhibitory impact.

Utilization of Extract from Bushcane (Costus Afer) as Green Corrosion Inhibitor for Mild Steel

Corrosion has adverse environmental consequences since it affects the manufacturing sector resulting in enormous economic loss. The corrosion characteristics and mechanism of mild in the solution of hydrochloric acid was studied. Extract of bush cane (Costus afer) was screened for physicochemical and phytochemical properties and utilized as corrosion inhibitor for mild steel, the process was optimized using Response Surface Methodology (RSM). The presence of OH, NH of alcohols, phenols, or substituents connected to aromatic rings, C=O for amides and ketones, C-N of aliphatic amines, and C=C of alkenes and nitriles were shown using Fourier Transform Infrared Spectroscopy (FTIR). The optimum condition was found by minimizing time, temperature, inhibitor concentration and corrosion rate while maximizing weight loss, and inhibitor efficiency. The results obtained revealed that the bush cane extract contain saponin, flavonoid, alkaloid and tannin, which suggests the potency of the extract as a good inhibitor as it contains a considerable amount of phytochemical with basic heteroatom. The statistical significance of the weight loss, corrosion rate and inhibitor efficiency were evaluated using the analysis of variance (ANOVA). it was observed that the regression was statistically significant at the F-value of 94.60, 25.87 and 4.72 respectively. P-value of > 0.0235, > 0.0001 and 0.0265 respectively. The optimum temperature, inhibitor concentration and contact time were found to be 27.9°C, 20.0% and 5 hours respectively at desirability value of 0.637. At this optimum condition, the weight loss was found to be 0.102%, corrosion rate was 1.583mg/cm<sup>2</sup>hr and inhibitor efficiency was 62.9%. From the results obtained in this experiment, It is concluded that the bushcane extract can be used as a corrosion inhibitor for the protection of mild steel.

Investigating the Effects of Urea-Zinc Sulfate-L Phenylalanine on the Corrosion Inhibition of Mild Steel Exposed to pH-4 Sulfuric Acid

Background: Corrosion of mild steel is a risk to material and stability. The practice of corrosion inhibitors is a cost-effective corrosion modification method for mild steel. Organic inhibitors rich in electrons might have an excellent ability to prevent corrosion. This study aims to assess the inhibitory effect of the mixture of Urea, Zinc Sulfate, and L-Phenylalanine, which has a high electron density Methods: MS corrosion was experimentally performed using H2SO4 at a pH of 4. Different gravimetric and conventional techniques, such as polarization, AC impedance AFM, UV, and fluorescence, were used to examine the studied data. Results: According to gravimetric measurements, this combination produced 93% effective inhibition. The findings of the impedance test proved that the mixture of inhibitors that was adsorbed on the metal surface effectively prevented corrosion. Conclusion: Likewise, according to the Polarization measurements, the inhibitor exhibits mixed-type performance with significant cathodic activity. UV, Fluorescence, and AFM findings showed that MS corrosion was suppressed because the inhibitor molecule adhered to the metal's surface and reduced.

Corrosion Inhibition Performance of Brachystegia eurycoma Leaf Extract on Mild Steel in Acid Media

