This study focuses on the extraction of phenolic compounds from spent coffee grounds by coupling hydrothermal delignification with ultrasound assisted extraction. The hydrothermal treatment was carried out at three different temperatures (200 °C, 230 °C and 260 °C) and two residence times (1 h and 3 h). The ultrasound assisted extractions were performed onto dry hydrochars and slurry fraction, prior treated with three solvents: water, methanol and a water-methanol mixture. The results show that ultra sound assisted extraction applied to the hydrochars using methanol as a solvent lead to the highest extraction of total phenolic content (11.7–20.3 mg GAE/mg of dry sample). The hydrothermal process conditions strongly affect the following extraction: the mildest the delignification process conditions, the highest the extraction of phenols from hydrochar. The hydrochars show also good energy properties in terms of fuel ratio (0.3–0.7), energy yield (83.0–95.2%) and HHV values (28.5–33.2 MJ/kg) and this is promising for their usage as solid biofuels.

这项研究的重点是通过将水热脱木质素与超声辅助提取结合起来，从废咖啡渣中提取酚类化合物。水热处理在三种不同的温度（200°C，230°C和260°C）和两个停留时间（1 h和3 h）下进行。超声辅助提取是在干燥的碳氢化合物和浆液馏分上进行的，事先用三种溶剂处理：水，甲醇和水-甲醇混合物。结果表明，采用甲醇作为溶剂的超音速辅助萃取法应用于水煤油的总酚含量最高（11.7–20.3 mg GAE / mg干样品）。水热工艺条件会严重影响以下提取：最温和的脱木质素工艺条件，从水煤中提取酚的量最高。在燃料比（0.3–0.7），能量产率（83.0–95.2％）和HHV值（28.5–33.2 MJ / kg）方面，水炭还显示出良好的能量特性，这有望将其用作固体生物燃料。