Fabrication of plate-on-plate SnS2/Bi2WO6 nanocomposite as photocatalyst for sunlight mediated degradation of antibiotics in aqueous medium

Abstract

Increase in the concentration of residual antibiotics in water bodies, including drinking water, has led to developing strategies for their remediation. Here we report a very efficient method of photocatalytic degradation of tetracycline (TC) and ciprofloxacin (CIP) antibiotics in aqueous medium using Z-scheme heterojunction based 0.10SnS2/Bi2WO6 solar photocatalyst. The photocatalyst synthesized by hydrothermal route is thoroughly characterized in terms of its structural, compositional, morphological, and optical properties. About 97% of tetracycline and 93% of ciprofloxacin is degraded in 90 min of sunlight exposure at a photocatalytic rate of 0.027 min−1 and 0.024 min−1, respectively. The total organic carbon estimation of the post-degradation reaction medium corresponded to 80.1% (TC) and 71.1% (CIP) mineralization. The photocatalytic degradation of TC and CIP is attributed to the in-situ generation of reactive oxygen species (ROS), e.g., superoxide radicals, hydroxide radicals, confirmed from ROS scavenging studies. ROS generation is favored by construction of Z-scheme heterojunction, and charge carrier mobility in the photocatalyst. The degradation mechanism has been discussed by analyzing the degradation products via ultra-performance liquid chromatography coupled to quadrupole-Time-of-Flight based mass spectrometry (UPLC-Q-Tof-MS).