Investigation of the corrosion inhibition effect of 3-methyl-6-oxo-4-(thiophen-2-yl)-4,5,6,7-tetrahydro-2H-pyrazolo[3,4-b]pyridine-5-carbonitrile (TPP) on mild steel in hydrochloric acid
By Priyanka Singh and M.A. Quraishi and S.L. Gupta and A. Dandia
Published in Journal of Taibah University for Science
2016
Abstract
The corrosion inhibition effect of the synthesized compound 3-methyl-6-oxo-4-(thiophen-2-yl)-4,5,6,7-tetrahydro-2H-pyrazolo[3,4-b]pyridine-5-carbonitrile (TPP) on the corrosion of \MS\ in 1 M \HCl\ was investigated using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. The results obtained for \TPP\ showed a good inhibition effect on the \MS\ in the 1 M \HCl\ solution. The inhibition efficiency was found to increase with a corresponding increase in the \TPP\ concentration, and the best inhibition of 96.83% occurred at a \TPP\ concentration of 200 ppm. The potentiodynamic polarization studies revealed that \TPP\ behaved as mixed-type of inhibitor that predominantly inhibited the cathodic reaction. The impedance parameters were indicative of the high inhibitory efficiency and the adsorption of \TPP\ on MS. Amongst the Frumkin, Temkin and Langmuir isotherms, the studied compound more closely followed the Langmuir adsorption isotherm. The scanning electron microscopy (SEM) examinations of the electrode surface confirmed the existence of such an adsorbed film.