Efficient Removal of Acetaldehyde Using KOH-Activated Adsorbents Derived from Pyrolysis Char of Waste Cigarette Filters

This study investigates the adsorption performance of activated carbon produced by activating cigarette filter pyrolysis char (CPC), derived from waste cigarette butts, with KOH. Pyrolysis of waste cigarette filters was conducted in a lab-scale reactor at 500 °C, producing gas, oil, and char with yields of 23.0%, 53.3%, and 23.7%, respectively. KOH activation was performed by mixing CPC with KOH at different ratios (1:1, 1:2, 1:3), followed by heating to 850 °C at a ramp rate of 5 °C/min. With increasing KOH content, the pore properties of the activated carbons improved significantly, with KOHCPC3 (CPC/KOH: 1:3) exhibiting a remarkable specific surface area of 2867 m²/g and a pore volume of 0.86 cm³/g. XPS analysis revealed the development of oxygen-containing functional groups due to KOH activation, which contributed to enhanced adsorption performance. The acetaldehyde adsorption capacity of the activated carbons increased with the KOH ratio, from 3.1 mg/g for CPC/KOH (1:1) to a maximum of 17.54 mg/g for CPC/KOH (1:3). These findings demonstrate the potential of cigarette pyrolysis char as a high-performance adsorbent for environmental and industrial applications.