Multidimensional insight into the corrosion inhibition of salbutamol drug molecule on mild steel in oilfield acidizing fluid: Experimental and computer aided modeling approach

Analysis of natural okra extracts as corrosion inhibitors for mild steel in acidic medium

Plant extracts have been shown to effectively inhibit metal corrosion. Using the Box-Behnken design, gravimetric, and electrochemical techniques, analyses were designed to investigate the anti-corrosion potential of okra in a 1M HCl medium. The inhibition performances derived from the various methods were in good agreement, demonstrating that physio-chemisorption was effective and adhered to the Langmuir isotherm model. The efficiency of okra mucilage extract was 96% at a much lower concentration compared to 91.2% and 88.4% for the unsieved extract and gelly-okra filtrate, respectively. FTIR results showed the presence of several functional groups in the okra mucilage extract that are associated with adsorption, and TGA analysis revealed that the extract has high thermal stability. FESEM analysis also supported evidence of adsorption. It was determined that corrosion inhibition by okra mucilage extract was primarily influenced by temperature, followed by extract concentration, with immersion time having the least effect. From the model optimization, it was observed that okra mucilage extract at 200 ppm, 60°C, and 24 h gave an inhibition efficiency of 89.98% and high desirability. These results demonstrate the high capacity of natural okra as an efficient biodegradable corrosion inhibitor.

Biodegradable polysaccharide grafted polyacrylamide inhibitor for corrosion in CO2- saturated saline solution

A biodegradable polysaccharide-based inhibitor is grafted with polyacrylamide (PAM) for oilfields' sweet corrosion. The green properties of agar and PAM were incorporated to synthesize an agar-grafted-PAM (AGGPAM) inhibitor. Electrochemical tests of Tafel and AC impedance, were used to determine the corrosion rate of carbon steel (C-steel) and protection efficiency in CO2-saturated 3.5 wt% NaCl solution. The surface morphology was characterized using FESEM coupled with EDX. Results demonstrated the promising performance of AGGPAM in improving steel resistivity, achieving 85% efficiency at 500 mg L-1 and reducing the corrosion rate from 33 to 4.9 mils per year at 25 °C. The electrochemical tests classified AGGPAM as a mixed-type inhibitor, yet with a larger potential to inhibit the cathodic hydrogen evolution. Kinetics study at a temperature of 50 °C revealed a deteriorated AGGPAM inhibition attributed to electrolyte diffusion through the weakly adsorbed AGGPAM film. Nevertheless, the AGGPAM-inhibited solution exhibited a corrosion rate of 26.7 mils per year at 50 °C, which is still lower than that of blank at 25 °C. The steel resistance was diminished from 1436 to 355 Ω cm2 at 50 °C. Implementing AGGPAM coating reduced the steel corrosion rate to 9.6 mils per year, achieving 71% efficiency. AGGPAM inhibitor toxicity was evaluated using ADMETlab, which predicted negligible hazardous impacts. Lastly, potentiostatic testing of steel with AGGPAM at an applied potential of 50 mV illustrated surface protection and decreased current over a prolonged time. Herein, the experimental investigation revealed the promising capabilities of AGGPAM as an efficient corrosion inhibitor in oilfields.

New benzisoxazole derivative: A potential corrosion inhibitor for mild steel in 0.5 M hydrochloric acid medium -insights from electrochemical and density functional theory studies

6-fluoro-3-(4-piperidinyl)-1,2-benzisoxazole. HCl (FPBH), a substituted benzisoxazole derivative, was prepared from isonipecotic acid and characterized using various spectroscopic techniques. Using electrochemical examinations such as potentiodynamic polarisation (PDP) and electrochemical impedance spectroscopic (EIS) technique, the corrosion mitigation capabilities of this compound for mild steel (MS) in 0.5 M HCl medium were investigated. Theoretical studies were performed using quantum chemical calculations and density functional theory (DFT). PDP results exhibited the mixed-type behavior of FPBH and showed a maximum efficiency of 94.5 % at 1 × 10-3 M. The development of a protective adsorbed layer of FPBH decreases the corrosion current density (icorr) and corrosion rate (CR). The EIS technique revealed that the rise in the charge transfer resistance (Rct) values and reduction in the thickness of the double-layer capacitance (Cdl) reflected the drop in corrosion rate. The adsorption of FPBH took place through physisorption by conforming Langmuir's isotherm. The DFT method was performed on the optimized structure of FPBH to get additional evidence on the action mode of FPBH with the metal surface.

