Preparation of amine-grafted spherical silica/cellulose aerogels and investigation of their carbon dioxide adsorption performance.

To address the poor moldability, high cost, and insufficient structural stability of conventional CO₂ adsorbents, a low-cost amine-grafted spherical silica/cellulose composite aerogel (AGSSCA) was fabricated in this work. Using defatted cotton-derived cellulose and diatomaceous earth-derived sodium silicate as raw materials, a homogeneous solution was obtained through alkali dissolution and blending, and silica/cellulose spherical gels were fabricated in situ via a droplet gelation approach; a series of AGSSCA materials were prepared through graft modification using the amino silane coupling agent (APTES); the effects of component ratios and grafting conditions on the material structure and CO₂ adsorption performance were systematically investigated. The results show that at 25 °C, the material exhibits an optimal CO₂ adsorption capacity of 2.14 mmol/g, which decreased by only 5% after five cycles. The CO₂ adsorption capacity increased with increasing silica content in the composite framework. Structural characterization suggested that APTES formed Si-O-Si and Si-O-cellulose covalent linkages within the silica/cellulose framework, thereby generating a porous three-dimensional interpenetrating network structure, with a maximum BET surface area of 300.87 m2/g.