Highly efficient removal of cefazolin on bowl-shaped nitrogen-doped pyrolytic carbon: multi-site cooperative interactions probed via molecular electrostaic potential mapping

Bowl-shaped pyrolytic carbon showed ultrahigh CEF uptake of 2.046 mmol/g. • N-tuned carbon electronics and high site exposure drive superior performance. • XPS/ ESP/ site-shielding revealed cooperative interactions for CEF adsorption. • Interactions resolved at N-, S-, and O-functional groups of CEF and bNPyC. • CEF removal by bNPyC showed broad pH tolerance, interference resistance, and stability. Pyrolytic carbons (PyCs) hold great potential for removing emerging organic micropollutants such as antibiotics from water. Cephalosporins, which contain β-lactam rings and N/S heterocycles, remain underexplored in their affinity interactions with PyCs. Here, solid, bowl, and hollow PyCs were synthesized via a soft-template method. Among them, bowl-shaped nitrogen-doped PyCs (bNPyC) showed faster kinetics and higher capacity for cefazolin (CEF). Its maximum CEF uptake fitted by the Dubinin–Astakhov model reached 2.046 mmol/g (∼929.93 mg/g), exceeding the controls by 25.7–800.9%, highlighting the contribution of nitrogen doping and high site exposure. CEF adsorption on bNPyC remained stable across pH 2–10, increased with temperature, and was slightly enhanced by tested inorganic salts, and exhibited good tolerance to representative organic interferents. XPS and electrostatic potential analyses showed that N-doping increased surface electronic heterogeneity and that multiple groups of CEF jointly engaged in π–π electron donor–acceptor, hydrogen-bonding, and electrostatic interactions with bNPyC. These cooperative forces contributed to the high adsorption capacity and strong affinity toward CEF. bNPyC also showed high adsorption capacities toward several other tested antibiotics and showed only a 10.8% capacity loss after five regeneration cycles. The findings offer new insights into the structure–affinity relationship in cephalosporin adsorption on PyCs. A bowl-shaped N-doped pyrolytic carbon with highly exposed active sites enables multi-site cooperative interactions for efficient and robust adsorption of cefazolin. Download: Download high-res image (222KB) Download: Download full-size image