engleski

Photocatalytic degradation of phenol on the suspended and immobilized TiO2

The advanced oxidation processes (AOPs) are recently widely studied in wastewater treatment to eliminate persistent organic pollutants, which cannot be completely removed with a conventional wastewater treatment methods (like adsorption, flocculation, air stripping, etc). Among these advanced technologies, photocatalytic oxidation processes using TiO2 are the most applied due to its chemical and biological inertness, nontoxicity, low price and high stability to light illumination. In the UV/TiO2 photocatalytic degradation, TiO2 can be applied in two modes: (1) immobilized on support material, e.g., glass, metal, fabrics etc., and (2) suspended in aqueous medium. Usually, the photocatalytic efficiency of the slurry system is greater than in the immobilized system, but the requirement of a catalyst post-separation increases operational costs. However, the problem in the use of immobilized TiO2 layer may be cracking and peeling off of the catalyst because of the poor adherence of the photocatalyst/support. This work represents the results of the phenol photodegradation in the slurry reactor using TiO2 Degussa P-25 nanocatalyst. Phenol was chosen as a model compound to degrade, since it is frequently found in various industrial effluents and has a toxicity effect. The influence of various operating conditions, such as temperature, initial phenol concentration and TiO2 loading on photodegradation of phenol was investigated. Also, a comparison of slurry and immobilized TiO2 at the same reaction conditions (temperature, initial phenol concentration, flow rate recirculation and irradiation intensity) has been studied. The photocatalytic TiO2 layer was prepared using chitosan [β-(1-4)-2-amino-2-deoxy- D-glucose] for immobilization on glass fibre woven roving. The degradation experiments were performed in a batch annular reactor with recirculation. The source of UV irradiation (commercial 8 W UV lamp ; =254 nm) was placed in the central part of the photoreactor. The phenol concentration in the reactor was measured using a UV/Vis method based on the 4- aminoantipyrine reaction. A pseudo-first order kinetic model was proposed and appropriate kinetic parameters were estimated for phenol photodegradation.

The advanced oxidation processes ; TiO2 ; Photocatalytic degradation ; phenol

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