The aim of this work is to investigate the corrosion inhibition of B. eurycoma leaves extract as a natural inhibitor for mild steel corrosion in 3 M H2SO4 solution. The corrosion inhibitory activity was analyzed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The surface roughness and its properties through scanning electron microscopy (SEM). The obtained result from EIS divulges that the gradual increase in inhibitor concentration and time of immersion leads to progressive increase in inhibition efficiency. At the end of 8 hours immersion time and inhibitor concentration of 1000 mg/l the highest inhibition efficiency of (88%) was obtained. The potentiodynamic polarization results indicated that addition of B. eurycoma leaves extracts hindered the reaction rates of anodic and cathodic reactions thereby performing as mixed- type inhibitor. The corrosion current density also revealed that in the presence of B. eurycoma leaves extracts the value of corrosion density reduced considerably from 265.2 \(\mu\) A/cm2 for sample without inhibitor to 67.8 \(\mu\) A/cm2 for sample with inhibitor. Again, it was observed that in the presence B. eurycoma leaves extracts the mechanism of hydrogen (effervescence) evolution was unique whereas the anodic dissolution of iron mechanism experienced the impact of the inhibitor. SEM inspection revealed that the mild steel surface showed smoother and lower damage in the presence of inhibitor. Obvious correlations were found between corrosion inhibition efficiency and some quantum chemical parameters such as energy of highest occupied molecular orbital (EHOMO), energy of lowest unoccupied molecular orbital (ELUMO), energy gap (EL–H) and electronic density etc. The obtained results were further elucidated with frontier molecular orbital theory.

In-situ biosynthesized plant exudate gums‑silver nanocomposites as corrosion inhibitors for mild steel in hydrochloric acid medium

Natural gums due to availability, multifunctionality, and nontoxicity are multifaceted in application. In corrosion inhibition applications, their performance, in unmodified form is unsatisfactory because of high hydration rate, solubility issues, algal and microbial contamination, as well as thermal instability. This work attempts to enhance the inhibitive performance of Berlinia grandiflora (BEG) and cashew (CEG) exudate gums through various modification approaches. The potential of biogenic BEG and CEG gums−silver (Ag) nanocomposites (NCPs) for corrosion inhibition of mild steel in 1 M HCl is studied. The nanocomposites were characterized using the FTIR, UV–vis, and TEM techniques. The corrosion studies through the gravimetric and electrochemical (PDP, EIS, LPR, and EFM) analyses reveal moderate inhibition performance by the nanocomposites. Furthermore, the PDP results reveal that both inhibitors are mixed-type with maximum corrosion inhibition efficiencies (IEs) of 61.2 % and 54.2 % for BEG-Ag NCP and CEG-Ag NCP, respectively at an optimum concentration of 1.0 %. Modification of these inhibitors with iodide ion (KI) significantly increased the IE values to 90.1 % and 88.5 % for BEG-Ag NCP and CEG-Ag NCP at the same concentration. Surface observation of the uninhibited and inhibited steel samples using SEM/EDAX, 3D Surface profilometer, and AFM affirm that the modified nanocomposites are highly effective.

Synthesis and characterization of a new eco-friendly dopamine derivative schiff base as an effective corrosion inhibitor for mild steel in acidic environment

The natural corrosion inhibitor behaviour of a newly synthesized dopamine derivative Schiff base (4-DBAB) has been inspected on mild steel in aggressive 1 M HCl using linear polarization, electrochemical impedance spectroscopy and potentiodynamic polarization techniques. The Schiff base was synthesized by eco-friendly pathway. Characterization of the synthesized new non-toxic inhibitor was performed using FT-IR and 1H-NMR spectroscopy techniques. The anti-corrosive efficiencies at optimum concentration of 4-DBAB inhibitor was 87.4% after 1 h and 98.4% after 120 h by impedance technique in acidic solution. The potential of zero charge of mild steel was also determined to elucidate the inhibition mechanism in the presence of the highest 4-DBAB solution. The atomic force microscopy and field emission scanning electron microscopy researches performed on surface morphology to provide additional support on the interaction between the mild steel surface and 4-DBAB molecules. Adsorption behaviour of the inhibitor was also studied at different durations by experimental inhibition results and showed the Langmuir isotherm involving chemisorption. Highlights A new dopamine-derived Schiff base (4-DBAB) with natural and environmentally friendly corrosion inhibition properties was synthesized. (Synthesis of eco-friendly compound). 4-DBAB demonstrated a high anti-corrosive efficiency after 120 hours in aggressive 1M HCl, as determined by impedance technique. (Exceptional corrosion inhibition). The determination of the potential of zero charge of mild steel provided insights into the inhibition mechanism in the presence of the highest 4-DBAB solution. (Mechanism elucidation). AFM and FE-SEM studies on surface morphology supported the interaction between the mild steel and 4-DBAB molecules, affirming its corrosion inhibition properties. (Surface interaction analysis).

