Comparative Study of new Pyridazine Derivatives Towards Corrosion of Copper in Nitric Acid: Part-1

The inhibition of the corrosion of copper in 2M HNO3 by 5-[hydroxy(phenyl)methyl]-6-methylpyridazin-3(2H)-one (P1), 4-(2-chlorobenzyl)-6-hydrazino-3-methyl-1,6-dihydropyridazine (P2), 5-(2,6-dichlorobenzyl)-6-methylpyridazin-3(2H)-one (P3) and 5-[(2-chlorophenyl)(hydroxy)methyl]-6-methylpyridazin-3(2H)-one (P4) has been investigated at 303K using weight loss measurements, potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) methods). Results obtained show that P3 and P4 are the best inhibitors and their inhibition efficiencies (E %) increase with the increase of inhibitor concentration and reach up to 96 and 94 % for P3 and P4 at 10(-3) M, respectively. Moreover, polarisation studies clearly reveal that the presence of inhibitors changes the mechanism of hydrogen evolution and that they act as mixed inhibitors. EIS study shows that charge transfer resistance increases with the inhibitor concentration. The adsorption of P3 obeys to the Langmuir isotherm. The activation parameters of copper in the presence and absence of P3 are also evaluated and discussed. Effect of temperature is studied between 298 and 353 K and determination of activation parameters is also discussed in part 2. Explanation by quantum indices to correlate inhibition efficiency should be given in part 3.