Surface Parameters and Corrosion Inhibition of Some Isothiouranium Derivatives

Abstract

Four alkyl isothiouronium halide compounds in which the alkyl groups are dodecyl, hexadecyl, and octadecyl, respectively, are prepared. The measured surface tension at various concentrations as aqueous solutions of each of these compounds at various temperatures enable the calculation of surface and thermodynamic parameters. The critical micelle concentrations of these compounds decreases with increase in temperature. The calculated free energy changes for micelle formation and ad sorption of these compounds shows that these processes are spontaneous in nature. The corrosion inhibition properties of these compounds for mild steel in sulphuric acid as determined through potentiodynamic polarization measurements, indicates that dodecyl isothiouronium bromide exhibits better inhibitor efficiency than its higher homologues. For the same compound studied, the iodide salt gives a better inhibitor efficiency than the bromide.