Effect of New Synthesised Pyridazine Derivatives on the Electrochemical Behaviour of Mild Steel in 1M HCl Solution: Part-1

The effect of adding new pyridazine derivatives, ethyl [4-(2-chlorobenzyl)-3-methyl-6-oxopyridazin-1(6H)-yl]acetate (P1), ethyl [4-(2-chlorobenzyl)-3-methyl-6-thioxopyridazin-1(6H)-yl]acetate (P2), 5-(2-chlorobenzyl)-2-(2-hydroxyethyl)-6-methylpyridazin-3(2H)-one (P3) and 5-(2-chlorobenzyl)-2-(2hydroxyethyl)-6-methylpyridazine-3(2H)-thione (P4), on the electrochemical behaviour of steel in molar hydrochloric acid was investigated by using weight loss method, potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) measurements. Results reported in this study show that the addition of these compounds inhibits the corrosion of steel and the extent of inhibition depends upon the type and concentration of the pyridazine compounds. The inhibition efficiency for four compounds studied increase with the increase in the inhibitor concentrations to attain 100% at the 10(-3)M of P1. Moreover, Potentiodynamic polarisation studies revealed that the inhibitors act as mixed inhibitors and cathodically predominant. The inhibition occurs through adsorption of the pyridazine compounds on the metal surface without modifying the mechanism of corrosion process. EIS study shows that charge transfer resistance increases with the inhibitor concentration. Effect of temperature is studied between 303 and 353 K and determination of activation and adsorption parameters is also discussed in part 2. Explanation by quantum indices to correlate inhibition efficiency should be given in part 3.