Synergistic Effect of BaCl2 on Corrosion Inhibition of Copper by Mentha Spicata Oil in 1M Nitric Acid: Gravimetric and Raman Spectroscopy Studies

Abstract

The effect of Mentha Spicata oil and the mixture of BaCl2 and Mentha Spicata oil on corrosion of copper in 1M HNO3 have been investigated using weight loss methods and Raman spectroscopy. The study revealed that copper is more efficiently inhibited by Mentha Spicata oil in the presence of BaCl2 than pure oil. The inhibition efficiencies increased with increased concentration of the additives. The highest inhibition efficiency of 56.12 % was observed with single Mentha Spicata oil. An improved inhibition efficiency of 75.13 % was observed with the mixture of Mentha Spicata oil and BaCl2 at 298 K in 1M HNO3, an effect attributed to synergism between Mentha Spicata oil and BaCl2. Inhibition efficiency decreased with increase in temperature from 298-328 K. The adsorption of inhibitor molecules on metal surface followed Frumkin and Langmuir isotherm. Thermodynamic parameters such as enthalpy ∆H, free energy of adsorption ∆G and entropy of adsorption are obtained from experimental temperatures ranging from 298-328 K. Raman Spectroscopy and mapping were used to characterize the surface layers.