Greenhouse gas recovery performance of chitin-derived porous carbons from waste chitinous biomass

This work upcycled waste chitin-based shells into porous carbons via a chemical-free steam activation route using only N 2 and water vapor, and investigated their adsorption/desorption behaviours toward the greenhouse gas n-butane. The textural and structural properties of chitin-based porous carbons (Ch-PCs) were characterized by N 2 adsorption-desorption, X-ray diffraction, and field-emission scanning electron microscopy. The n-butane working capacity (butane activity and retentivity) was also evaluated. The Ch-PCs exhibited specific surface areas of 720–1 350 m 2 /g and total pore volumes of 0.53–1.10 cm 3 /g, with micropore volumes of 0.25–0.48 cm 3 /g and mesopore volumes of 0.28–0.62 cm 3 /g. As the activation time increased, the n-butane adsorption capacity increased from 22.3% to 43.6%, while the retentivity (residual adsorption) decreased from 16.9% to 9.2%. The n-butane adsorption/desorption behaviours were strongly correlated with the pore structure of the Ch-PCs. The adsorption capacity showed a strong relationship with the pore size of 1.0–3.0 nm, whereas the retentivity was mainly associated with the pore size of 3.0–5.0 nm. These findings demonstrated that steam-activated chitin-derived carbons, prepared from waste biomass by a chemical-free activation process, could serve as promising bio-based adsorbents for efficient greenhouse gas capture and recovery.