Deciphering CO2 Adsorption Mechanisms at the Atomic Scale in Cellulose and Chitosan Aerogels

Year: 2025

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide Biopolymer-based aerogels have emerged as promising CO 2 adsorbents for large-scale implementation due to their abundance, renewability, and low cost. However, the CO 2 capture mechanisms of these materials remain poorly understood. In this study, we exploit the structural similarity between cellulose and chitosan to investigate how surface chemistry governs the CO 2 adsorption mechanisms using a combination of solid-state nuclear magnetic resonance (ssNMR) spectroscopy and density functional theory (DFT) modeling. We reveal that cellulose aerogels adsorb CO 2 exclusively via physisorption, whereas chitosan aerogels exhibit both physisorption and chemisorption. Chemical shift analysis, supported by DFT calculations, identifies two chemisorbed species in chitosan: carbamic acid (159.0 ppm) and ammonium carbamate (164.5 ppm). Additionally, ssNMR relaxation measurements reveal three distinct physisorbed CO 2 states (solid, liquid, and gas-like) in both aerogels. By systematically tailoring the amine density (i.e., the interchain distance) in chitosan, we elucidate its influence on the CO 2 chemisorption speciation. Based on well-established principles of polysaccharide chemistry, we engineered a blended cellulose dialdehyde–chitosan aerogel with reduced amino group density. In this material, only the carbamic acid peak was observed, demonstrating that ammonium carbamate formation requires closely spaced amino groups. These findings highlight the critical role of surface functional groups and amine density in dictating the CO 2 adsorption pathways. Our study provides valuable atomic level insights into the structure–function relationships of biopolymer-based sorbents, facilitating their optimized design for CO 2 capture technologies.

Source: ACS Applied Polymer Materials

DOI: 10.1021/acsapm.5c02075

Authors: Daniel Pereira, Mirtha A. O. Lourenço, Mariana Sardo, Armando J. D. Silvestre, Ildefonso Marin-Montesinos, Luís Mafra

Institutions: Laboratório Associado CICECO – Instituto de Materiais de Aveiro, University of Aveiro

Language: English

Topic: Carbon Dioxide Capture Technologies

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

SDG: Climate action

Open Access status: hybrid

Estimated APC paid: $4,500

Funders: European Commission, Universidade de Coimbra, Ministério da Ciência, Tecnologia e Ensino Superior, Centro de Investigação em Materiais Cerâmicos e Compósitos, Horizon 2020 Framework Programme, HORIZON EUROPE Framework Programme, European Research Council, Fundação para a Ciência e a Tecnologia

OpenAlex ID: W4414646412