Siberian Federal University

This paper describes the results of a study of the physicochemical properties of hydrochars obtained by hydrothermal carbonization of aspen and pine bark at temperatures of 180 and 230 °C. Chemical analysis revealed that at 230 °C, almost complete destruction of hemicelluloses and cellulose in the bark occurs, and the resulting hydrochars consist primarily of pseudolignin. It was shown, that regardless of the production temperature, aspen bark hydrochars contain less pseudolignin than pine bark hydrochars. A comparison of thermal analysis data revealed greater thermal stability of pine bark hydrochars. SEM study revealed the presence of carbon-containing microspheres on the surface of the hydrochars, the amount of which increases with increasing hydrothermal carbonization temperature from 180 to 230 °C. Pine bark hydrochars are characterized by smaller microspheres compared to aspen bark samples. The methylene blue sorption capacity of aspen and pine bark hydrochars was 69.7–115.2 mg/g, which is lower than the values established for clarifying charcoals. Based on their high Pb2+ sorption capacity (81.9–100.6 mg/g), aspen and pine bark hydrochars are promising sorbents for water purification from heavy metals