Electrochemical Behaviour and Inhibiting Properties of Isopropylamine on Mild Steel Corrosion In Phosphoric Acid Solution

V. Chandrasekaran¹*, K. Kannan¹* and M. Natesan²**

¹Department of Chemistry, Government College of Engineering, Salem- 636 011 (India)

²Central Electrochemical Research Institute, Karaikudi- 630 006 (lndia)

The inhibition effect of Isopropylamine (IPA) on corrosion of mild steel in phosphoric acid solutions was investigated by mass loss and potentiostatic polarization techniques at 303K-333K. The inhibition efficiency increased with increase in concentration of inhibitors and decreased with rise in temperature from 303K to 333K and in acid concentration from 1N to 5N. The adsorption of this compound on the mild steel surface from the acid has been found to obey Temikin’s adsorption isotherm. The potentiostatic polarization results revealed that Isopropylamine (IPA) is a mixed type inhibitor. Some of the electrochemical parameters i.e. activation energy (Ea), free energy of adsorption (DGads), enthalpy of adsorption (DH) and entropy of adsorption (DS) were also calculated. The plots of Wf against time (days) at 302K gives straight line, which suggested that it obeys first order kinetics and also calculate the rate constant k and half life time t.

Mild steel; Phosphoric acid; Corrosion inhibition; Temkin’s adsorption isotherm; potentiostatic polarization