Optimization of Fe3O4/SiO2/N-TiO2/Ag/AgCl core-shell nanomaterial and its properties, repeatability and photocatalytic mechanism

Abstract

In this study, the magnetic core-shell nanomaterial Fe3O4/SiO2/N-TiO2/Ag/AgCl (FSNT/Ag/AgCl) that efficiently degraded methyl orange (MO) was produced. The dosages of tetrabutyl titanate (TBOT), urea and AgNO3 were optimized by response surface methodology (RSM). Scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy analysis (XPS), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD), fourier transform infrared spectrometer (FT-IR), and UV–vis diffuse reflectance spectrum (UV–vis DRS) were used to characterize the nanomaterial. The particle size of FSNT/Ag/AgCl was 91.98 nm, and it presented a core-shell structure with Fe3O4 as the core, SiO2 and N-TiO2 wrapped in Fe3O4, and Ag/AgCl deposited on the outermost layer. Performance and mechanism research experiments showed that under the optimized conditions of 1 g/L FSNT/Ag/AgCl, pH = 9, temperature of 35℃ and initial MO concentration of 10 mg/L, about 90 % of MO was degraded in 20 min. The mineralization rate was 35.2 % within 120 min. Holes (h+) and superoxide anions (·O2−) were the main active substances in the whole photocatalytic degradation. FSNT/Ag/AgCl could be recovered by magnet. After 5 repeated experiments, the degradation rate of MO within 100 min still reached 88.5 %. This work provides a recyclable core-shell nanomaterial for faster degradation of dye wastewater.