The aim of this paper was to investigate the possibility of obtaining oil
from spent coffee grounds, which are left behind after the coffee is
prepared, as the potential feedstock for biodiesel production. The effect of
process parameters, such as are the type of solvent, the ratio of spent
coffee grounds/solvent and the extraction time on oil yielded from coffee
grounds was examined. The oil was obtained by maceration and extraction in
the Soxhlet apparatus. The obtain results show that the spent coffee grounds
could be used as an alternative raw material for biodiesel production,
because it contains a significant amount of oil that can be extracted. The
oil yield depends on the extraction (maceration) process parameters. The
maximum oil yield obtained by the Soxhlet extraction with the n-hexane for
the period of 5 h was 11.85% (the weight percentage of oil on dry mater),
whereas with petroleum ether the oil yield was slightly lower and amounted
to 10.44%. The yield of the oil extracted by maceration increases with the
decrease of spent coffee grounds/solvent ratio from 1/3 to 1/7 g/cm3, and
other parameters being constant. The oil yield increases with the duration
of the maceration. Greater oil yield, ranging from 3 to 8.5%, can be
obtained with n-hexane compared to the extraction with petroleum ether.
Furthermore, n-hexane is less volatile and flammable, compared to petroleum
ether, so it is more convenient to use.
Biodiesel Production from Spent Coffee Grounds Oil
