Effect of sintering temperature on the photocatalytic activities and stabilities of hematite and silica-dispersed hematite particles for organic degradation in aqueous suspensions.
The effect of sintering temperature (150-900 degrees C) on the photocatalytic activities of ferric oxide and silica-supported ferric oxide for Orange II degradation in water has been examined under UV light irradiation in the absence and presence of H2O2. The solids are characterized by X-ray powder diffraction, nitrogen adsorption, UV/vis diffuse reflectance spectroscopy, FTIR, and Raman spectroscopy. It was observed that the amount of dye adsorbed and the rate of dye photodegradation on these catalysts were a function of sintering temperature and the suspension pH. Evidence appears to correlate with the crystallinity, particle size, and flat-band potential of hematite, in agreement with the model of semiconductor photocatalysis. The recycling experiment showed that bare hematite was relatively stable, whereas silica-supported ferric oxide experienced a progressive degradation, due to preferential deposition of the dissolved ferric species onto silica, possibly with formation of amorphous and low photoactive ferric (hydr)oxide.
Department of Chemistry, Zhejiang University, Hangzhou 310027, China.
Yan
Y
Wang
Weiping
W
Du
Yiming
Y
Xu