(411c) Effect of Activation Temperature on Oxygen Functional Groups and Corresponding Electron Exchange Capacities on Hydrochar

Hydrothermal carbonization (HTC) a thermochemical process, where biomass is treated with high-pressure high-temperature liquid water. Hydrochar, the solid product of HTC, are carbon-dense microspheres and contains oxygen functional groups on the surface. Among other process parameters, HTC temperature is the most dominant for hydrochar functional properties.

The surface functional groups on the surface of chars play a vital role to use them as an adsorbent. Some research has been done some functional group analysis for hydrochar at different HTC temperature. However, this analysis is still required for the activated hydrochar. Although, the surface area and porosity of hydrochars increase with activation temperature, it is imperative to understand the content of such groups on the surface of activated hydrochar for its multifunctional applications.

Therefore, the objectives of this study were to quantification of oxygen functional groups and electron exchange capacities on activated hydrochars from model compounds (cellulose, wood). The hydrochars were activated in a Muffle Furnace at three different temperatures (400 °C, 500 °C, and 600 °C) for 1 hour. The change in functional groups on activated hydrochar surface was evaluated by surface morphology analysis, pH, Boehm titration, PZC, and FTIR. As prepared hydrochar shows relatively low surface area, mostly because of the lack of pores/ clogged pores with volatiles. An increase of surface area was observed but the oxygen functional groups were decreased with the increase of activation temperature as evident by the increase of pH, pKa, PZC. EAC values were in the range of 1.7-1.83 mmol e-/g activated hydrochar