Experimental and theoretical studies for corrosion inhibition of carbon steel by imidazoline derivative in 5% NaCl saturated Ca(OH)2 solution

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.

Comprehensive analysis (aerobic/anaerobic, molecular recognitions, band-position and degradation-mechanism) of undoped and Co-doped anatase-brookite - An experimental/theoretical evaluation of the less-studied TiO2 mixed phase

The molecular recognition (MRec) effect is required in the initial phase of organic reactions. The second stage involves molecular-orientations and molecular-orbitals energy-levels (MOrbE). The components of a reaction must be compatible in terms MRec and MOrbE. Therefore, the comprehension of photocatalytic systems applied in wastewater treatment will be improved if the MRec effect is also considered as an important factor. The purpose of this study is to provide a comprehensive understanding of the less studied anatase-brookite mixed-phase (doped and undoped). Anatase/brookite photocatalytic systems were evaluated utilizing experimental/theoretical approaches in H₂O (aerobic/anaerobic) environments with Vis-light and the organic pollutant (OrPo) methyl orange (MO). The compatibility of MRec and MOrbE of anatase-brookite mixed-phase (with the different reactive system components) confirmed this is the optimal combination for photocatalytic application. Using the sol-gel method, AM-TiO₂NP (amorphous), TiO₂NP (crystalline), and TiO₂NP-Co0.1 at% (crystalline Co-doped) anatase-brookite mixed-phase photocatalysts were obtained. The morphology and surface were characterized using XRD, BET, SEM, HR-TEM, FT-IR and XPS. Employing UV-vis DRS and PL, photo-response and electron-hole recombination were studied. LVS and Mott-Schottky plot were employed to determine photo-electrochemical activity. The results of TiO₂NP photocatalytic degradation in both aerobic and anaerobic environments are remarkable. The results of molecular dynamics (MD) simulation and Fukui Function (FF) based on density functional theory (DFT) validate the remarkable photocatalytic MO degradation.

A pH-Controlled Solid Inhibitor Based on PAM Hydrogel for Steel Corrosion Protection in Wide Range pH NaCl Medium

To provide carbon steel a long-term corrosion protection effect in NaCl solutions with different pH values, based on poly-acrylamide (PAM) and oleate imidazoline (OIM), a solid corrosion inhibitor with the properties of pH-controlled release was synthesized. SEM, FTIR and TGA results indicated that the OIM inhibitors were successfully loaded into PAM hydrogel with a high OIM encapsulation content (39.64 wt.%). The OIM release behavior from the hydrogel structure has two stages, quick release and sustained release. The pH of solutions could affect the initial release kinetics of OIM inhibitors and the diffusion path in the hydrogel structure. Weight loss measurement of L80 steel in different pH solutions with OIM@PAM proved the inhibitor responsive release mechanism and anticorrosion performance. The inhibition efficiency of OIM@PAM can maintain over 80% after long-term immersion in a harsh corrosive environment (pH 3), which is much higher than the inhibition efficiency of OIM@PAM in a moderate corrosive solution.

Computational Foretelling and Experimental Implementation of the Performance of Polyacrylic Acid and Polyacrylamide Polymers as Eco-Friendly Corrosion Inhibitors for Copper in Nitric Acid

Copper is primarily used in many industrial processes, but like many other metals, it suffers from corrosion damage. Polymers are not only one of the effective corrosion inhibitors but also are environmentally friendly agents in doing so. Hence, in this paper, the efficacy of two polyelectrolyte polymers, namely poly(acrylic acid) (PAA) and polyacrylamide (PAM), as corrosion inhibitors for copper in molar nitric acid medium was explored. Chemical, electrochemical, and microscopic tools were employed in this investigation. The weight-loss study revealed that the computed inhibition efficiencies (% IEs) of both PAA and PAM increased with their concentrations but diminished with increasing HNO₃ concentration and temperature. The results revealed that, at similar concentrations, the values of % IEs of PAM are slightly higher than those recorded for PAA, where these values at 298 K reached 88% and 84% in the presence of a 250 mg/L of PAM and PAA, respectively. The prominent IE% values for the tested polymers are due to their strong adsorption on the Cu surface and follow the Langmuir adsorption isoform. Thermodynamic and kinetic parameters were also calculated and discussed. The kinetics of corrosion inhibition by PAA and PAM showed a negative first-order process. The results showed also that the used polymers played as mixed-kind inhibitors with anodic priority. The mechanisms of copper corrosion in nitric acid medium and its inhibition by the tested polymers were discussed. DFT calculations and molecular dynamic (MD) modelling were used to investigate the effect of PAA and PAM molecular configuration on their anti-corrosion behavior. The results indicated that the experimental and computational study are highly consistent.

