Maximum Corrosion Inhibition Efficiency Research Articles

Enhanced anti-corrosion characteristics of epoxy-functionalized graphene oxide nanocomposite coatings on mild steel substrates

This experimental investigation focused on coating of functionalized graphene oxide (FGO) on the mild steel to minimize corrosion, using a new method. Prior to the coating, the fundamental chemical and morphological structures of FGO were studied with aid of some characterization techniques: X-ray diffraction (XRD), Raman, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Various epoxy/FGO coating formulations with 10, 20, 30, 40 and 50 ppm of FGO were prepared and coated on the mild steel substrate, adopting dip coating method. Immersion test was carried out to observe the corrosion inhibition efficiency of the graphene. The adsorption isothermal behavior was also studied using various models and compared with the data obtained from the experimental results. From the results obtained, the formation of irregular rough patches and separation of platelets like zebra lines indicated the formation of graphene nanoparticles, as observed through morphological analysis. The occurrence of sharp peak at 24.3° in the XRD pattern depicted the existence of graphene in nanoscale. Electrochemical impedance (EI) and potentiodynamic polarization (PP) studies reported the maximum corrosion inhibition efficiency of 87% at 50 ppm concentration of epoxy/FGO. It was evident that an increasing concentration of graphene exhibited significant corrosion resistance in both studies. The bonding energy of randomly oriented graphene platelets reduced the removal of metal, delaying the crack propagation in tortuous path on the coated surface. These results established the significance and applicability of this study in various relevant industries.

Corrosion inhibition performance and mechanism of triethanolamine-triisopropanolamine rust inhibitor in the simulated concrete pore solution

In this research, aiming to deal with the accelerated corrosion deterioration of steel reinforcement in reinforced concrete in harsh environments, a highly efficient rust inhibitor (triethanolamine (TEA)-triisopropanolamine (TIPA)) (abbreviated as TT), which TEA and TIPA compounded in a ratio 4:6, was proposed. The synergistic rust inhibition effect of TEA and TIPA on steel in the simulated concrete pore solution (SCPS), and its corrosion inhibition performance were investigated by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), dry and wet cycling, and scanning electron microscopy (SEM) measurements. The results showed that TT inhibitor could obviously inhibit the corrosion of steel in the SCPS and could inhibit both cathode and anode. The electrochemical corrosion inhibition performance was the most excellent at the dosage of 1.0 %, and the maximum corrosion inhibition efficiency (η1) reached 95.39 %. After 150 times of dry and wet cycling, the percentage of the corrosion area (S), and corrosion inhibition efficiency (η2) with 1.0 % TT inhibitor were 9.3 % and 84.03 %, respectively, and the mass loss rate (M) decreased by 68.4 %, indicating a better rust inhibition performance. The adsorption of the TT inhibitor conformed to the Langmuir adsorption isotherm and inhibited the corrosion of steel by forming a protective film on steel surface through physicochemical adsorption. This study is of great significance to provide new perspectives and improvement measures to build up the deterioration and extend the service life of reinforced concrete in harsh environments.

Schiff base derived from 2-hydroxy napthaldehyde as anti-corrosive for mild steel in acid media: experimental investigation and theoretical modelling

Schiff bases (SBs) have the fundamental characteristics of substances that are mostly eligible for testing as inhibitors of corrosion for various metal/electrolyte systems. Through their electron-rich centres, such as the > C = N– (imine) moiety, SBs adsorb and create a surface coating that mitigates corrosion. Because of its π-acceptor characteristics, the > C = N– (imine) moiety provides a strong bonding with the metallic ions. It's vital to note that SBs with polar substituents at the right locations can form chelates with the central metal ions; as a result, these SBs are anticipated to function better as corrosion inhibitors than SBs without substituents. Two distinct Schiff bases, NL1 and NL2, with naphthalene rings have been synthesised, and their structures have been confirmed by the use of 1H and 13C NMR spectrum methods. The anticorrosion potential of the NL1 and NL2 was further confirmed by quantum chemical calculations such as DFT studies and ESP diagrams. The corrosion inhibition potential of the NL1 and NL2 was investigated using the electrochemical method, demonstrating maximum corrosion inhibition efficiency up to 89.2% and 89.5%, respectively on mild steel in 1 M HCl media. The results are further supported by Scanning Electron microscopic (SEM) images and EDAX studies.