Testing the inhibition efficiency of the castor oil leaf as corrosion inhibitor of mild steel in H2SO4

This study focused on the testing of castor oil leaf as corrosion inhibitor of mild steel in H2SO4. It involved the examination of the dynamics of molecular forces at the inhibitor and mild steel interface. Findings of the study will promote industrial diversification of castor oil leaf. On the experiment, bio-molecular compounds of the leaf were identified by gas chromatography mass spectrophotometer. Then, gravimetric and potentiodynamic polarization techniques were employed, where the efficacy and type of the inhibitor were determined. Considering the gravimetric process, factors of inhibitor concentration (0.2 g/L - 1.0 g/L), temperature (303 K – 333 K) and time (8 hrs – 24 hrs) were considered, with the inhibitor efficiency as the response. The efficiency was determined and optimized using response surface methodology (RSM) and artificial neural network (ANN). On the other hand, potentiodynamic polarization process was used to identify the type of inhibitor. Adsorption quantities were ascertained through the subjection of the experimental raw data to various adsorption isotherms. The analyses showed that castor oil leaf contains methyl nicotinate and pyridine-4-carbohydrazide. The bio-molecular compounds possess heteroatoms (N, S and O), signifying strong corrosion inhibitive tendencies. High efficiency (96.25 %) was obtained, with ANN having better prediction capability than the RSM. Potentiodynamic polarization curves revealed castor oil leaf as mixed-type inhibitor. On the adsorption phenomenon, the process of the inhibition was best fitted by Frumkin isotherm, revealing physical adsorption mechanism of Gibb’s free energy less than -40 kJ/mole. As a mixed-type inhibitor, castor oil leaf should be applied for mitigation of anodic and cathodic corrosion.

UV radiation effect on the corrosion inhibition potential of Helichrysum kraussii plant extract on mild steel metal in sulphuric acid medium

The comparison of the effect of UV-radiated and non-radiated Helichrysum kraussii (H. kraussii) extracts was studied for mild steel corrosion in 1.0 M H2SO4 at 30–60 °C using Liquid chromatography-mass spectrometry (LCMS), gravimetric weight loss analysis, electrochemical analysis and Fourier Transform Infrared spectroscopy (FTIR). The LCMS confirmed the trans-to-cis shift geometrical isomerisation for H. kraussii due to UV radiation. From the gravimetric analysis data, the corrosion rate was calculated and found to be decreasing with an increase in the concentration of the inhibitor extracts, with the highest concentration at 30 °C having a corrosion rate of 3.920x10-4 and 1.700x10-4 g.cm2.h−1 for UV-radiated. Non-radiated H. kraussii extract gave the highest inhibition efficiency of 96.663 % compared to 92.503 % of the UV-radiated H. kraussii extract. The semi-circles diameter of the Nyquist plot from the electrochemical impedance spectroscopy (EIS) was found to increase with an increase in the inhibitor concentration, suggesting the increase in inhibition with an increase in the concentration of the two extracts. Functional groups such as C = C, O-H, and N-H, known to be functional groups of the most effective corrosion inhibitors, were observed for both extracts from FTIR. Based on the results obtained, it was found that the UV-radiated H. kraussii extract was more effective in inhibiting the corrosion of mild steel in sulphuric acid than the non-radiated H. kraussii extract. This suggests that UV radiation decreases the efficiency of the H. kraussii extract as a corrosion inhibitor for mild steel in H2SO4. Therefore, it is recommended that the H. kraussii extract be used only as a corrosion inhibitor for mild steel in 1.0 M H2SO4 in its original state without being exposed to UV radiation

