3-(alditol-1-yl)-1,2,4-triazolo[3,4-a]phthalazines as inhibitors for the acid corrosion of aluminium

Corrosion inhibition by 3-(alditol-1-yl)-1,2,4-triazolo(3,4-a)phthalazine and some related compounds of aluminium in hydrochloric acid was measured using chemical and electrochemical methods. Polarization curves showed that these compounds are cathodic inhibitors. It was found that the efficiency of the inhibitor decreases with the increase in the number of the carbon atoms in the sugar moiety of the molecule. The effect of the substituent in the heterocyclic part on the inhibition efficiency was studied. The results are discussed on the basis of the structure-inhibition relationship and the interaction between the adsorbed layer of the inhibitor and the bulk solution.