EFFECT OF STEEL SURFACE ROUGHNESS ON THE EFFICIENCY OF GREEN INHIBITOR DERIVED FROM SHRIMP SHELL WASTE IN ACIDIC SOLUTION

• Main Author: Safira, Faradilla
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/76596
• Institution: Institut Teknologi Bandung

Application of corrosion inhibitors is a common method to control the corrosion rate of steel in aqueous environments. Many recent studies have shown that various food wastes can be utilized as corrosion inhibitors, one of which is shrimp shell as a source of water soluble chitosan (WSC). This research studied the significance of metal surface roughness factor on the efficiency of WSC inhibitor in 0.5 M H2SO4 and 0.5 M HCl solution using analysis of variance (ANOVA) method. The concentration variation immersion test was conducted to determine the optimum concentration. The immersion test in H2SO4 solution was conducted with concentration variations of 0 gpl, 3 gpl, 5 gpl, 7 gpl, and 10 gpl for 24 hours, while in HCl solution was conducted with concentration variations of 0 gpl, 1 gpl, 2 gpl, 3 gpl, and 4 gpl for 24 hours. Then, immersion tests for 24 hours at room temperature in 0.5 M H2SO4 and 0.5 M HCl solutions were carried out with variations in surface roughness based on the roughness of the sandpaper last used for sample preparation, such as grits 60, 240, 800, and 2000. Electrochemical tests carried out include open circuit potential (OCP), electrochemical impedance spectrocopy (EIS), potentiodynamic polarization (PDP) tests on HCl blank and HCl solutions added with 3 gpl WSC inhibitor. In addition, surface characterization analysis using scanning electron microscope (SEM), characterization of organic compounds using fourier-transform infrared spectroscopy (FTIR), and ultravioletvisible spectroscopy (UV-Vis). The extraction process of WSC from shrimp shell waste is carried out through the process of demineralization, deproteination, deacetylation, and conversion of chitosan into WSC. Based on the research that has been done, the optimum concentration of WSC in H2SO4 and HCl solutions is 5 gpl and 3 gpl, respectively, with an inhibition efficiency of 61.85% and 94.31% at a roughness grit of 2000. Based on the results of the immersion, PDP, and EIS tests, the smoother the surface of a steel, the higher the inhibition efficiency value. Based on the OCP test, it is known that WSC is a mixed type inhibitor. The equivalent electrical circuit model in the blank solution is Rs-(CPEdl/Rp) and in the solution with WSC inhibitor added is Rs-(CPEi(Ri(CPEdl/Rp)). SEM test proved that the inhibitor can reduce the corrosion impact on the steel surface. FTIR and UV-Vis tests proved that the organic compounds in the inhibitor were adsorbed on the metal surface and played a role in reducing the metal corrosion rate. ANOVA results showed that surface roughness and solution type had a significant effect on metal weight loss, but the two factors did not significantly interact with each other.