Breakthrough CO₂ adsorption in bio-based activated carbons.

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Activated carbon is a key material for carbon dioxide (CO2) capture.
• Biochar derived from biomass offers a sustainable precursor for activated carbon.
• Activation methods significantly influence the properties and performance of activated carbon.

Purpose of the Study:

• To investigate the impact of steam, CO2, and Potassium hydroxide (KOH) activation on activated carbon's CO2 adsorption.
• To correlate surface area, porosity, and surface chemistry with CO2 adsorption capacity.
• To evaluate the long-term stability and regenerability of the activated carbons.

Main Methods:

• Activated carbon was prepared from wood biochar using steam, CO2, and KOH activation.
• CO2 adsorption was studied in a fixed-bed reactor under varying temperatures (25-65°C) and CO2 concentrations (10-30 mol%).
• Material characterization included N2 and CO2 adsorption for pore structure analysis; Central Composite Design optimized experimental conditions.

Main Results:

• Potassium hydroxide (KOH) activated carbon achieved the highest CO2 adsorption capacity (1.8 mol/kg) at 30 mol% CO2 and 25°C.
• This superior performance was attributed to its high surface area (1400 m²/g) and micropore volume (0.62 cm³/g).
• KOH and CO2 activated carbons showed stable adsorption capacity over 50 cycles with regeneration at 160°C.

Conclusions:

• KOH activation is highly effective in producing high-performance activated carbon for CO2 capture from biochar.
• The optimized activated carbon exhibits excellent capacity and durability for cyclic adsorption processes.
• This study highlights a sustainable and efficient pathway for CO2 mitigation using biomass-derived materials.