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.