OPTIMASI EKSTRAKSI BERBANTUAN GELOMBANG MIKRO DAN TRANSESTERIFIKASI BIO-CRUDE OIL DARI SPIRULINA (Arthrospira platensis)

ANGGELINA PURNAMA, Prof. Dr.rer.nat. Karna Wijaya, M.Eng.; Drs. Iqmal Tahir, M.Si.

2019 | Skripsi | S1 KIMIA

Optimasi ekstraksi berbantuan gelombang mikro atau Microwave-assisted Extraction (MAE) dan transesterifikasi bio-crude oil dari spirulina (Arthrospira platensis) telah dilakukan. Penelitian ini diawali dengan MAE bio-crude oil dari A. platensis dengan pelarut air, sentrifugasi, pengontakan dengan n-heksana, pemisahan, dan dilanjutkan dengan evaporasi. Optimasi kondisi ekstraksi dilakukan dengan variasi biomassa terhadap pelarut, suhu ekstraksi, waktu ekstraksi, dan waktu kontak dengan n-heksana. Optimasi kondisi transesterifikasi dilakukan dengan variasi bio-crude oil terhadap metanol, suhu reaksi, dan waktu reaksi. Kerusakan sel sebelum dan setelah ekstraksi serta setelah pemanasan konvensional diamati dengan SEM. Persentase kadar asam lemak bebas (free fatty acids, FFA) dan konsentrasi β-karoten bio-crude oil ditentukan dengan titrasi dan spektrofotometer UV-Visible. Bio-crude oil dan biodiesel dikarakterisasi dengan FTIR, GC-MS, 1H-NMR dan 13C-NMR. Berdasarkan hasil penelitian, rendemen rerata tertinggi bio-crude yang diperoleh sebesar 5,56%; rasio biomassa/pelarut 1:7, suhu ekstraksi 70 °C, waktu ekstraksi 15 menit, dan waktu kontak dengan n-heksana 25 menit sementara rendemen rerata tertinggi biodiesel sebesar 98%; rasio bio-crude oil/metanol 1:6, suhu reaksi 65 °C, dan waktu reaksi 50 menit. Kadar rerata FFA dan β-karoten bio-crude oil berturut-turut sebesar 1,41% dan 6,63 μg/mL. Kandungan asam lemak bio-crude oil hasil analisis GC-MS terdiri atas asam oleat 34,27%; asam palmitat 34,06%; asam linoleat 25,59%; dan asam stearat 6,09% sedangkan untuk biodiesel terdiri atas asam oleat 34,33%; asam palmitat 35,00%; asam linoleat 25,41%; dan asam stearat 5,26%. Analisis FTIR, 1H-NMR, dan 13C-NMR menunjukkan pembentukan puncak trigliserida untuk bio-crude oil dan metil ester untuk biodiesel.

Optimizations of Microwave-assisted Extraction (MAE) and transesterification of bio-crude oil from spirulina (Arthrospira platensis) have been conducted. This experiment was initiated by MAE of bio-crude oil from A. platensis using water as a solvent, centrifuged, contacted with n-hexane, separated, and continued to evaporation. Optimization for the extraction was conducted with varieties of biomass to solvent ratio, extraction temperature, extraction time, and n-hexane contact time. Optimization for transesterification was carried out with variations of bio-crude oil to methanol ratio, reaction temperature, and reaction time. Cells damages before and after extraction and also conventional heating were observed using SEM. The average percentage of free fatty acids (FFA) and β-carotene of bio-crude oil were determined by titration and UV-Visible spectrophotometer. The bio-crude oil and biodiesel were characterized using FTIR, GC-MS, 1H-NMR, and 13C-NMR. The results demonstrated that the highest average yield of the bio-crude oil was 5.56%; biomass/solvent 1:7, extraction temperature 70 °C, extraction time 15 minutes, and n-hexane contact time 25 minutes while the highest average yield of the biodiesel was 98%; bio-crude oil/methanol 1:6, reaction temperature 65 °C, and reaction time 50 minutes. The average percentage of FFA and β-carotene were 1.41% and 6.63 μg/mL respectively. The fatty acids content of the bio-crude oil based on GC-MS analysis consisted of oleic acid 34.27%, palmitic acid 34.06%, linoleic acid 25.59%, and stearic acid 6.09% while for the biodiesel were oleic acid 34.33%, palmitic acid 35.00%, linoleic acid 25.41%, and stearic acid 5.26%. The FTIR, 1H-NMR, and 13C-NMR analyses showed peaks of triglyceride for the bio-crude oil and methyl ester for the biodiesel.

Kata Kunci : bio-crude oil, biodiesel, MAE, optimasi, spirulina.