Solvent-free synthesis and corrosion inhibition performance of Ethyl 2-(1,2,3,6-tetrahydro-6-oxo-2-thioxopyrimidin-4-yl)ethanoate on carbon steel in pickling acids: Experimental, quantum chemical and Monte Carlo simulation studies

Electrochemical behavior and theoretical studies of arylazo (1-naphthyl-2-cyanoacetamide) derivatives as new corrosion inhibitors for Inconel 800 in chloride solution

In this study, synthesize and insight the corrosion inhibition properties of two novel derivatives of 1-naphthyl-2-cyanoacetamide (NCDs) [2-cyano-2-((5,6-dimethyl-1H-benzo[d]imidazol-2-yl) diazenyl)-N (naphthalene-1-yl)acetamide] (NCD1) and [2-Cyano-N-(naphthalene-1-yl)-2-[(4,6-dimethyl-1H-pyrazolo [3, 4-b] pyridine-3-yl) hydrazono] acetamide] (NCD2). The characterization of the synthesized NCDs was confirmed through the utilization of Mass fragmentation analysis, 1H-NMR, and IR. The corrosion inhibition performance of NCDs as a novel and environmentally safe corrosion inhibitor has been investigated by electrochemical techniques, a chemical technique, and theoretical studies for its anti-corrosion behavior of Inconel 800 in chloride medium. In addition, the surface morphology and inhibitor adsorption on the Inconel 800 surface were confirmed utilizing SEM, EDX, FTIR, and AFM. The advantages of NCDs include their low toxicity, environmental friendliness, ease of preparation, low odor, contain (N, O, and π-Bonds), and the inhibition efficiency elevated with decreasing solution temperature as well as inhibitor dose increase, yielding increased efficiencies of 91.8% and 95.7% for NCD1 and NCD2, respectively, at the optimum concentration of 21 × 10-6 mol. L-1 and 298 K temperature. An analysis of Tafel plots reveals that NCDs adhere to a mixed and isothermal Langmuir adsorption mechanism. Density Functional Theory (DFT) and Monte Carlo (MC) simulation manifest the two compounds of NCDs can be adsorbed at the Fe (110) surface in a paralleled way, and can have a smaller energy gap (ΔE) value and exhibit higher efficiency. The experimental and theoretical findings confirm that the synthesized compounds obtained are capable of protecting the Inconel 800 from corrosion by creating an anti-corrosion coating on the surface.

Green Synthesizing and Corrosion Inhibition Characteristics of Azo Compounds on Carbon Steel under Sweet Conditions: Experimental and Theoretical Approaches

The deterioration of carbon steel in saline solutions enriched with carbon dioxide represents a significant challenge within the oil and gas industry. So, this study focuses on the design and structural analysis of four azo derivatives: 4-(2-quinolinylazo)-catechol (AZN-1), 4-(4-phenoxyphenylazo)-1-naphthol (AZN-2), 4-(4-pyridylazo)-1-naphthol (AZN-3), and 4-(2-pyridylazo)-1-naphthol (AZN-4), and their first application as effective corrosion inhibitors for carbon steel in a carbon dioxide saturated 3.5% sodium chloride solution. Spectroscopic methods were used to characterize the structural configurations of these compounds. The corrosion protection properties of these compounds on carbon steel in a carbon dioxide saturated 3.5% sodium chloride solution (under sweet conditions) were investigated using Tafel polarization (PDP), electrochemical impedance spectroscopy (EIS), and field emission-scanning electron microscopy (FE-SEM) studies. The results indicate that the inhibition efficiency increases as the concentration of the inhibitors increases. There is a notable agreement between the results obtained from the PDP and EIS measurements, supporting the findings. Moreover, the results displayed that these compounds had significant corrosion protection capabilities at low concentrations, ranging from 91.0 to 98.3% at an additive concentration of 5 × 10-4 M. The PDP profiles showed that these compounds acted as mixed inhibitors, and their adsorption behavior followed the Langmuir isotherm model. Besides, EIS results corroborate the adsorption of AZN compounds through a reduction in double-layer capacitance (Cdl) alongside an augmentation in polarization resistance (Rp) after the addition of AZN compounds into the corrosive solution. Field emission scanning electron microscopy (FE-SEM) and Fourier-transform infrared spectroscopy (FTIR) analysis confirmed the formation of a protective layer on the surface of carbon steel when these inhibitors were applied. In addition, computational calculations and Monte Carlo simulations were performed to support the experimental observations, gain insights into the adsorption properties, and elucidate the corrosion inhibition mechanisms of these compounds.

