Institutional Repository UIN Sunan Kalijaga YogyakartaANALISIS STRUKTUR KRISTAL, KOMPOSISI UNSUR TOTAL, DAN GUGUS FUNGSI KATALIS HETEROGEN DARI KULIT PISANG KEPOK (Musa acuminata balbisiana) SERTA APLIKASINYA SEBAGAI KATALIS PADA TRANSESTERIFIKASI MINYAK KELAPA SAWITNIM.: 22106030041Hella Nazilni HidayahauthorBanana peels from kepok bananas (Musa acuminata balbisiana) are biomass waste that contain minerals with the potential to form metal oxides that act as catalysts through calcination. This study aims to analyze the crystal structure, functional groups, and elemental composition of the metal oxide catalysts, with values of 25.39°, 29.59°, and 40.56°, and to identify the KCl, K2CO3, CaO, and MgO phases produced by calcining kepok banana peel, as well as to examine its application in the transesterification reaction of palm oil. The catalyst was synthesized by calcination at 750°C for 3 hours, then characterized using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Fluorescence (XRF), and its basicity was tested using the Hammett Indicator-Benzoic Acid method. The resulting biodiesel was analyzed based on yield and compound composition using Gas Chromatography-Mass Spectrometry (GC-MS). XRD characterization results showed dominant K₂O diffraction peaks at 2θ values of 25.39°, 29.59°, and 40.56°, and identified the KCl, K2CO3, CaO, and MgO phases. XRF analysis showed K₂O as the dominant component at 53.85%, while FTIR results confirmed the presence of carbonate groups and metal-oxygen bonds such as K-O, Si-O-Si, CO32-, and Ca-O. The catalyst had a total basicity of 0.77 mmol/g. The product yield was 74% (w/w), and the total Fatty Acid Methyl Ester (FAME) content was 99.45%, dominated by methyl oleate (51.84%), methyl 3-hydroxy-2-tetradecyl octadecanoate (28.86%), and methyl eicosanoate (methyl arachidate) (28.86%). The research results show that the heterogeneous catalyst based on kepok banana peel was successfully used as a base catalyst in the transesterification reaction of palm oil.543 Kimia Analitikal, Kimia Analisis2026-08-28UIN SUNAN KALIJAGA YOGYAKARTA;FAKULTAS SAINS DAN TEKNOLOGIThesis

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