Pore‐Hierarchy Engineering of Cigarette Butt Waste Into Porous Carbon for CO 2 Adsorption
Joseph F. Olorunyomi, Shinen Yu, Lison Shaju, Nandish Hosadoddi Srikantamurthy, Jianjin Ruan, Jeremy D. Landry, Xavier Mulet, Ravichandar BabaraoABSTRACT
Cigarette butts are a persistent plastic‐rich waste stream commonly disposed of in landfill, creating environmental and resource‐recovery challenges. Their cellulose‐acetate‐rich filters and organic components, however, provide a potential precursor for waste‐derived porous carbons. Here, whole cigarette‐butt (WCB) waste was converted into hierarchical porous carbons by carbonization followed by Na 2 CO 3 activation. The pore structure was tuned from poorly developed porosity to a micro–mesoporous network whose development varied with Na 2 CO 3 loading. Pore development increased across the WCB‐ x series up to 83 wt.% Na 2 CO 3 , beyond which over‐activation reduced the effective adsorption network. WCB‐83, the highest‐uptake sample within the Na 2 CO 3 series, combined a specific surface area of 750 m 2 g − 1 with the micropore volume of 0.24 cm 3 g − 1 , delivering 3.0 mmol g − 1 CO 2 at 273 K and 1 bar. This exceeded both over‐activated WCB‐91 (2.6 mmol g − 1 ) and the NaOH‐activated counterpart WCB‐OH‐83 (1.2 mmol g − 1 ). At 298 K, WCB‐83 adsorbed 0.3 mmol g − 1 CO 2 at 0.15 bar and 1.0 mmol g − 1 at 1 bar. Temperature‐dependent adsorption gave apparent isosteric heats of approximately 53 to 59 kJ mol − 1 , while Ideal Adsorbed Solution Theory (IAST) ‐predicted CO 2 /N 2 selectivity reached 120. This work demonstrates a waste‐valorization strategy for converting cigarette‐butt waste into CO 2 ‐selective hierarchical carbon adsorbents.