Guenover Florette Y. Juarez, Kurt Branden C. Pabiloña, Kirck Brandon L. Manlangit, Alchris Woo Go
The conventional approach in the production of biofuels from biomass requires lipid extraction prior to hydrolysis for sugar recovery. This study investigated a new approach in the valorization of spent coffee grounds (SCG) by employing direct hydrolysis of non-delipidated SCG expecting to recover the available lipids in the solid residue present in higher concentrations. Sugar content (43–49%) as determined with the proposed approach and expressed in extractive-free basis, were comparable to that of conventional approaches employing lipid extraction prior to hydrolysis (41–51%). Experiments employing dilute acid hydrolysis were carried out under various sulfuric acid concentrations (1–5% v/v H2SO4) and hydrolysis times (30–180 min). A maximum sugar yield of 29% (~62% recovery) was obtained at a solvent-to-solid ratio of 8 mL/g with 5% v/v acid and a hydrolysis time of 3 h. Hydrolysates obtained contain 33.4 g/L of sugar, 0.056 g/L 5-HMF and 0.012 g/L furfural. Also, it was found that lipids remained intact even after hydrolysis and were successfully recovered with lipid recoveries of 99–103%. Solid residues after hydrolysis were ~68% of the initial biomass having a moisture content of ~65%, thus reducing the total amount of moisture to be removed and energy required in the drying step prior to lipid extraction. © 2017, Springer Science+Business Media Dordrecht.
Department of Chemical Engineering, University of San Carlos, Talamban Campus, Nasipit Talamban, Cebu City, 6000, Philippines
