Tiazofurin drug as a new and non-toxic corrosion inhibitor for mild steel in HCl solution: Experimental and quantum chemical investigations

Experimental Studies on the Effect of Expired Amiodarone Drug (EAD) as a Corrosion Inhibitor on Mild Steel in 1 M HCl

In the present investigation, the corrosion tendency of mild steel under acidic pH was studied by employing unused expired amiodarone (EAD) drug as a potential corrosion inhibitor by adopting the weight loss measurement method. The corrosion inhibition efficiency (IE) of the formed protective film (EAD) on the steel surface was analyzed using potentiodynamic polarization and AC-impedance spectroscopy studies. The surface morphology of the mild steel before and after corrosion (in 1.0 M HCl) was analyzed via scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDAX), atomic force microscopy (AFM), and thermodynamic studies. The weight loss measurement under different concentrations of EAD indicated that an excellent inhibition was displayed at a concentration of 0.001 M, and the IE was found to depend on both the concentration and molecular structure of EAD. A potentiodynamic polarization study revealed that EAD predominantly acted as a cathode inhibitor, and electrochemical impedance spectroscopy (EIS) confirmed the adsorption of EAD on the surface of mild steel, which obeyed Temkin's adsorption isotherm model. The calculated thermodynamic parameters revealed that adsorption was spontaneous and exothermic.

Heterocyclic Modulated Electronic States of Alkynyl-Containing Conjugated Microporous Polymers for Efficient Oxygen Reduction

The oxygen reduction reaction (ORR) is a key process in green energy conversion technology. Heteroatom doping has been proven to be a prospective strategy to prepare metal-free carbon-based electrocatalysts, but such methods often suffer from uncontrollable catalyst frameworks and imprecise active sites. Herein, an organic heterocyclic strategy is adopted to modulate the charge redistribution of alkynyl-containing conjugated microporous polymers (CMPs) by introducing varied five-membered heterocyclic structures. Among these CMPs, the S, 2N-containing thiadiazole heterocyclic molecule (CMP-Tdz) with carbonized alginate materials (C_CA ) displays a remarkable quasi-four-electron-transfer ORR pathway, exhibiting an excellent half-wave potential (E_1/2 ) of 0.77 V, coupled with superior methanol tolerance and electrochemical stability, which are among the highest performance in the metal-free organic catalytic material systems. Density functional theory calculations prove that the high catalytic performance of these catalysts originates from the sp-hybridized C atom (site-2) which is activated by their adjacent heterocyclic structures. Importantly, the five-membered heterocyclic structures can also modulate the local charge distribution, and increase dipole moment, with significantly improved catalytic kinetics. This incorporation of chemically designed heterocyclic-containing alkynyl-CMPs provides a new approach to developing efficient metal-free carbon-based electrocatalysts for fuel cells.

Colloidal and interface aqueous chemistry of dyes: Past, present and future scenarios in corrosion mitigation

The most effective corrosion inhibitors are organic compounds, especially heterocyclic ones with a certain balance of hydrophilicity, hydrophobicity, and conjugation. Most dyes develop the critical characteristics of a substance that can be utilized as an effective corrosion inhibitor. These include the presence of polar functional groups, nonbonding electrons and multiple bonds of the aromatic ring(s) and side chains. In aqueous electrolytes, dyes efficiently bind to metal surfaces through their electron-rich spots, known as adsorption centers. Literature studies show that many dye series have excellent anticorrosive properties for many metal/electrolyte combinations. They contain many electron-donating sites and behave as polydentate and chelating ligands. The polar functional for instance -OH, -CONH₂, -NH₂, -OR, -SO₃H, -COOH, -NMe₂, -N=N-, -CHO, -N=C < etc. also help in solubilizing relatively complex dye molecules in aqueous electrolytes. This review work seeks to explain the interfacial adsorption of dye molecules and how that negatively affects metallic corrosion. Through their adsorption, dye molecules block the active sites. They mainly achieved this by employing the Langmuir isotherm model. Additionally, the mechanism of corrosion inhibition is investigated, with a special emphasis on dyes.

Inhibition Mechanism of Some Vinylalkylimidazolium-Based Polymeric Ionic Liquids against Acid Corrosion of API 5L X60 Steel: Electrochemical and Surface Studies

A corrosion inhibition mechanism of API 5L X60 steel exposed to 1.0 M H₂SO₄ was proposed from the evaluation of three vinylalkylimidazolium poly(ionic liquids) (PILs), employing electrochemical and surface analysis techniques. The synthesized PILs were classified as mixed-type inhibitors whose surface adsorption was promoted mainly by bromide and imidazolate ions, which along with vinylimidazolium cations exerted a resistive effect driven by a charge transfer process by means of a protective PIL film with maximal efficiency of 85% at 175 ppm; the steel surface displayed less surface damage due to the formation of metal-PIL complex compounds.