Investigating the synergistic effect of iodide ion and Michelia alba leaf extract on carbon steel in 0.5M H2SO4

The study examined the inhibitory effect of Michelia alba leaf extract (MALE) on carbon steel (CS) in 0.5M H2SO4 solution. Furthermore, the investigation explored the effect of KI to enhance the protection provided by MALE. The study demonstrates that both MALE and KI have corrosion inhibiting properties on CS in acidic solutions. However, when MALE and KI are combined, they exhibit a greater inhibitory effect. Corrosion inhibition efficiency was limited to 86.55% with 400mg/L MALE. The maximum corrosion inhibition efficiency was 51.84% when 400mg/L KI was used alone. However, when 800mg/L MALE was combined with 400mg/L KI in 0.5M H2SO4 solution, the efficiency increased to 95.02%. This increase can be attributed to the synergistic effect between MALE and KI. The SEM and XPS results further confirmed that the addition of KI could be more effective in preventing the corrosion of CS. The theoretical calculations demonstrate that constituents found in the extract, which are rich in hydroxyl groups, benzene rings, N and S atoms have a higher probability of adsorption onto the CS surface in parallel, thereby increasing the efficiency of corrosion inhibition significantly.

Experimental and Theoretical Studies on Long Alkyl Chain-Bearing Dibenzotriazole Ionic Liquids as Eco-friendly Corrosion Inhibitors in Aqueous Hydrochloride Acid.

Three long alkyl chain-bearing dibenzotriazole ionic liquids (BTA-R-BTA, R = 8, 12, and 16) were synthesized with high yield (>98%) through a simple and eco-friendly process. Their anticorrosion performance for Q235 carbon steel in 6 M hydrochloride acid was comprehensively evaluated by weight loss tests, electrochemical methods (potentiodynamic polarization and electrochemical impedance spectroscopy), and surface analysis techniques. As the length of the alkyl chain increased, the maximum corrosion inhibition efficiency enhanced from 55.02% (for BTA-8-BTA at 1.2 mM) to 97.10% (for BTA-12-BTA at 0.3 mM) and 98.84% (for BTA-16-BTA at 0.3 mM). Density functional theory calculation indicated that the alkyl chain length had little influence on the inhibitors' electronic structures, while molecular dynamics simulations revealed that the thickness, surface coverage, and compactness of adsorption films formed at the metal-electrolyte interface increased with the elongated alkyl chain. Corrosion inhibition efficiency is strongly correlated with the structures of the adsorption film.

Investigation of a pyridazinone derivative as a corrosion inhibitor for carbon steel in acidic conditions using experimental and theoretical methods

The anti-corrosive properties of the newly synthesized compound pyridazinone, especially 2-(3-(4-fluorophenyl)-2-oxopropyl)-4-(3-nitrobenzyl)-6-phenylpyridazin-3(2 H)-one (FOPP), on carbon steel in a 1 M hydrochloric acid solution were thoroughly investigated. We used multiple techniques, including potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), surface morphology analysis, contact angle measurements, UV–visible spectrometry, and quantum chemical calculations. The maximum corrosion inhibition efficiency of FOPP was found to be 96.3 % at 10−3 M concentration and 303 K temperature. PDP studies showed that FOPP acts as a mixed-type inhibitor with anodic predominance. The hydrophobicity of the surface of the metal studied showed considerable improvement by the FOPP coating using the contact angle technique. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX) were used to confirm the results obtained using the contact angle technique. The two methods of theoretical chemistry, namely density functional analysis (DFT) and molecular dynamics simulation, were used to gain a better understanding of the interactions between the inhibitor and the surface of the metal studied and the ability of this inhibitor to adhere to the surface of the iron and form a protective film.