Trizma as an eco-friendly efficient inhibitor for the acidic corrosion of steel: experimental and computational studies

The inhibition characteristics of Trizma for corrosion of steel in 1 M HCl was investigated using the weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy techniques and the surface techniques XRD,SEM and EDX. The potentiodynamic results indicated that Trizma act as a mixed type inhibitor for steel in 1 M HCl giving efficiently 93.7% percent inhibition for 1 × 10^–2 mol/L. The electrochemical impedance spectroscopy results showed an increase in R_ct values and decrease in the value of C_dl with increasing the concentration of Trizma indicating that the presence of Trizma in the solution retards the steel corrosion due to the adsorption of its molecules at the steel/solution interface. The XRD and SEM results indicated that the surface of the steel contains Trizma molecules. The DFT method was investigated to correlate the molecular properties of the studied Trizma with the experimental inhibition efficiency. Langmuir, Flory–Huggins isotherm, and the Kinetic–thermodynamic model were used to fit the corrosion inhibition data of Trizma. The results indicated that the Langmuir isotherm does not fit with the experimental results due mainly to the non-ideal adsorption of its molecules at the steel/solution interface. However, Flory–Huggins isotherms, and the Kinetic–thermodynamic model are applicable and showed that the adsorption process of Trizma on the steel surface is cooperative (Chemical–Physical).

Electrochemical and Computational Approaches of Polymer Coating on Carbon Steel X52 in Different Soil Extracts

Using stationary electrochemical, polarization resistance, cathodic charging, transient electrochemical impedance spectroscopy, and theoretical and molecular mechanics studies, epoxy polymer-coated carbon steel specimens’ ability to protect metals from corrosion in various soil extracts was examined. According to the polarization resistance tests results, the polymer coating remained stable for 60 days in all three soil extracts, with a 90% efficiency for the steel coated in Soil Extract A, indicating that the sandy soil is less aggressive than the other two. The aggressiveness of clay soil was confirmed by the fact that a polymer-coated steel rod in the clay soil extract experienced a corrosion current density of 97 µA/cm². In contrast, the same rod in sandy soil had a current density of 58 µA/cm². The coating’s good adsorption contact with the metal surface was further guaranteed by molecular dynamics simulations, which provided atomic-level evidence of the epoxy molecule’s adsorption behavior (geometry) and adsorption energy on the carbon steel surface.

Structures, Energetics, and Spectra of (NH) and (OH) Tautomers of 2-(2-Hydroxyphenyl)-1-azaazulene: A Density Functional Theory/Time-Dependent Density Functional Theory Study

Tautomerization of 2-(2-hydroxyphenyl)-1-azaazulene (2OHPhAZ) in the gas phase and ethanol has been studied using B3LYP, M06-2X, and ωB97XD density functional theory (DFT) with different basis sets. For more accurate data, energies were refined at CCSD(T)/6-311++G(2d,2p) in the gas phase. Nuclear magnetic resonance (NMR), aromaticity, Fukui functions, acidity, and basicity were also calculated and compared with experimental data. Time-dependent density functional theory (TDDFT)-solvation model based on density (TDDFT-SMD) calculations in acetonitrile have been utilized for the simulation of UV-vis electronic spectra. In addition, electronic structures of the investigated system have been discussed. The results reveal that the enol form (2OHPhAZ) is thermodynamically and kinetically stable relative to the keto tautomer (2OPhAZ) and different rotamers (2OHPhAZ-R1:R3) in the gas phase and ethanol. A comparison with the experiment illustrates a good agreement and supports the computational findings.

Screening and Evaluation of Two Dye Wastewaters as Additives for Carbon Steel Corrosion Inhibitors in Acidic Environments

To reduce the cost of synthetic organic corrosion inhibitors in corrosion protection, dye wastewater exhibiting a synergistic effect is used with organic corrosion inhibitors to reduce the amount of high-cost molecules. The corrosion inhibition effects of the cationic dye methylene blue (MB) and the anionic dye methyl orange (MO) are tested. The test methods include electrochemical methods, weight-loss tests, and so on. MB exhibits better performance on the tested steel, with the anticorrosion efficiency reaching as high as 75.40%, which is chosen as an additive for organic corrosion inhibitors. After that, an organic inhibitor decamethylene bis-pyridinium dibromide (DBP) is selected for compounding with MB, and the corrosion inhibition effect under different ratios is tested. Similar effects of the compound inhibitor to the pristine sample are obtained at a ratio of MB/DBP = 6:4. In addition to experiments, theoretical calculations have also confirmed that the addition of dye molecules can inhibit corrosion. This research not only provides a way to reuse dye wastewater but also proposes measures to reduce the cost of organic corrosion inhibitors and, at the same time, provides new ideas for environmental protection and metal protection.

