Pharmaceuticals are increasingly used in daily life and have been massively discharged to the aquatic environment. The removal of pharmaceuticals from water by various nanomaterials including graphitic carbon nitride (g-C3N4) has received extensive attention. Herein, we synthesized a carbon-defective carbon nitride with pore structure through a simple thermal polymerization method for photodegradation of lidocaine, mepivacaine and ropivacaine (typical amide local anesthetics). The results showed that the degradation process conformed to the pseudo-first-order reaction kinetics, and the degradation rate constant of organic pollutants using CCN-600 (i.e., g-C3N4 synthesized at 600 °C) reached 5.05 × 10-2 min-1, about 2.5 times higher than that of the prototype g-C3N4 (2.09 × 10-2 min-1). The capture experiment of active species and the electron paramagnetic resonance (EPR) test demonstrated that superoxide radical (O2-) played a major role in the degradation process. Based on the possible photodegraded intermediate products identified, the degradation pathways were deduced. This study provides not only a new strategy for fabrication of pore-structured g-C3N4 with carbon vacancy, but also a reference method for the treatment of pharmaceuticals in water bodies.
Keywords: Active species; Anesthetics; Carbon-vacancy g-C(3)N(4); Catalytic mechanism; Intermediate degradants.
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