Sintesis Biodiesel dan Bahan Kimia dari Mikroalga Basah (Chlorella Vulgaris) Menggunakan Proses In Situ Transesterifikasi dalam Air Etanol Subkritis

Yasmin, Medina (2019) Sintesis Biodiesel dan Bahan Kimia dari Mikroalga Basah (Chlorella Vulgaris) Menggunakan Proses In Situ Transesterifikasi dalam Air Etanol Subkritis. Masters thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Produksi biodiesel dari mikrolaga dalam skala industri masih terhambat oleh konsumsi energi yang tinggi pada proses pengeringan. Penggunaan mikroalga basah hasil proses dewatering secara langsung sebagai bahan baku dipercaya mampu mengurangi konsumsi energi dari produksi biodiesel. Namun, kandungan air yang tinggi dapat menghambat ekstraksi minyak dari dinding sel mikroalga dan menurunkan efektifitas katalis dalam mempercepat reaksi konversi biodiesel. In situ transesterifikasi pada kondisi subkritis diketahui sebagai proses yang ramah lingkungan dan ekonomis untuk mengkonversikan biomassa menjadi biodiesel. Metode tersebut dikenal sebagai metode yang tidak terpengaruh oleh kondisi awal bahan baku seperti kandungan air dan kandungan free fatty acids (FFA). Selain itu, metode tersebut dinilai mampu memproduksi tak hanya biodiesel tapi juga bahan kimia (etil levulinat) dari mikroalga basah. Pada penelitian ini, bibit mikroalga (C.vulgaris, 20% dari volume total 1 L) dikultivasi secara mandiri dalam air laut (salinitas 27,1 ppt) sebagai media kultur. Kultur mikroalga dikultivasi dengan periode pencahayaan 24:0 (light:dark), laju aerasi 4 ml/menit, dan waktu kultivasi selama 10 hari. Selanjutnya, mikroalga basah (6 gram, kandungan air=90%) dimasukkan kedalam reaktor hidrotermal pada temperatur (135-205oC), waktu reaksi (15-120 menit), rasio air/alga kering (9-20 g/g), tekanan 105 bar, rasio alga basah/pelarut= 10/9 (g/ml), dan rasio etanol/etil asetat=4 (ml/ml). Yield FAEE sebesar 80,60% (kandungan FAEE=21,93%) diperoleh saat temperatur operasi ditingkatkan hingga 205oC sedangkan 45 menit waktu reaksi menghasilkan yield FAEE sebesar 47,40% (kandungan FAEE=14,53%) dan lebih tinggi dibandingkan penambahan waktu reaksi hingga 120 menit. Penambahan jumlah air (lebih dari 90%) didalam mikroalga basah akan menurunkan yield FAEE hingga 21,75% dengan kandungan FAEE sebesar 14,5%. Etil levulinat sebagai produk lain tidak terbentuk pada proses in situ dalam kondisi campuran air-etanol subkritis. Ketiadaan etil levulinat dalam crude biodiesel dapat dipengaruhi karena jumlah air yang terlalu tinggi pada proses in situ transesterifikasi dalam kondisi subkritis. ========================================================================================================================================
Biodiesel production from microalgae on an industrial scale is still hindered by high energy consumption in the drying process. Utilization of wet microalgae directly as raw material is convinced to be able to reduce energy consumption from biodiesel production. However, high water content inhibits oil extraction from microalgae cell walls and reduce the effectiveness of catalysts in accelerating biodiesel conversion reactions. In situ transesterification under subcritical conditions is known as an environmentally and economically friendly process for converting biomass to biodiesel. This method is found to be unaffected by the initial conditions of raw materials such as water content and free fatty acids (FFA). In addition, the method is considered to not only produce biodiesel but also chemicals (ethyl levulinate) from wet microalgae. In this study, microalgae (C. vulgaris, 20% of total volume of 1 L) were cultivated independently in seawater (salinity 27.1 ppt) as a culture medium. Microalgae culture was cultivated with a lighting period of 24: 0 (light: dark), aeration rate of 4 ml/minute, and cultivation time for 10 days. Furthermore, wet microalgae (6 grams, water content = 90%) are subjected into hydrothermal reactor at temperatures (135-205oC), reaction time (15-120 minutes), water/dry algae ratios (9-20 g / g), pressure 105 bar, wet algae/solvent ratio= 10/9 (g/ml), and ethanol/ethyl acetate ratio = 4 (ml/ml). FAEE yield of 80.60% (FAEE content= 21.93%) was obtained when the operating temperature was increased to 205oC while 45 minutes of reaction time obtain FAEE yield of 47.40% (FAEE content = 14.53%) which was higher than the increment of reaction time up to 120 minutes. Increasing in the amount of water (more than 90%) in wet microalgae will reduce FAEE yield to 21.75% with FAEE content of 14.5%. Ethyl levulinate as by-product was not formed from in situ process under the subcritical water-ethanol mixture. The absence of ethyl levulinate in crude biodiesel can be affected due to excessive amount of water from in situ transesterification under subcritical condition.

Item Type:	Thesis (Masters)
Uncontrolled Keywords:	Mikroalga; In situ transesterifikasi; Air-etanol subkritis; FAEE; Etil levulinat
Subjects:	T Technology > TP Chemical technology > TP339 Ethanol as fuel. Biomass energy.
Divisions:	Faculty of Industrial Technology > Chemical Engineering > 24101-(S2) Master Thesis
Depositing User:	Yasmin Medina
Date Deposited:	22 Jul 2026 02:48
Last Modified:	22 Jul 2026 02:48
URI:	http://repository.its.ac.id/id/eprint/69231

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