Corrosion Inhibition Effect Research Articles

Investigation of the Anticorrosive Activity of Piper divaricatum Essential Oil on Steel in 1 M HCl.

Piper divaricatum essential oil (PDEO), extracted from plants of the Brazilian Amazon, was investigated for the first time as a novel green or eco-friendly inhibitor for steel corrosion in 1 M HCl at 25 °C. Our electrochemical studies demonstrate that for different PDEO concentrations, lower E corr and i corr values were obtained. The influence of the oil concentration on corrosion inhibition, 0.5-4 g/L, was determined for 1 and 7 days of immersion. The corrosion rate (CR) and inhibition efficiency (IE) were determined by mass loss. The steel surface in the presence and absence of oil was investigated by scanning electron microscopy (SEM). The main PDEO compounds, determined by gas chromatography-mass spectrometry (GC-MS), were methyleugenol (20.68%) and eugenol (15.42%). The CR and IE for 2 g/L PDEO exhibited an optimal value of 4.31 mm/year and 98.3% for 7 days of immersion, respectively. The surface with 2 g/L oil for 7 days exhibited a less rough morphology, which was attributed to the corrosion inhibitory effect of PDEO. In addition, the PDEO adsorption process on the steel surface obeyed the Langmuir isotherm model. Negative values found for free standard energy ( < 0 kJ·mol-1) were attributed as a favorable process, i.e., an indicative of physisorption and chemisorption between the PDEO components and the steel surface. Our results reveal that the PDEO has a promising character for anticorrosive steel applications and metal coating in industries.

Experimental and computational analysis of poly(4-vinyl pyridine) and polyvinylpyrrolidone as effective corrosion inhibitors for low carbon steel in sulfuric acid

This study investigates the inhibitory effects of poly(4-vinyl pyridine) (P4VP) and polyvinylpyrrolidone (PVP) on the corrosion of low carbon steel (LCSt) in 1 M H2SO4. Protection efficacy (%PE) was measured using mass loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). Results showed %PE values increased with higher polymer concentration and lower temperature. At 450 mg/L, %PE reached 93.13% and 94.19% for P4VP and PVP, respectively. These polymers function as mixed inhibitors, adsorbing onto the LCSt surface per Langmuir’s model as a mode of physical adsorption. EIS indicated that higher polymer concentration increased charge transfer resistance and decreased effective double-layer capacitance. Both P4VP and PVP also reduced pitting corrosion in chloride-containing solutions. Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT) optimized the molecular structures of the inhibitors, evaluating electronic parameters such as frontier molecular orbital (FMO) energies, energy gap, softness, hardness, electron transfer fraction, dipole moment, and hyperpolarizability ( β ° ). Monte Carlo (MC) and molecular dynamics (MD) simulations provided insights into adsorption mechanisms, corroborating experimental findings and highlighting the effect of protonation. This comprehensive study enhances our understanding of the relationship between molecular structure and function in polymer inhibitors, improving their application in corrosion protection.

Eco-friendly Chlorella vulgaris extracts for corrosion protection of steel in acidic environments

This study evaluates the potential of Chlorella vulgaris sp. extracts as eco-friendly corrosion inhibitors for API 5L 42 Steel in a 1M HCl acidic environment, offering sustainable alternatives for industrial applications. Two corrosion inhibitors were obtained through solvent extraction methods: M1 (methanol) and M2 (methanol/chloroform). The extracts were characterized using infrared spectroscopy, the analysis revealed hydroxyl, methyl and vinyl groups as the most representative. The effect of corrosion inhibition was study by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The results show significant reductions in corrosion current density and increases in charge transfer resistance, with M2 achieving the highest protection efficiency of 91.20 % and a charge transfer resistance of 501.80 Ω at a 120 ppm concentration, while M1 reached 88.22 % efficiency with a charge transfer resistance of 102.30 Ω. Uv–Vis measurements were performed to determine the electronic transitions of the metal-inhibitor system for each of the extracts. ANOVA highlighted the significant influence of biomass concentration on corrosion resistance. The adsorption of M1 and M2 extracts on the carbon steel surface obeyed the Langmuir isotherm and Gibbs free energy calculations indicated a physisorption mechanism for both extracts. Surface morphology analysis by Scanning electron microscope (SEM) revealed less pitting and reduced surface roughness as inhibitor concentration increased. These findings underscore the potential of Chlorella vulgaris extracts, particularly M2 at 120 ppm, as effective and sustainable corrosion inhibitors for steel in acidic environments.

