Methylenedisalicylic Acid as a Biocorrosion Inhibitor for Aluminum in Concentrated Sodium Chloride Solutions.

ABSTRACT

3,3'-Methylenedisalicylic acid (MDS) was synthesized and ascertained on the basis of elemental analyses (C, H) and spectral measurements (IR, mass, 1H NMR, and UV-vis). Moreover, the prepared MDS compound has been assayed for its antimicrobial action against the growth of fungi as well as Gram-positive and Gram-negative bacteria. The results demonstrated the possibility of its usefulness to restrain the growth of both fungi and bacteria, whereas MDS showed its best impact against Candida albicans. The inhibitive impact of MDS on the corrosion of aluminum (Al) in concentrated sodium chloride solution (3.5 wt % NaCl) has been investigated. The corrosion work was done by potentiodynamic cyclic polarization, electrochemical impedance spectroscopy, and chronoamperometric current-time measurements and complemented by scanning electron microscopy and energy-dispersive X-ray investigations. It was found that MDS molecules protect the aluminum against corrosion, and its ability increases with the increase of concentration from 5 × 10-5 to 1 × 10-4 M and further to 5 × 10-4 M. The electrochemical results were supported by the morphological analysis and proved that the presence of MDS inhibits the uniform and pitting corrosion of Al in the chloride solutions.