Exploring the efficacy of novel thiohydantoin derivatives with arylacetamide core as corrosion inhibitors for mild steel in acidic medium: insights from electrochemical analysis, comprehensive characterization, and quantum studies

Two new compounds of Thiohydantoin Derivatives N-(4-nitrophenyl)-2-((5-oxo-4,4-diphenyl-4,5-dihydro-1H-imidazole-2-yl)thio) acetamide and N-(4-fluorophenyl)-2-((5-oxo-4,4-diphenyl-4,5-dihydro-1H-imidazole-2-yl)thio) acetamide symbolized by NNOITAcetamide and N-FOITAcetamide respectively, were synthesized and characterized by NMR spectroscopy. Their effectiveness in inhibiting mild steel (M-S) corrosion in 1.0 M HCl at 298 K was investigated by potentiodynamic polarisation (PDP), electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM), and surface examinations via energy dispersive spectroscopy (EDS), and scanning electron microscopy (SEM) as well as X-ray photoelectron spectroscopy (XPS). Experimental results have been supported by theoretical studies such as Density Functional Theory (DFT) calculations and Monte Carlo (MC) simulation studies. All findings indicate that inhibitors have a considerable impact on lowering the rate of corrosion, and that the efficiency of the inhibitors rises with the concentration of the inhibitor. Experimental results revealed that the efficacy of the new thiohydantoin derivatives with an arylacetamide nucleus increased with increasing inhibitor concentration, where their inhibition efficiencies reached maximum values of 92.1 %, 94.1 %, for NNOITAcetamide and N-FOITAcetamide, at 10−3 M, respectively. In addition, the icorr decreased with increasing concentration up to 85 µA cm−2 and 58 for NNOITAcetamide and N-FOITAcetamide respectively, with a blank as a reference of 1045 µA cm−2, while the efficacy reduces as the temperature increases. The activation and thermodynamic parameters indicated that these products act via chemical adsorption on the mild steel surface. Furthermore, the surface analysis (SEM, EDS, and XPS) confirmed the formation of a protective layer adsorbed on the mild steel surface. Polarization curves indicated that NNOITAcetamide and N-FOITAcetamide are mixed-type inhibitors. Moreover, the quantum chemical calculation well supports the experimental results.

Origanum Grosii Extracts as Novel Eco-Friendly Corrosion Inhibitors for Mild Steel In HCl Medium.

Two green inhibitors extracted from an endemic species (Origanum grosii (Og)) using two solvents of different polarity (water and ethanol), OgW (aqueous extract) and OgE (ethanolic extract), were used for the anticorrosion of mild steel (M steel) in a 1 M HCl medium. Anticorrosive performance of OgW and OgE was assessed using standard electrochemical techniques, EIS/PDP measurements, weight loss method and SEM/EDX surface analysis. The results show that OgW achieves a maximum inhibition efficiency of 92 % and that the extract in aqueous medium (more polar) is more efficient than the extract in ethanolic medium (less polar). Both extracts act as mixed inhibitors and their corrosion process is predominantly governed by a charge transfer. Concentration and temperature effect was studied and shown that they are two antagonistic parameters for the evolution of inhibitory effectiveness of both OgW and OgE. The adsorption isotherms of the two inhibitors OgE and OgW obey to the Langmuir adsorption model. Moreover, the examination of SEM images and EDX spectra support a deposit of both extracts on the metal surface by an adsorption phenomenon. Besides, theoretical approach of the molecular structures of the major compounds M-OgW and M-OgE and inhibition efficiency was examined via DFT calculations and molecular dynamics simulations and it was consistent with the experimental findings.