Walnut (Juglans regia L.) fruit septum alcoholic extract as corrosion inhibitor for Fe B500B steel bars in mixed acidic solution

The corrosion inhibition performance of the walnut fruit (Juglans regia L.) septum alcoholic extract for Fe B500B steel bars in a mixed acidic solution (H2SO4/HCl) is reported. Weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy measurements were performed at 298 to 318 K, with the addition of various extract concentrations. Results showed the maximum corrosion inhibition efficiency of 86.99 % for 300 mg L-1 extract added. The extract acts as a mixed-type inhibitor, predominantly affect­ing the anodic side, following Flory-Huggins adsorption isotherm. Thermodynamic analysis indicated an endothermic process with both chemisorption and physisorption on the steel bar surface. Surface characterization was conducted using ATR-FTIR, UV-vis and SEM techniques to prove the adsorption of the inhibitor molecules on the steel bar surface. Also, a possible adsorption mechanism of inhibitor molecules was proposed.

Facile synthesis, corrosion inhibition, adsorption and DFT studies of 2-(4-(methylsulfanyl) phenyl) −4, 5-diphenyl-1H-imidazole for mild steel in acidic environment

A green, solvent-free, cost effective one-pot synthesis method is employed to produce the innovative corrosion-inhibiting compound 2-(4-(methylsulfanyl)phenyl)-4,5-diphenyl-1H-imidazole (MDPI). The molecular structure of MDPI can be identified using CHN analyses, FT-IR, 1H and 13C NMR spectra. Various electrochemical and gravimetric techniques are utilized to evaluate the anti-corrosion properties of MDPI. The results indicate that MDPI effectively inhibits the corrosion of mild steel under all tested conditions. At 306 K, MDPI achieved a maximum corrosion inhibition efficiency of 98.01 % at a concentration of 10 mM. MDPI exhibited strong adsorption and excellent anti-corrosion properties, forming a protective layer on the mild steel surface. The Langmuir adsorption isotherm, with a ΔGoads value of −39.55 kJ/M was found to be more suitable for this study, indicating that the process occurred by physisorption. Tafel curves indicated that MDPI functions as a mixed-type corrosion inhibitor. Surface characteristics were analyzed using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and atomic force microscopy (AFM). Quantum chemistry studies revealed a HOMO-LUMO energy gap of 3.926 eV, corroborating the anti-corrosion effectiveness of MDPI in hydrochloric acid solution. MDPI exhibited promising anti-corrosion activity due to its heterocyclic ring containing nitrogen heteroatoms as well as a methylsulfanyl functional group.

Okra leaves extract as green corrosion inhibitor for steel in sulfuric acid: Gravimetric, electrochemical, and surface morphological investigations

Utilizing plant extracts as an alternative source for corrosion inhibitors holds significant promise in minimizing the risk of corrosion. In this study, an okra leaf extract (OLE) was employed as a corrosion inhibitor for N80 steel in 1.0 M H2SO4. The corrosion rate was assessed concerning temperature (30, 40, 50, and 60 °C) and inhibitor concentrations (blank, 25, 50, 75, and 100 ml/l) through weight loss and electrochemical polarization techniques. The results indicated that OLE functions as a mixed-type corrosion inhibitor, with corrosion rates increasing with temperature and decreasing with inhibitor concentration. The maximum corrosion inhibition efficiency reached 96 % at 30 °C and 100 ml/l. Adsorption studies revealed that OLE physically adsorbed onto the mild steel surface, following the Langmuir adsorption isotherm. Gravimetrical and electrochemical techniques were confirmed by FTIR and UV measurements, which showed the presence of a protective layer on the metal surface. Optical microscopy, AFM, and SEM images demonstrated the formation of a protective layer on the metal surface. Thermogravimetric analysis (TGA) highlighted the thermal stability exhibited by inhibitor molecules, which showed that OLE was thermally stable up to 85 °C.

