Inhibiting effect of anisidines on corrosion of aluminium in hydrochloric acid

Abstract

<smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="metricconverter"> Anisidines (<i style="">o</i>-, <i style="">m</i>- and <i style="">p</i>-) were used as corrosion inhibitors for aluminium in hydrochloric acid solution. The inhibition efficiency depended on the concentration and type of the anisidine. The inhibition efficiency ranged between 76 and 93% at the highest concentration (80 mM), and between 65 and 85% at the lowest concentration (20 mM) of inhibitor in 0.4 M HCl solution. Inhibition efficiency decreased with rise in temperature, this corresponded to surface coverage of the metal by the inhibitor. The calculated degrees of surface coverage, θ, were found to increase with the inhibitor concentration. The results also showed that, the inhibitors were adsorbed on the aluminium surface according to Langmuir adsorption isotherm. Polarization study revealed that all the three anisidines functioned as slightly anodic but significantly cathodic inhibitors. </smarttagtype>