Preparation and adsorption properties of aerocellulose-derived activated carbon monoliths

Activated carbon was prepared from cellulose-based aerogel (aerocellulose) monoliths by carbonization and subsequent CO₂ activation. The monolithic structure of the as-synthesized aerocellulose was retained during the carbonization and activation processes. The as-synthesized aerocellulose monolith was mainly mesoporous with well-developed surface area, large total pore volume, with only moderate CO₂ uptake. In order to enhance CO₂ adsorption, microporosity of carbonized aerocellulose was increased upon CO₂ activation. The resulting activated carbon showed an enhanced specific surface area of ~750 m² g⁻¹, total pore volume of 0.43 cm³ g⁻¹, and volume of micropores (pore widths <2 nm) of ~0.27 cm³ g⁻¹. Activation of carbonized aerocellulose resulted in about five-fold increase in the specific surface area and over 27-fold increase in the volume of micropores as compared to the as-synthesized material. The resulting activated carbon showed excellent adsorption properties toward CO₂ reaching 5.8 mmol g⁻¹ of CO₂ at 0 °C and 1 atm and 3.7 mmol g⁻¹ of CO₂ at 25 °C and 1.2 atm. High microporosity and surface area of the activated aerocellulose-derived carbon combined with its biocompatibility, biodegradability, non-toxicity, low cost, and good thermal stability makes this material beneficial for CO₂ capture at ambient temperatures.