Evaluation of engineered hydrochar from KMnO₄ treated bamboo residues: Physicochemical properties, hygroscopic...

In this study, a novel approach was developed to prepare engineered hydrochar from KMnO₄ treated bamboo residues through hydrothermal carbonization. The hydrochar yields were within a specified range of 61.8-67.8% at 180 °C and 39.8-45.0% at 260 °C, respectively. The higher temperature led to the higher C content, lower H/C and O/C ratio, whereas the ash content increased with increasing KMnO₄ concentration, causing the increase of solid yield as well as the decrease of C content. Pseudo-second kinetic model was optimal to describe bamboo hydrochar's hygroscopic dynamic, and the engineered hydrochar produced at 260 °C and 1.0 wt% concentration obtained the better hydrophobicity of 0.82%. SEM-EDS and XRD analysis confirmed the existence of manganese carbonate on the surface of engineered hydrochar, from which we inferred the chemical complexation between KMnO₄ and hydrochar.