Bishydrazone ligand and its Zn-complex: synthesis, characterization and estimation of scalability inhibition mitigation effectiveness for API 5L X70 carbon steel in 3.5% NaCl solutions

Bishydrazone ligand, 2,2'-thiobis(N'-((E)-thiophen-2-ylmethylene) acetohydrazide), H2TTAH and its Zn- complex were prepared and characterized through elemental analysis and various spectroscopic performances as well as (IR, 1H and 13C NMR, mass and (UV-Vis) measurements. The synthesized complex exhibited the molecular formula [Zn2(H2TTAH)(OH)4(C5H5N)3C2H5OH] (Zn-H2TTAH). To assess their potential as anti-corrosion materials, the synthesized particles were assessed for their effectiveness for API 5L X70 C-steel corrosion in a 3.5% NaCl solution using electrochemical methods such as potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS). Additionally, X-ray photoelectron spectroscopy (XPS) was employed to examine the steel surface treated with the tested inhibitors, confirming the establishment of an adsorbed protecting layer. The results obtained from the PP plots indicated that both H2TTAH and Zn-H2TTAH act as mixed-type inhibitors. At a maximum concentration of 1 × 10-4 M, H2TTAH and Zn-H2TTAH exhibited inhibition efficiencies of 93.4% and 96.1%, respectively. The adsorption of these inhibitors on the steel surface followed the Langmuir adsorption isotherm, and it was determined to be chemisorption. DFT calculations were achieved to regulate the electron donation ability of H2TTAH and Zn-H2TTAH molecules. Additionally, Monte Carlo (MC) simulations were conducted to validate the adsorption configurations on the steel surface and gain insight into the corrosion inhibition mechanism facilitated by these molecules.

Design of New Ecofriendly Schiff Base Inhibitors for Carbon Steel Corrosion Protection in Acidic Solutions: Electrochemical, Surface, and Theoretical Studies

Corrosion poses a significant problem for several industrial sectors, inducing continuous research and development of corrosion inhibitors for use across a wide range of industrial applications. Here, we report the effectiveness of three newly developed Schiff bases derived from amino acids and 4-aminoacetophenone, namely, AIP, AMB, and AImP, as environmentally friendly corrosion inhibitors for Q235 steel in hydrochloric acid using electrochemical and surface analyses, in addition to theoretical techniques. The electrochemical findings of potentiodynamic polarization (PDP) demonstrated that the explored compounds serve as mixed-type inhibitors and can effectively suppress steel corrosion, with maximal protection efficiencies of 93.15, 96.01, and 77.03% in the presence of AIP, AMB, and AImP, respectively, at a concentration of 10 mM. The electrochemical impedance spectroscopy (EIS) and polarization results confirmed the growth of a durable protective barrier on the steel surface in the existence of the inhibitors, which is responsible for decreasing the metallic dissolution. Results were further supported by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), UV-vis, and Fourier transform infrared (FTIR), which ascribed the development of inhibitor-adsorption films on the steel surface. The results of EDS and XPS analyses demonstrated the existence of the distinctive elements of the inhibitors on the metallic surface. Furthermore, density functional theory (DFT) calculations and Monte Carlo (MC) simulations showed the electronic structure of the examined inhibitors and their optimized adsorption configurations on the steel surface, which helped in explaining the anticorrosion mechanism. Finally, the theoretical and experimental findings exhibit a high degree of consistency.

