Sintesis Metil Ester Asam Lemak dari Minyak Jelantah Melalui Tahapan Reaksi Amidasi dan Reaksi Transesterifikasi Menggunakan Peralatan Pendispersi Homogen

Abstract

The synthesis of fatty acid methyl esters from waste cooking oil was carried out by amidation reaction with monoethanolamine and transesterification reaction using homogenizer. The amidation reaction was carried out on waste cooking oil to decrease the acid number of waste cooking oil from 8.815 mg KOH/g sample to 0.78 mg KOH/g sample. The maximum conversion was obtained 91,15 ± 0.09% at the reaction conditions of molar ratio of used cooking oil to monoethanolamine 1:1.5, reaction time 30 min and rotation speed of 5000 rpm. Waste cooking oil that has been reduced free fatty acids, transesterified into MEAL using sodium hydroxide (NaOH) catalyst. MEAL conversion of 91.50 ± 0.2% was obtained at the reaction conditions of molar ratio of waste cooking oil: monoethanolamine 1:9, 1% w/w catalyst concentration and rotational speed of 4000 rpm in 5 minutes reaction time. The formation of fatty acid amide compounds from waste cooking oil was confirmed by FT-IR spectroscopy which shows the N-H group formation at wave number 3307.3 cm-1 with a sharp peak supported by C-N stretching vibrations at wave number 1159.8 cm-1 and there are bending vibrations on the N-H amide functional group at wave numbers 1641.2 cm-1 and 1556.4 cm-1. GC-MS spectra confirmed the formation of fatty acid amide compounds such as N-(2-hydroxyethyl)-dodecanamide, N-(2-hydroxyethyl)-octanamide and N-(2-hydroxyethyl)-decanamide with % area at 1.61%, 1.89% and 8.00%, respectively. The formation of fatty acid methyl esters is characterized by differences in the shape of the -C-O-C- stretching vibration at wave numbers 1300-1000 cm-1 where in waste cooking oil the strongest absorption of the 3 peaks is in the second position (middle) while in the fatty acid methyl esters the strongest absorption appears in the right position.