Elsevier

Corrosion Science

Volume 43, Issue 6, June 2001, Pages 1031-1039
Corrosion Science

Inhibition of acid corrosion of aluminum using vanillin

https://doi.org/10.1016/S0010-938X(00)00127-XGet rights and content

Abstract

The inhibition efficiency (IE) of vanillin towards the corrosion of aluminum in 5 M HCl solution was measured using weight loss measurement, hydrogen evolution method, thermometry and potentiostatic polarization techniques. The results drawn from the different techniques are comparable and exhibit a small discrepancy. It was found that vanillin acts as a good inhibitor for the corrosion of aluminum in 5 M HCl solution. The IE increases as the concentration of vanillin is increased. The inhibition action of vanillin is discussed in view of the adsorption of its molecules on the electrode surface through the active centers contained in its structure. It was found also that adsorption of vanillin on aluminum surface follows Langmiur adsorption isotherm.

Introduction

Aluminum has a remarkable economic and industrial importance owing to its low cost, lightweight, high thermal and electrical conductivity. The most important feature in aluminum is its corrosion resistance due to the formation of a protective film on its surface upon its exposure to atmosphere or aqueous solutions. Many researches were devoted to study the corrosion of aluminum in the different aqueous solutions [1], [2], [3]. Hydrochloric acid solutions are used for pickling of aluminum or for its chemical or electrochemical etching. It is very important to add a corrosion inhibitor to decrease the rate of aluminum dissolution in such solutions. The inhibition of aluminum corrosion in acidic solutions was extensively studied using organic and inorganic compounds [4], [5], [6], [7], [8], [9], [10], [11]. It was found that the organic compounds are effective corrosion inhibitors due to their ability to form an adsorbed protective film at the metal surface. The adsorption of carbonyl compounds on the metal surface was shown to occur through their carbonyl group [12]. Vanillin is an aromatic aldehyde that possesses a pleasant fragrance. Vanillin is the key component in vanilla flavoring and can be found in perfumes and other scented products, as well. Very little information is known about the use of vanillin as corrosion inhibitor for metals.

The objective of the present work is to study the inhibitive action of vanillin toward the corrosion of aluminum in 5 M hydrochloric acid solution. Weight loss measurements, hydrogen evolution method, thermometry and potentiostatic techniques were used to evaluate the inhibition efficiency (IE) of vanillin.

Section snippets

Experimental method

Aluminum metal with purity of 99.99% provided by the “Aluminum Company of Egypt, Nagh ammady” was used in the present study. Aluminum sheets with double side’s surface area of 1 cm2 were used for weight loss, thermometry and hydrogen evolution measurements. The aluminum sheets were bent into a U form and introduced into the test solutions with their edges downward. A new test piece was used for each experiment. For potentiostatic studies, a cylindrical rod embedded in araldite with exposed

Weight loss measurements

The loss in weight of aluminum strips in 5 M HCl in absence and in presence of different concentrations of vanillin, for 1 h, was determined. The IE was calculated and represented in Table 1. Inspection of the data in Table 1 reveals that vanillin acts as a very good inhibitor for corrosion of aluminum in hydrochloric acid. The IE of vanillin increases with the increase of its concentration.

Vanillin is an aromatic aldehyde containing carbonyl, methoxy and hydroxyl groups arranged around the

Conclusions

  • 1.

    Vanillin acts as a very good inhibitor for corrosion of aluminum in high concentrated hydrochloric acid.

  • 2.

    The high IE of vanillin is attributed to adsorption of its molecules, probably horizontally oriented, on aluminum surface.

  • 3.

    The adsorption of vanillin on aluminum surface follows Langmuir adsorption isotherm. Thus, there is no interaction between the adsorbed molecules.

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