Comparative investigation into the kinetics of corrosion inhibition of aluminium alloy AA 1060 in acidic medium

The corrosion of commercial aluminium alloy sheets in different concentrations of H2SO4 and HCl solutions was studied using the weight loss technique from 303 K to 313 K. The difference in corrosion rate of aluminium in H2SO4 and HCl solutions without inhibitor was attributed to difference in activation energies of the metal acid solution reaction. Pre-exponential factors derived from the Arrhenius plot for both acids were observed to be approximately the same value at constant temperature and concentration. 2- acetyl pyridine-(4-phenyl) thiosemicarbazone (PTSC) was used as corrosion inhibitor. The maximum % inhibitor efficiencies obtained were 76% and 28% in HCl and H2SO4 solutions respectively at concentration of 5 x 10(-4) M at 303 K. Mechanism of physical adsorption is proposed. PTSC was found to obey the Langmuir isotherm at 303 K and 313 K in H2SO4 solution but obeyed the Flory-Huggins isotherm at 323 K in HCl solution. First order type of reaction mechanism was obtained from the kinetic treatment of the weight loss data. The difference in inhibition behaviour of PTSC in both acid solution has been explained in terms of metal corrodent inhibitor interaction.