NEPHELIUM LAPPACEUM (RAMBUTAN) PEEL EXTRACT AS AN INHIBITOR FOR API 5L GRADE X52M STEEL UNDER SWEET CORROSION CONDITION

• Main Author: Soegiardjo, Jovita
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/75715
• Institution: Institut Teknologi Bandung

Corrosion is a degradation process that occurs spontaneously on metal surfaces due to chemical, biochemical and electrochemical interactions between metals and alloys with their environment. One of the common types of corrosion in the oil and gas industry is sweet corrosion, and one of the methods to control corrosion in the industry is the addition of inhibitors. Nowadays many researchers develop Green Corrosion Inhibitors (GCI) because they are nontoxic compared to commercial inorganic inhibitors. GCI can be derived from organic waste, such as rambutan peel that contains flavonoids and tannins. This research studied rambutan peel extract as corrosion inhibitor for API 5L Grade X52M steel in sweet corrosion condition in 3.5 wt% NaCl solution injected with CO2 gas. A series of experiments were conducted to study the effect of variations in inhibitor concentrations and immersion time. Experiment began with the preparation of rambutan peel extract, preparation of the test solution, and preparation of steel sample. Then, corrosion tests were carried out using immersion test and electrochemical test. From these tests, the corrosion rate and inhibitor efficiency were obtained. The weight loss data were analyzed with analysis of variance (ANOVA) method to determine the significance effect of variations in immersion time and inhibitor concentration. The characterization of steel surface, oxide layer and organic compounds were also carried out for sample immersed in the blank solution and solution with the optimum inhibitor concentration. The results of the immersion test with inhibitor concentrations varied from 0 – 7 gpl, the optimum inhibitor concentration was 5 gpl with the efficiency were 80.714% for 6 hours of immersion time and 86.142% for 94 hours of immersion time. Among the immersion time variations of 6, 24, 74, and 94 hours, the highest inhibitor efficiency was obtained in 94 hours. From the results of electrochemical tests using Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Polarization (PDP) methods, the highest inhibitor efficiency was obtained at the inhibitor concentration of 5 gpl in accordance with the results of the immersion test. From the Scanning Electron Microscope (SEM), it was obtained that the sample surface was smoother in the inhibitor – added solution compared to the blank solution. There was an increase in the thickness of the corrosion product with increasing immersion time. However, the corrosion product in inhibitor – added solution was thinner than blank solution. From the fourier-transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV – Vis) characterization, it can be concluded that there were inhibitor compounds adsorbed onto the steel surface.