Abstract
Biodiesel is one of several alternative fuels as it reduces the amount of greenhouse gases that cause global warming in the world. Coffee consumption produces a by-product called ground coffee, raw material for the oil used in the production of biodiesel. In the investigation, the conversion efficiency of the oil extracted from the coffee grounds into biodiesel was determined, from the obtaining and characterization of the oil extracted from the coffee grounds, which presented a density of 0.875 g/mL, viscosity of 44.7 mm²/s, free fatty acids of 2.729%, acid value of 5.722 mg KOH/g, iodine value 111.672 g I2/100 g and saponification value of 31.422 mg KOH/g. With the extracted oil, biodiesel was obtained by the transesterification process through a completely randomized design analysis, the stirring speed significantly influenced the conversion of the oil to biodiesel, the results obtained under a stirring speed of 100 rpm the conversion was 77.78 % while the biodiesel produced at a stirring speed of 400 rpm the conversion was 92.48 % and presented a density of 0.88 g/mL, viscosity of 5.47 mm²/s, free fatty acids of 0.1605 %, acid value of 0.3366 mg KOH/g and iodine value of 83.754 g I2/100 g. Biodiesel was obtained with good efficiency as an environmentally friendly fuel.
