Solving two environmental problems simultaneously: Scalable production of carbon microsheets from structured packing peanuts with tailored microporosity for efficient CO₂ capture

Highly porous carbon microsheets (CMS) were prepared by the bulk carbonization and activation of waste packing peanuts, and applied to CO₂ capture and release. Two different activation methods, physical activation using CO₂ and chemical activation using KOH, were used for the preparation of porous CMS, and the effects of different activation methods were compared. Chemical activation functioned better than the physical activation, successfully producing highly microporous carbon structures with higher carbon yield. Textural properties such as specific surface area and total pore volume increased proportionally to the mass ratio of KOH/carbon because of the development of the porous structure and enlargement of pore size through KOH activation. Among the samples prepared, the highest CO₂ adsorption capacities of 6.51 mol kg⁻¹ at 0 °C and 4.07 mol kg⁻¹ at 25 °C were obtained at 1 bar in the packing-peanut-derived CMS prepared with a KOH/carbon ratio of 3 (CMS-K3). It is noteworthy that the CO₂ adsorption uptake was significantly dependent on the volume of narrow micropores of pore sizes less than 0.8 nm rather than the specific surface area or total pore volume. CMS-K3 also exhibited excellent cyclic stability, good CO₂/N₂ selectivity, fast adsorption kinetics, and low heat of adsorption, being regarded as a promising adsorbent for CO₂ capture.