Application of TiO2-containing mesoporous spherical activated carbon in a fluidized bed photoreactor—Adsorption and photocatalytic activity

Authors:   Mi-Hwa Baek, Ji-Won Yoon, Ji-Sook Hong, Jeong-Kwon Suh

Abstract:
A TiO₂-containing mesoporous spherical activated carbon (meso-TiO₂/SAC) with high adsorption capacity and photocatalytic activity was prepared using ion-exchange method and heat-treatment process. The prepared meso-TiO₂/SAC was characterized by SEM, TEM, EDS, XRD, and BET analysis. Results obtained showed that meso-TiO₂/SAC had a smooth spherical shape (0.30–0.45 mm) and TiO₂ with crystalline size of 10–30 nm was well dispersed on the spherical activated carbon. XRD study confirmed that TiO₂ existed in a mixture of anatase (83%) and rutile (17%) phase. The meso-TiO₂/SAC presented a high specific surface area of 1649 m²/g. The meso-TiO₂/SAC was used for the removal of humic acid (HA) in a fluidized bed photoreactor, the rate of adsorption reaction of HA by meso-TiO₂/SAC followed the pseudo secondorder kinetic, the adsorption isotherm fitted well to the Freundlich and Langmuir isotherm models. The maximum adsorption capacity of meso-TiO₂/SAC determined from Langmuir isotherm was 2.92 mg/g. The effect of the photocatalysis of HA by meso-TiO₂/SAC under UV irradiation was investigated under various conditions of varying catalyst dosage, initial HA concentration, and coexisting anion. HA was mineralized up to 80.3% under optimal experimental conditions for a catalyst dosage of 9 g/L and at an initial HA concentration of 20 mg/L. In the presence of coexisting anions, the degradation efficiency of HA was reduced to 72.1% and 72.8% for SO₄^-2  and NO₃ −, respectively. In the cyclic reuse experiment, over 85% of the initial TOC and COD were removed after the eighth cycles, indicating the relatively high photocatalytic stability of meso-TiO₂/SAC. TiO₂ was not released from the spherical activated carbon during the photocatalytic reaction. The meso-TiO₂/SAC developed, therefore has potentials for practical applications in water treatment.

Keywords:
Adsorption
Photocatalysis
Spherical activated carbon
Titanium dioxide
Humic acid

Published in: Applied catalysis A: General  (Volume 450, Pages 1-274, 15 January 2013)

Publisher: Elsevier

ISSN Information: 0926-860X

Application of TiO2-containing mesoporous spherical activated carbon in a fluidized bed photoreactor—Adsorption and photocatalytic activity

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