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

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 (CO 2 ) 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 m 2 g −1 ), high pore volume (1.87 cm 3 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 CO 2 -derived carbon adsorbents in the treatment of antibiotic wastewater.