Sodium nitrite as a corrosion inhibitor of copper in simulated cooling water

The corrosion inhibition behavior of sodium nitrite (NaNO₂) towards pure copper (99.95%) in simulated cooling water (SCW) was investigated by means of electrochemical impedance spectroscopy (EIS) and dynamic electrochemical impedance spectroscopy (DEIS). NaNO₂ interferes with metal dissolution and reduce the corrosion rate through the formation or maintenance of inhibitive film on the metal surface. Surface morphologies illustrated that the surface homogeneity increased on adding sodium nitrite. Sodium nitrite's adsorption on copper surface followed the modified form of Langmuir, Freundlich and Frumkin isotherms. Physiosorption mode was involved in the corrosion protection. Electrochemical results revealed an corrosion resistance of copper increases on increasing the inhibitor concentration. The DEIS results indicated that copper corrosion mechanism could be hindered by 50% even after interval of 24 h by optimum concentration of sodium nitrite. The maximum inhibition was achieved with 2000 ppm of NaNO₂. With this concentration, inhibition efficiency of up to 61.8% was achievable.

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.

The Bonding Mechanism of the Micro-Interface of Polymer Coated Steel

As food and beverages require more and more green and safe packaging products, the emergence of polymer coated steel (PCS) has been promoted. PCS is a layered composite strip made of metal and polymer. To probe the bonding mechanism of PCS micro-interface, the substrate tin-free steel (TFS) was physically characterized by SEM and XPS, and cladding polyethylene terephthalate (PET) was simulated by first-principles methods of quantum mechanics (QM). We used COMPASS force field for molecular dynamics (MD) simulation. XPS pointed out that the element composition of TFS surface coating is Cr(OH)₃, Cr₂O₃ and CrO₃. The calculation results of MD and QM indicate that the chromium oxide and PET molecules compound in the form of acid-base interaction. The binding energies of Cr₂O₃ (110), (200), and (211) with PET molecules are -13.07 eV, -2.74 eV, and -2.37 eV, respectively. We established a Cr₂O₃ (200) model with different hydroxyl concentrations. It is proposed that the oxygen atom in C=O in the PET molecule combines with -OH on the surface of TFS to form a hydrogen bond. The binding energy of the PCS interface increases with the increase of the surface hydroxyl concentration of the TFS. It provides theoretical guidance and reference significance for the research on the bonding mechanism of PCS.

Chitosan derivatives as green corrosion inhibitors for P110 steel in a carbon dioxide environment

Two chitosan derivatives were synthesized for the first time as green corrosion inhibitors for the carbon dioxide corrosion of P110 steel. The structures of the synthesized products were characterized by infrared spectroscopy. Electrochemical and weight-loss experiments were used to test the effect of corrosion inhibitors, while SEM-EDS, AFM and other analysis methods were used to study the protection mechanism of corrosion inhibitors. The experimental results show that synthetic corrosion inhibitors CHC and CAHC are all good corrosion inhibitors for carbon dioxide corrosion inhibition. Both chitosan derivatives can form hydrophobic protective films on the metal surface. For inhibition performance, CAHC is better than CHC, which is the same conclusion drawn from practical experiments and quantum chemical calculations. Investigation into chitosan inhibitors has opened up a new area of research of environmentally friendly corrosion inhibitors, which is of great significance for metal protection without toxicity and side effects.

Copolymer of Pyrrole and 1,4-Butanediol Diglycidyl as an Efficient Additive Leveler for Through-Hole Copper Electroplating

A copolymer comprising of pyrrole and 1,4-butanediol diglycidyl ether (PBDGE) was designed and synthesized as a leveler to improve the throwing power for printed circuit board (PCB) through-hole electroplating. The results of linear sweep voltammetry (LSV), galvanostatic measurements (GMs), and cyclic voltammetry (CV) reveal the strong coordination effect of PBDGE with other additives and confirm the advantageous performance of PBDGE to effectively assist the electroplating of through-hole. An increment of 35.5% in the throwing power was achieved under the addition of PBDGE in through-hole plating. Additionally, the reaction mechanism was studied by quantum chemical calculations and molecular dynamics (MD) simulations, indicating that the pyrrole rings of the PBDGE molecule are adsorbed on the copper surface as the adsorption sites to balance the copper plating regardless of the through-hole position differences.

