Abstract: TiO₂-bonded active carbon (TiO₂/AC) composites were prepared via a sol-gel dip-bonding 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:
D_t²=ktⁿ{ exp(-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.

Key words: TiO₂-bonded active carbon, crystallite growth, phase transform, apparent activation energy