Pyrrolidine-based quaternary ammonium salts containing propargyl and hydrophobic C-12 and C-16 alkyl chains as corrosion inhibitors in aqueous acidic media

Anticorrosion of Copper by Turtle Shape-Like Long Fatty Chain Linker-Included Bis-Schiff Base Molecules Synthesized from a Natural Analogue of Vanillin

Copper and alloys suffer from severe corrosion during acid picking and acid cleaning in the industry. In this study, the corrosion inhibition of copper in sulfuric acid solution was inspired by the turtle shape-like bis-Schiff bases bearing fatty chain linkers (BSBs 1-3), which were synthesized from a natural analogue of vanillin under mild conditions. The chemical structures of the BSBs were fully identified, and the presence of hydrogen bonding in the BSBs was confirmed. The target BSBs display affinity to the copper surface using the Schiff base parts (like turtle feet), and thus, the fatty linkers in the BSBs could resist aggressive species invading the copper surface (like turtle shell). The corrosion resistance and corrosion inhibition mechanism of BSBs for copper were investigated experimentally in 0.5 M H2SO4 solution. The results show that target BSBs might significantly inhibit the corrosion of copper in acid solution. The corrosion inhibition efficiencies of BSBs 1-3 were maximized at a concentration of 1.00 mM under 298 K, which reached 97.99, 96.22, and 94.58%, respectively. It is shown that the corrosion inhibition effect of the BSBs for copper increased with an increase in the length of fatty linkers, which was consistent with the order of hydrogen bonding strength. The adsorption and anticorrosion mechanisms of the target molecules for copper were analyzed. The results presented in this study could provide an experimental insight for engineering new efficient, low-cost, and environmentally friendly corrosion inhibitors for copper through simple preparation using natural compounds as starting molecules.

Corrosion Inhibition of Mild Steel by Coumarate-Based Ionic Liquids and Coatings

The use of ionic liquids (ILs) as corrosion inhibitors is gaining significant attention due to their attractive properties such as high inhibition efficiency and ability to absorb onto metal surfaces. In this work, six protic ILs, based on the coumarate anion in combination with the nitrogen containing ammonium, pyrrolidinium and imidazolium cations with a short or long alkyl chain attached to the nitrogen atom, have been synthesized and evaluated as corrosion inhibitors for mild steel. The anticorrosion properties of these ILs in solution as inhibitors were investigated electrochemically and the metal surface was analyzed by Scanning Electron Microscopy. Moreover, the IL prepared from the coumarate anion and N-dimethyl-N-tetradecyl ammonium ([DTA]Cou) was incorporated into an acrylic UV-cured coating formulation as an additive and by designing a similar ionic monomer which covalently links to the acrylic coating formulation. Both coatings were analyzed using impedance spectroscopy during 11 days of exposure to a solution of 0,01 M NaCl, confirming the high performance of the inhibitor in both solution and when incorporated into a coating. The synthesized ILs present efficiencies in solution exceeding 70 %, in particular the ILs [DTA]Cou and the tetradecyl imidazolium coumarate ([C14Im]Cou) showed efficiencies of 88 % and 91 % respectively. Surface analysis after 24 h confirmed that the inhibitors efficiently adsorb onto the mild steel surface to form a protective film. The obtained inhibitors showed interesting anticorrosion behaviors and demonstrated how different cations and an increase in the chain length affect the corrosion inhibition properties.

Synthesis of a new quaternary ammonium salt for efficient inhibition of mild steel corrosion in 15 % HCl: Experimental and theoretical studies

The corrosion phenomenon and its economic impacts can hardly be ignored in any application. This study synthesized a quaternary ammonium salt (3) containing hydrophobic dodecyl and electron-rich diallylbenzyl amine moieties to be used in 15 % HCl as a corrosion inhibitor of mild steel. Several techniques, such as 1H and 13C NMR, IR, TGA, and elemental analysis, have been used to characterize inhibitor 3. Popular corrosion measurement techniques, namely weight loss, potentiodynamic polarization techniques, and electrochemical impedance spectroscopy, have been used to determine the efficiency of inhibitor 3. At 303 K and a moderately low concentration of 50 ppm, the quaternary ammonium salt-based inhibitor demonstrated a maximum efficiency of ≈95.0 %. At elevated temperatures of 313, 323, and 333 K, the inhibition efficacy values were recorded as 91.3, 82.8, and 75.0 %, respectively. Adsorption isotherm study revealed that the adsorption of inhibitor 3 followed Langmuir adsorption isotherm. The value ofΔ G a d s ° was found to be - 40.19 kJ mol-1, indicating that inhibitor 3 became adsorbed via a mixed physi-chemisorption mechanism. A very high adsorption constant (K a d s ) of 1.53 × 105 L mol-1 suggested strong adsorption of inhibitor 3. The difference in activation energy (E a ) value of 42.4 kJ mol-1 between the control and the inhibited solution indicated an efficient adsorption of inhibitor 3. The ability of inhibitor 3 to retard both anodic and cathodic half-cell reactions was proved via open circuit potential and Tafel curves studies. Detailed discussions on the change in corrosion current densities (i c o r r ), polarization (R p ) and charge transfer (R c t ) resistances have been offered to discuss the inhibition efficiency. Water contact angle measurement showed a drastic increase in mild steel surface hydrophobicity following inhibitor 3 adsorption. SEM-EDX and XPS studies confirmed the definitive presence of inhibitor 3 on the mild steel surface. Density functional theory (DFT) studies revealed the frontier molecular orbitals with which the metal surface interacts. A detailed corrosion inhibition mechanism has been offered in the context of adsorption isotherm and DFT studies.

