Fig. 7.

The process mass balance analysis of the products obtained at the reaction temperature of 175 °C for 15, 30, 60 and 120 min based on the raw material. a Hydrothermal treatment at 175°C for 15 min, b hydrothermal treatment at 175 °C for 30 min, c hydrothermal pretreatment at 175 °C for 60 min, and d hydrothermal treatment at 175 °C for 120 min