Biodiesel and activated carbon from arabica spent coffee grounds

Abstract

This study aims to analyze the potential and characteristics of biodiesel and activated carbon from spent coffee grounds (SCG). • Biodiesel was obtained by extracting oil from SCG using Soxhlet extraction method with n-hexane solvent with an oil yield of 18.14% w/w of dry SCG. Furthermore, the coffee oil was esterified and transesterified to produce biodiesel with 57.32 % yield of coffee oil and higher heating value of 36.69 MJ/kg, density (15°C) of 0.89 g/mL, kinematic viscosity (40°C) of 7.67 mm2/s, acid number of 1.19 mg KOH/g oil. • The residue in form of grounds after oil extraction process was turned into activated carbon using two step activation process. Carbonization process was carried out at 500, 600, 700, and 800°C for 30 minutes and then chemically activated using potassium hydroxide (KOH) at 750°C for 2 hours. As the comparison, activated carbon was also made from SCG without oil extraction process. This study shows that the adsorption capacity of activated carbon made from SCG with oil extraction was better than without oil extraction. The best adsorption of activated carbon was obtained from SCG with oil extraction and carbonized at 700°C with iodine value of 1,224.59 mg/g and methylene blue value of 153.08 mg/g.

Keywords

• Transesterification for biodiesel and chemical activation for activated carbon