Evaluation of ionic liquids based imidazolium salts as an environmentally friendly corrosion inhibitors for carbon steel in HCl solutions

The features of this work on corrosion inhibition have been investigated based on the ecological awareness and according to the strict environmental legislations. This was done by studying how different imidazolium derivatives ionic liquids containing different alkyl chains R8, R10 and R12 affected the corrosion reaction of carbon steel specimen immersed in 1 M hydrochloric acid at various temperatures. Weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy were utilized to examine the corrosion inhibition behavior on carbon steel. In addition, FT-IR spectroscopy was used to analyze the coated film that has been formed on the metal surface. The prepared ionic liquids showed effective inhibition efficiency, where the corrosion rate after the using of 100 ppm of R8-IL, R10-IL and R12-IL was decreased from 5.95 (µg cm-2 min-1) to 0.66, 0.56, and 0.44 (µg cm-2 min-1), respectively at 20 °C. In the polarization curves, the corrosion current, Icorr, decreases by ILs addition and suggest that ILs act as mixed type inhibitors. From EIS findings, the increase in Rct and decrease in Cdl values proves the adherence of inhibitor molecules on carbon steel surface. The temperature effect was also studied on the film formed, where increasing the temperature from 20 to 50 °C, the corrosion rate increased and the inhibitors efficacy decreased. The increasing in the length of the attached alkyl chain, the efficacies of the prepared inhibitors increases. Various thermodynamic parameters such as the reaction activation free energy (ΔG*), the entropy of activation (ΔS*), and the enthalpy of activation (ΔH*), as well as the adsorption isotherm were investigated in order to interpret the mechanism and obtain the most accurate perception.

Electrochemical Investigation of C-Steel Corrosion Inhibition, In Silico, and Sulfate-Reducing Bacteria Investigations Using Pyrazole Derivatives

The inhibitory impact of the two synthesized pyrazole derivatives (3 and 4) toward metallic and microbial corrosion was investigated. Using open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy, it was possible to determine their ability to prevent the corrosion of C-steel in 1 M HCl, which was significantly enhanced with increasing concentration (ex. 93%). They act as mixed-type inhibitors, according to polarization curves. The compounds under investigation were adsorbed on a C-steel surface in 1 M HCl following the Langmuir isotherm model. The double-layer capacitance was decreased, and the charge transfer resistance (Rct) was raised due to the examined inhibitors' adsorption. Investigating changes in the surface morphology and confirming the corrosion inhibition mechanism are done using scanning electron microscopy. Density functional theory calculations and Monte Carlo simulations were also conducted to show the adsorption affinity of the understudied compounds over the steel substrate in neutral and protonated forms. Furthermore, the antimicrobial performance of the two synthesized pyrazoles against sulfate-reducing bacteria was evaluated, and the recorded inhibition efficiency was 100%. The current research shows important developments in producing highly effective anticorrosion and antimicrobial pyrazole derivatives.

Novel Imine-Tethering Cationic Surfactants: Synthesis, Surface Activity, and Investigation of the Corrosion Mitigation Impact on Carbon Steel in Acidic Chloride Medium via Various Techniques

Novel imine-tethering cationic surfactants, namely (E)-3-((2-chlorobenzylidene)amino)-N-(2-(decyloxy)-2-oxoethyl)-N,N-dimethylpropan-1-aminium chloride (ICS-10) and (E)-3-((2-chlorobenzylidene)amino)-N,N-dimethyl-N-(2-oxo-2-(tetradecyloxy)ethyl)propan-1-aminium chloride (ICS-14), were synthesized, and the chemical structures were elucidated by various spectroscopic approaches. The surface properties of the target-prepared imine-tethering cationic surfactants were investigated. The effects of both synthesized imine surfactants on carbon steel corrosion in a 1.0 M HCl solution were investigated by weight loss (WL), potentiodynamic polarization (PDP), and scanning electron microscopy (SEM) methods. The outcomes show that the inhibition effectiveness rises with raising the concentration and diminishes with raising the temperature. The inhibition efficiency of 91.53 and 94.58 % were attained in the presence of the optimum concentration of 0.5 mM of ICS-10 and ICS-14, respectively. The activation energy (E_a) and heat of adsorption (Q_ads) were calculated and explained. Additionally, the synthesized compounds were investigated using density functional theory (DFT). Monte Carlo (MC) simulation was utilized to understand the mechanism of adsorption of inhibitors on the Fe (110) surface.

