Jurnal Teknik Kimia Vol. 28, No. 2, 2022, 51-59 e-ISSN: 2721-4885 DOI: https://doi.org/10.36706/jtk.v28i2.1003 Online at http://ejournal.ft.unsri.ac.id/index.php/jtk Received February 2022, Revised May 2022, Accepted for publication July 2022 Karakteristik Biodiesel dari Campuran Bahan Bakar Dexlite dan Minyak Jelantah Tanpa Perlakuan pada Mesin Diesel Biodiesel Characteristics from Dexlite Fuel Blends with Untreated Waste Cooking Oil in a Diesel Engine Bayu A Saputro 1)* , Abdurrahman 1) 1 Pendidikan Teknik Otomotif Universitas Negeri Semarang, Semarang - Indonesia *Email: ajisaputro938@students.unnes.ac.id Abstrak Minyak Jelantah (Waste Cooking Oil) memiliki potensi untuk dapat dimanfaatkan menjadi campuran bahan bakar diesel. Penelitian ini bertujuan untuk menganalisa karakteristik dan pengaruh minyak jelantah tanpa perlakuan sebagai alternatif campuran bahan bakar pada mesin diesel. Minyak jelantah dicampur dengan dexlite pada persentase B0 (100% Dexlite), B25 (25% Minyak Jelantah + 75% Dexlite) dan B50 (50% Minyak Jelantah + 50% Dexlite). Sebelum minyak jelantah dicampurkan dilakukan analisa bilangan asam dengan menggunakan metode titrasi mendapatkan hasil rata-rata 0,87 mg/mL, sehingga dimungkinkan minyak jelantah untuk dicampurkan dengan bahan bakar diesel. Kemudian dilakukan analisa sifat fisik dan sifat kimia bahan bakar campuran mendapatkan hasil mendekati sifat bahan bakar diesel. Pengujian performa mesin berupa torsi, daya, dan konsumsi bahan bakar spesifik (sfc) mendapatkan hasil bahan bakar B25 memiliki nilai torsi mendekati B0, selisih rata–rata torsi yang dihasilkan sebesar -0,01% pada tiap variasi putaran mesin. Sedangkan pada bahan bakar B50 memiliki selisih rata–rata torsi sebesar -2,38% dengan bahan bakar B0 pada tiap variasi putaran mesin. Daya yang dihasilkan oleh bahan bakar B25 menghasilkan nilai mendekati bahan bakar B0, selisih nilai rata–rata daya yang dihasilkan sebesar 0,35% pada tiap variasi putaran mesin. Sedangkan pada bahan bakar B50 memiliki selisih rata–rata torsi sebesar -2,13% Sedangkan untuk konsumsi bahan bakar spesifik (sfc) yang dihasilkan bahan bakar B25 dan B50 memiliki nilai lebih tinggi masing–masing sebesar 18,11% dan 13,76%. Dari sifat dan hasil pengujian performa mesin menunjukkan bahwa campuran bahan bakar minyak jelantah B25 dan B50 dapat digunakan tanpa melakukan modifikasi apapun pada mesin diesel. Kata Kunci: Minyak Jelantah, Biodiesel, Mesin Diesel Abstract Waste Cooking Oil (WCO) has the potential to be used as a diesel fuel mixture. This study aims to analyze the characteristics and effects of untreated waste cooking oil as an alternative fuel mixture for diesel engines. Waste cooking oil was mixed with dexlite at the percentages of B0 (100% Dexlite), B25 (25% WCO + 75% Dexlite) and B50 (50% WCO + 50% Dexlite). Before the waste cooking oil was mixed, the acid number analysis was carried out using the titration method and get an average result of 0.87 mg/mL, so that it was possible for waste cooking oil to be mixed with diesel fuel. Then the analysis of the physical and chemical properties of the mixed fuels is carried out to obtain results that are close to the properties of diesel fuel. Testing engine performance in the form of torque, power, and specific fuel consumption (sfc) results in B25 fuel having a torque value close to B0, the difference in the average torque produced is -0.01% for each variation of engine speed. While the B50 fuel has an average torque difference of -2.38% with B0 fuel at each variation of engine speed. The power produced by B25 fuel produces a value close to B0 fuel, the difference in the average value of the power generated is 0.35% for each variation of engine speed. While the B50 fuel has an average torque difference of -2.13%. Meanwhile, the specific fuel consumption (sfc) produced by B25 and B50 fuels has a higher value of 18.11% and 13.76%, respectively. From the properties and results of engine performance testing, it shows that the fuel mixture B25 and B50 can be used without making any modifications to the diesel engine. Keywords: Waste Cooking Oil, Biodiesel, Diesel Engine