RESUMO
This study developed a novel in situ transesterification process by combining the solvent and catalyst functions of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) for biodiesel synthesis from spent coffee grounds (SCG). The influence of reaction parameters on the reaction was investigated. The maximum biodiesel yield of 96.13% was observed at DBU-to-SCG and methanol-to-SCG ratios of 20 and 10â¯mL/g, respectively; a reaction temperature of 130⯰C; and a reaction time of 60â¯min. Notably, the polarity of DBU could be reversibly regulated, thus facilitating excellent product separation. Moreover, DBU could be effectively reused for 10 cycles to yield high biodiesel conversion. DBU-catalyzed in situ transesterification of SCG is a promising, ecofriendly, and economically viable biodiesel production process.