PHYTOCHEMISTRY OF ETHANOL EXTRACT OF YOUNG COCONUT FIBER AND ITS EFFECTIVENESS AS AN IRON CORROSION INHIBITOR IN SEAWATER MEDIA

This study aims to examine the effectiveness of tannin extract as an iron corrosion inhibitor in seawater media. Tannin extract was obtained through a maceration extraction process using 96% ethanol solvent. Its properties were analysed by UV-Vis Spectrophotometry and FTIR, while the corrosion rate and inhibitor efficiency were tested using Gravimetry and Electrochemistry methods based on tannin concentration and immersion time in seawater media. The results of qualitative and quantitative analysis obtained an extract yield of 13.47% and contained active compounds including alkaloids (21.32%), saponins (9.87%), terpenoids (8.32%), condensed tannins (1.73%), phenolic compounds (1.16%), and flavonoids (0.36%), while the results of the analysis with UV-Vis Spectrophotometry showed that absorption occurred at a wavelength of 302 nm due to the π → π * Transition from longer conjugated bonds, while the results of the FTIR Spectrophotometry analysis showed that absorption occurred at wave numbers 1714.72 cm-1 , 1612.48 cm-1 and 3390.86 cm-1 indicating the interaction between the C = O, C = C aromatic and -OH groups indicating the presence of polyphenol structures in tannins. The results of Gravimetry showed the formation of a protective layer on the iron surface, thereby reducing the corrosion rate significantly. The highest inhibition efficiency reached 75.83% at a concentration of 600 ppm for 168 hours (7 days), and Tannin formed a regular monolayer layer and which was in accordance with the Langmuir adsorption isotherm. This shows that Tannin has the potential as a natural inhibitor to prevent corrosion of iron in the marine environment.