Natural Polymers as Corrosion Inhibitors for Aluminium and Tin in Acidic Media

DOI : http://dx.doi.org/10.13005/msri/040207

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Some natural polymers (carrageenans) were tested as corrosion inhibitors for pure aluminium and pure tin in hydrochloric and nitric acid solutions, respectively, using the weight loss and thermometric techniques. It was found that the investigated compounds exhibited a very good performance as inhibitors for corrosion of these metals in all tested media. The degree of inhibition depends on the nature of the metal, nature of the inhibitor and type of the medium. The inhibition efficiency increases with increasing the concentration of the inhibitor in the order: k-carrageenan < i-carrageenan < l-carrageenan. The inhibitive action of these natural polymers was discussed in view of adsorption of the molecules on the metal surface. This adsorption was found to follow TemKin adsorption isotherm in all tested media. Also, effect of temperature on the corrosion parameters was studied and discussed. Molecular orbital treatment was done to rationalize the electronic structure and the ground state properties of the studied carrageenan compounds.

Aluminium; tin; corrosion; weight loss; thermometry; carrageenan