Synergistic inhibition effect of Chlorella sp. and benzotriazole on the corrosion of Q235 carbon steel in alkaline artificial seawater

The interaction of microalgae on the reinforced concrete with corrosion inhibitor is not well understood. Moreover, the inhibition role of microalgae on corrosion has been reported in recent years. In this study, the corrosion inhibition behavior of Q235 carbon steel (CS) due to the presence of Chlorella sp. and benzotriazole (BTA) in alkaline artificial seawater was investigated by means of weight loss, electrochemical measurements including open circuit potential, electrochemical impedance spectroscopy, and potentiodynamic polarization curves, and surface analysis including scanning electron microscopy, energy dispersion spectrometer, and X-ray photoelectron spectroscopy. The results of reduced corrosion rates in the algae-BTA system demonstrated that Chlorella sp. could facilitate the corrosion inhibition efficiency of BTA on the CS specimens. Moreover, polarization measurement showed the algae-BTA system had a mixed-type corrosion inhibition effect. The mechanisms of inhibition were proposed to be the precipitation of iron complexes such as Fe-BTA-EPS and Fe-BTA and iron compounds on the steel surface in the presence of the microalgae and BTA–. This study highlights the application of CS corrosion control by combining biological and chemical approaches that can be used for future research and practice, rather than purely chemical approaches.

Anticorrosion and rheological properties of Calyptocarpus vialis extract as a green coating for mild steel in 2MH2SO4

This study assesses the rheological properties and corrosion inhibition efficacy of Calyptocarpus vialis (CV) extract, a wild plant in Asteraceae family. Shear and dynamic rheology studies show that CV extract has shear-thinning behaviour, with viscosity changes occurring at higher shear rates, most likely owing to aggregate formation. These aggregates may develop due to certain solvent characteristics and a jamming tendency is due to the presence of extract phytochemicals. Dynamic rheology confirms its viscoelastic nature. Corrosion inhibition effectiveness was investigated using Mild Steel (MS) in 2 M H2SO4, resulting in an 82.69 % inhibition with an extract concentration of 1 g/L. Adsorption isotherm indicates phytochemical adsorption on MS surface. Contact angles of polished MS (87.30°), with extract (80.10°), and without extract (51.25°) show decrease in wetting and increase in hydrophobicity which indicates that a thin protective layer is formed at MS surface. FE-SEM (Field Emission Scanning Electron Microscopy) images reveal that the CV extract forms a protective barrier on the MS surface, significantly reducing corrosion as compared to the unprotected surface exposed to the mild acid solution. Theoretical calculations, including Density Functional Theory (DFT) simulations, Monte Carlo (MC), and Molecular Dynamics (MD) simulations, support the experimental findings, elucidating phytochemicals adsorption on the MS surface. Further research is required to examine the scalability of CV extracts for industrial applications, as well as their long-term stability and efficacy in various corrosive conditions.

How does the integration of amino acids enhance the bonding ability of triazine-based inhibitors with iron surfaces: Insights from SCC-DFTB, COSMO-RS and molecular dynamics simulations

Theoretical investigations into the adsorption of molecules on metal surfaces play a pivotal role in the development of more efficient corrosion inhibitors. This study offers a novel approach by combining Density Functional Tight Binding (DFTB), Molecular Dynamics (MD) simulations, and conductor-like screening model for realistic solvation (COSMO-RS) calculations to comprehensively assess the interaction and diffusion properties of glycine (Gly), 2,2′-azanediyldiacetic acid (IDA), and 5-aminopentanoic acid (5-APA) with two 1,3,5-triazine (Tris) derivatives (Tris-Gly and Tris-IDA) for corrosion protection of carbon steel in acidic medium. The solvation properties of these molecules were evaluated alongside their interaction strength with the Fe(1 1 0) surface, considering both neutral and protonated forms. DFTB simulations revealed a clear trend in interaction energies, following the order: Tris-IDA > Tris-Gly > 5-APA > IDA > Gly. It ranges from −1.191 eV to −1.853 eV, with the highest stability observed for protonated Tris-IDA (−1.853 eV), while protonated Glycine exhibits the lowest interaction energy (−1.191 eV). These theoretical results diverged slightly from experimental observations, with Tris-Gly outperforming Tris-IDA, which was attributed to steric effects and solvent interactions. The DFTB results also indicated strong covalent interactions, particularly involving acetic groups, between the inhibitors’ orbitals and the iron’s 3d orbitals. MD simulations further demonstrated the impact of protonation on inhibitor mobility, with reduced diffusion coefficients due to enhanced electrostatic interactions and hydrogen bonding. COSMO-RS solvation analysis confirmed the strong hydrogen bonding capabilities of these molecules with water. Overall, this study elucidates the mechanisms of corrosion inhibition by integrating multiple simulation techniques, providing key molecular insights that can guide the design of more effective corrosion inhibitors. The findings emphasize the significance of electronic interactions and molecular structure in enhancing inhibitor performance, making this a valuable contribution to corrosion science.

