PREPARATION AND PHOTOCATALYTIC PROPERTIES OF TiO₂/ Fe₂O₃ ANDTiO₂/ Fe₂O₃/ SiO₂ NANO-COMPOSITE PHOTOCATALYST BYSUPERCRITICAL FLUID DRYING

TiO₂/ Fe₂O₃ and TiO₂/ Fe₂O₃/ SiO₂ nanocomposite photocatalysts were prepared with Na₂SiO₃ ·9H₂O , Fe(NO₃ )₃·9H₂O and TiCl₄ as precursors by chemistry coating processes and supercritical fluid drying (SCFD ) methods. Thephotocatalytic activity was evaluated by photocatalytic degradation of phenol as model reaction. Characterizations withXRD , TEM and FTIR show that in addition to anatase type TiO₂ is also formed in the range of the studied doping concentration , and SiO₂ remains amorphous at all samples. It could hold up the growth of the nanoparticle size and transformation from anatase to rutile. Compared with pure TiO₂ , or TiO₂/ Fe₂O₃ catalyst prepared by sol-gel method , nano-composite photocatalyst shows significant improvement in catalytic activity : The photocatalytic degradation rate of phenolin 6 h reached 9519 %. The optimum doping of Fe₂O₃ is 0106 %. Application of the TiO₂/ Fe₂O₃/ SiO₂ composite catalysts for the photocatalytic decomposition of phenol could not only give the same activity relative to pure ultrafine TiO₂ ,but also reduce cost . The experimental results prove that the thermal stability of TiO₂ is greatly enhanced after mixingwith slight amount of SiO₂ . The optimum doping of SiO₂ is 1010 %. The photo-catalytic particles prepared by SCFD combination technology have small size , large surface area and high activity.