RESUMO
A novel Bi2MoO6/Bi2Ti2O7 heterojunction photocatalyst was firstly prepared by a simple solvothermal route. The as-synthesized photocatalysts were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy and photoluminescence spectra. The effect of the material ratio, solution pH, and the salinity on glycolic acid degradation were discussed. The Bi2MoO6/Bi2Ti2O7 (2:1) nanocomposite exhibits highest photocatalytic performance and chemical stability. The glycolic acid degradation efficiency can reach 99.9% at pH 4 after 150 min irradiation under visible light. The enhanced photocatalytic activity can be ascribed to the heterojunction interface in the composite, which is beneficial to the efficient charge carriers transfer. The degradation conforms to the pseudo-first-order kinetics. According to the oxidation species trapping experiments, the ·O2-, h+ and ·OH are found to play important roles in the photocatalytic degradation and ·O2- is the main active species. The possible photocatalytic mechanism was further discussed on account of valence band, conduction band positions and possible transition states.
RESUMO
Nanoscale zero-valent iron (NZVI) was first assembled on magnetic carbon/Fe3O4 (CM) with a combination of hydrothermal and liquid phase reduction methods. The novel NZVI@CM magnetic nanocomposites have the merits of large surface area, unique magnetic property, low cost and environmental friendliness. They can be used for Pb(II) removal in aqueous solution. The materials were characterized by using transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) adsorption. The various parameters, such as reaction time, dosage of catalyst, solution pH and acid ions concentrations were studied. The removal efficiency of Pb(II) can be obviously increased by the combination of appropriate CM and NZVI. The removal efficiency of Pb(II) is 99.7% by using 60 mg of NZVI@CM at pH 7. The kinetics study indicates that the Pb(II) removal accords to pseudo-second-order kinetics model.
