Development of biomass derived highly porous fast adsorbents for post-combustion CO₂ capture

This study is carried out for a comparative screening of three groups of biomasses; soft or non-woody (peanut shell); intermediate woody (walnut shell) and hard woody (pine wood) for the development of adsorbents/activated carbons for post-combustion CO₂ capture (over N₂ balance). Three different groups of biomass residues are selected to study the role and nature of the material in adsorption and selection of the raw material for CO₂ adsorbents synthesis for future researches because of the hot issue of anthropogenic CO₂ emissions. The adsorption isotherms studied by the thermal gravimetric analyser (TGA) revealed that CO₂ adsorption capabilities are in the range of 2.53–3.92 mmol/g (over N₂ balance) at 25 °C. The newly synthesised activated carbons (ACs) exhibited a fast rate of adsorption as 41–94% in the initial 2 min. Porous surface development with catalytic KOH activation is seen clearly through SEM surface morphological analyses and mathematically confirmed from S_BET ranges from 146.86 to 944.05 m²/g. FTIR and XRD peaks verify the generation of basic or inorganic O₂-rich moieties that help in acidic CO₂ capture. It has also been observed from adsorption isotherms that the order of higher adsorption groups is as; peanut shell > pine wood > walnut shell, while the best activation mass ratio (sample/KOH) is 1:3. The synthesised low cost ACs with an amount of 1.93 US$ per kg production could help to overcome the environmental hazards and problems caused by CO₂ and biomass waste.