Anticorrosion Evaluation of Novel Water-Soluble Schiff Base Molecules for C1018 Steel in CO2-Saturated Brine by Computational and Experimental Methodologies

In this work, three different derivatives of Schiff base, as mono- and di-Schiff bases, were successfully synthesized by the facile condensation of 2-aminopyridine, o-phenylenediamine, or 4-chloro-o-phenylenediamine with sodium salicylaldehyde-5-sulfonate (H1, H2, and H3, respectively). A combination of theoretical and practical studies was accomplished on the corrosion mitigation effect of the prepared Schiff base derivatives on C1018 steel in CO₂-saturated 3.5% NaCl solution. The corrosion inhibition effect of the synthesized Schiff base molecules was studied by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) methods. The outcomes exhibited that Schiff base derivatives have an outstanding corrosion inhibition effect on carbon steel at particularly low concentrations in sweet conditions. The outcomes showed that Schiff base derivatives exhibited a satisfactory inhibition efficiency of 96.5% (H1), 97.7% (H2), and 98.1% (H3) with a dosage of 0.5 mM at 323 K. SEM/EDX analysis confirms the adsorbed inhibitor film's formation on the metal surface. The polarization plots indicate that the studied compounds behaved as inhibitors of the mixed type according to the isotherm model of Langmuir. The computational inspections (MD simulations and DFT calculations) display a good correlation with the investigational findings. The outcomes could be applied to assess the efficiency of the inhibiting agents in the gas and oil industry.

Advanced Protective Films Based on Binary ZnO-NiO@polyaniline Nanocomposite for Acidic Chloride Steel Corrosion: An Integrated Study of Theoretical and Practical Investigations

Due to their thermal stability characteristics, polymer/composite materials have typically been employed as corrosion inhibitors in a variety of industries, including the maritime, oil, and engineering sectors. Herein, protective films based on binary ZnO-NiO@polyaniline (ZnNiO@PANE) nanocomposite were intended with a respectable yield. The produced nanocomposite was described using a variety of spectroscopic characterization methods, including dynamic light scattering (DLS), ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) approaches, in addition to other physicochemical methods, including X-ray powder diffraction (XRD), transmission Electron Microscopy (TEM), field emission scanning electron microscopy (FESEM), and selected area electron diffraction (SAED). By using open-circuit potentials (OCP) vs. time, electrochemical impedance spectroscopic (EIS), and potentiodynamic polarization (PDP) methods, the inhibitory effects of individual PANE and ZnNiO@PANE on the mild steel alloy corrosion in HCl/NaCl solution were assessed. The ZnNiO@PANE composite performed as mixed-type inhibitors, according to PDP findings. PANE polymer and ZnNiO@PANE composite at an optimal dose of 200 mg/L each produced protective abilities of 84.64% and 97.89%, respectively. The Langmuir isotherm model is used to explain the adsorption of ZnNiO@PANE onto MS alloy. DFT calculations showed that the prepared materials' efficiency accurately reflects their ability to contribute electrons, whereas Monte Carlo (MC) simulations showed that the suitability and extent of adsorption of the ZnNiO@PANE molecule at the metal interface determine the materials' corrosion protection process.