Quinoline derivatives as corrosion inhibitors for mild steel in acid medium: Deeper insights from experimental, ab initio density functional theory modeling, and in silico ecotoxicity investigations

Two (E)-2-(((2-((7-chloroquinolin-4-yl)amino)ethyl)imino)methyl)-4-R-phenol Schiff bases derivatives CMN (R = NO2) and CMP (R = H) were successfully prepared. Then, CMN and CMP were evaluated as corrosion inhibitors for 1020 mild steel in 1.0molL–1 HCl using different methods. Gravimetric experiments have shown that CMN and CMP reach efficiencies of 80 and 91% at 1.45mmolL–1. Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) measurements have indicated the formation of a protective adsorbed film on the mild steel surface. Electrochemical Impedance Spectroscopy (EIS), Linear Polarization Resistance (LPR), Potentiodynamic Polarization (PP), and Electrochemical Frequency Modulation (EFM) have also shed some light on electrochemical behavior of compounds. These data have depicted better polarization resistance and lower corrosion current density in the presence of both organic molecules, also proving that the process is controlled by charge transfer and that CMN and CMP are mixed-type corrosion inhibitors. ab initio Density Functional Theory (DFT) investigated how two quinoline-based molecules (CMN and CMP) prevent corrosion on iron surfaces. Simulations revealed CMP bonds more strongly to iron than CMN, leading to better protection. Simulations also showed that these inhibitor molecules form a protective layer on the iron, slowing down the movement of corrosive substances. Environment risk assessment through QSAR-based models have indicated that the corrosion inhibitors do not have the potential to bioaccumulate in fish. Still, the acute and chronic toxicity values at the different trophic levels investigated call for attention for environmentally friendly structural optimization.

Corrosion inhibition of acid pickling –descaling-cleaning action on mild steel using aqueous hydroxyethyl cellulose

The corrosion inhibition capability of aqueous Hydroxyethyl cellulose (HEC) on mild steel corrosion in 1 M HCl solution proposed for mild steel pickling, industrial cleaning, and descaling was evaluated at different concentrations and immersion times using gravimetric measurement. HEC demonstrated efficiency in mild steel corrosion inhibition with a maximum inhibition efficiency of 87% for a 300 ml acid pickling, industrial cleaning, and descaling solution composed of 20% aqueous solution of 0.01 M HEC and 80% of 1 M HCl solution, within an immersion time of 120 hours. The inhibition efficiency was found to increase with the increase in the concentration of HEC implying that HEC’s inhibition action is concentration and time-dependent. The mechanism of adsorption of HEC was identified to be chemisorption with hydroxyl (-OH) moiety donated to the active sites of mild steel coupled with HEC molecules encapsulation of chloride ions on mild steel surface thus preventing the corrosive action of Cl ions on the mild steel.

Isoindigo derivatives as some potential corrosion inhibitors for mild steel in hydrochloric acid solution: Synthesis, experimental and theoretical studies

This investigation synthesized two isoindigo derivatives (IIDBr-NBr and IIDBr-MBr). These derivatives were then applied as green corrosion inhibitors for mild steel in a 1 mol L−1 HCl aqueous solution. The study investigated the corrosion inhibition performance of IIDBr-NBr and IIDBr-MBr through electrochemical and weight loss (WL) measurements, as well as surface analysis (SEM, AFM and XPS). The results showed that both IIDBr-NBr and IIDBr-MBr exhibited excellent corrosion inhibition performance (inhibition efficiency of 96.27 % for IIDBr-NBr and 96.46 % for IIDBr-MBr). Quantum chemical calculations based on density functional theory (DFT) and molecular dynamics (MD) were used to reveal the adsorption mechanisms of IIDBr-NBr and IIDBr-MBr at the steel/solution interface.

