Inhibition action of thiosemicabazone and some of it is ρ-substituted compounds on the corrosion of iron-base metallic glass alloy in 0.5M H2SO4 at 30°C

Abstract The study of the effect of thiosemicarbazone compounds on the corrosion of the iron-base Fe81B13.5Si3.5C2 metallic glass in 0.5 M H2SO4 solutions by electrochemical technique shows that these compounds were very effective inhibitors, their protection percentage exceeded 98% at low concentrations as much as 10−4 M. A mixed type of inhibition from polarization and a charge transfer mechanism from impedance study in absence and presence of these compounds were found. Langmuir adsorption isotherm is obtained. Linear free energy relationships (LFER) have used to correlate the protection percentage of thiosemicarbazone and it is ρ-substituted derivatives with the Hammett substitute constant (σ). The value of ρ = +0.328 indicates weak dependence of the substitution on the adsorption character of the reaction center. The reactivity of these compounds was analyzed through theoretical calculations based on density functional theory to confirm that ( ) is the reactive center. The effect of immersion time at certain concentration was studied.