Selective Bis-N-Aryl Thiosemicarbazones as Efficient Corrosion Inhibitors

A. Shamitha Begum, D. Nalini and K. Suvarnna

Department of Chemistry, P.S.G.R. Krishnammal College for Women, Coimbatore - 641 004 (India).

The study of the effect of the Bis-N-aryl thiosemicarbazone compounds on the corrosion behaviour of mild steel in 1M sulphuric acid and in1M hydrochloric acid shows that these compounds are very efficient inhibitors. Their inhibition efficiency increased with increase in concentration and also increased with temperature. The inhibitors showed a mixed type of inhibition in potentiodynamic polarization study and in impedance method in presence and absence of inhibitors. The adsorption of inhibition followed Langmuir adsorption isotherm. The thermodynamic parameters such as activation energy (Ea) and free energy of adsorption Gads were calculated. The Ea value of the uninhibited solution was less than the inhibited solutions revealing chemisorption of the inhibitor on the mild surface.

chemisorption; mild steel; thiosemicarbazone; Langmuir adsorption isotherm; mixed type