Role of methyl group in increasing inhibition efficiency of pyridine and its derivatives for 1060 aluminium-hydrochloric acid system

The inhibitive effect of pyridine, aniline, 2-picoline. 3-picoline, 4-picol ine and 2,4-lutidine on the corrosion of 1060 aluminium in one percent hydr ochloric acid has been carried out. The inhibition efficiencies generally d ecrease in the order: 2,4-lutidine > 4-picoline > 3-picoline > 2-picoline > aniline > pyridine. The inhibitive effect of the studied compound increase s with the concentration of inhibitors but decreases with the rise of tempe rature. Activation energy increases by increasing both concentration of inh ibitors as well as temperatures. Langmuir adsorption isotherm is obeyed by all inhibitors at studied temperatures with deviations. Polarisation studie s reveal that all these compounds are mixed inhibitors.