PRODUKSI DAN UJI KARAKTERISTIK BIOETANOL DARI BEKATUL BERAS PUTIH (ORYZA SATIVA LINNAEUS) DENGAN PENAMBAHAN BENTONIT

PRODUCTION AND CHARACTERISTIC TESTING OF BIOETHANOL FROM WHITE RICE BRAN (ORYZA SATIVA LINNAEUS) WITH THE ADDITION OF BENTONITE

Minyak bumi adalah sumber energi tak terbarukan yang kian menipis dan menyebabkan dampak lingkungan, sehingga mendorong pengembangan bioetanol sebagai energi alternatif ramah lingkungan. Salah satu bahan bakunya adalah bekatul beras putih, limbah kaya pati dari pengolahan beras. Indonesia memiliki potensi besar dalam pemanfaatan bekatul untuk produksi bioetanol melalui proses fermentasi. Untuk meningkatkan kadar etanol sesuai standar, digunakan teknik distilasi lanjutan dan adsorpsi dengan bentonit, yang terbukti efektif menyerap air dan meningkatkan kadar etanol. Penelitian ini bertujuan mengkaji pembuatan bioetanol dari bekatul dengan bentonit sebagai adsorben serta mengevaluasi kualitasnya.

Penelitian ini merupakan eksperimen untuk memproduksi bioetanol dari bekatul beras putih yang dihidrolisis menggunakan enzim α-amylase dan glucoamylase, kemudian difermentasi dengan ragi Saccharomyces cerevisiae. Hasil fermentasi didistilasi menggunakan rotary evaporator sebanyak lima kali pada suhu 78°C, di mana distilasi pertama dan kedua tanpa adsorben, distilasi ketiga menggunakan bentonit untuk menentukan berat paling efektif, serta distilasi keempat dan kelima ditambahkan etil asetat 30% v/v dengan berat bentonit terbaik. Karakteristik bioetanol diuji sesuai ASTM dan SNI 7390:2012 meliputi viskositas, densitas, kadar etanol, nilai kalor, titik nyala, dan FTIR, dengan variabel bebas berupa variasi berat bentonit 35, 40, dan 45 gram serta lama fermentasi 3, 4, dan 5 hari.

           Hasil penelitian menunjukkan bahwa fermentasi terbaik terjadi pada hari ke-5 dan berat bentonit optimal adalah 40 gram. Kadar etanol yang dihasilkan mencapai 98,72% berdasarkan GC dan 99,7% berdasarkan alkohol meter dengan selisih 0,98%, keduanya sesuai standar SNI. Bioetanol memiliki nilai kalor 7,0984 kal/g, titik nyala 13°C, densitas 0,778 g/mL, viskositas 1,053 cP, serta gugus C–H, O–H, dan C–O berdasarkan uji FTIR. Nilai ekonomis produksi menunjukkan biaya sebesar Rp59.400,00 per liter.

Petroleum is a non-renewable energy source that is increasingly depleting and has environmental impacts, thus encouraging the development of bioethanol as an environmentally friendly alternative energy. One of the raw materials is white rice bran, a starch-rich waste from rice processing. Indonesia has great potential in utilizing rice bran for bioethanol production through a fermentation process. To increase the ethanol content according to standards, advanced distillation and adsorption techniques with bentonite are used, which have been proven to be effective in absorbing water and increasing ethanol content. This study aims to examine the production of bioethanol from rice bran with bentonite as an adsorbent and evaluate its quality.

This research is an experiment to produce bioethanol from white rice bran hydrolyzed using α-amylase and glucoamylase enzymes, then fermented with Saccharomyces cerevisiae yeast. The fermentation results were distilled using a rotary evaporator five times at a temperature of 78°C, where the first and second distillations were without adsorbent, the third distillation used bentonite to determine the most effective weight, and the fourth and fifth distillations were added with 30% v/v ethyl acetate with the best bentonite weight. The characteristics of bioethanol were tested according to ASTM and SNI 7390:2012 including viscosity, density, ethanol content, calorific value, flash point, and FTIR, with independent variables in the form of variations in bentonite weight of 35, 40, and 45 grams and fermentation times of 3, 4, and 5 days.

The results showed that the best fermentation occurred on the 5th day and the optimal bentonite weight was 40 grams. The ethanol content produced reached 98.72% based on GC and 99.7% based on alcohol meter with a difference of 0.98%, both according to SNI standards. Bioethanol has a calorific value of 7.0984 cal/g, a flash point of 13°C, a density of 0.778 g/mL, a viscosity of 1.053 cP, and C–H, O–H, and C–O groups based on FTIR tests. The economic value of production shows a cost of Rp59,400.00 per liter.