H. Hasby
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PEMODELAN KOMPUTASI KOMPONEN CIS DAN TRANS METIL OLEAT DALAM BIODIESEL YANG DISINTESIS DARI MINYAK KELAPA SAWIT H. Hasby; N. Nurhafidhah; G. Pamungkas
Jurnal Kimia (Journal of Chemistry) Vol. 15, No.2, Juli 2021
Publisher : Program Studi Kimia, FMIPA, Universitas Udayana (Program of Study in Chemistry, Faculty of Mathematics and Natural Sciences, Udayana University), Bali, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24843/JCHEM.2021.v15.i02.p12

Abstract

Biodiesel adalah senyawa Fatty Acid Methyl Ester (FAME) yang dapat disintesis dari minyak nabati, seperti minyak sawit. Tujuan penelitian ini untuk mengetahui seberapa besar pengaruh metil oleat sebagai komponen dominan FAME terhadap kualitas biodiesel yang disintesis dari minyak kelapa sawit berdasarkan hasil eksperimen dan komputasi. Metode sintesis biodiesel meliputi pengujian kadar FFA, proses esterifikasi, dan proses transesterifikasi. Selanjutnya persentase kandungan metil oleat ditentukan dengan menggunakan GC-MS (Chromatography Gas-Massa Spectroscopy). Metode komputasi yang digunakan dalam penelitian ini adalah DFT/B3LYP/6-31G dengan melakukan optimasi parameter geometris, analisis energi HOMO-LUMO dan energi gap terhadap molekul cis dan trans metil oleat. Hasil sintesis biodiesel pada pengujian kadar FFA dari minyak sawit adalah sebesar 4,022%, sehingga harus dilanjutkan dengan tahap esterifikasi dan transesterifikasi. Biodiesel berwarna kuning keemasan beraroma khas minyak sawit, merupakan produk dari penelitian ini. Pengujian kualitas biodiesel didapatkan hasil pH 3, densitas 852 kg/m3, viskositas 5,9 Mm2/s, bilangan asam 0,28 mg-KOH/g dan titik nyala 1400C, yang telah memenuhi SNI 7028:2015. Hasil karakterisasi dengan menggunakan GC-MS menunjukkan bahwa kandungan metil oleat sebesar 42,72%. Pengaruh keberadaan metil oleat dalam biodiesel tidak hanya meningkatkan kinerja suhu rendah biodiesel, tetapi juga berdampak positif pada stabilitas oksidasi biodiesel. Hasil komputasi menunjukkan bahwa celah energi (energi gap) untuk trans metil oleat dan cis metil oleat, masing-masing sebesar 6.18730069 eV dan 6.09342137 eV ini membuat trans metil oleat sedikit kurang stabil dan kemungkinan lebih reaktif di bandingkan molekul cis metil oleat. Kata kunci: biodiesel, esterifikasi, studi komputasi, transesterifikasi. Biodiesel is a Fatty Acid Methyl Ester (FAME) compound which can be synthesized from vegetable oils, such as palm oil. The purpose of this study was to determine how much influence methyl oleate as the dominant component of FAME had on the quality of biodiesel synthesized from palm oil based on experimental and computational results. Biodiesel synthesis methods include testing FFA levels, esterification process, and transesterification process. Furthermore, the percentage of methyl oleate content was determined using GC-MS (Gas-Mass Chromatography Spectroscopy). The computational method used in this research is DFT/B3LYP/6-31G by performing geometric parameter optimization, energy analysis of HOMO-LUMO and energy gap of cis and trans-methyl oleate molecules. The yield of the biodiesel synthesis in testing the FFA content of palm oil was 4.022%, so it had to be continued with the esterification and transesterification stages. Biodiesel with a distinctive golden yellow aroma of palm oil was the product of this research. The biodiesel quality tests resulted in pH of 3, density of 852 kg/m3, viscosity of 5.9 Mm2/s, acid number of 0.28 mg-KOH/g and flash point of 1400C, that had met SNI 7028: 2015. The characterization results using GC-MS showed that the methyl oleate content was 42.72%. The effect of the presence of methyl oleate in the biodiesel not only increased the low temperature performance, but also had a positive impact on the oxidation stability of the biodiesel. The computation results indicated that the energy gaps for trans methyl oleate and cis methyl oleate were 6.18730069 eV and 6.09342137 eV respectively, made the trans methyl oleate slightly less stable and possibly more reactive than the cis methyl oleate molecule. Keywords: biodiesel, computational studies, esterification, transesterification.