Highly efficient removal of cefixime based on graphitized carbon nitride nanosheets through two pathways: Direct photocatalysis and persulfate activation under simulated sunlight

The removal and the treatment of antibiotics in environmental water by advanced oxidation process (AOP) has attracted much attention. In this paper, a metal-free graphitized carbon nitride nanosheets (g-C3N4-NS) was synthesized by gas template method. Cefixime in water was removed by direct photocatalysis and activation of persulfate (PS) under simulated sunlight. The flaky morphology made g-C3N4-NS's band gap narrow, charge separation enhanced, light absorption enhanced, and more active sites were exposed. The specific surface area of g-C3N4-NS was about 6 times than that of bulk g-C3N4, and its photocurrent was about 3 times. The effects of different PS concentrations and pH values on photocatalytic activation in two ways were studied. The influence of anions on the removal of cefixime was also studied. The synthesized g-C3N4-NS has good stability, and its performance is well maintained after continuous photocatalysis and photoactivation catalysis. The degradation rate of cefixime by g-C3N4-NS was three times than that of bulk g-C3N4, and the removal rate of cefixime by g-C3N4-NS /PS system was 30 times than that of PS. This work provides advanced idea for metal-free AOP in environmental chemistry.