Removal of methylene blue by one-step pyrolytic carbon derived from used cigarette filters

The carbons were prepared with used cigarettes filters (UCFs) as the raw material using a facile one-step pyrolysis strategy at different temperatures. The prepared carbons, denoted as CPC, were characterized by various techniques and used in methylene blue (MB) batch adsorption experiments from simulated dye wastewater under various operating conditions including dosage, time, nitial solution pH, concentration and temperature. It was observed that the CPC-800 sample had S BET of 530.6 m²/g and V tol of 0.31 cm 3 /g, and exhibited a maximum adsorption capacity of 53.55 mg/g at 25℃. In addition, the process of MB adsorption onto CPC-800 is best conforming to the Pseudo-second-order (PSO) kinetic model, indicative of the dominance of chemisorption mechanism. The Freundlich isothermal model (R 2 =0.95) best fitted the equilibrium data, indicating heterogeneous adsorption characteristics. Furthermore, the calculated thermodynamic data revealed that MB adsorption on CPC-800 occurred spontaneously and the process was endothermic. The MB adsorption onto CPC-800 is attributed to the synergistic effect of multiple mechanisms, including pore filling, hydrogen bonding, electrostatic attraction, and π-π interactions. Generally, this study provided reference for the high-value utilization of UCF and served as a baseline study to demonstrate the feasibility of minimal-processing, and paved the way for future activation or doping with heteroatoms.