Synthesis and Characterization of the Mixed Metal Oxide of ZnO-TiO2 Decorated by Polyaniline as a Protective Film for Acidic Steel Corrosion: Experimental, and Computational Inspections

In this work, the preparation, characterization, and evaluation of a novel nanocomposite using polyaniline (PANi) functionalized bi-metal oxide ZnO-TiO₂ (ZnTiO@PANi) as shielding film for carbon steel (CS)-alloy in acidic chloride solution at 298 K was studied. Different spectroscopic characterization techniques, such as UV-visible spectroscopy, dynamic light scattering (DLS), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR) approaches, as well as other physicochemical methods, such as X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), and field emission scanning electron microscope (FESEM), were used to describe the produced nanocomposites. The significance of these films lies in the ZnO-TiO₂ nanoparticle's functionalization by polyaniline, a material with high conductivity and electrochemical stability in acidic solutions. The mechanistic findings of the corrosion inhibition method were obtained by the use of electrochemical methods including open-circuit potentials (OCP) vs. time, potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). The results indicate that the synthesized ZnTiO@PANi is a powerful acidic corrosion inhibitor, and its inhibition effectiveness is 98.86% in the presence of 100 ppm. Additionally, the charge transfer resistance (R_p) value augmented from 51.8 to 432.7, and 963.7 Ω cm² when the dose of PANi, and ZnTiO@PANi reached 100 ppm, respectively. The improvement in R_p and inhibition capacity values with an increase in nanocomposite dose is produced by the nanocomposite additives covering a larger portion of the surface, resulting in a decrease in alloy corrosion. By identifying the probable regions for molecule adsorption on the steel substrate, theoretical and computational studies provided significant details regarding the corrosion mitigation mechanism. The possibility of substituting old poisonous small substances with inexpensive and non-hazardous polymeric materials as shielding layers for utilization in the oilfield sectors is an important suggestion made by this research.

Gravimetric and electrochemical statistical optimizations for improving copper corrosion resistance in hydrochloric acid using thiosemicarbazone-linked 3-acetylpyridine

Thiosemicarbazone-linked 3-acetylpyridine (T3AP), was synthesized and tested on copper strips in hydrochloric acid. Gravimetric measurements and electrochemical impedance spectroscopy were used to investigate the optimized inhibitory behavior of T3AP using the response surface methodology (RSM), with the optimized result obtained using a temperature of 42.90 °C, acid concentration of 2.38 M, inhibitor concentration of 3.80 mM, and time of 18.97 h, with inhibition efficiency up to approximately 93%. Validation of the experimental and predicted RSM showed that no significant difference in the inhibition efficiency with the confidence level value up to 97% was obtained. The isotherm study shows that T3AP obeys the Langmuir isotherm adsorption model, with physisorption and chemisorption adsorption mechanisms. The effectiveness of inhibitor performance of T3AP can be visually observed using scanning electron microscopy and X-ray photoelectron spectroscopy. The characterization revealed that the reactive S and N atoms in the T3AP inhibitor form strong chemical adsorption through N-Cu and Cu-S bonds on the copper surface. Computational analysis was also carried out, and we found that the stable energy gap between the occupied and unoccupied molecular orbitals (4.6891 eV) and high binding energy (540.962 kJ mol-1) adsorption from molecular dynamics were in agreement with the experimental findings.

Facile Synthesis and Characterization of CeO2-Nanoparticle-Loaded Carboxymethyl Cellulose as Efficient Protective Films for Mild Steel: A Comparative Study of Experiential and Computational Findings

Corrosion is considered to be the most severe problem facing alloys and metals, one that causes potentially dangerous industrial issues such as the deterioration of buildings and machinery, and corrosion in factory tanks and pipelines in petroleum refineries, leading to limited lifetime and weak efficacy of such systems. In this work, novel CeO₂-nanoparticle-loaded carboxymethyl cellulose (CMC) was successfully prepared by using a simple method. The structural configuration of the prepared CeO₂-nanoparticle-loaded CMC was investigated by FE-SEM/EDX, TEM, FT-IR, and thermal analyses. The corrosion protection proficiency of uncoated and coated mild steel with CeO₂-CMC systems in 1.0 M HCl solutions was studied by E_OCP-time, EIS, and PDP tools. Moreover, the relationship between the structure of coating films and their corrosion protection was confirmed by DFT calculation and MC simulation. The obtained findings from the studied methods showed that the prepared CeO₂-CMC-coated films reported high corrosion resistance. The protection capacity augmented with ceria presents an increase of up to 3% to achieve 98.4%. DFT calculation and MC simulation confirmed the influence of the chemical construction of coated films on its protection capacity, which was in accordance with the experimental results.

