Amine-functionalized cellulose-chitosan composites as an efficient adsorbent for CO₂ capture.

The present study investigated the novel amine-functionalized cellulose/chitosan (Ce/Cs) composite materials for efficient carbon dioxide (CO₂) adsorption. Cellulose (Ce) was chemically modified by tetraethylenepentamine (TEPA) functionalization and subsequently blended with chitosan (Cs) to enhance the composite's CO₂ capture capability. Characterization techniques, including Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), N₂ adsorption-desorption, and field emission scanning electron microscopy (FESEM), confirmed successful amine incorporation, composite formation, and a well-defined mesoporous structure. Experimental optimization revealed that a TEPA loading of 15 wt% coupled with a Ce-to-Cs mass ratio of 3:1 provided optimal CO₂ adsorption performance. Under 25 °C and 9 bar, Ce₃-TEPA15%/Cs₁ reached a maximum experimental CO₂ uptake of 358.44 mg g⁻¹, compared with 270 mg g⁻¹ for Ce₃Cs₁. Adsorption isotherms and kinetics data were best fitted by the Freundlich model with R² of 0.999 and the fractional-order kinetic model with R² of 0.863-0.986, indicating favorable and heterogeneous adsorption. Thermodynamic results (ΔH° ≈ -23.94 kJ mol⁻¹) confirmed an exothermic process and supported a mixed physisorption/chemisorption mechanism. The optimized composite also showed good regenerability, retaining ~92% of its initial capacity after 10 adsorption-desorption cycles under mild regeneration (~40 °C). Overall, the combination of covalent amine anchoring and a bio-based matrix provides a practical route to efficient, reusable sorbents for CO₂ capture.