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ABSTRAK
Biodiesel yang dibuat dari etanolisis lebih dapat diperbaharui dan memiliki karakteristik (stabilitas oksidasi yang lebih baik, cloud dan pour point yang lebih rendah) yang lebih baik dibandingkan metanolisis, namun etanolisis memiliki kelemahan seperti sulitnya pemisahan dan pencucian. Untuk menyelesaikan masalh ini, Deep eutectic solvent (DES) dapat dibuat dari campuran a quarternary
ammonium salt and hydrogen bond donour, adalah solvent yang tidak beracun, biodegradable, dibandingkan solvent organik seperti heksana. Pada penelitian ini,
DES dibuat dari campuran Choline Chloride dan gliserol dengan rasio molar 1:2. Hasil biodiesel tertinggi yang diperoleh adalah 83,67 % dengan kemurnian 99,72 % dengan rasio molar etanol : minyak 9:1, jumlah DES 2%, katalis 1,2 %, temperatur reaksi 70 °C, dan kecepatan pengadukan 400 rpm. DES sebagai cosolvent dalam etanolisis terbukti dapat mengurangi reaksi samping seperti reaksi saponifikasi sehingga memudahkan pemisahan dan pencucian,serta mampu meningkatkan yield biodiesel.
Kata kunci: Biodiesel, Deep Eutectic Solvent, Choline hydroxide, Crude Palm Oil, Etanolisis
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ABSTRACT
Biodiesel produced from Ethanolysis is more renewable and have better properties (higher oxidation stabillity, lower cloud and pour point) compared to methanolysis, but have disadvantage such as complicated purification. To improve ethanolysis process, Deep eutectic solvent (DES) can be prepared from choline chloride and glycerol and used as co-solvent in ethanolysis. Deep eutectic solvent is formed from a quarternary ammonium salt (Choline Chloride) and a hydrogen bond donour (Glycerol), it is a non toxic, biodegradable solvent compared to conventional volatile organic solvent such as hexane. Deep eutectic solvent is prepared by mixing choline chloride and glycerol with molar ratio 1:2 at temperature 80 °C, stirring speed 300 rpm for 1 hour. The DES is characterized by its density and viscosity. The ethanolysis is performed at reaction temperature of 70 °C, ethanol to oil molar ratio 9:1, potassium hydroxide as catalyst concentration 1,2 % wt, DES as co-solvent with concentration 0,5 to 3 % wt, stirring speed 400 rpm, and reaction time 1 hour. The obtained biodiesel is then characterized by its density, viscosity and ester content. The oil - ethanol phase condition is observed in reaction tube. The oil - ethanol phase with DES tends to form meniscus compared to without DES, showed that oil and ethanol become more slightly miscible, which favours the reaction. Using DES as co-solvent in ethanolysis showed increasing in yield and easier purification. The esters properties meets the international standards ASTM D6751, with highest yield achieved 79,43 % with 99,77 % conversion at DES concentration 2 %. Increasing DES concentration above 2 % in ethanolysis decrease the conversion and yield, because of the excessive glycerol in the systems makes the reaction equilibrium moves to the reactant side.