Efficient Synthesis of 6,7-Dihydro-5H-cyclopenta[b]pyridine-3-carbonitrile Compounds and Their Applicability As Inhibitor Films for Steel Alloy Corrosion: Collective Computational and Practical Approaches

An effective method for designing new heterocyclic compounds of 6,7-dihydro-5H-cyclopenta[b]pyridine-3-carbonitrile derivatives (CAPDs) was presented through cyclocondensation reaction between 2,5-diarylidenecyclopentanone derivatives and propanedinitrile, and the cyclocondensation reaction succeeded using a sodium alkoxide solution (sodium ethoxide or sodium methoxide) as the reagent and the catalyst. The synthesized CAPD derivatives were employed as novel inhibitors for carbon steel (CS) corrosion in a molar H2SO4 medium. The corrosion protection proficiency was investigated by electrochemical measurements (open circuit potential vs time (E OCP vs t), potentiodynamic polarization plots (PDP), and electrochemical impedance spectroscopy (EIS)) and surface morphology (scanning electron microscopy (SEM)) examinations. The results show that the CAPD derivatives exhibit mixed type inhibitors and a superior inhibition efficiency of 97.7% in the presence of 1.0 mM CAPD-1. The adsorption of CAPD derivatives on the CS interface follows the Langmuir isotherm model, including physisorption and chemisorption. Scanning electron microscopy (SEM) exploration confirmed the adsorption of the CAPD derivatives on the CS substrate. Monte Carlo (MC) simulations and DFT calculations revealed that the efficacy of the CAPD molecules correlates well with their structures, and this protection was attributed to their adsorption on the CS surface.

Experimental and In-Silico Computational Modeling of Cerium Oxide Nanoparticles Functionalized by Gelatin as an Eco-Friendly Anti-Corrosion Barrier on X60 Steel Alloys in Acidic Environments

An eco-friendly and a facile route successfully prepared novel cerium oxide nanoparticles functionalized by gelatin. The introduced CeO₂@gelatin was investigated in terms of FE-SEM, EDX, TEM, chemical mapping, FT-IR, and (TGA) thermal analyses. These characterization tools indicate the successful synthesis of a material having CeO₂ and gelatin as a composite material. The prepared composite CeO₂@gelatin was used as an environment-friendly coated film or X60 steel alloys in acidizing oil well medium. Moreover, the effect of CeO₂ percent on film composition was investigated. LPR corrosion rate, E_ocp-time, EIS, and PDP tools determined the corrosion protection capacity. The CeO₂@gelatin composite exhibited high protection capacity compared to pure gelatin; in particular, 5.0% CeO₂@gelatin coating film shows the highest protection capacity (98.2%), with long-term anti-corrosive features. The % CeO₂@gelatin-coated films formed the protective adsorbed layer on the steel interface by developing a strong bond among nitrogen atoms in the CeO₂@gelatin film and the electrode interface. Surface morphology using FESEM measurements confirmed the high efficiency of the fabricated CeO₂@gelatin composite on the protection X60 steel alloys. DFT calculations and MC simulations were explored to study the relations between the protection action and the molecular construction of the coated systems, which were in good alignment with the empirical findings.