Corrosion inhibition effect of sodium silicate/triethanolamine complex inhibitor on AZ91D magnesium alloy in 50% ethylene glycol coolant

Corrosion inhibition effect of sodium silicate/triethanolamine complex inhibitor on AZ91D magnesium alloy in 50% ethylene glycol coolant

Corrosion Inhibition Effect of Mg-Al-pAB-LDH Coating for Steel in the Marine Environment

In this study, the surface of steel was coated with a Mg-Al-pAB-LDH coating in order to enhance its corrosion resistance in the marine environment. The crystal structure, micro-morphology, and chemical composition of the Mg-Al-pAB-LDH coating were characterised using physicochemical techniques. The corrosion protection performance in a simulated marine environment was evaluated through electrochemical methods. The results indicate that the Mg-Al-pAB-LDH coating effectively adsorbs chloride ions from the environment, thereby increasing the corrosion potential of the steel in chloride environments and reducing its corrosion current density. In addition, the Mg-Al-pAB-LDH coating applied to the surface of steel not only enhances the corrosion resistance in the marine environment but also possesses self-healing capabilities in areas of local damage to the steel surface.

Corrosion and scaling inhibition effects of Passiflora edulis Sims peel extract in simulated circulating cooling water: Experimental and theoretical insights

Passiflora edulis Sims peel extract (PESPE) is a biodegradable substance derived from agricultural waste. In this study, we tested PESPE as a corrosion and scale inhibitor in simulated circulating cooling water (SCCW) and its effect on CaCO3 scale formation via static scale inhibition. The chemical composition and microstructure of CaCO3 scale were analyzed using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and field-emission scanning electron microscopy (FE-SEM). The ability of PESPE to inhibit the corrosion of mild steel (MS) in SCCW was investigated via electrochemical tests and microscopic analyses. PESPE exhibited excellent performance in inhibiting both CaCO3 scale formation and MS corrosion, with inhibition efficiencies of 93.5 % and 85.0 %, respectively. PESPE converted the stable CaCO3 deposits into unstable, flocculent, and fine particles, decreasing their size from 57 to 2 μm. Furthermore, it acted as an anode-type corrosion inhibitor for MS, with its corrosion inhibition efficiency being positively correlated with its concentration. The active components of PESPE adsorb onto the MS surface to form a protective film; the synergistic adsorption behavior of the active components was confirmed via density functional theory (DFT) and molecular dynamics (MD) simulations. Our findings prove that PESPE is a sustainable alternative to conventional chemical inhibitors.

Unlocking the power of Dryopteris filix mas extract: A green solution for corrosion inhibition in A210Gr carbon steel in acidified 3% wt. NaCl environment

This study investigates the corrosion inhibition effectiveness of Dryopteris filix-mas L. (DFM) extract for A210Gr carbon steel in a 3 % NaCl solution. The DFM ethanolic extract was successfully prepared and comprehensively characterized using a combination of spectroscopic and physicochemical techniques, including HPLC, FTIR, and NMR (1H and 13C). These analyses confirmed the presence of key phenolic compounds, with Quercetin-3-O-diglucoside (Q3ODG) being the major component, comprising 82.14 % peak area as identified by HPLC. The extract, obtained via an economical ethanol extraction method, exhibited a maximum inhibition efficiency up to 88 % at a concentration of 400 ppm, as determined through electrochemical impedance spectroscopy (EIS), open circuit potential (OCP), potentiodynamic polarization (PDP), and weight loss measurements. Temperature studies revealed a drop in efficiency to 70.14 % at 323 K, indicating a temperature-sensitive inhibition mechanism. Extended immersion times led to a slight decrease in efficiency due to partial desorption, though significant protection remained after 72 h. The primary corrosion inhibition mechanism was determined to be physisorption, following the Langmuir isotherm model, with a ΔGads0 value of − 24.02 kJ/mol, indicating a spontaneous adsorption process. Thermodynamic analysis revealed an increase in Ea from 22.11 kJ/mol (blank) to 56.61 kJ/mol (400 ppm), confirming the formation of a strong protective barrier. Surface characterization techniques, including FTIR, XRD, SEM, and AFM, further confirmed the presence of a protective film rich in polar organic compounds. Complementary Density Functional Theory (DFT) and Quantum Theory of Atoms in Molecules (QTAIM) studies provided detailed insights into the molecular interactions, highlighting the key role of hydrogen bonding and van der Waals forces in the adsorption of Q3ODG onto the steel surface. These findings underscore the potential of DFM extract as an effective and sustainable corrosion inhibitor, advancing the application of biocompounds in corrosion control and encouraging further exploration of their industrial applications and environmental benefits.

