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Author(s): Nídia S. Caetano
Vânia F. M. Silva
Ana C. Melo
Teresa M. Mata
Title: Potential of spent coffee grounds for biodiesel production and other applications
Issue Date: 2013
Abstract: This work studied the extraction of lipids from spent coffee grounds (SCG) and the possibility of using theextracted lipids for biodiesel production. Thus, the SCG were first characterized, in particular for theircarbon/nitrogen ratio (C/N 8) and higher heating value (HHV = 19.0 MJ/kg). These results show thatbesides its common use as fertilizer rich in nitrogen, SCG can be used as solid fuel. Concerning the lipidsextraction, the best results were obtained using pure hexane and a 50:50 (vol/vol) mixture of hexane andisopropanol and yielded about 6 % (vol/dwt), being higher (about the double) when dry SCG was usedinstead of wet SCG (with a moisture content of about 66 %, vol/wt). The use of ultrasounds had nosignificant effect on the extracted lipids. Regarding the lipids characterization, results have shown an acidvalue in the range of 3.9-12.5 mg KOH/g, a density at 15 ºC in the range of 912-934 kg/m3, a viscosity at40 ºC in the range of 14.9-44.0 mm2/s, an iodine number in the range of 47.6-70.5 g iodine/100 g, and aHHV in the range of 35.4-39.9 MJ/kg, which are negatively influenced by the lipids water content and bythe solvents used for the extraction. Due to the relatively high free fatty acid content of the extracted lipids,their conversion into biodiesel was done in a two steps process: an esterification of the free fatty acidfollowed by a transesterification of triglycerides. The characterization of biodiesel revealed an iodinenumber of about 70.0 g iodine/100 g lipids, an acid value of about 1.8 mg KOH/g lipid and an ester contentof about 86 % (determined by GC analysis). Although these values are not within the NP EN 14214:2009standard of biodiesel quality, there is the potential for using lipids from SCG for biodiesel production if theyare blended with lipids from other sources in order to meet the standard requirements.
Subject: Ciências Tecnológicas, Ciências da engenharia e tecnologias
Technological sciences, Engineering and technology
Scientific areas: Ciências da engenharia e tecnologias
Engineering and technology
Related Information: info:eu-repo/grantAgreement/FCT - Fundação para a Ciência e Tecnologia/Projetos Estratégicos/PEst-C/EQB/UI0511/2013/PROJECTO ESTRATÉGICO - UI 511 - 2013-2014/UI0511
Document Type: Artigo em Revista Científica Internacional
Rights: restrictedAccess
Appears in Collections:FEUP - Artigo em Revista Científica Internacional

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