Highly stable β-Bi2O3/Ag decorated nanosilica as an efficient Schottky heterojunction for ciprofloxacin photodegradation in wastewater under LED illumination

Abstract

A novel mesopours SiO2/β-Bi2O3/Ag plasmonic heterojunction was first fabricated by a simple multi-step approach. The fabricated heterojunction was applied for ciprofloxacin (CIP) degradation in wastewater. The ternary SiO2/β-Bi2O3/Ag photocatalyst exhibited a wide absorption in the visible region (400–700 nm) with the assistance of the surface plasmonic resonance (SPR) behavior of Ag0 metal. Furthermore, the experimental results indicated that 96% of CIP was degraded with a TOC removal efficiency of 65% in 105 min under 140 W of light-emitting diode (LED) irradiation. The kinetics studies showed that the degradation rate of SiO2/β-Bi2O3/Ag is 0.02651 min−1, which is 3.17, 2.62, and 1.99 times higher than that of pure β-Bi2O3, SiO2/β-Bi2O3, and β-Bi2O3/Ag, respectively. The impacts of operational parameters like solution pH, CIP concentration, and SiO2/β-Bi2O3/Ag dosage were also assessed. The trapping experiments suggested that the main reactive species is the •OH radical, which can be easily generated on the valence band of β-Bi2O3. The Schottky heterojunction between β-Bi2O3 and Ag nanoparticles was well depicted based on trapping tests and characterization techniques. The stability experiments suggested that the SiO2/β-Bi2O3/Ag nanocomposite possessed high stability in five consecutive cycles and could be applied for CIP removal with acceptable photodegradation performance. Finally, it can be concluded that the nanosilica exhibited an efficient support structure, which can significantly improve the surface properties of SiO2/β-Bi2O3/Ag by inhibiting the agglomeration effects of β-Bi2O3/Ag nanoparticles as well as enhance the adsorption and stability of nanocomposite.