Carbon steel corrosion inhibition activity of tofu associated proteins

Abstract

Green corrosion inhibitors are required to reduce the rate of corrosion on metal surfaces. Proteins have specific functional sites for amino acids that can be used to inhibit corrosion. In this research, protein and its amino acids, isolated from tofu pulp, were evaluated as corrosion inhibitors in brackish water media using electrochemical impedance spectroscopy method. The inhibition efficiency (IE %) of isolated protein in fraction 3 was found to be 92% at 80 ppm. Glycine, methionine, proline, threonine, and tryptophan were found in the isolated protein content in fraction 3. The isolated protein's adsorption isotherm mechanism on the carbon steel surface follows the Langmuir isotherm with ∆Gads of −33.5 kJ/mol. Semi-chemical or physical adsorption was observed between isolated protein as a corrosion inhibitor and metal surfaces.