Optimasi Transesterifikasi dalam Preparasi Biodiesel Biji Nyamplung (Calophyllum inophyllum) melalui Proses Dua Tahap
SHAMIL HUSSEINI, Ir. Nunung Prabaningrum, M.T., Ph.D.
2024 | Skripsi | FISIKA TEKNIK
Pemerintah terus mendorong penggunaan campuran biodiesel hingga 35% (B35) dalam Program Mandatori Biodiesel. Produksi biodiesel diutamakan menggunakan bahan non pangan supaya tidak bersaing dengan industri makanan. Salah satu bahan non pangan yang dapat dijadikan bahan baku biodiesel adalah biji nyamplung. Biji nyamplung memiliki kandungan minyak yang tinggi. Namun, kandungan asam lemak bebas (FFA) pada minyak nyamplung tinggi sehingga dapat mempersulit konversi minyak nyamplung menjadi biodiesel. Maka dari itu, dibutuhkan proses dua tahap yang terdiri dari esterifikasi in situ dan transesterifikasi untuk menurunkan kandungan FFA pada biji nyamplung.
Proses esterifikasi in situ dilakukan dengan pelarut metanol dan n-heksana dengan katalis H2SO4 sebagai tahap pertama. Hasil dari esterifikasi in situ menjadi bahan baku pada optimasi proses transesterifikasi dengan pelarut metanol dan katalis NaOH sebagai tahap kedua. Optimasi transesterifikasi menggunakan 24 full factorial Central Composite Design-Response Surface Methodology. Variabel bebas proses transesterifikasi yang digunakan adalah perbandingan molar metanol terhadap minyak hasil esterifikasi in situ, persentase massa katalis NaOH, suhu reaksi, dan waktu reaksi. Respon penelitian ini adalah yield dan bilangan asam. Bilangan asam ditentukan dengan metode titrasi berdasarkan AOCS Cd 3d-63. Uji GC-MS pada minyak nyamplung bertujuan untuk menentukan komposisi fatty acid methyl ester (FAME).
Kondisi optimum proses transesterifikasi diperoleh pada perbandingan molar metanol terhadap minyak hasil esterifikasi in situ sebesar 5,10:1, persentase massa katalis NaOH sebesar 0,79 wt.%, suhu reaksi sebesar 30?, dan waktu reaksi selama 1,23 jam. Kondisi optimum transesterifikasi menghasilkan yield maksimum sebesar (88,19 ± 1,38)?n bilangan asam minimum sebesar (0,83 ± 0,05) mg KOH/g.
The government continues to encourage the use of biodiesel blends of up to 35% (B35) in the Mandatory Biodiesel Program. Biodiesel production was prioritized using non-edible ingredients to avoid competition with the food industry. One of the non-edible ingredients that could be used as biodiesel raw material was nyamplung seeds. Nyamplung seeds had a high oil content. However, the free fatty acid (FFA) content of nyamplung oil was high, which could complicate the conversion of nyamplung oil into biodiesel. Therefore, a two-step processes consisting of in situ esterification and transesterification were needed to reduce the FFA content of nyamplung seeds.
In situ esterification process was carried out with methanol and n-hexane solvents catalyzed with H2SO4 as the first step. The result of in situ esterification became the raw material in the optimization of the transesterification process with methanol solvent and NaOH catalyst as the second step. Transesterification optimization used 24 full factorial Central Composite Design-Response Surface Methodology. The independent variables of the transesterification process were the molar ratio of methanol to oil from in situ esterification, mass percentage of NaOH catalyst, reaction temperature, and reaction time. The response of this research was yield and acid number. The acid number was determined by titration method based on AOCS Cd 3d-63 method. The GC-MS test on nyamplung oil aimed to determine the composition of fatty acid methyl ester (FAME).
The optimum conditions of the transesterification process were obtained at a molar ratio of methanol to oil from in situ esterification of 5.10:1, NaOH catalyst mass percentage of 0.79 wt.%, reaction temperature of 30?, and reaction time of 1.23 hours. The optimum transesterification conditions resulted in a maximum yield of (88.19 ± 1.38)% and a minimum acid number of (0.83 ± 0.05) mg KOH/g.
Kata Kunci : Biodiesel, nyamplung, dua tahap, esterifikasi in situ, transesterifikasi, yield, bilangan asam
