A novel porous carbon derived from CO2 for high-efficient tetracycline adsorption: Behavior and mechanism

Abstract High-performance adsorbents derived from wastes are of paramount significance for environmental remediation and value-added utilization. Herein, a novel porous carbon (i.e. electrolytic carbon, EC), prepared from greenhouse gas (CO2) by electrochemical reduction in molten carbonate, was investigated as an efficient adsorbent to remove tetracycline (TC) from water. The EC possessed oxygen-containing functional groups, large specific surface area (1064.8 m2 g−1), high pore volume (1.87 cm3 g−1), and rich mesopore, availing the removal of bulky TC. A rapid adsorption equilibrium (within 1 h) and a high removal efficiency (98.7%) were obtained. Moreover, the adsorption was an exothermic reaction and the whole process obeyed the pseudo-second-order kinetic and Langmuir models, gaining a saturated adsorption capacity of 393.5 mg g−1 at 25 °C, which was superior to various reported biochar and commercial carbon materials. Besides, the adsorption of EC exhibited a wide pH adaptability ranged from 2 to 9, and excellent recyclability. A π-π interaction was identified as the predominant mechanism by investigating the adsorption performance of EC and IR, XPS characterizations. These results highlight significant implication for the future application of CO2-derived carbon adsorbents in the treatment of antibiotic wastewater.