Ferma P.C., Carmona J.M., Dalawampu K.A.D., Canlas M.A.G., Melendres A.V., 2026, Amino Acid Extract as a Green Corrosion Inhibitor for Low-Carbon Steel in an Acidic Medium, Chemical Engineering Transactions, 124, 415-420.
This study investigates the potential of an amino acid-rich extract as a green corrosion inhibitor for low-carbon steel in an acidic medium. The extract was derived from a natural protein source and applied at concentrations ranging from 1000 to 4000 ppm to steel samples immersed in acidic conditions. Fourier-transform infrared spectroscopy (FTIR) confirmed the presence of functional groups characteristic of amino acids, supporting their ability to adsorb onto the steel surface. Corrosion behavior was evaluated using gravimetric weight loss analysis and open-circuit potential (Ecorr) measurements recorded via a Fluke 115C True RMS multimeter. The results showed a clear concentration-dependent inhibition effect. At 4000 ppm, the corrosion rate decreased from 20.60 to 1.37 mils per year, while Ecorr shifted positively from 0.50 V (uninhibited) to 0.61 V, indicating enhanced surface passivation. The maximum inhibition efficiency reached 93.3%. These findings demonstrate that amino acid extracts offer a sustainable, cost-effective, and environmentally friendly alternative to conventional corrosion inhibitors for protecting steel in aggressive acidic environments. A simulated Tafel analysis supported the hypothesis of both anodic and cathodic suppression.
