Comparative studies of amino acid and soybean as corrosion inhibitors of steel in hydrochloric acid / Nurul Izzati Rosli

Amino Acid and Soybean potentials as organic corrosion inhibitors were examined through a few tests conducted. Sample characterization is performed to analyze compounds contained in soybean and glycine by using FTIR and UV-VIS. From FTIR spectrum obtained both soybean and glycine has N-H and C-N bond indicating the presence of nitrogen as a compound that reduces corrosion rate. UV-Visible spectrum runs show that both soybean and glycine are spotted in the range of 260nm. The potential of amino acid and soybean as corrosion inhibitors are measured through immersion test and potentiodynamic polarization test. Immersion test were performed with and without the presence of corrosion inhibitors for 3 days. Corrosion rate and inhibition efficiency of soybean and glycine were measured in this test. From the immersion test conducted, we found out that both soybean and glycine work best at 1.5g/L in 0.5M HCl medium. The purpose of potentiodynamic polarization test is to analyze type of inhibitions of soybean and glycine. As the results obtained, both soybean and glycine show anodic inhibition. Based on microstructure result, pitting corrosion is observed on the metal sample. The highest inhibitions recorded by soybean is 72.75% whereas the highest inhibition by glycine is only 69.10%. This shows that soybean has better inhibition compared to glycine.