RESUMEN
This work introduces biodiesel production from wet spent coffee grounds (SCGs) with supercritical methanol without any pre-drying process. Supercritical methanol and subcritical water effectively produced biodiesel via in situ transesterification by inducing more porous SCG and enhancing the efficiency of lipid extraction and conversion. It was also found that space loading was one of the critical factors for biodiesel production. An optimal biodiesel yield of 10.17â¯wt% of dry SCG mass (86.33â¯w/w% of esterifiable lipids in SCG) was obtained at reaction conditions of 270⯰C, 90â¯bars, methanol to wet SCG ratio 5:1, space loading 58.4â¯ml/g and reaction time 20â¯min. Direct use of wet SCG waste as feedstock for supercritical biodiesel production eliminates the conventional dying process and the need of catalyst and also reduces environmental problems caused by landfill accumulation.
Asunto(s)
Biocombustibles , Café , Esterificación , Lípidos , MetanolRESUMEN
This work addresses non-catalytic biodiesel production from spent coffee ground (SCG) by integrating solvo-thermal effect of 1,2-dichloroethane (DCE) with in situ transesterification over 160⯰C. The SCG water content has a positive effect on the DCE hydrolysis up to 60â¯wt% due to the bimolecular substitution mechanism. The hydrolysis gives an acidic environment favorable for cellulose decomposition, SCG particle size reduction and lipid conversion. The optimal fatty acid ethyl ester yield was 11.8â¯wt% based on the mass of dried SCG with 3.36â¯ml ethanol and 3.16â¯ml DCE at 196.8⯰C through the response surface methodology. Using the solvo-thermal effect, direct utilization of wet SCG as a biodiesel feedstock provides not only economic feasibility without using drying process and additional acid catalyst but also environmental advantage of recycling the municipal waste.
Asunto(s)
Biocombustibles , Café , Esterificación , Dicloruros de EtilenoRESUMEN
This study introduces a process combining wet in situ transesterification and hydrothermal liquefaction (iTHL) for fatty acid ethyl ester (FAEE) production from intact microalgae, Nannochloropsis gaditana without catalyst at temperatures higher than 160°C. It is found that the chlorinated hydrocarbon solvents, SolvCl (dichloromethane, chloroform, and dichloroethane (DCE)), enhances the FAEE production by providing hydrogen chloride in an ionized form that can act as an acid catalyst. The SolvCl effect on iTHL is compared to acid catalyst assisted wet in situ transesterification. The most effective solvent is DCE with the FAEE selectivity in biocrude equal to 91.85% (maximum transesterifiable lipid basis). The optimum point for maximizing the FAEE yield is 185.08°C with 4.69mL ethanol and 1.98mL DCE/g of dry algal cells based on the response surface methodology. iTHL with both Nannochloropsis and Chlorella species provides a possibility of the process applicable to the other algal species.