Mechanical properties of CoCrFeNi-X (X = Ti,Sn) high entropy alloy and tribological properties in simulated seawater environment

Five multimajor element CoCrFeNi-X(X = Ti,Sn) high entropy alloys (HEA) were prepared by vacuum hot press sintering. The phase composition, mechanical properties and tribological properties of CoCrFeNi-X(X = Ti,Sn) alloys in simulated seawater were investigated. The phase structure of CoCrFeNiTi high-entropy alloy is solid solution FCC phase, R phase, σ phase, and Laves phase. But after addition Sn elements, the phase structure become the FCC phase and Ni-Sn solid solution phase. CoCrFeNiTi alloy has lower density (7.17 g/cm3) and higher hardness (750 HV) than that of CoCrFeNiSn. The compressive yield strength of CoCrFeNiTi HEA is better than CoCrFeNiSn HEA. The CoCrFeNiSn high-entropy alloys showed lower wear rates. The main reason is that SnO2 is generated on the wear scar surface, which has good wetting and corrosion inhibition effects, so CoCrFeNiSn HEA shows better wear resistance in simulated seawater. The main wear mechanism of the CoCrFeNiSn HEA is abrasive wear, oxidative wear, exfoliation wear and corrosive wear.

Natural and synthetic polymers as effective corrosion inhibitors: a concise review

Natural and synthetic polymers as effective corrosion inhibitors: a concise review

Significantly enhanced corrosion resistance for Fe-based amorphous coatings via sealing treatment: Based on hybridisation and superhydrophobicity strategy

Based on the synergistic effect of hybridisation-superhydrophobicity, a simple and facile spraying method was used to achieve efficient sealing of Fe-based amorphous metallic coatings. In this paper, we employed rare-earth neodymium salts as inorganic sealant raw materials and loaded low surface energy fluorosilanes into epoxy resins to act as organic sealant raw materials. The surface structure and chemical composition of the sealing coatings were systematically characterised. The sealing mechanism as well as the anti-corrosion mechanism of the coating were investigated intensively. The results indicate that the superior corrosion resistance and self-cleaning ability of the sealed coating stems from the inorganic–organic-complex trinity effect: the corrosion inhibition effect of Nd oxide deposited during the inorganic sealing process, the shielding effect of the resin in the organic sealing, and the cross-linking and superhydrophobicity behaviour (liquid repellency effect) of the FDTES-Nd3+-Fe2+ complexes formed on the surface of the coating. This work provides valuable guidelines and insights for the design of subsequent corrosion-resistant and sealing coating.

Exploring the performance of Coriandrum sativum extract as an effective corrosion inhibitor for mild steel in a [formula omitted] medium, and its sustainable application in the eco-friendly removal of heavy metals

This research investigated the performance of coriander seeds, for the first time, in two critical phenomena: wastewater treatment and corrosion inhibition in acidic environments. On one hand, the aqueous extracts from Coriandrum sativum seeds (CE) were evaluated for mild steel corrosion inhibition in a 2.0 M phosphoric acid medium using several techniques such as phytochemical analysis (GC-MS), potentiodynamic polarization, electrochemical impedance spectroscopy, scanning electron microscopy (SEM-EDAX) and theoretical analyses, including DFT calculations and Molecular Dynamic Simulations, further elucidated the major chemical components. First, the phytochemical analysis has proved that CE contains heteroatoms. Second, the electrochemical results indicate that CE behaves as a mixed type inhibitor and the corrosion reaction is controlled by charge transfer process. Finally, The theoretical calculations confirmed that the active compounds of CE can be adsorbed on the Fe (1 1 0) surface through physical patterns and by sharing charges with iron to form coordinate bonds. The acquired results have shown a strong correlation between corrosion inhibition efficiency that was about 93 %, SEM-EDAX and DFT parameters. On the other hand, the study examined coriander seeds (CS) in powder form as a removal of copper ions in aqueous solutions through Atomic Absorption Spectroscopy and Inductively Coupled Plasma analysis. The parametric study was effectuated by establishing the effect of contact time, adsorbent mass, solution pH and stirring speed. The removal rate was about 79 %. Regeneration studies showed that CS could be reused for five cycles without significant loss of effectiveness. SEM-EDAX analysis has proved the studied process.

