PERBANDINGAN PENGGUNAAN KATALIS ASAM SULFAT DAN ENZIM LIPASE DALAM REAKSI TRANSESTERIFIKASI MINYAK JELANTAH

TRI ANTIKA UTAMI, Dr. Tri Joko Raharjo, M. Si.

2015 | Skripsi | S1 KIMIA

Telah dilakukan penelitian mengenai perbandingan penggunaan katalis asam sulfat dan enzim lipase dalam reaksi transesterifikasi minyak jelantah. Penelitian ini bertujuan untuk menentukan kondisi optimum reaksi transesterifikasi dengan katalis asam sulfat dan enzim lipase serta membandingkan konversi biodiesel yang diperoleh dari dua jenis katalis tersebut. Sifat-sifat fisik dan kimia minyak jelantah seperti komposisi asam lemak, berat molekul, densitas, kandungan asam lemak bebas dan bilangan saponifikasi ditentukan sebelum dilakukan uji transesterifikasi dengan beberapa variabel. Variabel yang diuji antara lain perbandingan mol metanol:minyak dengan variasi 3:1; 6:1; 15:1; dan 30:1 ; jumlah katalis dengan variasi 1, 2, 3 dan 4% b/b; dan temperatur reaksi dengan variasi 30, 40, 50 dan 60 °C. Reaksi transesterifikasi dilakukan di dalam shaker incubator selama 5 jam. Produk yang diperoleh dianalisis menggunakan kromatografi gas untuk mengetahui jumlah konversi metil ester yang terbentuk. Hasil konversi metil ester tertinggi pada penggunaan katalis asam sulfat diperoleh pada rasio mol metanol:minyak 30:1 sebesar 6,48%, jumlah katalis 4% sebesar 5,34% dan kondisi temperatur 60 °C sebesar 21,58%. Sedangkan pada penggunaan katalis enzim lipase metil ester tertinggi diperoleh pada rasio mol metanol:minyak 6:1 sebesar 0,87%, jumlah katalis 2% sebesar 1,19% dan kondisi temperatur 30 °C sebesar 2,82%. Berdasarkan hasil tersebut diketahui bahwa katalis asam sulfat memberikan konversi metil ester yang lebih tinggi dibandingkan katalis enzim lipase.

The study of comparison of sulfuric acid and lipase enzyme as catalysts in transesterification reaction of waste frying oil have been done. The study aimed to determine the optimum conditions for the transesterification reaction using sulfuric acid and lipase enzyme as catalysts. Moreover to compare the conversion of biodiesel obtained from the two types of catalysts. Physical and chemical properties of waste frying oil such as fatty acid composition, molecular weight, density, free fatty acid percentage and saponification numbers were determined before the test of transesterification with multiple variables. The variable tests included the ratio mole of methanol:oil with variations 3:1; 6:1; 15:1; and 30:1; the amount of catalyst with variations 1, 2, 3 and 4% w/w; and the reaction temperature with variations 30, 40, 50 and 60 °C. Transesterification reaction was done in the shaker incubator for 5 hours. The products were analyzed using gas chromatography to determine the amount of methyl ester conversion. The highest result of methyl ester conversion using sulfuric acid catalyst was obtained at the mole ratio of methanol:oil 30:1 at 6.48%, the amount of 4% catalyst at 5.34% and temperature at 60 °C at 21.58%. While the reaction using lipase enzyme catalyst, the highest methyl ester was obtained at the mole ratio of methanol:oil 6:1 at 0.87%, the amount of 2% catalyst at 1.19% and temperature at 30 °C at 2.82%. Based on these results were known that the sulfuric acid catalyst had higher methyl ester conversions than the lipase enzyme catalyst.

Kata Kunci : transesterifikasi, asam sulfat, enzim lipase, minyak jelantah/transesterification, sulfuric acid, lipase enzyme, waste frying oil