Self-forming barrier layer for carbon dioxide corrosion protection of mild steel in NaCl solution containing hydroxychavicol isolated from Piper betle L. leaf

Hydroxychavicol compound was isolated from Piper betle L. leaf and identified via preparative high performance liquid chromatography (Prep-HPLC) and nuclear magnetic resonance (NMR) spectroscopy. Hydroxychavicol compound was demonstrated to be a potential inhibitor for mild steel corrosion in carbon dioxide-containing environments due to the formation of a barrier layer on the steel surface. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) results indicated that the inclusion of hydroxychavicol in the aggressive environment made steel surfaces more homogeneous and smoother with a rough mean square roughness of 7.78 nm, whereas the steel surface was severely corroded in the blank solution. Moreover, X-ray photoelectron spectroscopy (XPS) results showed an enrichment of hydroxychavicol species combined with iron oxides and hydroxides on the mild steel surface. This can lead to the creation of a protective layer on the mild steel surface, thereby enhancing corrosion protection and localized inhibition. The work suggested a novel approach to isolate corrosion inhibitors from natural products, particularly agricultural by-products for mild steel in carbon dioxide and chloride ion environment with high inhibition performance.

Synthesis and evaluation of a novel pyridinyl thiazolidine derivative as an antioxidant and corrosion inhibitor for mild steel in acidic environments

A new synthesized (Z)-2-((3,5-dichloropyridin-2-yl)imino)thiazolidin-4-one (DICPT) was evaluated as an antioxidant and a corrosion inhibitor for mild steel (M.STL) in a 0.5 M HCl solution. The antioxidant activity of newly synthesized DICPT was screened using a DPPH assay, and the results showed that DICPT has good antioxidant activity. Electrochemical assessments were conducted utilizing potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). A new compound, DICPT, was synthesized, and its chemical structure was established and validated through various spectroscopic techniques, including including infrared (FTIR), nuclear magnetic resonance (NMR), and mass spectroscopy. PDP measurements revealed DICPT to be a mixed-type inhibitor. Charge transfer resistance (Rct) increased when inhibitor concentrations increased, according to EIS tests. The inhibition efficiency (%I) showed a corresponding rise with increasing inhibitor concentration, peaking at approximately 94.2 % at 3 × 10−5 M. Langmuir’s adsorption isotherm was found to govern the preferred adsorption mode of DICPT molecules onto the metal surface. UV–visible spectra confirmed the chemical interaction between DICPT molecules and the M.STL surface. AFM investigation indicated the formation of a protective layer on the metal surface, shielding it from corrosive environmental factors. Quantum chemical calculations were compared to experimental results to learn more about how corrosion is stopped and how well it works. Our study demonstrates the innovation of DICPT as a dual-function compound, offering both antioxidant and corrosion protection properties. This research contributes to the development of effective corrosion inhibitors for industrial applications.

Corrosion inhibition of mild steel by Praecitrullus fistulosus (tinda fruit and peel) extracts

Metal corrosion has recently emerged as a growing concern, impacting both local and industrial operations and disrupting conventional production methods. The utilization of green inhibitors to mitigate the metal degradation has garnered extensive attention from researchers and industrial professionals due to their prominent advantages: high efficiency, cost-effectiveness, and eco-friendliness. A novel ecofriendly inhibitor was prepared from Praecitrullus fistulosus (tinda fruit and peel) for mild steel (MS) corrosion in 1 M HCl. The presence of phenol, 3,5-bis (1,1-dimethyl ethyl)-, 9-octadecenoic acid, methyl ester, hexadecanoic acid 15-methyl-, methyl ester, 9, 12-octadecadienoic acid, methyl ester, 9, 12, 15-octadecatrienoic acid, methyl ester, (Z,Z,Z-), ascorbic acid, and phytol were identified as major constituent through LC/MS analysis of tinda extracts. The existence of these compounds was further confirmed through FTIR analysis, which shows the presence of various functional groups, such as -OH, CO, C-O-C, CC, and aromatic rings in the tinda extracts. Electrochemical and gravimetric analyses were used to investigate the inhibitory effect of tinda extracts. Outcomes of Tafel analysis revealed that both tinda extracts significantly reduced the corrosion current as compared to blank and achieved 83.73 % and 87.59 % inhibition efficiencies at 200 mg L−1 of tinda peel extract (TPE) and tinda fruit extract (TFE), respectively. The change in corrosion potential (Ecorr) was within an ±85 mV range compared to that of the uninhibited system, indicating that both tinda extracts demonstrated a mixed-type inhibition behavior. During adsorption studies, the best fit was obtained for the Langmuir adsorption model. The obtained values of standard Gibbs free energy (ΔG°ads) for TPE and TFE lie between −20 and − 40 kJ mol−1 but close to −20 kJ mol−1, which reveals preferential physical adsorption of the extracts on the metal surface. Thermodynamic parameters, including activation energy, enthalpy, and entropy, were computed across the temperature range of 303 to 323 K, suggesting that corrosion occurs spontaneously by the endothermic process. FESEM analysis depicted that inhibited systems exhibited smooth and crack-free surfaces as compared to blank system. AFM images demonstrated that surface roughness was significantly reduced for the inhibited system. In EDX analysis, the weight percentage of Cl was reduced in the presence of tinda extracts as compared to blank, and in XRD analysis, iron chloride (FeCl2) peak did not appear in the presence of inhibitor but it was in the uninhibited system. All surface-related findings signify that tinda extracts are adsorbed on the MS surface and form a protective layer that separates the metal from the corrosive solution.

