Preparation of porous carbon derived from waste tobacco stalks by KOH activation and its ability to adsorb menthol

Using waste tobacco stalks as biomass precursors, a series of porous carbon materials (CSB-X) were prepared with different chemical activators (KOH, K₂CO₃, ZnCl₂), and their adsorption performance to menthol was systematically investigated. The structure and properties of the porous carbon materials were characterized by various methods such as SEM, TEM, BET, XRD, Raman, and XPS, and the adsorption experiment was conducted. The results showed that: 1) The sample prepared by KOH activation (CSB-KOH) exhibited a well-developed microporous structure, with specific surface area of 2 481 m²/g, a high defect density (I_D/I_G=3.3), and abundant surface hydroxyl functional groups. 2) CSB-KOH achieved a menthol adsorption of 826.3 mg/g. The adsorption kinetics followed a pseudo-second-order model, and the adsorption behavior was consistent with the Langmuir isotherm model, indicating that the adsorption process was dominated by monolayer adsorption. 3) Structure-function relationship analysis revealed that KOH activation significantly increased the specific surface area of the carbon material, and led to a well-developed microporous structure, a higher defect density, and abundant surface functional groups. These structural features synergistically increased the effective adsorption sites, resulting in superior adsorption capacity of the carbon material.