Anti-corrosion and microstructural properties of Ni-W alloy coatings: effect of 3,4-Dihydroxybenzaldehyde

In the present work impact of 3,4-Dihydroxybenzaldehyde on the microstructural and corrosion behavior of nanocrystalline Ni-W alloy coatings has been elucidated. A systematic investigation on the protection ability of Ni-W alloy coatings in 0.2 M H₂SO₄ solution was done with the aid of tafel polarization curves and electrochemical impedance spectroscopy (EIS) studies. Corrosion performance of the alloy films obtained in the absence and in the presence of different concentrations of 3,4-Dihydroxybenzaldehyde (0–500 ppm) in the bath was explained in the light of additive concentration. Compared to the blank and other concentrations of additive, 250 ppm of additive containing bath was predicted as the most promising one for the introduced citrate based Ni-W alloy electrodeposition. Low corrosion rate (0.06 mm/year) and high charge transfer resistance (2505.3 Ω cm²), for the electrodeposits, obtained from the bath containing 250 ppm of 3,4-Dihydroxybenzaldehyde supports for its high anticorrosion performance. The marked difference in the corrosion resistance property is ascribed to the formation of fine-grained deposits, smooth surface, and inclusion or adsorption of additive within the deposits in the presence of the additive (250 ppm) in the bath. Further, the adsorption of additive molecules on the metal surface was explored with the help of quantum chemical calculations based on DFT.

Mannich Base as Corrosion Inhibitors for N80 Steel in a CO₂ Saturated Solution Containing 3 wt % NaCl

In this paper, a corrosion inhibitor containing nitrogen atoms and a conjugated π bond was synthesised, and its final product synthesised by the optimal conditions of the orthogonal test results is named multi-mannich base (MBT). The corrosion inhibition effect on the N80 steel sheet of the corrosion inhibitor was evaluated in a CO₂ saturated solution containing 3 wt % NaCl; the corrosion rate was 0.0446 mm/a and the corrosion inhibition rate was 90.4%. Through electrochemical and adsorption theory study, MBT is a mixed corrosion inhibitor that mainly shows cathode suppression capacity. The adsorption of MBT on the surface of the steel sheet follows the Langmuir adsorption isotherm; it can be spontaneously adsorbed on the surface of the N80 steel sheet, which has a good corrosion inhibition effect. The surface of the N80 steel sheet was microscopically characterised by atomic force microscope (AFM). It can be seen from the results that the N80 steel sheet with MBT added is significantly different from the blank control group; the surface of the steel sheet is relatively smooth, indicating that MBT forms an effective protective film on the surface of N80 steel, which inhibits the steel sheet.

Chitosan oligosaccharide derivatives as green corrosion inhibitors for P110 steel in a carbon-dioxide-saturated chloride solution

Two chitosan oligosaccharide derivatives (PHC and BHC) were synthesized for use as corrosion inhibitors. They were characterized using Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The inhibition efficiency of PHC and BHC on P110 steel corrosion in a 3.5 wt.% NaCl CO₂-saturated solution at 80℃ was studied using gravimetric measurement, scanning electron microscopy (SEM), atomic force microscopy (AFM), electrochemical analysis, and quantum chemical calculation. The results indicated that inhibition efficiency increased with increasing concentration of inhibitor. Energy dispersive X-ray (EDX), contact angle, and electrochemical impedance spectroscopy (EIS) measurements showed that the inhibitors had been successfully adsorbed to the surface of the P110 steel. The results of potentiodynamic polarization indicated that both compounds were mixed-type inhibitors.

Experimental and theoretical investigation on corrosion inhibitive properties of steel rebar by a newly designed environmentally friendly inhibitor formula

