SYNTHESIS OF WATER-SOLUBLE CHITOSAN FROM SHRIMP SHELL WASTE AS GREEN CORROSION INHIBITOR FOR API 5L X52M STEEL IN SULFURIC ACID SOLUTIO

• Main Author: Muhammad, Fachri
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/76608
• Institution: Institut Teknologi Bandung

According to the latest study by NACE International, it was stated that the global losses due to corrosion were estimated to reach $2.5 trillion USD. Not only that, corrosion-related failures contributed to approximately 17% of pipeline accidents in the United States, as referenced by the Pipeline and Hazardous Materials Safety Administration (PHMSA). Application of corrosion inhibitor was a common method to reduce corrosion rate of steel in aqueous environments. However, most of the inhibitors used in the industry were synthetic inhibitors that were toxic and were not environmentally friendly. Therefore, a corrosion inhibitor was needed which can not only effectively protects metals from corrosion, but also has low toxicity. This research was conducted to evaluate the effectiveness of water-soluble chitosan (WSC) extracted from shrimp shell waste as a green inhibitor that could substitute synthetic inhibitor. The WSC inhibitor is tested on API 5L X52M steel in a 0.5 M H2SO4 solution. The WSC inhibitor was extracted from shrimp shell waste through a series of processes, including demineralization, deproteinization, deacetylation, and depolymerization. The WSC samples were tested for their performance on steel in an acidic environment using several testing methods categorized into three groups: immersion tests, electrochemical tests, and characterization tests. The test was conducted with varying inhibitor concentrations, namely 3, 5, 7, and 9 g/l, as well as different solution temperatures ranging from 25 to 55°C. Based on the experimental results, the highest inhibition efficiency value of the WSC inhibitor was found to be 73.28% at an inhibitor concentration of 9 g/l. Furthermore, the adsorption isothermal model of the WSC inhibitor on steel in an acidic environment was found to follow the Langmuir model, and the adsorption mechanism was identified as physisorption. The addition of the inhibitor also influenced the electrochemical test, showing an increase in the polarization resistance (Rads). Based on the Nyquist and Bode plots, it can be concluded that the Randles equivalent circuit for this system was (CPEdl/Rdl/(Lads-Rads))-L1. Furthermore, from the surface characterization test using scanning electron microscope (SEM) method, the solution with the addition of the inhibitor resulted in a smoother surface and smaller pit sizes on the steel.