Abstract
Five new sulfur containing heterocyclic derivatives of sulfanyl pyridazine type compounds (1-5) were synthesized, characterized by FT-IR and H-1 NMR, and evaluated as corrosion inhibitors for carbon steel in 1.0 M HCl at various concentration and temperatures. Five different analytical techniques were used in this study, namely, gravimetrical, gasometrical, atomic absorption spectroscopy, AAS, thermometric, and acidimetric techniques. The corrosion inhibition efficiency increases with increasing inhibitor concentration but decreases with temperature. The inhibition of corrosion is due to adsorption on the metal surface and formation of a barrier film that separates the metal from the corrosive medium. The inhibition is due to physicochemical adsorption of a heterocyclic compound on steel surface, and the adsorption obeys the Langmuir isotherm. Thermodynamic parameters for both activation and adsorption were computed and discussed. The reduction in reaction number (RR%) and Atm increased with increasing inhibitor concentrations. The pH increased and the hydrogen ion concentration in the medium decreased upon addition of inhibitors as an inhibitor molecule acts as a ligand for protons in acidic media. The ferrous ion Fe+2 concentrations determined by AAS decreased in the solution with increasing inhibitor concentration. The data obtained from different analytical techniques are in good agreement within (+/- 2%).