Aniline and some of its derivatives as corrosion inhibitors for nickel in 1M HCl solution

The inhibiting action of aniline and some of its derivatives (o-, m- and p- anisidine) towards the corrosion behaviour of nickel in 1M HCl solution has been studied using weight loss and polarization techniques. These compound s were found to retard the corrosion rate of nickel. At constant temperatur e, the corrosion rate decreases with increasing inhibitor concentration. On the other hand, at any inhibitor concentration, the increase in temperatur e leads to an increase in the corrosion rate. The activation energy, Delta E-a,, the equilibrium constant, k, as well as the other thermodynamic param eters (Delta G(ads)(o), Delta H-ads(o) and Delta S-ads(o)) for inhibitor pr ocess were calculated and analysed. The inhibitor efficiencies calculated f rom both weight loss and polarization methods are in good agreement and wer e found to be in the order: p-anisidine > o-anisidine > m-anisidine > anili ne. The inhibitive action of these compounds was attributed to the adsorpti on of molecular species and their inhibitive efficiencies depend on the rel ative position of the -OCH3 group in the aniline ring. (C) 1999 Society of Chemical Industry.