Valorization of cigarette butt and tobacco wastes into activated hydrochars for sustainable copper removal from water

Abstract The accumulation of cigarette butts and tobacco residues represents a persistent environmental challenge due to their toxic composition and widespread disposal. In this study, these hazardous wastes were valorized into functional hydrochar adsorbents through hydrothermal carbonization followed by chemical activation. The prepared materials were evaluated for copper (Cu 2+ ) removal from aqueous solutions. Comprehensive characterization, including proximate analysis, elemental analysis, BET surface area, FTIR, SEM, TGA, and zeta potential measurements, revealed that cigarette‐butt‐derived hydrochar possessed a more developed porous structure and a more negative surface charge compared to tobacco‐derived hydrochar. Under optimized conditions (initial concentration of 50 mg/L, adsorbent dosage 1.66 g/L, and contact time 90 min), the adsorbent achieved copper removal efficiencies of up to 99%. Adsorption behavior was best described by the Freundlich isotherm and pseudo‐second‐order kinetic models, indicating a heterogeneous adsorption process governed by both physical and chemical interactions. These findings demonstrate that tobacco‐related wastes can be converted into low‐cost adsorbents for water treatment applications. The proposed waste‐to‐resource strategy contributes to waste minimization, pollution prevention, and resource conservation by transforming problematic solid wastes into functional remediation materials.