International Journal of Corrosion

T. K. Chaitra ¹, K. N. Mohana ¹, H. C. Tandon ²

Affiliations
1 Department of Studies in Chemistry, Manasagangotri, University of Mysore, Mysuru, Karnataka 570006, IN
2 Department of Chemistry, Sri Venkateswara College, Dhaula Kuan, New Delhi 110021, IN

Abstract

Three new thiazole based pyridine derivatives 5-(4-methoxy-phenyl)-thiazole-2-carboxylic acid pyridin-2-ylmethylene-hydrazide (2-MTPH), 5-(4-methoxy-phenyl)-thiazole-2-carboxylic acid pyridin-3-ylmethylene-hydrazide (3-MTPH), and 5-(4-methoxyphenyl)- thiazole-2-carboxylic acid pyridin-4-ylmethylene-hydrazide (4-MTPH) were synthesized and characterized. Corrosion inhibition performance of the prepared compounds on mild steel in 0.5M HCl was studied using gravimetric, potentiodynamic polarisation, and electrochemical impedance techniques. Inhibition efficiency has direct relation with concentration and inverse relation with temperature.Thermodynamic parameters for dissolution and adsorption process were evaluated. Polarisation study reveals that compounds act as both anodic and cathodic inhibitors with emphasis on the former. Impedance study shows that decrease in charge transfer resistance is responsible for effective protection of steel surface by inhibitors.The filmformed on themild steel was investigated using FTIR, SEM, and EDX spectroscopy. Quantum chemical parameters like E_HOMO, E_LUMO, ΔE, hardness, softness, and ionisation potential were calculated. Higher value of E_HOMO and lower value of ΔE indicate the better inhibition efficiency of the compounds. Lower ionisation potential of inhibitors indicates higher reactivity and lower chemical stability.

Full Text