Photocatalytic degradation of ammonia-nitrogen via N-doped graphene/bismuth sulfide catalyst under near-infrared light irradiation

Abstract

The N-doped graphene/bismuth sulfide (NG/Bi2S3) composite was synthesized by hydrothermal method. The structure and properties of the catalyst were characterized by X-ray powder diffraction, Raman spectroscopy, scanning electron microscopy and UV-visible near-infrared diffuse reflectance spectroscopy. The degradation of ammonia-N was studied using 0.050 g NG/Bi2S3 as photocatalyst under near-infrared light irradiation. The results show that the degradation ratio of ammonia-N reaches 91.4% in 100.0 mg·L-1 ammonia-N solution with pH 9.0 under near-infrared light irradiation for 10 h. Under similar conditions，the degradation ratio of ammonia-N is only 65.5% when pure Bi2S3 is used as the photocatalyst. Kinetic studies show that the ammonia-N degradation follows the first-order reaction kinetics, and the average value of the apparent rate constant is 0.1240 h-1. Catalyst stability studies show that the degradation ratio of ammonia nitrogen in 7 runs is still greater than 85.5%, which indicates that the NG/Bi2S3 composite catalyst is very stable.