Attenuation of Acid Corrosion of Mild Steel Using a Novel Organic Dye: Electrochemical and Surface Measurements

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.

Electrochemical and quantum chemical study to assess the role of (2E)-2-(furan-2-ylmethylidene) hydrazine carbothioamide as inhibitor for acid corrosion of mild steel

Synthesis and inhibition effectiveness of (2E)-2-(furan-2-ylmethylidene) hydrazine carbothioamide (FMHC) as an inhibitor for corrosion of mild steel in 0.5 M H2SO4 is reported. Experiments were conducted at various temperatures (303–323 K) by adopting potentiodynamic polarization and electrochemical impedance spectroscopy. Readings obtained demonstrated that percentage inhibition efficiency (% IE) improved with the upsurge in the concentration of FMHC, while it decreased with a rise in temperature. The highest % IE observed was 60% for 2.5 × 10–4 M FMHC at 303 K. FMHC worked moderately as a mixed inhibitor. FMHC obeyed the Langmuir model of adsorption and the mode of adsorption was physisorption on the mild steel surface which was further endorsed by examining the surface using the scanning electron microscope. A clear insight into the mechanistic features of corrosion inhibition by using FMHC was acquired. Calculation of activation parameters helped to suggest an appropriate mechanism for the adsorption of FMHC on mild steel through quantum chemical calculations using density functional theory (DFT).

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