Jimma University, Ethiopia
Scientific Tracks Abstracts: J Fundam Renewable Energy Appl
In this study, methyl-ester, bioethanol and briquette samples were sequentially produced from spent coffee ground.
The oil extracted from spent coffee ground with solvent extraction route at hexane to spent coffee ground ratio
of 22.5 g/g with an extraction time of 30.4min resulting in 11.892% of oil yield. This was comparable with literature
values and subsequently used for methyl-ester production experiments using a 1% by wt of NaOH at reaction
temperatures and residence times ranging from 50 to 65°C and 20 to 60min, respectively. The optimization carried
out using central composite design methodology gave 81.507% of methyl-ester yield at a reaction temperature of
57.133°C and reaction time (residence time) of 45.117 min with model determination coefficient (R2) of 0.9465
while the optimum reducing sugar yield for dilute acid hydrolysis experiments for ranges of operating parameters
of temperature (70-100°C) and (1-3M ) of H2SO4 concentrations was found to be 39.161% at a temperature of
98.313°C and H2SO4 acid concentration of 2.962M.The central composite design optimization results for transesterification
and dilute acid hydrolysis experiments were verified by running experiments at optimum conditions
and in turn resulted 79.65% of biodiesel yield (out of 11.892 g of oil) and reducing sugars yield of 37.28% (out of the
hydrolysate). This implied that the verification experimental results weren???t far from the predicted values so that the
experimental results were sufficiently represented by the central composite design models. The bio ethanol produced
by simple distillation having alcohol by volume yield of 55% can be considered as a good result and it can be easily
concentrated to a fuel grade ethanol by using fractionating column. Moreover, the characteristics of the biodiesel
produced were in good agreement with ASTM and EN standards. The end product of the process which is briquette
has been produced from 75% wt of dilute acid hydrolysis residue and 25% wt of glycerol, resulted a calorific value of
13.35 MJ/kg, volatile matter value of 88.15%, ash content of 3.95%, and fixed carbon contents of 1.74% with its easily
moldable physical status showed that it can as well be used for fueling purpose like firewood and charcoal. This study
signifies the value addition that can be affected from spent coffee ground and the potential and results obtained in
this regard are discussed.
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Muluken Eshetu Tefera has been working as a Lecturer at Jimma University, Jimma Institute of Technology under the school of Chemical Engineering since Aug 2014. He has been working on giving Lectures on fluid mechanics for chemical engineers, mass transfer unit operation and entrepreneurship for engineers courses, assisting undergraduate students in thermal and mass transfer unit operations laboratory, advising graduating students, mentoring industrial intern students and many more activities.
E-mail: [email protected]