Synthesis and characterization of novel dicarbohydrazide derivatives with electrochemical and theoretical approaches as potential corrosion inhibitors for N80 steel in a 3.5% NaCl solution

Two novel ethanoanthracene-11,12-dicarbohydrazide derivatives N'11,N'12-bis((Z)-4-hydroxybenzylidene)-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarbohydrazide (H2HEH) and N'11,N'12-bis((Z)-4-methoxybenzylidene)-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarbohydrazide (H2MEH) were synthesized and characterized by FT-IR spectroscopy, electronic spectra, and NMR spectroscopy. These two derivatives as novel anticorrosion inhibitors for N80 steel in a 3.5% NaCl solution were studied using electrochemical techniques including potentiodynamic polarization (PP), electrochemical impedance spectroscopy (EIS), and electrochemical frequency modulation (EFM). Corrosion parameters and adsorption isotherms were determined from current-potential diagrams (i.e., Tafel slopes). The impact of temperature and inhibitor concentration on the corrosion performance was studied using the PP method. The PP results suggested mixed-type inhibitors. The inhibition prohibition increased and decreased when the dose was increased and the temperature was increased, respectively. The adsorption of the hydrazides on the N80 exterior followed the Langmuir isotherm. The maximum inhibition proficiency for H2MEH and H2HEH were 93.3% and 92.2%, respectively, at 1 × 10-4 M. Moreover, the investigated surface was studied with the synthesized compounds through X-ray photoelectron spectroscopy (XPS) to confirm the construction of an adsorbed shielding barrier. An evident association was established between the corrosion inhibition proficiency and theoretical variables acquired using the density functional theory (DFT) method and Monte Carlo (MC) simulations. The experimental data were in good agreement with the theoretical results.

5-Arylidene-1,3-dialkylbarbituric acid derivatives as efficient corrosion inhibitors for carbon steel in molar hydrochloric acid solution

The inhibiting impact of two ecofriendly 5-arylidene barbituric acid derivatives (5-ABA), namely 5-(3,4-dimethoxybenzylidene)-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione (inhibitor I, 3a) and 5-(3,4-dimethoxybenzylidene)-1,3-diethyl-2-thioxodihydropyrimidine-4,6(1H,5H)-dione (inhibitor II, 3b), in 1 M HCl on the corrosion of carbon steel has been examined via the weight loss (WL) method, potentiodynamic polarization (PP), electrochemical impedance spectroscopy (EIS), and electrochemical frequency modulation (EFM) tests. In addition, DFT calculations and MC simulations were used to study the relationship between the inhibitor structure and its inhibition performance. The attained outcomes exhibit that the investigated compounds are excellent inhibitors and their inhibition efficiency (%IE) increases with the increase in the concentration and temperature. The adsorption of 5-arylidene barbituric acid on the C-steel surface was found to follow the Langmuir adsorption isotherm. The adsorption process of the investigated compounds is spontaneous and considered as the chemisorption type. The PP curves revealed that 5-arylidene barbituric acid derivatives are mixed-type inhibitors. Moreover, the EIS results confirmed the adsorption of 5-arylidene barbituric acid derivatives on the C-steel surface by increasing the charge transfer resistance (R ct) values. The %IE of the inhibitors (II & I) reached 92.8% and 86.6% at a concentration of 21 × 10-6 M, according to the WL method. The surface analysis of the C-steel surface was confirmed by scanning electron microscopy and energy dispersive X-ray techniques. Finally, the experimental and theoretical results are in good agreement.

Comparative Computational Study of L-Amino Acids as Green Corrosion Inhibitors for Mild Steel

This research evaluates the inhibitory effect of L-amino acids (AAs) with different side chain lengths on Fe (100) surfaces implementing Monte Carlo (MC) simulation. A quantitative and qualitative description of the adsorption behavior of AAs on the iron surface has been carried out. Calculations have shown that the absolute values of the adsorption energy of L-amino acids increase with side chain prolongation; they are also determined by the presence of heteroatoms. The maximum absolute value of the adsorption energy AAs on the iron surface in accordance with the side chain classification increases in the following sequence: Glu (acidic) < Gln (polar) < Trp (nonpolar) < Arg (basic). AAs from nonpolar and basic groups have the best adsorption ability to the iron surface, which indicates their highest inhibitory efficiency according to the results of the MC simulation. The calculation results agree with the experimental data.