Preparation of magnetic core-shell Fe3O4@MBT-LDH composite and its application as an effective inhibitor for carbon steel

The core-shell structural Fe3O4@MBT-LDH was synthesized via the ion exchange method, with MBT (2-mercaptobenzothiazole) inhibitor ions intercalated lamellar ZnAlCe-LDH attaching closely to the Fe3O4 microspheres surface. The morphology, composition, structure, and magnetic properties of the composite were measured by transmission electron microscope, X-ray diffraction, Fourier transform infrared spectra, and vibrating sample magnetometer. The release behavior of MBT ions and corrosion inhibition performance of the Fe3O4@MBT-LDH under “no MF” (without an external magnetic field) and “MF ON” modes (under an external magnetic field) were measured by UV–vis spectroscopy, electrochemical tests, scanning electron microscopy, and X-ray photoelectron spectrometer (XPS). Calcinating the composite after the release test and redispersing the sintered products in MBT ions-containing solution, the composite was reestablished. Results showed that the Fe3O4@MBT-LDH possessed moderate MBT loadings amount (12.0%) and presented strong superparamagnetic properties with saturation magnetization (Ms) of 27.6 emu⋅g−1. The release behavior of the MBT− from the composite was sustainable and could be further slowed down by using an external magnetic field with changing the release mechanism. The release curve reached equilibrium with a longer time of 48 h and a lower release amount of 57.0% under MF ON mode than that of no MF mode with a time of 7 h and a release amount of 74.7%. The Fe3O4@MBT-LDH owned a good and long-term protection performance for Q235 carbon steel with maximum corrosion inhibition efficiency (ηe) of up to 93.30%. As a promising controlled-release inhibitor, it could be recycled and regenerated by simple treatment, still having high ηe higher than 80% and excellent magnetic properties with Ms of 21.47 emu⋅g−1 after five cycles. The corrosion mechanism for carbon steel was further analyzed by quantum chemical calculations and molecular dynamics simulation.

Experimental and computational exploration of the biodegradable platanus acerifolia leaf extract against mild steel corrosion in hydrochloric acid

This study delved into the potential application of Platanus acerifolia leaf extract (PALE) as an environmentally benign corrosion inhibitor. Evaluation of corrosion inhibition was conducted using electrochemical methods, field emission scanning electron microscopy equipped with energy dispersive spectrometer. The results reveal that PALE offers efficient protection for Q235 steel across the temperature range of 298 K–318 K, achieving a maximum corrosion inhibition efficiency of approximately 93%. Furthermore, Density functional theory (DFT) calculations and molecular dynamics (MD) simulations were performed to elucidate the spontaneous and stable adsorption of PALE molecules onto the surface of Q235 steel. This adsorption impedes the diffusion of corrosive substances towards the steel surface, thereby endowing Q235 steel with robust corrosion resistance.

In-Depth Insight into Corrosion Inhibition Performance of Sweet Potato Leaf Extract as a Green and Efficient Inhibitor for 6N01 Al Alloy in the Seawater: Experimental and Theoretical Perspectives.

