An Investigation of Two Novel Pyridazine Derivatives as Corrosion Inhibitor for C38 Steel in 1.0 M HCl

Corrosion inhibition of two pyridazine derivatives, namely ethyl (6-oxo-3-phenylpyridazin-1(6H)-yl)acetate (GP2) and ethyl (3-phenyl-6-thioxopyridazin-1(6H)-yl)acetate (GP3) on C38 steel was investigated by gravimetric measurements, polarisation and electrochemical impedance spectroscopy (EIS). Gravimetric measurements indicate that the inhibitor GP3 is more effective than GP2 for protection against C38 steel corrosion in 1.0 M HCl medium. The protective power of these products increases with increasing concentration but decreases with rise temperatures. The effectiveness of inhibition reached 91.83% and 83.90% for GP3 and GP2 respectively at 10(-3)M. Moreover, Potentiodynamic polarisation studies revealed that the inhibitors act as mixed inhibitors. The inhibition occurs through adsorption of the pyridazine compounds on the metal surface without modifying the mechanism of corrosion process. EIS shows that increasing the concentration of the inhibitors leads to an increase of the charge transfer resistance and reducing the double layer capacitance. Effect of temperature was studied between 308 and 343 K and determination of activation parameters and adsorption is also discussed.