PENINGKATAN KADAR GLISEROL HASIL SAMPING PEMBUATAN BIODIESEL DENGAN METODE ADSORPSI ASAM LEMAK BEBAS (ALB) MENGGUNAKAN FLY ASH

Proses produksi biodiesel menimbulkan hasil samping crude glycerol sekitar 10% (w/w). Kadar gliserol dalam crude tersebut masih rendah karena masih mengandung pengotor sehingga perlu pemurnian agar dapat dimanfaatkan untuk bahan baku industri, misalnya industri obat dan kosmetika. Penelitian ini bertujuan meningkatkan kemurnian crude glycerol dengan metoda adsorpsi menggunakan fly ash dan menentukan kapasitas adsorpsinya. Data kesetimbangan adsorpsi asam lemak bebas dalam gliserol didekati dengan Model Langmuir dan Freundlich. Berat adsorben pada penelitian ini berturut- turut 2,5; 5,0; 7,5 dan 10 gram dengan waktu adsropsi bervariasi selama 40, 50, 60 , 70 dan 80 menit. Hasil pemurnian dianalisa kandungan asam lemak bebas dan gliserol. Kadar asam lemak bebas dapat teradsorpsi maksimum ketika pemurnian menggunakan 10 g adsorben selama 60 menit. Kapasitas maksimum adsorpsi sebesar 5,186x10-4 mmol/g. Berdasarkan nilai koefisien korelasi (R2) menunjukkan bahwa model Langmuir dan Freundlich cocok untuk penelitian ini. Kata kunci : adsorpsi, Crude glycerol, biodiesel, fly ash Crude glycerol is a byproduct of the production of biodiesel produced about 10% (w/w) of the weight of biodiesel . Crude glycerol still contains many impurities that cause low levels of glycerol into that utilization is not maximized . Purified glycerol widely used in several fields such as manufacture of drugs and cosmetic. Therefore, there needs to be a process of purification in order to obtain higher levels of glycerol . This study aims to perform the purification of crude glycerol to determine the method of adsorption and adsorption capacity of fly ash. Adsorption processes associated with the equilibrium adsorption performed at constant temperature (isotherms) to obtain the maximum adsorption capacity data. Langmuir and Freundlich models proposed to interpret the data of adsorption equilibrium of free fatty acids in the glycerol . This research was carried out by varying the mass of adsorbent 2.5g , 5.0g , 7.5g and 10g, and the adsorption time 40, 50, 60, 70 and 80 minutes. Purification of crude glycerol were analyzed using analysis of free fatty acids and glycerol analysis. The results showed that 10g Mass adsorbent and adsorption time of 60 minutes can reduce Free Fatty Acid (FFA) that glycerol levels increased . The maximum adsorption capacity of 5.186 x10- 4 mmol/g. Based on the value of the correlation coefficient (R2) indicates that the Langmuir and Freundlich models are suitable for this study. Keywords: adsorption, crude glycerol, biodiesel, fly ash