In order to mitigate the corrosion of steel rebar in concrete, a new environmentally friendly corrosion inhibitor formula (WKI) was designed and the corrosion inhibitive effects of WKI on steel rebar were studied by gravimetric method, electrochemical impendence spectroscopy (EIS), potentiodynamic polarization and Mott–Schottky scanning in simulated concrete pore solution. Furthermore, surface analysis and quantum chemical calculations were conducted in order to illustrate the corrosion inhibitive mechanism. The results indicate that WKI exhibits excellent corrosion inhibitive activities on steel rebar in simulated concrete pore solution. By the presence of WKI, local corrosion was significantly suppressed and no pitting could be detected during the whole experimental period. The total corrosion resistance was increased from 5469 Ω cm² to 64 440 Ω cm² and the corrosion current density was reduced from 3.23 μA cm⁻² to 0.21 μA cm⁻² for the sample immersed in the corrosion medium for 7 d with WKI. The corrosion potential of the steel rebar electrode moved to a higher level and the charge transfer resistance increased, indicating that the anti-corrosion properties of the steel rebar were enhanced. The corrosion inhibitive mechanism of WKI can be attributed to the fact that it can promote the formation of a passive film and reduce its defect concentration via its adsorption and interaction with the metal surface, consequently inhibiting the corrosion of steel rebar caused by chloride ions.

A new corrosion inhibitor formula was designed and the inhibitive mechanism was analyzed based on HSAB theory and the PDM model.

A Detailed Molecular Dynamics Simulation and Experimental Investigation on the Interfacial Bonding Mechanism of an Epoxy Adhesive on Carbon Steel Sheets Decorated with a Novel Cerium-Lanthanum Nanofilm

The influences of steel surface treatment by a novel cerium-lanthanum (Ce-La) nanofilm on the adhesion mechanism of an epoxy adhesive were studied through experimental and modeling approaches. The surface morphology and microstructure of the film deposited were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The surface free energy and work of adhesion values were evaluated through contact angle analysis. Also, the interfacial adhesion strength between the epoxy adhesive and steel surface, together with failure forms, were examined through pull-off test, under dry and wet conditions, and Fourier transform infrared (FT-IR) spectroscopy. The results obtained from experiments revealed that depositing a Ce-La nanofilm on the steel surface increased its roughness and surface free energy, and strengthened the epoxy coating adhesion. It was also observed that the epoxy adhesion on the Ce-La treated steel was stronger, compared to the Ce-treated surface. Furthermore, the adhesion extent and surface bonding mechanism of aminoamide-cross-linked epoxy resin were computationally modeled by applying atomistic molecular dynamics (MD) and electronic density functional theory (DFT) methods. The modeling results evidenced that epoxy resin adhered more strongly to the conversion layer (represented by CeO₂ and La₂O₃), compared to an untreated steel surface (i.e., pure and oxidized iron). The epoxy binding onto CeO₂(111), La₂O₃(001), Fe₂O₃(110), and Fe₃O₄(100) almost occurred via electrostatic interactions, while its adhesion mechanism over FeO(100) and Fe(110) surfaces was based on van der Waals forces. The computations also demonstrated that the epoxy adsorption energy decreased in wet environments, because of solvent affinity toward the epoxy and the surface, but the rate of reduction was smaller over CeO₂ and La₂O₃, compared to that observed with iron oxides. These modeling outcomes were consistent with our experiments and proposed the superior epoxy adhesion on modified steel sheets.

Synthesis of Quaternary Ammonium Salts Based on Diketopyrrolopyrroles Skeletons and Their Applications in Copper Electroplating

A series of DPP derivatives bearing quaternary ammonium salt centers with different lengths of carbon chains have been designed and synthesized. Their inhibition actions on copper electroplating were first investigated. A total of four diketopyrrolopyrrole (DPP) derivatives showed different inhibition capabilities on copper electroplating. To investigate interactions between metal surface and additives, we used quantum chemical calculations. Static and dynamic surface tension of four DPP derivatives had been measured, and the results showed DPP-10C (1c) with a faster-decreasing rate of dynamic surface tension among the four derivatives, which indicated higher adsorption rate of additive on the cathode surface and gives rise to stronger inhibiting effect of copper electrodeposition. Then, DPP-10C (1c) as the representative additive, was selected for the systematic study of the leveling influence during microvia filling through comprehensive electroplating tests. In addition, field-emission scanning electron microscope images and X-ray diffraction results showed the surface morphology, which indicated that addition of DPP derivative (1c) could lead a fine copper deposit and cause the preferential orientations of copper deposits to change from [220] to [111], which happened in particular at higher concentrations.

4,6-Dimethyl-2-mercaptopyrimidine as a potential leveler for microvia filling with electroplating copper

Filling performance of microvia was defined as following equation: η = (A/B) × 100%.

Corrosion properties of steel in 1-butyl-3-methylimidazolium hydrogen sulfate ionic liquid systems for desulfurization application

The corrosivity of [BMIM]HSO₄-based systems for desulfurization applications were investigated by weight loss and surface analyses.