Mono Azo Dyes Compounds as Corrosion Inhibitors for Dissolution of Aluminium in Sodium Hydroxide Solutions

Abstract

The effect of some mono azo dyes compounds on the dissolution of aluminium in 0.01 M NaOH solutions was studied using weight loss and galvanostatic polarization techniques. The percentage inhibition efficiency was found to increase with increasing concentration of inhibitor and with decreasing temperature. The inhibition mechanism was discussed on the basis of the formation of complex compound adsorbed on the metal surface. The adsorption process follows Frumkin isotherm. The effect of temperature on the rate of corrosion in the absence and presence of these compounds was also studied. Some activated thermodynamic parameters were computed. Introduction Aluminium (Al) and its alloys are widely used in technology because of their low density, pleasing appearance, and corrosion resistance. For these reasons, the corrosion inhibition of Al in aqueous solution, has attracted the attention of many investigators [1-7]. Inhibition of metal corrosion by organic compounds is a result of adsorption of organic molecules or ions at the metal surface forming a protective layer. This layer reduces or prevents the corrosion of the metal. The extent of adsorption depends on the nature of the metal, the metal surface condition, the mode of adsorption, the chemical structure of the inhibitor, and the type of corrosive media [8]. The aim of the present work is to study the inhibitive action of some mono azo dyes based on 1,5-dihydroxynanphthalene toward the corrosion inhibition of aluminium in 0.01 M NaOH solution using weight loss and galvanostatic polarization techniques. The effect of temperature on the dissolution of