Evaluation of white tea as a potential corrosion inhibitor

This research work presents an evaluation of the alcoholic extract of the white tea as potential corrosion inhibitor for the carbon steel P110 in the presence of 1 mol.L-1 hydrochloric acid. Corrosion Inhibitors stand out in the protection of metallic parts in acid environments, and many of the substances present in the composition of the commercial inhibitors are harmful to the environment. For this reason, plant extracts began to be evaluated as potential corrosion inhibitors because of their non toxic nature, as well as their renewable character, constituting the so called green corrosion inhibitors. The white tea comes from the Camellia sinensis, leaves and dry branches are used in the preparation of the extract in ethanol. Mass loss tests were performed for different concentrations of the extract (100, 200, 300 ppm) with the concentration of 300 ppm showing the best result, with an inhibition efficiency of 90,2%. Polarization and electrochemical impedance tests were carried out with reduction in the anodic and cathodic currents, increase in the resistance to charge transfer and reduction in the capacitance of the electric double layer, indicating a process of adsorption of the extract over the active areas of the metal. The results indicate the potential use of the alcoholic extract of white tea as an active material in the formulation of an environmentally safe corrosion inhibitor.