Photocatalytic Removal Of Phenol Using Titanium Dioxide (Tio2) In Fluidized Bed Reactor

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Date
2012
Authors
Tan, Yong Nian
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Publisher
Universiti Sains Malaysia
Abstract
Fluorinated titanium dioxide (F-TiO2) and immobilized F-TiO2 were synthesized by sonication-hydrothermal method and binding method. Fluorine doping, immobilization, hydrothermal method and fluidized bed reactor used in this study. The samples were characterized by X-ray diffraction (XRD), Brunauer- Emmett-Teller (BET) analysis, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). The photocatalytic degradation of phenol using the prepared photocatalyst was evaluated under UV light irradiation in batch mode fluidized bed reactor. Based on the XRD patterns, all the diffraction peaks of the F-TiO2 photocatalysts corresponded to the anatase phase of TiO2. The surface morphology of F-TiO2 observed by both SEM and TEM was uniformly distributed and the largest of BET surface area, total pore volume, and average pore size of F-TiO2 at the Ti:F molar ratio of 0.15 under hydrothermal duration of 10 h. The presence of F, Ti, and O on the surface of F-TiO2 was confirmed by EDX analysis. The optimum composition of the photocatalyst comprising F-TiO2, quartz sand, and colloidal silica was 1:1.5:1. Based on TEM images, F-TiO2 prepared in the Ti:F molar ratio of 0.15 under hydrothermal duration of 10 hours (8.4 nm) had a relatively smaller crystalline size compared to the supported F-TiO2 (45-60 nm). F-TiO2 produced at the Ti:F molar ratio of 0.15 for hydrothermal duration of 10 h showed the highest degradation rate of phenol. The results for the studied operating parameters were: the optimal catalyst loading was found to be 4 g/L; the optimum initial phenol concentration was observed to be 20 mg/L; the air flow rate gave an optimum value of 2 L/min; the presence of metal cations impeded the photocatalytic activity of photocatalyst in the order of K+ > Ca2+ > Zn2+; the addition of inorganic anions also inhibited the photocatalytic reaction in the order of SO4 2- > HCO3 - > NO3 -. Immobilized F-TiO2 gave the better photocatalytic activity as compared to commercial Degussa TiO2 P25. The photocatalytic degradation of phenol fitted well with pseudo first order kinetic model with its reaction rate constant, k equal to 2.19 mg/L.min and the adsorption constant, K equal to 0.0305 L/mg, respectively. Response surface methodology (RSM) based on the central composite design (CCD) used to optimize the photocatalytic degradation of phenol. The optimum phenol photodegradation was achieved in 105 minutes at the catalyst loading of 4 g/L, air flow rate of 2 L/min, and initial phenol concentration of 20 mg/L.
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Keywords
Photocatalytic removal of phenol using , titanium dioxide in fluidized bed reactor
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