Computational and electrochemical analysis on quinoxalines as corrosion inhibitors for mild steel in acidic medium

Abstract

In this investigation, quinoxaline derivatives namely, 2-(5-(2-chlorophenyl)-3-phenyl-4,5-dihydro-1H-pyrazol-1-yl)naphtho[2,3-d]thiazole (CPTQ) and 2-(3,5-diphenyl-4,5-dihydro-1H-pyrazol-1-yl)naphtho[2,3-d]thiazole (DPTQ) were synthesized and applied as corrosion inhibitors for mild steel (MS) in15% HCl solution. The corrosion inhibition behaviour of CPTQ and DPTQ was studied through weight loss measurement, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The maximum corrosion inhibition efficiency of DPTQ and CPTQ was found to be 96.01 and 95.62%, respectively at 100 ppm concentration and 303 K temperature. Potentiodynamic polarization studies showed that CPTQ and DPTQ act as mixed type inhibitors. Surface morphology of uninhibited and inhibited MS specimens was characterized using AFM and SEM studies. DFT, molecular dynamic simulations and calculation of Fukui functions were performed for correlation of theoretical parameters with the experimental results.