Microwave‐Assisted Synthesis of Fluorinated 5‐Membered Nitrogen Heterocycles

The fluorinated 5‐membered N‐containing heterocyclic compounds have wide utility in varied fields. The importance of these compounds has encouraged researchers to explore environment‐friendly synthetic techniques for their synthesis. In this context, microwave‐assisted synthesis has proved beneficial for the synthesis of fluorinated 5‐membered N‐heterocycles in an environmentally benign and energy‐efficient manner. Compared to conventional heating, it offers several advantages, including quick heating, short reaction times, higher yields, and fewer side reactions. This article highlights the microwave‐assisted fluorination of 5‐membered N‐heterocyclic compounds along with the synthesis of fluorinated 5‐membered N‐heterocyclic compounds using fluorinated starting materials.

Use of orange peel extract as an inhibitor of stainless steel corrosion during acid washing in a multistage flash desalination plant

Environmentally friendly and cost-effective inhibitors based on orange peel extract (OPE) have been developed for potential applications in ejector tubes of a multistage desalination plant during the acid cleaning process. After conducting tests under both static and hydrodynamic circumstances, it was determined that the inhibitor formulation was effective against corrosion of stainless steel (SS) in 1 M HCl solution at 30 °C under the conditions tested. Electrochemical methods were used along with electron microscopy to collect information on the corrosion inhibition efficiency of the extract. Experiments were conducted for 1, 2, 3, 4, 6, 12, and 24 h, and the performance of OPE was compared to that of a commercial acid corrosion inhibitor to determine which performed better. The results revealed that OPE demonstrated outstanding corrosion inhibition performance compared to the commercial acid corrosion inhibitor. With remarkable inhibition efficacy for up to 24 h under both static and dynamic settings, 0.4% of OPE displayed typical mixed-type corrosion inhibitor behavior in the tested environment. All of the procedures that were used produced results that were in good agreement. Due to the synergistic action between the two compounds, the corrosion inhibition of OPE on SS was improved in 1 M HCl in the presence of iodide ions. In the absence of KI, OPE was found to inhibit SS corrosion at a concentration-dependent rate, with the concentration of OPE being the most significant factor. A study of the adsorption of OPE onto a SS surface revealed that the Langmuir adsorption isotherm controls the process. Based on the quantity of free energy of adsorption observed, it was determined that there is physical contact between the OPE and the surface of SS in this experiment. It was possible to identify the most effective phytochemicals for corrosion inhibition based on the findings of quantum chemical calculations, which were subsequently evaluated in the laboratory.

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Synthesis of Novel Nano-Sulfonamide Metal-Based Corrosion Inhibitor Surfactants

The synthesis of novel corrosion inhibitors and biocide metal complex nanoparticle surfactants was achieved through the reaction of sulfonamide with selenious acid to produce a quaternary ammonium salt. Platinum and cobalt surfactants were then formed by complexing the first products with platinum (II) or cobalt (II) ions. The surface properties of these surfactants were then investigated, and the free energy of form micelles (ΔG_omic) and adsorption (ΔG_oads) was determined. The obtained cationic compounds were evaluated as corrosion inhibitors for carbon steel dissolution in 1N HCl medium. The results of gravimetric and electrochemical measurements showed that the obtained inhibitors were excellent corrosion inhibitors. The anti-sulfate-reducing bacteria activity known to cause corrosion of oil pipes was obtained by the inhibition zone diameter method for the prepared compounds, which were measured against sulfate-reducing bacteria. FTIR spectra, elemental analysis, H1 NMR spectrum, and 13C labeling were performed to ensure the purity of the prepared compounds.

Performance of Waterborne Polyurethanes in Inhibition of Gas Hydrate Formation and Corrosion: Influence of Hydrophobic Fragments

The design of new dual-function inhibitors simultaneously preventing hydrate formation and corrosion is a relevant issue for the oil and gas industry. The structure-property relationship for a promising class of hybrid inhibitors based on waterborne polyurethanes (WPU) was studied in this work. Variation of diethanolamines differing in the size and branching of N-substituents (methyl, n-butyl, and tert-butyl), as well as the amount of these groups, allowed the structure of polymer molecules to be preset during their synthesis. To assess the hydrate and corrosion inhibition efficiency of developed reagents pressurized rocking cells, electrochemistry and weight-loss techniques were used. A distinct effect of these variables altering the hydrophobicity of obtained compounds on their target properties was revealed. Polymers with increased content of diethanolamine fragments with n- or tert-butyl as N-substituent (WPU-6 and WPU-7, respectively) worked as dual-function inhibitors, showing nearly the same efficiency as commercial ones at low concentration (0.25 wt%), with the branched one (tert-butyl; WPU-7) turning out to be more effective as a corrosion inhibitor. Commercial kinetic hydrate inhibitor Luvicap 55 W and corrosion inhibitor Armohib CI-28 were taken as reference samples. Preliminary study reveals that WPU-6 and WPU-7 polyurethanes as well as Luvicap 55 W are all poorly biodegradable compounds; BODt/CODcr (ratio of Biochemical oxygen demand and Chemical oxygen demand) value is 0.234 and 0.294 for WPU-6 and WPU-7, respectively, compared to 0.251 for commercial kinetic hydrate inhibitor Luvicap 55 W. Since the obtained polyurethanes have a bifunctional effect and operate at low enough concentrations, their employment is expected to reduce both operating costs and environmental impact.