PRODUCTION OF BIODIESEL AND ACTIVATED CARBON FROM ARABICA SPENT COFFEE GROUNDS

• Main Author: KUSUMA, JEFRY
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/53817
• Institution: Institut Teknologi Bandung

Biodiesel is a renewable energy resource produced from vegetable oil or animal fat that currently used as a substitute for fossil diesel. Activated carbon is a material with good adsorption capability due to it’s large volume and pore surface area. The purpose of this study was to determine the potential and characteristics of biodiesel and activated carbon made from one of the most abundant resources in Indonesia, namely coffee and particularly spent coffee grounds. Coffee is the second largest commodity traded in world trade after crude oil. Indonesia as the 4th largest coffee producing country in the world with total production of 565.08 thousand tons and consumption of 288 thousand tons in 2018/2019 makes the availability of spent coffee grounds abundant. Biodiesel was obtained by extracting oil from spent coffee grounds using Soxhlet extraction method with n-hexane as a solvent and the oil yield was 18.1% by weight of dry spent coffee grounds. The coffee oil was then esterified and transesterified to produce biodiesel with 57.3% yield from coffee oil or 10.4% by mass of dried spent coffee grounds with heating value of 36.7 MJ/kg. From the test carried out, biodiesel from spent coffee grounds has density (15°C) of 0.9 g/mL, kinematic viscosity (40°C) of 7.7 mm2/s, acid number of 1.2 mg KOH/g oil, saponification value of 197.2 mg KOH/g oil, iodine value of 26.9 %-w (g-I2/100g), and oxidation stability of 0.1 hours. Not all characteristics of the biodiesel produced meet the national biodiesel standards (SNI 7182:2015) such as kinematic viscosity, acid number, and oxidation stability. Biodiesel obtained from spent coffee grounds can be used as an additive or complementary material along with biodiesel from palm oil such as B30 which is biodiesel product sold in Indonesia. The residue in form of grounds after the oil extraction process still has the potential to be turned into activated carbon with two step activation process. The carbonization process was carried out at temperature 500, 600, 700, and 800°C for 30 minutes and then chemically activated using kalium hydroxide (KOH) at activation temperature of 750°C for 2 hours. As the comparison, the process of making activated carbon from spent coffee ground was also carried out without the oil extraction from spent coffee grounds to determine the effect of oil extraction on the characteristics and adsorption performance of activated carbon. Activated carbon that meets the national activated carbon standard (SNI 06 – 3730 – 1995) was activated carbon made from spent coffee grounds, whether oil has been extracted or not been extracted and has gone through carbonization process at temperatures of 600, 700, and 800°C. The adsorption capability of activated carbon made from spent coffee grounds that have been through oil extraction process was better than coffee grounds without oil extraction process. The best adsorption of activated carbon was obtained from spent coffee ground that have been pass through oil extraction process and carbonized at 700°C with iodine value of 1224.6 mg/g, methylene blue value of 153.1 mg/g, water content of 2.1%, ash content of 3.0%, volatile matter content of 18.2%, and fixed carbon content of 76.7%. Whereas for activated carbon made from spent coffee grounds without oil extraction process, the best adsorption was obtained on activated carbon with 800°C carbonization process with iodine value of 966.0 mg/g, methylene blue value of 133.3 mg/g, water content of 1.8%, ash content of 5.7%, volatile matter content of 23.7% and 68.9% of fix carbon content.