Biomass-derived carbon aerogels with tailored ultra-microporosity for CO 2 adsorption Soniya Mariya Varghese 1,2 , Additi Roy Chowdhury 1 , Dali Naidu Arnepalli 2 , G. Ranga Rao 1 1 Department of Chemistry 2 Department of Civil Engineering, Indian Institute of Technology Madras, India Adsorption of CO 2 on porous solid materials is proposed to be a viable solution for excessive CO 2 emissions. Ultra-microporous carbon materials with high pore volume are excellent CO 2 adsorbents. Porous carbon materials are usually obtained by activation with alkali or other corrosive chemicals. Here, we report a simple alkali-free method to obtain microporous carbon from chitosan. Chitosan is a natural material with amine functionality, which can aid in CO 2 adsorption. The material is fully bio-degradable and follows a green synthesis route. Carbon aerogel is synthesized from chitosan, citric acid, and urea through simple hydrothermal treatment followed by carbonization under a nitrogen atmosphere. Under the reaction conditions, citric acid and urea react with chitosan resulting in a crosslinked three-dimensional network. The cross-linking can be tuned by varying concentrations of reactants. This in turn is used to control the pore size distribution of carbon aerogels. A series of ultra-microporous carbon with controllable pore size distribution are synthesized and optimized for improved CO 2 adsorption. The properties of aerogel are evaluated using X-ray diffraction, thermogravimetric analysis, FTIR, and scanning electron microscopy. The microstructure is characterized by N 2 adsorption-desorption measurements and CO 2 adsorption-desorption measurements at 273K. The effect of changes in pore size distribution on the adsorption of pure CO 2 is studied using the Quantachrome autosorb iQ, gas sorption system. Maximum CO 2 adsorption of 1.8 mmol/g is obtained for carbon aerogels at 298K and 1 bar. References 1. Rehman, A.; Park, S.-J. From Chitosan to Urea-Modified Carbons: Tailoring the Ultra-Microporosity for Enhanced CO 2 Adsorption. Carbon 2020 , 159 , 625–637. https://doi.org/10.1016/j.carbon.2019.12.068. 2. Alhwaige, A. A.; Ishida, H.; Qutubuddin, S. Carbon Aerogels with Excellent CO 2 Adsorption Capacity Synthesized from Clay- Reinforced Biobased Chitosan-Polybenzoxazine Nanocomposites. ACS Sustain. Chem. Eng. 2016 , 4 , 1286–1295. https:// doi.org/10.1021/acssuschemeng.5b01323.
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