Effects of Active Carbon Carrier on Phase Transform and Crystallite Growth of Titanium Dioxide in TiO_2/AC

TiO2-bonded active carbon (TiO2/AC) composites were prepared via a sol-gel dipbonding process by a carrier of active carbon. The as-prepared composites were characterized by scanning electrical microscope (SEM) and X-ray diffraction (XRD). The effects of active carbon on crystallite growth and phase transform of TiO2 in composites were studied by calculating and analysing the formula: Dt2 =ktnexp(-E/RT). The results show that, comparing with TiO2 powders, the time of crystallite growth of the composite is shorter, and the composite has an average particle size of 50nm, smaller than that ot TiO2 powder. Temperature of crystalline phase transform from anatase to rutile and temperature of crystallite-rapidity growth for the composites are higher than that for TiO2 powder. The activation energies E(anatase) and E(rutile) are respectively 6.21±1.27kJ/mol and 46.5±1.56kJ/mol for the composites, while they are respectively 5.76±1.02kJ/mol and 36.4±1.14kJ/mol for TiO2 powder. The reaction exponent n(anatase) and n(rutile) are respectively 0.19 and 0.35 for the composites and 0.13 and 0.26 for TiO2 powder. Above narrated differences between composites and TiO2 powder attribute to the fact that the great adsorbability and no-crystalline layer of active carbon retard TiO2 crystallite growth.