Electrochemical, surface, and theoretical investigations of palm kernel shell extract as an effective inhibitor for carbon-steel corrosion in 1M HCl solution.

Herein, we employed palm kernel shell extract (PKSE) as an eco-friendly inhibitor for carbon steel in acidic-induced corrosion. The corrosion inhibition of PKSE on carbon steel in 1M HCI solution was investigated by electrochemical impedance spectroscopy, weight loss, and potentiodynamic polarization measurements. The surface was characterized by scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy. Moreover, the elastic modulus and hardness tests were conducted. Weight loss measurements revealed that the optimum concentration of inhibitors is 500ppm with 95.3% inhibition efficiency in 1M HCl solution. Electrochemical results showed that the inhibitor could exhibit excellent corrosion inhibition performance and displayed mixed-type inhibition. The electrochemical impedance spectroscopy analysis shows that the inhibition performance increases by increasing the concentration of PKSE. The surface studies ensure the PKSE effectiveness in carbon steel surface damage reduction. Also, the adsorption of PKSE molecules on the carbon steel surface occurs according to the Langmuir isotherm model. The primary goal of this investigation was the utilization of palm kernel shell extract as corrosion inhibitor for 1018 low carbon steel in 1M HCl solution, which highlights its novelty. The present results will be helpful to uncover the versatile importance of palm kernel shell compounds in the corrosion inhibition process.

Drimia maritima as a New Green Inhibitor for Al-Si Alloy, SAE Steel and Pure Al Samples in 0.5 M NaCl Solution: Polarization and Electrochemical Impedance Analyses

The corrosion inhibition effects of Drimia maritima (L.) Stearn sin. Urginea maritima (L.) Backer on three different materials, i.e., as-cast Al-7 wt.% Si alloy, SAE 1020 low carbon steel, and commercially pure Al samples, into a stagnant and naturally aerated 0.5 M NaCl solution are evaluated. For this purpose, both the potentiodynamic polarization curves and electrochemical impedance spectroscopy with an equivalent circuit are utilized. It is found that inhibition effect increases up to certain minor Drimia maritima content. Adsorption isotherms (e.g., Langmuir and Temkin) indicate that all three examined materials comprise physical adsorption mechanisms. Al-Si alloys attained inhibition efficiencies of about 96% at 25 °C with 1250 ppm of Drimia maritima and ~43% with 625 ppm at 45 °C. On the other hand, the cp. Al and SAE 1020 samples attain ~89% and 68% with 1250 ppm and 500 ppm at 25 °C, respectively. This clearly indicates that the dosage of Drimia maritima green inhibitor into NaCl solution possesses certain susceptibility for each distinctive material examined. Impedance parameters obtained by using CNLS (complex non-linear least squares simulations) are correlated and discussed.

Synergistic corrosion inhibition of 4-hydroxypyridine and halogen ions: Insights from interfacial nonlinear spectroscopy.

4-Hydroxypiridine (4-HPy) is a green chemistry corrosion inhibitor for low-carbon steel, valued for its environmental compatibility and low toxicity. Despite lower initial effectiveness than 4-mercapto/4-aminopyridine, 4-HPy's performance is markedly enhanced by halogen ions. By employing second harmonic generation (SHG) spectroscopy combined with electrochemical methods, Raman spectroscopy, atomic force microscopy, x-ray photoelectron spectroscopy, and in situ UV spectroscopy, this study elucidates the synergistic enhancement mechanism of 4-HPy with Cl-, Br-, and I- in 0.5 mol/L HCl solution. Time-dependent SHG measurements showed a two-step process of rapid adsorption and subsequent orientation change, with a proposed mechanism to interpret the temporal changes in SHG intensity. Deducing the adsorption kinetic equations and their application to the experimental data yields the adsorption rate (kad) and orientation change rate (Kre). Halogens reduce the orientation angle of 4-HPy, facilitating its adsorption on the substrate surface and effectively inhibiting corrosion via distinct mechanisms. Cl- and Br- ions primarily adsorb onto the metal surface, forming an adsorption film that not only enhances the subsequent adsorption of 4-HPy but also provides a protective effect for the metal surface. Conversely, I- forms mainly complexes with 4-HPy in solution, co-adsorbs onto the metal surface, and demonstrates a significant synergistic effect. This study revealed the synergistic efficacy hierarchy among halogen ions, with the order 4HPy + NaCl < 4HPy + NaBr < 4HPy + NaI. This study enhances our molecular-level understanding of the synergistic mechanism between halogen ions and corrosion inhibitors and provides valuable insights for designing and developing effective corrosion inhibitors.

