hrvatski

Green routine for biodiesel production from waste coffee grounds

Biodiesel can be produced from different types of feedstock. The quality of feedstock influences the quality of biodiesel as well as the quality of exhaust gases. When low quality feedstock is used for base catalysed transesterification, feedstock needs to be purified since only high quality oil or fat will assure production of high quality biodiesel. Waste coffee grounds are proven to be an excellent feedstock for biodiesel production. In this work coffee oil was extracted from dried waste coffee grounds. Since the total acid number was too high, the concentration of free fatty acids was reduced by means of liquid- liquid extraction with deep eutectic solvents based on potassium carbonate. Biodiesel was then synthesised by chemical transesterification in the presence of a homogeneous base catalyst (NaOH) at different reaction conditions (time and quantity of catalyst). Impurities present in crude biodiesel were extracted with a deep eutectic solvent (choline chloride:ethylene glycol, 1:2.5). The feasibility of the proposed methodology was evaluated by extraction efficiency. Optimal extraction time, temperature and mass ratio solvent/biodiesel was selected.

biodiesel ; deep eutectic solvents ; liquid-liquid extraction ; waste coffee grounds

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