The properties of Chinese Baijiu distilled spent grain-derived hydrochar: effect of in situ deep eutectic solvents formation during hydrothermal carbonization

Abstract

Distilled spend grain with rice husk (DSGH), a by-product of Chinese Baijiu, can be used as a solid fuel after hydrothermal carbonization (HTC) treatment. To enhance carbonization during HTC, a new strategy based on the addition of lactic acid to DSGH and AlCl3 is proposed for the in situ formation of deep eutectic solvents (DESs). The results show that in situ DES formation significantly enhanced the recovery of organic matter, thereby increasing the yield of hydrochar. Moreover, in situ DES formation effectively hindered the reaction between NH4+ and polysaccharides. Additionally, DES disrupted the protein structure in DSGHP, thereby intensifying protein hydrolysis and deamination. Furthermore, the DES altered the HTC process of the DSGHP. In summary, the incorporation of in situ DESs significantly influenced the HTC of DSGHP, leading to notable improvements in the recovery and quality of hydrochar. This study provides valuable insights into the potential of DESs in enhancing HTC processes, particularly for biomass such as DSGHP.