Corrosion behaviors of Q235 carbon steel under imidazoline derivatives as corrosion inhibitors: Experimental and computational investigations

Experimental and Computational Anticorrosion Behaviors of Pyrazole s-Triazine/anilino-morpholino Derivatives for Steel in Acidic Solutions

The corrosion inhibition of C-steel by two s-triazine/morpholino-anilino-pyrazole derivatives, namely, 4-(3,5-dimethyl-1H-pyrazol-1-yl)-6-morpholino-N-phenyl-1,3,5-triazin-2-amine (1) and N-(4-bromophenyl)-4-(3,5-dimethyl-1H-pyrazol-1-yl)-6-morpholino-1,3,5-triazin-2-amine (2) was investigated by impedimetric and potentiometric studies. It was found that (1) and (2) acted as cathodic-type corrosion inhibitors that retard the hydrogen evolution reaction. The percent corrosion inhibition, 98.5% for compound (2) (with bromo substituent) at 80 ppm, was slightly higher than 97.8% for (1) at 100 ppm. Thus, the replacement of a -H with -Br substituent increased the corrosion inhibition properties. Compound (2) exhibited Temkin isotherm adsorption, whereas compound (1) exhibited Langmuir adsorption. Scanning electron microscopy (SEM) analysis of the steel surface indicated that the inhibitors caused protection of the surface. The weight loss experiment also proved the decrease in the corrosion rate when inhibitors were added. The difference in inhibitory efficiency between compounds (1) and (2) was investigated by density functional theory (DFT) to study neutral and protonated species in gaseous and aqueous phases. The theoretical analysis demonstrated that compound (2) exhibited higher inhibitory activity on a metal surface compared to compound (1), aligning with the experimental results. The energy associated with the metal/adsorbate arrangement, represented by dE ads/dNi , was higher for (2) (-380.91 kcal mol-1) compared to (1) (-371.64 kcal mol-1). This indicated better adsorption of (2) over (1).

Silver sulfide anchored bismuth molybdate p-n heterojunction nano-coating with excellent photo-thermal self-healing performance

In this research, a self-healing nano-coating with excellent photo-thermal response to near-infrared (NIR) laser is prepared. This coating incorporates silver sulfide anchored bismuth molybdate (Ag2S@Bi2MoO6) into a shape memory epoxy resin to achieve for a good photo-thermal conversion capability. The Ag2S@Bi2MoO6 p-n heterojunction could photo-generate more electron-holes pairs under the NIR laser irradiation. Also, it shows a wider absorption range of visible light, leading to effectively absorb the light energy, generate enough heat to induce the shape memory recovery in the coating, and seal the scratch. The results indicate that the temperature of EP-1 % Ag2S@Bi2MoO6 coating has reached about 88 °C, while good self-healing and anti-corrosion properties with a self-healing rate of 88.41 % have been achieved. Furthermore, calculations based on Density Functional Theory and Finite Element Method pointed out that the formation of p-n heterojunction effectively has enhanced the photo-thermal effect. This research opens a new way for developing self-healing coatings with an ultra-fast response time and high self-healing efficiency.

Unveiling green corrosion inhibitor of Aloe vera extracts for API 5L steel in seawater environment

This study evaluated Aloe vera extract as a green inhibitor to prevent corrosion in seawater environments. A. vera extract was produced by maceration with methanol-water at room temperature. Electrochemical techniques were used to evaluate the corrosion inhibitor effectiveness of the A. vera extract. The morphology of the corrosion products was analyzed by FE-SEM equipped with EDS and AFM. FT-IR and LCMS characterized the functional and structural groups in this extract. The electrochemical measurements show that A. vera extract could effectively reduce the corrosion of API 5L steel in seawater environments. Inhibition efficiency (IE) increases with increasing concentration. Optimal corrosion inhibition efficiency of around 83.75% (PDP) and 88.60% (EIS) was obtained by adding 300 mg L-1 of extract at 310 K. Furthermore, the higher the concentration of A. vera extract, the greater the activation energy (Ea), with the highest activation energy being 48.24 kJ mol-1 for the concentration of 300 mg L-1. Conversely, increasing the temperature and exposure duration reduces the corrosion inhibition efficiency (IE) values; the best exposure period was 30 min with 88.34% IE by a concentration of 300 mg L-1 at 300 K. This corrosion inhibition is achieved by the adsorption process of A. vera bioactive on metal surfaces with a mixed inhibitor through a physisorption-chemisorption mechanism. This finding was confirmed by the smoother surface morphology of the steel treated with A. vera extract than without. This unveiling investigation found that A. vera extract has the potential to be an environmentally friendly corrosion inhibitor in the seawater environment.

