Construction of Ag/g-C3N4 composites with uniform-sized Ag nanoparticles and the application for sulfisoxazole degradation in the presence of visible radiation

To ensure efficient removal of SIX, Ag/g-C 3 N 4 with uniform-sized Ag nanoparticles was synthesized. With the employment of poly vinylpyrrolidone in synthesis process, Ag sizes were controlled and the photoabsorption ability of Ag/g-C 3 N 4 for visible-light was improved. In comparison with g-C 3 N 4, the degradation kinetic constant of SIX was increased by 1.75 times when Ag content was optimized (5 wt.% in this work, i.e. Ag/g-C 3 N 4 -5). The primary species for SIX degradation by Ag/g-C 3 N 4 -5 were holes and ·O 2 − in the presence of visible radiation. Besides, the intermediate products generated in reaction processes were identified and the transformed pathways were proposed in photocatalytic process of SIX by Ag/g-C 3 N 4 -5, including the rupture of the chemical bond between S and benzene ring, the rupture of S N bond, the hydroxylation and nitration of benzene ring. Finally, the photocatalytic degradation of SIX in two authentic water bodies revealed the efficient removal of SIX can still be realized by Ag/g-C 3 N 4 -5.