inhibition of the acid corrosion of aluminium by some derivatives of thiosemicarbazone

The inhibition of corrosion of aluminium in HCl solution by some derivatives of thiosemicarbazones has been studied using weight loss and hydrogen evolution techniques. The thiosemicarbazone derivatives used are 2-acetyl pyridine-(4-phenylthiosemicarbazone) (PTSC), 2-acetyl pyridine-(4-phenyl-iso-methylthiosemicarbazone) (PIMTSC) and 2-acetyl pyridine-(4-phenyl-iso-ethylthiosemicarbazone) (PIETSC). The inhibition efficiency depended on the compounds concentration until at very low concentration studied where they reversed their functions and became accelerators. Kinetic treatment of the results gave a first order type of mechanism. The results reported in this paper elucidate the effects of inhibitor concentration, temperature and the molecular structure on the inhibition efficiency.