A magnetic sonophotocatalyst Fe 3 O 4 @SiO 2 @TiO 2 is synthesized for the enhanced biodegradability of organophosphate pesticide. The as-prepared catalysts were characterized using different techniques, such as Xray diffraction (XRD) and transmission electron microscopy (TEM). The radial sonophotocatalytic activity of Fe 3 O 4 @SiO 2 @TiO 2 nanocomposite was investigated, in which commercial dichlorvos (DDVP) was chosen as an object. The degradation efficiency was evaluated in terms of chemical oxygen demand (COD) and enhancement of biodegradability. The effect of different factors, such as reaction time, pH, the added amount of catalyst on COD Cr removal efficiency were investigated. The average COD Cr removal efficiency reached 63.13% after 240 min in 12 L sonophotocatalytic reactor (catalyst 0.2 g L −1, pH 7.3). The synergistic effect occurs in the combined sonolysis and photocatalysis which is proved by the significant improvement in COD Cr removal efficiency compared with that of solo photocatalysis. Under this experimental condition, the BOD 5 / COD Cr ratio rose from 0.131 to 0.411, showing a remarkable improvement in biodegradability. These results showed that sonophotocatalysis may be applied as pre-treatment of pesticide wastewater, and then for biological treatment. The synthesized magnetic nanocomposite had good photocatalytic performance and stability, as when it was used for the fifth time, the COD Cr removal efficiency was still about 62.38%.

Zr, Al) mixed oxides with a MOx:SiO2 mass ratio of 1:1 were prepared by co-precipitation. Pt-only diesel oxidation catalysts supported on these mixed oxides were obtained by the incipient wetness method. The catalytic activities in simplified diesel exhaust gas before and after SO2 treatment were analyzed. The catalysts were characterized by X-ray diffraction, N2 adsorption-desorption, NH3/O2/CO2 temperature programmed desorption (NH3/O2/CO2-TPD) and X-ray photoelectron spectroscopy (XPS). The results of NH3-TPD suggested that the surface of the catalysts had multiple acidic sites, and the number of medium-strength acidic sites increased following treatment with SO2. The results of O2-TPD revealed that there were α and β oxygen species in the catalysts, and the amount of O2 desorption decreased for the SO2-treated catalysts. The Pt/Al2O3-SiO2 catalyst exhibited the lowest surface acidity and the largest amount of oxygen desorption. XPS indicated that the binding energy of Pt 4f5/2 decreased when the catalysts were treated with SO2. All the catalysts showed excellent activity for CO and C3H8, and the Pt/ ZrO2-SiO2 catalyst exhibited the best SO2 poisoning resistance, showing the potential for these catalysts to be applied in diesel oxidation.

No abstract

No abstract

No abstract