Experimental and theoretical investigation of novel ammonium-derived dihydroxyl ionic liquid as corrosion inhibitor for mild steel in 1 M HCl: Effects of dihydroxyl and head groups

A novel ammonium-derived dihydroxyl ionic liquid ([C16DPOA]Br) and a control ionic liquid ([C16DPA]Br) are synthesized to reveal the effect of dihydroxyl and head groups on their inhibition property via the weight-loss method, surface analysis, electrochemical measurements, and adsorption isotherm studies. [C16DPOA]Br exhibits the optimal inhibition ability (93.47 %) for mild steel in 1 M HCl in contrast to [C16DPA]Br (88.03 %) and the traditional cationic surfactant CTAB (92.34 %). Based on the experimental results, it can be inferred that the short alkyl chain (propyl) impedes the tight alignment of [C16DPA]Br on the metal surface and the interactions between hydroxyl and iron atoms enable [C16DPOA]Br to overcome the negative effects of the short alkyl chain on the inhibition property. Finally, molecular electrostatic potential (MEP) distribution and molecular dynamics (MD) simulation verify the reactive sites and adsorption capacity of corrosion inhibitors from the microscopic scale, which further confirms the proposed mechanism. This study focuses on the significance of dihydroxyl and head groups on the inhibition property and provides unique insights into the development of efficient ionic liquid corrosion inhibitors.

Synthesis and Application Insights of New Phosphate Materials A2MnP2O7 (A = Na, K, Li) as Corrosion Inhibitors

This study comprehensively characterizes synthesized phosphate materials, specifically A2MnP2O7 (where A represents Na, K, or Li), utilizing the X-ray diffraction (XRD) and infrared (IR) spectroscopy techniques. The XRD results corroborate the crystalline nature of these compounds, while the IR spectra disclose pivotal structural characteristics, including the bent geometry of the POP bridge. A significant observation is the mismatch of specific IR bands, suggesting a non-centrosymmetric arrangement in the A2MnP2O7 crystal lattice. The synthesized materials were evaluated as corrosion inhibitors for mild steel (MS) in 3 wt.% NaCl. Electrochemical assessments indicate that these materials act as mixed-type inhibitors, demonstrating high inhibition efficiencies (η%), reaching peak values of 88.3% for Na2MnP2O7, 87% for K2MnP2O7, and 86.7% for Li2MnP2O7 at a concentration of 10−3 mol/L. The study also elucidates the thermodynamic and kinetic parameters dictating the inhibition phenomena. Additionally, scanning electron microscopy (SEM) was employed to examine the surface morphology of mild steel in the presence of these inhibitors.