Preparation of porous carbon from weathered coal humic acid and its high-efficiency adsorption for tetracycline

This study utilized humic acid (HA) extracted from weathered coal as a carbon precursor to prepare porous carbon materials (KHC) via solid-phase grinding with KOH followed by one-step high-temperature activation. The structural properties of the materials were characterized using SEM, XRD, FTIR, N₂ adsorption–desorption, and XPS, and their adsorption performance toward tetracycline (TC) was evaluated. Under optimal preparation conditions, the resulting KHC exhibited a high specific surface area of 3108.96 m2·g–1 and a pore volume of 1.985 cm³·g–1, achieving a maximum TC adsorption capacity of 1046.17 mg·g–1. Adsorption behavior, analyzed through kinetics, isotherms, and thermodynamics, followed the Langmuir isotherm and pseudo-second-order kinetic models, indicating a monolayer chemical adsorption process. The adsorption mechanism involved synergistic effects including pore filling, π–π interactions, hydrogen bonding, and electrostatic interactions. Moreover, KHC demonstrated excellent removal efficiency for various pollutants. Continuous dynamic adsorption and cycling experiments confirmed its stability and potential for practical wastewater treatment. This work not only presents an efficient porous carbon adsorbent for antibiotic removal but also offers a sustainable strategy for the high-value utilization of weathered coal resources.