Taguchi optimization and life cycle assessment of biodiesel production from spent ground coffee

Abstract

In this study, Vietnamese spent coffee ground (SCG) were subjected to produce biodiesel for fuel application. The extraction processes were conducted with three organic solvents, i.e., hexane, petroleum ether and dimethyl ether. The extraction oil seems to be favored in hexane solvent (17.06%) as compared with petroleum ether (16.62%) and dimethyl ether (16.18%). The extraction processes tend to sufficiently follow the empirical hyperbolic model with R 2 of 0.973, 0.970 and 0.969 for hexane, petroleum ether, and dimethyl ether. The transesterification was optimized using Taguchi design with three variable molar ratios of MeOH and extracted oil (MeOH/EO), catalyst (NaOH) concentration and temperature. The transesterification reached the best yield 76.23% at MeOH of 6:1, NaOH of 0.75 wt% and temperature of 55 °C. Some acquired biodiesel quality was determined within the American Society for Testing and Materials and European standards (EN) norms for biodiesel. Life cycle assessment was also performed to evaluate the impact of the SCG biodiesel production; the industrial process was designed based on laboratory tests aimed with TRACI 2.1 tool. The obtained results indicated that oil extraction is the most effective on biodiesel production, contributing to global warming around 21.04 kg CO 2 eq/kg.

Integrated Approach to Spent Coffee Grounds Valorization in Biodiesel Biorefinery

“…The lowest ester content after IEE + TE could be influenced by the different molar ratio of MeOH/SCGO (8:1). Bui et al (2021) reported that the increase in the MeOH/SCGO ratio from 4:1 to 6:1 resulted in an increase transesterification yield, which was, however, reduced with further increase of the MeOH/SCGO ratio [62]. Additionally, the lower unidentified matter was observed in the sample of final biodiesel after AE + TE.…”

<strong>A Critical Review on Briquettes Developed from Spent Coffee Ground Wastes</strong>

“…Following this, the dehydrated SCG wastes are treated with solvents like hexane or toluene to remove their lipid fraction (Fehse et al, 2021;Tongcumpou et al, 2019;Setter et al, 2020), which later on can be used in the production of SCG oil biodiesel (Bui et al, 2022). In general, these wastes are refluxed with these solvents for 4-6 hours, at temperatures maintained slightly above the corresponding boiling point of the solvent used; and are treated in a Soxhlet extractor for lab scale studies.…”