Corrosion protection of metal has become an important and urgent topic, which requires the development of an inexpensive, environmentally friendly, and highly efficient corrosion inhibitor. Herein, a sweet potato leaf extract (SPL) was obtained by a simple water-based extraction method and then as a green corrosion inhibitor for 6N01 Al alloy in the seawater was well investigated by the weight loss method and various electrochemical tests. Fourier transform infrared (FT-IR) and ultraviolet-visible (UV-vis) spectroscopies were carried out to investigate the compositions of SPL. The findings from the potentiodynamic polarization (PDP) curves suggest that SPL functions as a typical mixed-type corrosion inhibitor. Notably, the maximum corrosion inhibition efficiency reaches 94.6% following a 36 h immersion period at 25 °C. The adsorption behavior of SPL on the Al alloy surface belongs to the Langmuir adsorption isotherm. The Gibbs free energy value illustrates that the adsorption of SPL contains both physisorption and chemisorption. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) indicate that SPL is firmly attached to the Al alloy surface by making a protective layer, which can effectively inhibit the corrosion of the Al alloy in the seawater. Furthermore, quantum chemical calculations were applied to validate the chemical adsorption and elucidate the relationship between the electronic structure of the active components in SPL and their effectiveness in corrosion inhibition.

Corrosion inhibition activity of a natural polysaccharide from Dysosma versipellis using tailor-made deep eutectic solvents

In this work, a total of 18 types of choline chloride, betaine, and L-proline-based deep eutectic solvents (DESs) were synthesized to determine the extraction yield of a natural polysaccharide (PSA) from Dysosma versipellis using an ultrasound-assisted extraction method. Results indicate that the choline-oxalic acid-based DES has the best extraction yield for PSA due to the proper physical-chemical properties between PSA and DES. To evaluate the optimal extraction conditions, a response surface methodology was carried out. Under the optimal conditions, the extraction yield of PSA reaches 10.37 % (± 0.03 %), higher than the conventional extraction methods. Findings from FT-IR and NMR suggest that the extracted PSA belongs to a neutral polysaccharide with (1 → 6)-linked α-d-glucopyranose in the main chain. Interestingly, results from various electrochemical measurements show the extracted PSA exhibits excellent corrosion inhibition performance for mild steel (MS) in a 0.5 M HCl solution, with 90.8 % of maximum corrosion inhibition efficiency at 210 mg L−1. SEM and XPS measurements reveal the formation of a protective layer on the MS surface. The adsorption behaviour of extracted PSA well obeys the Langmuir adsorption isotherm containing the chemisorption and physisorption. Additionally, theoretical calculations validate the experimental findings.

Corrosion mitigation of mild steel in 1 M HCl acid using an expired drug: An experimental approach

The research undertaken highlights the effectiveness of pharmaceutical drug Phenobarbitone (5-Ethyl-5-phenyl-1,3-diazinane-2,4,6-trione) (PB) as inhibitor to mitigate corrosion of mild steel (MS) in 1 M HCl. Corrosion studies were done by electrochemical techniques including potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) in the absence and presence of the Phenobarbitone (PB) drug. Kinetic parameters were calculated by studying the corrosion rate at different temperatures. Results were fitted into suitable adsorption isotherm and from the adsorption data thermodynamic parameters were computed and discussed in detail. Surface morphology studies were conducted using scanning electron microscopy (SEM), electron-dispersive X-ray (EDAX), and atomic force microscopy (AFM) techniques. The nature of the protective layer formed over the metal was studied by measuring the contact angle (CA), which demonstrated the formation of the adsorbed inhibitor layer. Inhibition efficiency increased with increase in concentration of inhibitor and with increase in temperature. For the addition of 0.04 gL-1, the maximum corrosion inhibition efficiency of 78.3 % was achieved at 313 K. Inhibitor acted as a mixed inhibitor with more control over the anodic reaction. Increase in efficiency with increase in temperature suggested the possibility of chemical adsorption. Inhibitor obeyed Langmuir adsorption isotherm, supporting chemical adsorption. Surface morphology clearly demonstrated the formation of barrier film on the surface of metal which prevented further dissolution of metal thereby decreasing the corrosion rate.

