Recyclable Co2/Des-Enabled Microalgae Efficient Pretreatment and In-Situ Transesterification for Biodiesel Production from All Component

The conventional microalgae biodiesel production requires more solvents and energy due to cell wall stubbornness and process complexity. This study synthesized a functional DES (fDES) for microalgae pretreatment and in-situ transesterification to obtain biodiesel with a 98.9% yield. The fDES can be used for pretreatment, oil extraction, transesterification catalysis because of its high hydrogen bond acceptability, basicity and low polarity. Injecting CO2 can switch fDES from low polarity to strong polarity to separate biodiesel and recover fDES components. The chemical interaction process shown by the pseudo-second-order kinetic model of adsorption and desorption further proves the process of CO2 regulating the polarity of fDES. The remaining microalgae components were transformed into yeast lipids with 3.3 g/L for biodiesel by enzymolysis and continuous fermentation. Overall, this strategy of integrating pretreatment, production, separation and solvent recovery to funnel the all-component of microalgae into biodiesel provides an efficient solution for biodiesel production.