Corrosion inhibition of mild steel by 3-amino-4-(4 '-substituted benzeneazo)-pyrazoline-5-ones in artificial seawater

The corrosion of mild steel in artificial seawater containing various conce ntrations of 3-amino-4-(4'-substituted benzeneazo)-Pyrazoline-5-ones has be en studied by polarization technique. These compounds inhibit corrosion eff ectively even in trace concentration. The degree of corrosion inhibition is a function of temperature, concentration and nature of the inhibitor. The corrosion current density, percentage inhibitor efficiency and thermodynami c parameters for the surface adsorption of inhibitors were calculated for t he inhibition process. The IR spectra of the firm formed on the corroding s urface indicated the formation of a complex between the inhibitor molecule and the mild steel. The inhibitors appeared to function through a general a dsorption mode following the Frumkin adsorption isotherm and Langmuir adsor ption isotherm. The thermodynamic parameters of adsorption showed a strong interaction of these inhibitor molecules with the mild steel surface. The r esults revealed that these compounds act as mixed inhibitors for mild steel in artificial seawater.