Ação do ácido oxálico como inibidor de corrosão do aço-carbono

Abstract

We evaluated the action of oxalic acid as an inhibitor of corrosion of carbon steel in solutions containing different concentrations of the inhibitor (10-3, 10-4 e 10-5 mol.L-1) at different pH's: 3,0; 4,0 and 5,0. The technique employed was by gravimetric tests, whereby it was possible, from the carbon steel mass loss values, calculate the corrosion rate of the same subject in different conditions. The results indicated that the oxalic acid is effective as a corrosion inhibitor in prominence when the concentration is 10-5 mol.L-1 in the medium pH to 3,0. This is due to carboxyl groups present in the inhibitor molecule promote the formation of a protective film on the metal-corrosive medium interface, affecting the corrosion.