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The present study focuses on the axial-mixing characteristics and flow behavior of fluidized particles, which so far have received scant attention compared to the bubbling and flow behavior of fluidizing fluids. On the basis of the axial dispersion model, the mixing coefficients in a gas−liquid−solid fluidized bed with an i.d. of 0.152 m have been estimated from the composition of a binary-particle mixture in the mixing region of the bed. The complex mixing behavior has been interpreted by means of the fractal analysis of pressure fluctuations generated in the bed. It has been found that the axial-mixing coefficient increases with an increase in the gas flow rate or the particle size and that it exhibits a local maximum with respect to the variation of the liquid flow rate. The Hurst exponent recovered from the Pox diagram of pressure fluctuations decreases with increasing gas flow rate, but it displays a local maximum with variation of the liquid flow rate in the bed containing a binary mixture of particles. The axial-mixing coefficient has been correlated in terms of the operating variables. Moreover, a correlation has been obtained, which includes the Peclect number containing the mixing coefficient and the dimensionless groups derived from the isotropic turbulence theory.

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This paper mainly discussed the performance of photocatalysts which are prepared cation exchange resin and TiCl 3 precursor via heat treatment process to enhance their photocatalytic potentials. The morphology and size of TiO 2 photocatalyst was well ordered spherical shape and average diameter of 0.30 ~0.45 mm with well dispersed by TiO 2 on the surface of spherical activated carbon. TiO 2 supported on spherical activated carbon contains two different phases; anatase (83%) and rutile (17%). The TiO 2 photocatalyst had high specific surface area of 1,649 m 2 /g and high total pore volume of 1.61 cm 3 /g. Adsorption characteristics and photocatalytic activity of TiO 2 photocatalyst were evaluated by the removal of humic acid from waste water model aqueous solution. Catalyst dosage, initial humic acid concentration, and coexisting ions have influences on the photocatalytic degradation of humic acid. The degradation of humic acid by meso-TiO2/SAC was dependent on catalyst dosage, initial its concentration. TiO 2 photocatalyst has potentials for application as adsorbent and also as a photocatalyst in the removal of humic acid from groundwater and surface water.