Rhododendron simsii leaf extract as a corrosion inhibitor for Cu in 0.5 M H2SO4: Experimental and theoretical studies

This study focuses on the utilization of a facile method to obtain Rhododendron simsii leaves extract (RSLE) as an efficient green corrosion inhibitor for Cu in 0.5 M H2SO4. The functional groups in RSLE were characterized using Fourier transform infrared spectroscopy (FTIR). The corrosion inhibition effect of RSLE was comprehensively evaluated by combining weight loss, electrochemical and surface analysis methods. The results showed that the maximum corrosion inhibition efficiency for Cu in the temperature range of 298 K∼308 K was more than 92.6% when the concentration of RSLE was 500 mg/L. RSLE is a mix-type corrosion inhibitor, and the adsorption on the surface of Cu was in accordance with the Langmuir model. In addition, the reaction sites and adsorption configurations on the Cu (1 1 1) surface of several typical active molecules in RSLE were analyzed by quantum chemistry (QC) and molecular dynamics simulation (MDS). The combination of experimental and theoretical results confirms that RSLE has excellent corrosion inhibition properties for Cu in acidic environments. In this study, an efficient corrosion inhibitor for copper corrosion in acidic environments was extracted for the first time from Rhododendron simsii leaves, providing a new perspective for future Cu corrosion prevention studies.

Expired butamirate drug as eco-friendly corrosion inhibitor for aluminum in seawater: Experimental and theoretical studies

In this work, an expired butamirate drug (EBD) was used as a corrosion inhibitor for aluminum in artificial seawater (3.5% NaCl solution). The corrosion rate was evaluated as a function of temperature and inhibitor concentrations using the electrochemical polarization technique. These data indicated that the EBD acts as a mixed-type corrosion inhibitor with a slight effect on the cathodic reaction. Corrosion current densities increased with temperature and decreased with inhibitor concentration. At a temperature of 328 K and an inhibitor concentration of 24 ml/l, the maximum corrosion inhibition efficiency was 84.4%. The cyclic polarization test confirmed the greater pitting resistance in the presence of butamirate drugs in solution. Adsorption studies showed that EBD adsorbed chemically on the metal surface following the Langmuir adsorption isotherm. Electronic microscopy showed enhancements in the surface morphology in the presence of EBD. While FTIR was used for the diagnosis of functional groups in EBD and surface corrosion products. In addition, theoretical quantum chemical calculations were used as a powerful tool to support the experimental studies.

Optimization studies of expired mouthwash drugs on the corrosion of aluminum 7475 in 1 M hydrochloric acid: Gravimetrical, electrochemical, morphological and theoretical investigations

The aim of the present work is to study the corrosion inhibition of Al 7475 alloy by an expired mouthwash drug (EMWD) in a 1 M HCl solution. The corrosion rate was optimized by the Doehlert experimental design at various temperatures, concentrations of inhibitor, and rotational velocity. The corrosion behavior was investigated by mass loss, Tafel potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) techniques. SEM, MOMT, XRD, FT-IR spectrum, and drop wettability measurement were used in characterizations of EMWD and surface morphology. Optimum conditions for corrosion control of EMWD on aluminum were 44.12 °C, 141.71 mL/L of EMWD per liter of acid, and 234.89 rpm. Maximum corrosion inhibition efficiency was 84.717% at higher levels of temperature and inhibitor concentration. It is observed that EMWD follows the Langmuir Adsorption Isotherm with negative values of ΔGadso, proposing a stable spontaneous inhibition process. The inhibitor efficiency increased as the inhibitor concentration increased. Moreover, increasing the solution temperature and rotational velocity had an adverse influence on inhibitor efficiency. The results of mass loss were in good agreement with potentiodynamic polarization and EIS. Polarization diagrams revealed that the inhibitor acts as a mixed-type inhibitor. It could be concluded that response surface Doehlert design (RSDD) was adequately applicable in the optimization of corrosion inhibition process variables and that EMWD sufficiently inhibited the corrosion of the aluminum at the studied conditions. Simulation of the EMWD molecules adsorption on the metal surface by quantum chemical theoretical studies was a powerful tool for supporting experimental outcomes.