Synthesized Heterocyclic Compounds as Corrosion Inhibitors for Steel in Acidic Environments: A Mini-Review

Corrosion is a significant problem in various industries, leading to the degradation of steel structures and causing significant economic losses. Heterocyclic compounds, which contain heteroatoms such as nitrogen, sulfur, and oxygen, have been found to be effective corrosion inhibitors for steel in acidic environments. This mini-review discusses the synthesis and use of heterocyclic compounds as corrosion inhibitors for steel in acidic solutions. The review highlights the potential of these compounds as effective and low-cost corrosion inhibitors for various industries.

A novel corrosion inhibitor of bis-benzimidazole derivative for mild steel: Synthesis, properties and mechanism investigation

The application of corrosion inhibitor is still one of the effective ways to protect metals under high temperature and high pressure environment. In this paper, we have introduced a synthetic method for a novel bis-benzimidazole derivative, i.e., N, N-bis (-2-heptadecyl-benzimidazole) -1-hexylammonium chloride (HBH), and its solubility was improved by adding a specific surfactant (AEO-5) to form a highly efficient corrosion inhibitor system (HBH-A), and its corrosion inhibition was studied by weight loss, electrochemical measurements, SEM, EDS and XRD. The results showed that HBH-A inhibited the corrosion of N80 carbon steel in the corrosive medium. As the concentration of HBH-A increases, the corrosion inhibition rate exhibits a pattern of rapid initial growth followed by a slower increase. Electrochemical measurements demonstrate that HBH-A behaved as an effective mixed-type corrosion inhibitor, exhibiting a significant enhancement in the corrosion inhibition rate (η) with increasing concentrations of HBH-A. At a HBH-A concentration of 100 mg⋅L-1, the inhibition rate can outstrip 98 %. Corrosion surface analysis further confirm that the HBH molecules are indeed adsorbed to form an adsorption film, and the surface exposure of N80 carbon steel was significantly decreased with the action of HBH-A, thus reducing the corrosion rate of N80 carbon steel.

The Performance of Amino‐ and Hydroxy‐Substituted Benzothiazoles in Inhibiting the Corrosion of Carbon Steel in HCl and the Molecular‐Level Mechanisms

AbstractIn the pickling process and acidizing program for oil wells, the acidic corrosion of metals is a problem that needs to be addressed. Various acid corrosion inhibitors have been studied and used to mitigate the acidic corrosion of carbon steel. In this paper, the corrosion inhibition of 2‐aminobenzothiazole (2 N‐BT), 2‐amino‐4‐hydroxybenzothiazole (2 N4O‐BT), and 2‐amino‐6‐hydroxybenzothiazole (2 N6O‐BT) on carbon steel in 0.5 mol/L HCl was investigated using electrochemical and quantum chemical methods. All three molecules exhibited corrosion inhibition effects. Compared to 2 N‐BT, 2 N4O‐BT and 2 N6O‐BT showed less sensitivity to the environmental conditions and the surface state of the metal. Among them, 0.0010 mol/L 2 N6O‐BT demonstrated the highest and most persistent corrosion inhibition, exhibiting a mixed inhibition mechanism with cathodic inhibition dominance. The adsorption of 2 N6O‐BT on the carbon steel surface was found to be non‐uniform, preferentially adsorbing at certain active sites on the surface, following Freundlich‐Langmuir thermodynamic characteristics. It showed initial strongly adsorbed points and weakly adsorbed regions. With continued adsorption of 2 N6O‐BT, the differences between strongly adsorbed points and weakly adsorbed regions decreased. The introduction of hydroxyl groups, especially in 2 N6O‐BT, extended the negative potential region and enhanced the coordination activity of the molecule, generating the orbital distribution that was advantageous to flat adsorption and the formation of feedback bonds. This provided a molecular structural basis for the excellent corrosion inhibition properties of 2 N6O‐BT.