Novel water-soluble organoselenocyanates and symmetrical diselenides tethered N-succinanilate and N-maleanilate as corrosion inhibitors for reinforced steel in the simulated concrete pore solution

Effects of Vitamins as Green Inhibitors on the Surface of Steel Bars in Chloride-Polluted Simulated Concrete Pore Solution: Experimental, Characteristic Analysis, and Theoretical Calculation

This study evaluates the effects of vitamins B1 (VB1), B6 (VB6), B3 (VB3), and C (VC) as green corrosion inhibitors for steel bars in a chloride-polluted simulated concrete pore (SCP) solution. Electrochemical tests demonstrated that VB6 achieves the highest corrosion inhibition efficiency (IE%) of 92.86%, and the IE% of VB1 and VC are 91.96 and 91.51%, respectively, while VB3 shows the least effectiveness of 83.49% at their respective optimum concentrations. Scanning electron microscopy revealed that vitamin treatment significantly improves the surface morphology, enhancing smoothness. Energy dispersive X-ray spectroscopy confirmed the presence of protective molecular layers and precipitated calcium (Ca) on the steel surface, indicating effective adsorption. X-ray photoelectron spectroscopy revealed that vitamin interacts with iron (Fe) through chemisorption and physisorption, contributing to the formation of protective FeOOH compounds. Moreover, it also suggests that the main component of precipitated Ca is protective calcium carbonate (CaCO3). Density functional theory calculations showed that vitamins adhere to the surface of γ-FeOOH through hydrogen bonds. These findings underscore the potential of vitamins as effective green inhibitors in corrosion prevention applications.

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.

Unraveling the anti-corrosion mechanisms of a novel hydrazone derivative on steel in contaminated concrete pore solutions: An integrated study

INTRODUCTION

Corrosion-induced deterioration of infrastructure is a growing global concern. The development and application of corrosion inhibitors are one of the most effective approaches to protect steel rebar from corrosion. Hence, this study focuses on a novel hydrazone derivative, (E)-N'-(4-(dimethylamino)benzylidene)-2-(5-methoxy-2-methyl-1H-indol-3-yl)aceto-hydrazide (HIND), and its potential application to mitigate corrosion in steel rebar exposed to chloride-contaminated concrete pore solutions (ClSCPS).

OBJECTIVES

The research aims to evaluate the anti-corrosion capabilities of HIND on steel rebar within a simulated corrosive environment, focusing on the mechanisms of its inhibitory effect.

METHODS

The corrosion of steel rebar exposed to the ClSCPS was studied through weight loss and electrochemical methods. The surface morphology of steel rebar surface was characterized by FE-SEM-EDS, AFM; oxidation states of the steel rebar and crystal structures were examined using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) methods. Further, experimental findings were complemented by theoretical studies using self-consistent-charge density-functional tight-binding (SCC-DFTB) simulations. The performance of HIND was monitored at an optimal concentration over a period of 30 days.

RESULTS

The results indicated a significant reduction in steel rebar corrosion upon introducing HIND. The inhibitor molecules adhered to the steel surface, preventing further deterioration and achieving an inhibition efficiency of 88.4% at 0.5 mmol/L concentration. The surface morphology analysis confirmed the positive effect of HIND on the rebar surface, showing a decrease in the surface roughness of the steel rebar from 183.5 in uninhibited to 50 nm in inhibited solutions. Furthermore, SCC-DFTB simulations revealed the presence of coordination between iron atoms and HIND active sites.

CONCLUSION

The findings demonstrate the potential of HIND as an effective anti-corrosion agent in chloride-contaminated environments. Its primary adsorption mechanism involves charge transfer from the inhibitor molecules to iron atoms. Therefore, applying HIND could be an effective strategy to address corrosion-related challenges in reinforced infrastructure.

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.

Inhibition performance of uniconazole on steel corrosion in simulated concrete pore solution: An eco-friendly way for steel protection

Corrosion inhibitors play a vital role in impeding the corrosion process of steel bars within concrete structures exposed to corrosive environments. Nevertheless, conventional corrosion inhibitors pose environmental risks. In contrast, contemporary studies have explored corrosion inhibitors that are eco-friendly. However, these inhibitors are burdened by high costs and complex production processes, impeding the widespread application in concrete structures. Consequently, this study presents an innovative solution by incorporating uniconazole, an agricultural fungicide, as a corrosion inhibitor for steel bars in concrete structures. The steel bars were exposed to corrosion within a simulated concrete pore solution containing 0.6 mol/L NaCl, both with and without the presence of uniconazole. The morphology and hydrophilicity of the steel bar surface were investigated via optical microscope and contact angle experiments. Electrochemical tests (open circuit potential, potentiodynamic polarization, electrochemical impedance spectroscopy, and Mott-Schottky analysis) and X-ray photoelectron spectroscopy were employed to investigate the corrosion inhibition performance and mechanism of uniconazole. The results demonstrate that uniconazole elevates the hydrophobicity and contributes to the corrosion inhibition of steel bars. Electrochemical test results indicate that as the concentration of uniconazole increases from 1 × 10-4 mol/L to 1 × 10-3 mol/L, the inhibition efficiency likewise demonstrates a corresponding increase, escalating from around 50 %-90 %. Uniconazole molecules function as mixed-type inhibitors, exhibiting characteristics of both anode-type and cathode-type inhibitors. The adsorption of uniconazole enhances the stability and thickness of the passive-adsorbed layer on the steel surface, effectively impeding the charge transfer process and obstructing the interaction of corrosive substances with the base metal. In summary, the application of uniconazole exhibits the highlights of efficient, cost-effective, environmentally friendly, and the potential for scalable production. This positions uniconazole as a promising candidate for use as a corrosion inhibitor in the domain of concrete structures.

Corrosion mitigation characteristics of some novel organoselenium thiourea derivatives for acid pickling of C1018 steel via experimental and theoretical study

Two organoselenium thiourea derivatives, 1-(4-(methylselanyl)phenyl)-3-phenylthiourea (DS036) and 1-(4-(benzylselanyl)phenyl)-3-phenylthiourea (DS038) were produced and categorized using FTIR and NMR (1H and 13C). The effectiveness of the above two compounds as C-steel corrosion inhibitors in molar HCl was evaluated using the potentiodynamic polarization (PD) and electrochemical impedance spectroscopy (EIS) techniques. PD findings indicate that DS036 and DS038 have mixed-type features. EIS results show that growing their dose not only changes the polarization resistance of C-steel from 18.53 to 363.64 and 463.15 Ω cm2 but also alters the double layer capacitance from 710.9 to 49.7 and 20.5 μF cm-2 in the occurrence of 1.0 mM of DS036 and DS038, respectively. At a 1.0 mM dose, the organoselenium thiourea derivatives displayed the highest inhibition efficiency of 96.65% and 98.54%. The inhibitory molecule adsorption proceeded along the Langmuir isotherm on the steel substrate. The adsorption-free energy of the adsorption process was also intended and indicated a combined chemical and physical adsorption on the C-steel interface. FE-SEM studies support the adsorption and protective abilities of the OSe-based molecule inhibitor systems. In Silico calculations (DFT and MC simulations) explored the attraction between the studied organoselenium thiourea derivatives and corrosive solution anions on a Fe (110) surface. The obtained results show that these compounds can make a suitable preventing surface and control the corrosion rate.