High-Efficiency Adsorption of Tetracycline Hydrochloride on Coal Gangue-Based Hierarchical Porous Carbon: Adsorption Behavior and Mechanism

In this study, a high-performance hierarchical porous carbon (HPC) adsorbent was prepared from coal gangue (CG) by a simple one-step calcination activation and acid–base treatment, and it was effective in removing tetracycline hydrochloride (TCH). In comparison to pristine CG, the specific surface area and pore volume of HPC significantly increased, reaching 1287.2 m2·g–1 and 0.72 cm3·g–1, respectively. The greatest adsorption capacity of HPC toward TCH was 357 mg·g–1 at 298.15 K and pH 7.0. The TCH adsorption process onto HPC was best described by the pseudo-second-order (PSO) and Freundlich isotherm models, according to adsorption kinetics and isotherms. The suggested adsorption process involved in TCH adsorption on HPC mostly relied on the synergistic effect of pore filling, hydrogen bonding, π–π stacking interactions, and electrostatic interactions, according to adsorption experiments and more research. This work offers a useful resource for creating CG-based adsorbents to remove antibiotics from water.