RAMBUTAN PEEL EXTRACT AS A CORROSION INHIBITOR FOR CARBON STEEL IN SULFURIC ACID SOLUTION

• Main Author: Fandi Luthfianto, Rizkiawan
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/67909
• Institution: Institut Teknologi Bandung

Mild steel type A36 is one of the steels that is widely used in everyday life. However, it is susceptible to corrosion. Therefore, corrosion protection methods are needed in low carbon steels, especially when we consider about applying the principle of green chemistry. Such methods are green inhibitors. Rambutan peels has been shown to be beneficial in areas such as health and cancer-preventing cells. In addition, close relatives of rambutan such as lychee and longan have proven effective as corrosion inhibitors. Therefore, this study studied the potential of rambutan peel extracts as a green inhibitor of corrosion in sulfuric acid solutions. The study used rambutan peel extracts in a test solution of 0.5 M H2SO4. The rambutan peel was extracted by dissolution in 0,5 M H2SO4 solution. In general, the tests were carried out in three groups, namely immersion, electrochemical, and characterization tests. In the immersion test, variations in inhibitor concentrations were 3,4,5, and 6 grams per liter (gpl) and the temperature variations were 25, 35, 45, and 55oC. For electrochemical tests, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization were carried out using potentiostat. For characterization tests were used fourier transfrom infrared (FTIR), ultraviolet visible spectroscopy (UV-Vis) and scanning electron microscope (SEM). In immersion tests at 25oC for 24 hours, the optimum concentration of rambutan peel extract was 65.61 % at the addition of 5 gpl of extract. The adsorption of rambutan peel extract to the metal surface follows the Langmuir adsorption isotherm model with a physisorption mechanism with a range value of ?G°ads from -13.52 to -17.95 kJ/mol. In the electrochemical test with EIS, the optimum inhibitor concentration was obtained by 82.99% in the addition of 5 gpl of extract. In the polarization test, the optimum concen tration of inhibitors was 73.03% at the addition of 4 gpl of extract. FTIR test of corrosion products formed on the steel surface after immersion in 3 gpl and 5 gpl solutions revealed the presence of O - H, C = C, and aromatic C - H bonds. It confirms the adsorption of rambutan peel extract on the steel surface. While in UV-Vis it was found that in the solution after immersion, ferrous ions were found. It was indicated at a peak wavelength of 213 nm. In addition, in the solution after immersion, there was a decrease in the absorbance capacity which indicated that the organic compounds in the rambutan peel extracts were adsorbed. SEM analysis showed that after immersion in 0,5 M H2SO4 solution in the absence of inhibitor, the steel surface was very rough with the presence of deep pits. Meanwhile, in the presence of inhibitor the surface was relatively smoother than without inhibitor.