Investigating the Potential of L-Hydroxy-Proline as a Biodegradable Amino Acid in Preventing the Corrosion of Low Carbon Steel

here, the potential of of L-hydroxy-proline as a biodegradable amino acid in tackling the corrosion of low carbon steel coupons immersed in 0.1 M hydrochloric acid electrolyte was illustrated. Therefore, some techniques including weight-loss, electrochemical evaluations (e.g., EIS) and surface analysis (e.g. AFM) were employed. The weight loss evaluations showed that at ambient temperature (298 K), raising the concentration of L- hydroxy-proline dissolved in the harsh electrolyte from 50 ppm to 500 ppm dropped the corrosion rate of the metallic pieces from 37.7 mpy to 5.4 mpy, while the corrosion rate of steel was in the absence of inhibitor was 96.8 mpy. It was also recorded that heating up the temperature of the harsh solution between 298 K and 343 K has dropped the ability of L- hydroxy-proline to minimize the corrosion phenomenon. Thermodynamic data showed that L- hydroxy-proline raised the energy barrier needed for the initiation of the metal dissolution. It was also calculated that the adsorption of the tested amino acid was in perfect agreement with the Langmuir adsorption isotherm. In terms of the electrochemical studies, it can be said that the Tafel polarization diagrams showed that 500 ppm L- hydroxy-proline changed the corrosion current density from 3.98 μA.cm-2 recorded without the tested aminod acid to 1.9 μA.cm-2. This was in accordance with the Nyquist plots gathered from the electrochemical impedance spectroscopy analysis in which the resistance for the charge transfer increased from 82 Ω.cm2 to 1750 Ω.cm2. In addition, the 3D topography images highlighted that L- hydroxy-prolin reduced the surface roughness of the coupons immersed in the corrosive electrolyte.