Experimental and computational investigations on the anti-corrosive and adsorption behavior of 7-N,N'-dialkyaminomethyl-8-Hydroxyquinolines on C40E steel surface in acidic medium

Two new 7-N,N'-dialkylaminomethyl-8-Hydroxyquinolines, namely 7-N,N'-dipropylaminomethyl-8-Hydroxyquinoline (DPQ) and 7-N,N'-dimethylaminomethyl-8-Hydroxyquinoline (DMQ), were synthesized and characterized using ¹H/¹³C NMR and Elemental analysis methods. Corrosion inhibition effect of DMP and DPQ for C40E steel in 1 M HCl was evaluated at different concentrations (10^-3 to 10^-6M) and temperatures (298 to 328 K) using several experimental and computational approaches. Weight loss and electrochemical studies showed that protection efficiencies (η_max) of DPQ and DMQ increase with increase in concentrations. The DPQ and DMQ showed maximum efficiencies of 96.1% and 94.4%, respectivelyat 10^-3 M. Polarization measurements showed that DMQ and DPQ act as mixed type corrosion inhibitors. Adsorption of DPQ and DMQ on C40E steel in 1 M HCl obeyed the Langmuir adsorption isotherm. Variation in surface morphology of corroded metallic surface with and without DMQ and DPQ was demonstrated using scanning electron microscopy. Molecular dynamics (MD) simulations studies showed that DPQ and DMQ acquire the flat or horizontal orientation over the C40E steel. DFT analyses revealed that both DPQ and DMQ interact with the C40E steelusing electron-sharing(donor-acceptor)mechanism. Computational analyses conducted using DFT and MD simulations well corroborate the experimental results.

Adsorption and Corrosion Performance of New Cationic Gemini Surfactants Derivatives of Fatty Amido Ethyl Aminium Chloride with Ester Spacer for Mild Steel in Acidic Solutions

Three new cationic gemini surfactants with ester spacer type 2-2′-(ethane-1,2-diyl bis(oxy)) bis(N-(2-alkanamidoethyl)-N,N-dimethyl-2-oxoethan-1-aminium)) dichloride) (CGSES12, CGSES14 and CGSES16), based on N,N-dimethyl fatty amido ethylamine, were produced. These gemini quaternary ammonium salts were synthesized using a three-step reaction method, starting from th/e condensation of the fatty acid chloride (RCOCl) of various hydrophobic chain lengths (R, C₁₁H₂₃, C₁₃H₂₇, C₁₅H₃₁) with N,N-dimethyl ethylene diamine, followed by the quaternization of the tertiary amino group formed with the spacer of the ester group formed in the second step. The chemical configuration of the surfactants was established by FT-IR, ¹HNMR, ¹³CNMR and Mass spectroscopies. The inhibition performance of three surfactants was studied by weight loss and electrochemical measurements. The results show that CGSES12, CGSES14 and CGSES16 behave as effective inhibitors and surface agents. The maximum efficiency was higher than 94% at 2.5 mM, and the inhibition order was CGSES16 > CGSES14 > CGSES12. This was due to the increment in hydrophobicity of the gemini surfactants. Their adsorption on a mild steel surface followed the Langmuir isotherm. CGSES12, CGSES14 and CGSES16 can be considered mixed-type inhibitors. The presence of CGSES12, CGSES14 and CGSES16 increased charge transfer resistance and decreased the corrosion rate. The adsorption focused on heteroatoms and the surface properties of cationic gemini surfactants.

Corrosion inhibition of carbon steel in hydrochloric acid solution using newly synthesized urea-based cationic fluorosurfactants: experimental and computational investigations

The results of this report show that synthesized fluorosurfactants can be applied as effective corrosion inhibitors with good anticorrosion properties for hydrochloric acid pickling of carbon steel.