Efficiency of Expired Drugs Used as Corrosion Inhibitors: A Review

Corrosion inhibitors represent one of the most commonly used methods for significantly reducing the corrosion rate of metals and alloys. Adsorption inhibitors have a wide range of applications in cooling water systems, deicing solutions for aircrafts, airports and ways, etching and degreasing solutions, oil pipelines, paints and coatings and metal processing solutions. Adsorption corrosion inhibitors of metals and alloys are generally organic compounds that contain structures with heteroatoms (N, P, S, As, O) in their molecules, having lone pair electrons or π electrons in aromatic rings or multiple bonds. They enable relatively strong interactions between the metal atoms and organic molecules, resulting in a protective layer of organic molecules adsorbed at the metal-corrosive solution interface. Most molecules of active substances from drugs contain similar structures, which is why many drugs have been already tested as corrosion inhibitors. One of the major disadvantages of using drugs for this purpose is their particularly high price. To overcome this impediment, the possibility of using expired drugs as corrosion inhibitors has been investigated since 2009. The present paper is an exhaustive compilation of the scientific published papers devoted to the use of expired drugs as corrosion inhibitors in various aggressive solutions. The inhibitory efficiencies of expired drugs are presented as a function of the studied metal or alloy and the nature of the aggressive solution, as well as the concentration of the inhibitor in such a solution. Research has especially been focused on mild and carbon steel and less on stainless steel, as well as on some metals such as copper, zinc, nickel, tin and aluminum and its alloys. The experimental methods used to assess the inhibitory efficiencies of expired drugs are briefly discussed. Also, the available information on the stability of the active substances in the drugs is presented, although most authors were not concerned with this aspect. Finally, several actions are revealed that must be undertaken by researchers so that the results obtained in the study of the anticorrosive action of expired drugs can be applied at the industrial level and not remain only an academic concern.

1-Butyl-3-methylimidazolium methane sulfonate ionic liquid corrosion inhibitor for mild steel alloy: Experimental, optimization and theoretical studies

The current research reports the performance of 1-butyl-3-methylimidazolium methane sulfonate ([C4MIM][OMs](IL)) as effective corrosion inhibitor for mild steel in 1 M H2SO4 electrolyte. For proper evaluation, weight loss, electrochemical study, theoretical modeling and optimization techniques were used. Weight loss and electrochemical methods shows that the inhibition performance of [C4MIM][OMs] on the metal surface strengthens as the concentration increases. Maximum inhibition efficiency of 85.71%, 92.5% and 91.1% at 0.8 g L-1 concentration of [C4MIM][OMs] were obtained from the weight loss, polarization and impedance studies, respectively. In addition, response surface methodology (RSM) a statistical tool was used for modeling and optimization of the empirical data. The RSM model validates the empirical findings. Also, DFT/MD-simulation investigations evidenced that [C4MIM][OMs] forms a barrier film on the mild steel surface. The result shows that the synthesized [C4MIM][OMs] could open up opportunities in corrosion and materials protection for sustainability.

Synthesis and Corrosion Inhibition Performance of Mannich Bases on Mild Steel in Lactic Acid Media

Heterocyclic Mannich bases, N-(3-oxo-3-phenylpro-pyl)thiazol-2-aminium chloride (DTZA) and N-(3-oxo-3-phenylpropyl)-1H-pyrazol-3-aminium chloride (DPZA), were developed for the corrosion inhibition of N80 steel in a 15 wt % lactic acid solution. Weight loss measurements, electrochemical techniques, surface characterization, and theoretical calculations were combined to investigate their anticorrosion performance and mechanism. The results showed that DTZA exhibited a satisfactory inhibitor efficiency of 97.56% with a dosage of 0.15% at 363 K, while DPZA achieved only 58.3% under the same conditions. Adsorptions of both inhibitors on the metal surface followed the Langmuir model with physical and chemical adsorptions. Based on X-ray photoelectronic spectroscopy (XPS) analysis, DFT calculations, and molecular dynamics (MD) simulations, stronger interactions between DTZA and iron than those in the case of DPZA were revealed, leading to the formation of a compact protective film on the metal surface, which is attributed to the presence of a thiazole ring in the DTZA chemical structure.

A General Use QSAR-ARX Model to Predict the Corrosion Inhibition Efficiency of Drugs in Terms of Quantum Mechanical Descriptors and Experimental Comparison for Lidocaine

A study of 250 commercial drugs to act as corrosion inhibitors on steel has been developed by applying the quantitative structure-activity relationship (QSAR) paradigm. Hard-soft acid-base (HSAB) descriptors were used to establish a mathematical model to predict the corrosion inhibition efficiency (IE%) of several commercial drugs on steel surfaces. These descriptors were calculated through third-order density-functional tight binding (DFTB) methods. The mathematical modeling was carried out through autoregressive with exogenous inputs (ARX) framework and tested by fivefold cross-validation. Another set of drugs was used as an external validation, obtaining SD, RMSE, and MSE, obtaining 6.76%, 3.89%, 7.03%, and 49.47%, respectively. With a predicted value of IE% = 87.51%, lidocaine was selected to perform a final comparison with experimental results. By the first time, this drug obtained a maximum IE%, determined experimentally by electrochemical impedance spectroscopy measurements at 100 ppm concentration, of about 92.5%, which stands within limits of 1 SD from the predicted ARX model value. From the qualitative perspective, several potential trends have emerged from the estimated values. Among them, macrolides, alkaloids from Rauwolfia species, cephalosporin, and rifamycin antibiotics are expected to exhibit high IE% on steel surfaces. Additionally, IE% increases as the energy of HOMO decreases. The highest efficiency is obtained in case of the molecules with the highest ω and ΔN values. The most efficient drugs are found with pK_a ranging from 1.70 to 9.46. The drugs recurrently exhibit aromatic rings, carbonyl, and hydroxyl groups with the highest IE% values.