Imidazoline As a Volatile Corrosion Inhibitor for Mitigation of Top- and Bottom-of-the-Line CO2 Corrosion in Carbon Steel Pipelines

A fatty acid imidazoline-based inhibitor was synthesized via a facile solvent-free synthesis method between tall oil fatty acid (TOFA) and diethylenetriamine (DETA) under atmospheric conditions with a short reaction time. The as-synthesized imidazoline (S-Imd) acted as an effective inhibitor for reducing or preventing corrosion of carbon steel pipelines at both bottom of the line (BOL) and top of the line (TOL) positions under simulated conditions of a gas pipeline in a CO2-saturated environment. The inhibition efficacy was examined by both weight loss and electrochemical measurements, such as the electrochemical impedance spectrum (EIS), potentiodynamic polarization (PDP), and linear polarization resistance (LPR). The results revealed that the S-Imd, 2-(8-heptadecenyl)-2-imidazoline-1-ethanamin, at 300 ppm exhibited a superior inhibition efficiency of up to 91.6 and 89.9% for BOL and TOL corrosion tests, respectively. The surface morphology of the carbon steel test specimens was also examined using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX), and contact angle analysis. It was found that the as-synthesized S-Imd acted as a mixed-type inhibitor that exhibited a decreased surface roughness and oxide layer on carbon steel surfaces. However, the water contact angle was found to increase, implying enhanced hydrophobicity of the surface. Adsorption of the imidazoline molecules on carbon steel surfaces followed the Langmuir adsorption isotherm. The present work provides very promising results in the synthesis and utilization of the studied imidazoline as a volatile corrosion inhibitor (VCI), especially for carbon steel pipelines in petroleum industries.

Synthesis of phytic acid-modified chitosan and the research of the corrosion inhibition and antibacterial properties

In this study, chitosan (CS) and phytic acid (PA) were employed as raw materials to synthesize a range of chitosan-phytic acid complexes (CP) with different ratios (CS:PA = 12:1, 9:1, 6:1, 3:1, 1:1). The structures and elemental compositions of the compounds were characterized using Fourier-Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDS). The thermal stability of the synthesized materials was analyzed using a Thermogravimetric Analyzer (TG). Electrochemical testing was conducted to explore the corrosion inhibition effect of the modified inhibitors with varying ratios on Q235 steel in 3.5 wt% NaCl solution. Additionally, Scanning Electron Microscopy (SEM) was utilized to investigate the surface morphology of the immersed samples. When the CS:PA ratio was 3:1, CP exhibited an impressive corrosion inhibition efficiency of 94.9 %. Furthermore, the antimicrobial properties of CP were evaluated using the colony plate counting method. At a CS:PA ratio of 1:1, CP demonstrated the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) at 0.1250 % and 0.5000 %, respectively. This research introduces a novel green corrosion inhibitor capable of simultaneously reducing the electrochemical corrosion of Q235 while inhibiting biocorrosion, avoiding the antagonistic effects arising from the simultaneous use of biocides and corrosion inhibitors in the system.

Synthesis and Structure of Water-Soluble Sb Quantum Dots and Enhanced Corrosion Inhibition Performance and Mechanisms

Generally, single organic or inorganic inhibitors could effectively inhibit corrosion for metallic materials; however, there are rarely reports about the hybrid corrosion inhibitors consisting of organic and inorganic inhibitors. Thus, in this work, we synthesize a hybrid environment-friendly water-soluble corrosion inhibitor (Sb quantum dots) containing Sb, Sb₂O₃, Sb₂O₄, and carbon using the electrochemical exfoliation method. The inhibition effectiveness in short- and long-term immersion tests is measured using electrochemical methods, weight loss, and surface analysis. The results exhibit that the corrosion inhibition efficiency sensitively relates to the concentration of Sb quantum dots (SQDs), which achieves the largest value as the concentration of SQDs increases to 200 mg/L. Atomic force microscopy, scanning electron microscopy, and contact angle analysis reveal that the SQDs well-disperse on and cover the Q235 steel surface at 200 mg/L. According to the Langmuir adsorption data, the physicochemical adsorption and effective antioxidation of SQDs on the passivated Q235 steel surface are in charge of the effective corrosion inhibition efficiency in 0.5 M H₂SO₄ solution.

Insights into the newly synthesized N-doped carbon dots for Q235 steel corrosion retardation in acidizing media: A detailed multidimensional study

N-doped carbon quantum dots (NCQDs) were synthesized by a hydrothermal method using folic acid and o-phenylenediamine as precursors. The inhibition behaviour of the NCQDs on Q235 steel in 1 M HCl solution was appraised through electrochemical impedance spectroscopy (EIS), potentiodynamic polarization curves (PDP), and surface analysis. The results demonstrated that the synthesized NCQDs had an effective anticorrosion effect on Q235 steel, and the corrosion inhibition efficiency of 150 mg/L NCQDs reached 95.4%. Additionally, the analysis of the PDP corrosion potential changes indicated that the NCQDs acted as a mixed corrosion inhibitor. Moreover, the NCQDs adsorbed onto the surface of steel by coordinating its electron-rich atoms with the iron metal to form a protective film, which slowed the dissolution reaction of the anodic metal to achieve corrosion inhibition. The adsorption mechanism of the NCQDs was consistent with Langmuir adsorption, including physical and chemical adsorption. Therefore, this work can inspire and facilitate, to a certain extent, the future application of doped carbon quantum dots as efficient corrosion inhibitors in pickling solutions.