Conversion of rice husks into carbonaceous materials with porous structures via hydrothermal process

Abstract

Carbonaceous materials hydrothermally produced using waste biomass have small specific surface areas (SSA) and poor porosity properties. In this study, we prepare a novel carbonaceous material with excellent porosity properties by suppressing the formation of a secondary char phase (spheres) and promoting biomass hydrolysis by controlling the hydrothermal conditions. Rice husk powders, as the starting material, are hydrothermally treated using acidic solvents of different types and concentrations at 180 °C. The surfaces of the samples hydrothermally prepared using the acidic solvents have no spheres. In the case of 0.1–0.2 mol L−1 hydrochloric acid (HA), the amorphous carbonaceous materials contain numerous mesopores and exhibit a larger SSA (approximately 100 m2 g−1) than those prepared using acetic acid and distilled water. An increase in the hydrothermal temperature reduces the porosity properties of the materials. Finally, the high-porosity amorphous carbonaceous material showed excellent trimethylamine adsorption ability.