In this study, we report biodiesel production from waste cooking oil using CaO catalyst derived from Madura limestone through a transesterification reaction. Many limestone quarries in Madura can be used as heterogeneous catalysts because they are cheap, easy to separate, and have high basicity. Conversion of limestone into CaO catalyst through calcination at 900°C for 3 hours. The CaO catalyst formed was characterized using X-Ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR), and Scanning Electron Microscopy-Energy Dispersive X-Ray (SEM-EDX) instruments. Biodiesel formed through the transesterification reaction was analyzed using GC-MS. Furthermore, biodiesel blends from waste cooking oil and pure diesel were prepared in volume percentages (B-10, B-20, B-30, B-40, and B-100) for testing on diesel engine performance. The results of testing the highest torque and brake horsepower (BHP) were obtained on pure diesel fuel (S-100) at 2.49 Nm and 381.12 watts, respectively. The lowest fuel consumption at 1500 rpm is produced on the B-20 at 0.186 kg/h. Overall, the emission characteristics of carbon monoxide (CO), nitrogen oxides (NOx), and nitrogen monoxide (NO) with the lowest concentration resulted from biodiesel blends rather than pure diesel.

Pada penelitian ini dipelajari pemanfaatan biodiesel dari minyak nyamplung (Calophyllum Inophyllum) melalui reaksi transesterifikasi menggunakan katalis heterogen CaO dari batu kapur yang berasal dari Pamekasan, Madura. Perbandingan komposisi yang digunakan antara minyak nyamplung terhadap metanol pada reaksi transesterifikasi adalah 1:12 (mol/mol) dengan penambahan 4% katalis CaO. Biodiesel yang terbentuk kemudian diuji kinerja dan karakteristik emisinya pada mesin diesel dengan variasi campuran bahan bakar antara solar murni dan biodiesel (B-10, B-20, B-30, B-40, B-100 dan S-100). Hasil pengujian campuran biodiesel dengan daya tertinggi dihasilkan dari bahan bakar B-10, B-20, B-30 dan B-100 masing-masing sebesar 0,26 kW pada beban 250 watt. Sedangkan pada beban 500 watt, daya tertinggi diperoleh pada bahan bakar B-40 yaitu sebesar 0,58 kW. Hasil pengujian kinerja menggunakan bahan bakar S-100 diperoleh nilai daya yang paling tinggi masing-masing sebesar 0,27 dan 0,58 kW dengan beban 250 dan 500 watt. Pengujian kinerja untuk campuran biodiesel, nilai torsi paling tinggi diperoleh ketika menggunakan bahan bakar B-10, B-20, B-30 dan B-100 yaitu masing-masing sebesar 1,65 N.m dengan beban 250 watt.  Sedangkan pada beban 500 watt, torsi tertinggi diperoleh pada bahan bakar B-40 yaitu sebesar 3,69 N.m. Bahan bakar S-100 menghasilkan torsi masing-masing sebesar 1,71 dan 3,69 N.m dengan beban 250 dan 500 watt. Karakteristik gas emisi karbon monoksida (CO), nitrogen monoksida (NO) dan nitrogen oksida (NOx) menunjukkan konsentrasi terendah diperoleh pada bahan bakar B-100 masing-masing sebesar 387 ppm, 92 ppm dan 96 ppm. Sedangkan konsentrasi gas emisi CO, NO dan NOx tertinggi dihasilkan dari bahan bakar solar murni (S-100) yaitu masing-masing sebesar 574 ppm, 126 ppm dan 132 ppm. In this study, the use of biodiesel from nyamplung oil (Calophyllum Inophyllum) was studied through a transesterification reaction using a heterogeneous catalyst of CaO from limestone originating from Pamekasan, Madura. The composition ratio used between nyamplung oil and methanol in the transesterification reaction was 1:12 (mol/mol) with the addition of 4% CaO catalyst. The biodiesel that is formed is then tested for its performance and emission characteristics in diesel engines with various fuel mixtures between pure diesel and biodiesel (B-10, B-20, B-30, B-40, B-100 and S-100). The test results for biodiesel blends with the highest power produced from B-10, B-20, B-30 and B-100 fuels were 0.26 kW each at a load of 250 watts. While at a load of 500 watts, the highest power is obtained from the B-40 fuel, which is 0.58 kW. The results of performance testing using S-100 fuel obtained the highest power values of 0.27 and 0.58 kW, respectively, with a load of 250 and 500 watts. Performance testing for biodiesel blends, the highest torque value was obtained when using B-10, B-20, B-30 and B-100 fuels, which were 1.65 N.m each with a load of 250 watts. While at a load of 500 watts, the highest torque is obtained on B-40 fuel, which is 3.69 N.m. The fuel S-100 produces torque of 1.71 and 3.69 N.m, respectively, with a load of 250 and 500 watts. Emission gases characteristics of carbon monoxide (CO), nitrogen monoxide (NO) and nitrogen oxides (NOx) showed the lowest concentrations obtained in B-100 fuel were 387 ppm, 92 ppm and 96 ppm, respectively. Meanwhile, the highest concentrations of CO, NO and NOx emissions were produced from pure diesel fuel (S-100), namely 574 ppm, 126 ppm and 132 ppm, respectively.