Stable zinc anode achieved through ultramicro long chain cationic surfactant as interface regulator in aqueous electrolyte

The large-scale commercialization of aqueous zinc ion batteries (AZIBs) is still restricted due to rampant side reactions and serious dendritic growth. Therefore, a high-efficiency, low-cost and environment-friendly multifunctional electrolyte additive hexadecyltrimethylammonium bisulfate (CHN(HSO4)) is developed and first introduced into 2 M ZnSO4 solution as a cationic surfactant to enhance the stability of Zn-ion batteries (ZIBs). Electrochemical experiments and theoretical calculations confirm that long-chain CHN+ cation can regulate the Zn2+ ions nucleation to inhibit dendrite growth and isolate H2O molecules to inhibit harmful side reactions with the preferential adsorption on the Zn metal surface. Because of the effective protection of CHN+ cation adsorption layer, the corrosion of the Zn anode surface is inhibited, and the maximum corrosion inhibition efficiency exceeds 90%. Furthermore, with an ultra-micro dosage of 0.01 mM CHN(HSO4) electrolyte, the stable plating/stripping for the symmetric Zn|Zn cell without dendritic growth is realized for 3000 h at 1 mA cm−2 for 0.5 mAh cm−2, which is almost 21 times of that without additives. Meanwhile, high coulombic efficiency (CE) of 99.6% for Zn plating-stripping is achieved, and the Zn|MnO2 full cell exhibits stable cycling performance and high specific capacity, showing great potential for practical application.

Experimental and theoretical investigations of three Mannich-base imidazoline quaternary ammonium salts as efficient inhibitors for Q235 steel in sulfuric acid

Three Mannich base imidazoline quaternary ammonium salt corrosion inhibitors were designed and successfully synthesized, and their inhibition properties and mechanisms for Q235 steel in H2SO4 solution were investigated by experiments and theoretical calculations. It is found that three inhibitors act as mixed inhibitors to effectively inhibit the corrosion of Q235 steel in H2SO4 solution by chemisorption, and the maximum corrosion inhibition efficiency reaches 96.9 %, 97.3 % and 98.2 %, respectively. Theoretical calculations reveal that three inhibitors exhibit multi-center adsorption features and spontaneously adsorb on the surface of Q235 steel through horizontal orientation.

A comprehensive assessment of carbon steel corrosion inhibition by 1,10-phenanthroline in the acidic environment: insights from experimental and computational studies.

1,10-Phenanthroline (PHN) is a nitrogen-containing heterocyclic organic compound that is widely used in a variety of applications, including chemosensors, biological studies, and pharmaceuticals, which promotes its use as an organic inhibitor to reduce corrosion of steel in acidic solution. In this regard, the inhibition ability of PHN was examined for carbon steel (C48) in a 1.0M HCl environment by performing electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), mass loss, and thermometric/kinetic. Additionally, scanning electron microscopy (SEM) was used to examine the surface morphology of C48 immersed in 1.0M HCl protected with our inhibitor. According to the PDP tests, increasing the PHN concentration resulted in an improvement in corrosion inhibition efficiency. Besides, the maximum corrosion inhibition efficiency is about 90% at 328K. Furthermore, the PDP assessments demonstrated that PHN functions as a mixed-type inhibitor. The adsorption analysis reveals that our title molecule mechanism is due to physical-chemical adsorption, as predicted by the Frumkin, Temkin, Freundlich, and Langmuir isotherms. The SEM technique exhibited that the corrosion barrier occurs due to the adsorption of the PHN compound through the metal/1.0M HCl interface. In addition, the computational investigations based on a quantum calculation using density functional theory (DFT), reactivity (QTAIM, ELF, and LOL), and molecular-scale by Monte Carlo (MC) simulations confirmed the experimental results by providing further insight into the mode of adsorption of PHN on the metal surface, thus forming a protective film against corrosion on the C48 surface.