CO2adsorption in hydrochar produced from waste biomass

Sugar and ethanol plants produce a large amount of sugarcane bagasse. Such biomass can be the raw material for the production of an adsorbent to uptake CO2. Thus, this work aimed to evaluate the hydrocarbonization of sugarcane bagasse and to study its use as a CO2adsorbent from a simulated flue gas. The temperature of the hydrothermal carbonization (HC) was set at 220 °C, while the operating time ranged from 12 to 48 h. Through the SEM–EDS analysis, the 48-h sample (HC48) was selected for chemical activation with KOH, resulting in activated hydrochar (AHC). The CO2and N2simple adsorption isotherms were obtained at 50, 70 and 80 °C. The results have shown a higher adsorption at a temperature of 50 °C for both gases. Activated hydrochar clearly preferred CO2instead of N2at 100 kPa as the maximum adsorption was 1.99 and 0.207 mmol g−1, respectively. The highest selectivity of CO2/N2was 12–50 °C, according to the “Ideal adsorbed solution theory” model. Therefore, AHC is clearly an eco-friendly adsorbent that can be used to minimize the resulting release of climate-damaging CO2from flue gas to atmosphere.