The study of m-pentadecylphenol on the inhibition of mild steel corrosion in 1 M HCl solution

Eco-friendly anti-corrosion performance of chitosan modified with fused heterocyclic compound on mild steel in acidic medium

This study aims to explore the prevention of chitosan modified with a fused heterocyclic compound as a sustainable corrosion inhibitor for mild steel in 1 M HCl. Electrochemical instruments, including potentiodynamic polarization techniques, and electrochemical impedance spectroscopy (EIS), were employed to evaluate the corrosion protection performance. The outcomes showed that the chitosan modified with a fused heterocyclic compound has outstanding inhibition performance, with an inhibition effectiveness of 98.25 % at 100 ppm. The anti-corrosion features of modified chitosan were ascribed to the presence of hetero atoms in modified chitosan composite which leads to the creation of a protective layer, The modified chitosan composite behaved as mixed-typed inhibitors, as shown by the PDP results. The modified chitosan composite adsorbs on mild steel in the investigated corrosive media via chemisorption interactions, and its adsorption followed the Langmuir adsorption model. Furthermore, increasing the temperature from 303 to 333 K enhanced the corrosion rate, most likely due to the desorption of the inhibitor agent from the steel surface.

Laboratory Evaluation of a Low-Damage Authigenic Mud Acid System for Bai-823 Well Block

Aiming at the problem of single and poor adaptability of Bai-823 plugging removal system, an authigenic mud acid system using methyl formate, ammonium chloride, and ammonium fluoride as raw materials is proposed, which can adapt to the temperature of 60-80 °C of the target reservoir and sandstone lithology. The acid-generating capacity of the authigenic acid system at different temperatures was evaluated. The results showed that the H+ concentration remained at 3.35 mol/L after 180 min at 80 °C, which indicated that authigenic acid could generate acid continuously and thus be competent for acidizing and plugging removal of further wells. The corrosion rate of authigenic acid to N80 steel was further investigated. When 2 wt % SA1-3B corrosion inhibitor was used, the corrosion rate was only 0.15 g/(m2·h). At the same time, the corrosion capacities of authigenic acid to rock core and scale samples were studied, which were 19.38 and 93.81%, respectively, indicating that the authigenic acid system realized pipeline and reservoir friendliness when it was able to effectively remove plugging. Finally, a core displacement experiment was carried out to simulate reservoir acidizing for plugging removal. The results showed that the core permeability increased from 1.00 to 1.63 after acidizing modification with authigenic acid. All of the above studies show that a kind of authigenic mud acid has been successfully prepared, and a new idea for the authigenic acid system has been proposed.

Insight into the corrosion mitigation performance of three novel benzimidazole derivatives of amino acids for carbon steel (X56) in 1 M HCl solution

Three new organic molecules having a benzimidazole base were synthesized and used for the protection of carbon steel (X56) against corrosion in 1.00 M HCl solution. The protection against corrosion was assessed by electrochemical frequency modulation (EFM), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). In addition, the electronic and molecular structure of the synthesized molecules were computationally investigated and correlated to corrosion inhibition. Global reactivity descriptors, molecular orbitals (FMO and NBO) and local reactivity descriptors (molecular electrostatic potential map and Fukui functions) were discussed. The results showed a maximum protective efficiency range between 95% and 98% indicating high corrosion inhibition. Moreover, all molecules were able to combat the cathodic as well as anodic reaction simultaneously, revealing a mixed-type resistance. SEM and EDX verified effective adhering film formation to the metal surface. In accordance, the theoretical calculations showed effective electron reallocation from the organic film to the X56 c-steel surface. Furthermore, the adsorption annealing calculations revealed that structural layers of these molecules hold parallel and close to the metal surface with adsorption energy from 249.383 to 380.794 kcal mol^-1, showing strong inhibitor-metal contact.

Inhibition performance of halogen-substituted benzaldehyde thiosemicarbazones as corrosion inhibitors for mild steel in hydrochloric acid solution

Halogen-substituted benzaldehyde thiosemicarbazone derivatives were synthesized and their inhibition performance for mild steel in hydrochloric acid solution were investigated systematically using weight loss measurements, electrochemical techniques, scanning electron microscopy and quantum chemical calculations. Results of weight loss measurements indicated that all these compounds exhibited excellent inhibition performance and the inhibition efficiency increased with increasing inhibitor concentrations. Polarization results revealed that the synthesized benzaldehyde thiosemicarbazone derivatives were mixed-type inhibitors. Adsorption of these compounds onto a mild steel surface was mainly chemisorption and complied with the Langmuir adsorption isotherms. Both theoretical calculations and experimental measurements suggested that the inhibition efficiency of these compounds followed the order of Br-BT > Cl-BT > F-BT > H-BT.

Corrosion inhibition of a novel antihistamine-based compound for mild steel in hydrochloric acid solution: experimental and computational studies

Focused on the assessment of the diphenhydramine hydrochloride (DPH) capabilities as an alternative to conventional and harmful industrial corrosion inhibitors, electrochemical techniques were employed. The optimum concentration of 1000 ppm was determined by molecular simulation and validated through electrochemical experiments. The results acquired from the electrochemical impedance spectroscopy (EIS) study showed that DPH at a concentration of 1000 ppm has a corrosion efficiency of 91.43% after 6 h immersion. The DPH molecules' orientation on the surface was assessed based on EIS predicting horizontal adsorption on the surface. Molecular simulations were done to explore the adsorption mechanism of DPH. The DPH molecules' orientation on the surface was also assessed based on computational studies confirming the horizontal adsorption predicted by EIS.

Thiophene derivatives as corrosion inhibitors for 2024-T3 aluminum alloy in hydrochloric acid medium

Thiophene derivatives, namely (E)-thiophene-2-carbaldehyde oxime (OXM) and (E)-5-(thiophen-2-yl)-1H-tetrazole (TET), were synthesized and characterized via¹H and ¹³C NMR. Furthermore, their inhibitory property for AA2024-T3 in 1 M HCl solution was investigated via electrochemical impedance spectroscopy and potentiodynamic polarization at 293 K, together with DFT/B3LYP-based calculations. Numerous global and local descriptors of reactivity such as EHOMO, ELUMO, energy gap, electronegativity (χ), hardness (η), and frontier molecular orbital repartitions were investigated to describe the reactivity of each molecule. Alternatively, Monte Carlo simulations were performed under the solvation condition on the Al (111) surface to understand the adsorption behavior of the as-studied inhibitors deeply. The inhibition efficiency increased with an increase in the inhibitor concentration, achieving maximum values of 94.0% and 96% at 10⁻³ M, respectively. The polarization curves showed that the examined compounds act as mixed-type inhibitors. In addition, the adsorption of these compounds obeyed the Al Awady, Flory-Huggins and Temkin isotherms. The surface characterization analysis via SEM/EDX confirmed the presence of a barrier layer covering the aluminum surface. The experimental inhibition efficiencies were correlated with global descriptors, which confirmed that this theoretical study is useful for the protection of aluminum alloy metal in an acidic medium.

Thiophene derivatives: thiophene-2-carbaldehyde oxime (OXM) and 5-(thiophen-2-yl)-1H-tetrazole (TET), were synthesized and characterized. Furthermore, their inhibitory property for AA2024-T3 in 1 M HCl solution was investigated via electrochemical and with theoretical study.