Shi Zaifeng

Effects of Flow Pattern on Photodegradation of Phenol and MB with TiO2 Thin Film Immobilized on Ceramic Tube

This study focuses on the effects of two flow patterns on photo degradation of organic compounds withTiO2 film immobilized on the inner wall of glazed ceramic tube. Pattern 1 is to pump the solution into the tube from the bottom and overflow from the top. Pattern 2 is to spray the solution on the inner surface and flow from the top to the bottom along the inner wall. Experimental results indicated that the first-order reaction rate constants for photo degradation of phenol with pattern 1 is about 2 times of that with pattern 2 because phenol can be directly degraded easily by UV lights. However, the corresponding degradation rate constants of MB with pattern 2 is about 2to 3 times of that with pattern 1 because MB can not be directly degraded easily by UV lights. In addition, effects of tube radius and extinction coefficient on the reaction constant were also studied. The rate constant will increase with the decrease of extinction coefficient while the tube radius is fixed, and an optimal tube radius for the maximum value of reaction rate constant can be found while extinction coefficient is fixed.

Characteristics of TiO2 Film Immobilized on Glass and Stainless Steel Tube and Photodegradation of Phenol

In this work, the TiO2 film was immobilized on the surface of glass and stainless steel tubes by sol-gel method and phenol was photo degraded with the TiO2 film. Compared with stainless steel, the photo catalytic activity ofTiO2 film on glass is lower, although the surface of glass is more even. According to the XPS results, appearance of the element Na decreases the photo catalytic activity. Photo degraded with TiO2 film immobilized on stainless steel tube for 20 min, phenol removal were 36.58% and 98.36% for initial concentrations of 118.90 and 1.83 mg. L-1 respectively. In this review, TiO2 film immobilized on the inner wall of stainless steel tube is fit to treat contaminants with low concentration.

Preparation of Ag+ Doped Nanometer TiO2 Photocatalyst with Sol-gel Auto-igniting Synthesis Method

To investigate the photo catalytic activity of metalion doped TiO2 synthesized with sol-gel auto igniting synthesis (SAS) method, Ag-TiO2 photo catalyst was synthesized with TiCl4 as raw materials, citric acid as combustion agent, ammonium nitrate as assistant. Methylene blue was degraded with synthesized catalyst illuminated by UV light and sun light separately. Results showed that the photo catalytic activity increased when Agloading was 1.5% (mol), which was 2.18 times of that with UV light and 1.14 times of that with sun light as light source separately. However, excessive loading of Ag would decrease the photo catalytic activity of TiO2.

Degradation of Methylene Blue Using Sunlight with Fixed and Suspended Ag/TiO2 Photocatalyst

In this work, Ag/TiO2 photo catalyst was prepared by depositing elemental Ag on the surface of TiO2 particle surface. Ag was got by reducing ion Ag+ in the suspension of TiO2 with illumination of UV light. When it was used to degrade ethylene blue (MB) using UV light, Ag/TiO2 gave higher catalytic activity than TiO2. To examine the influence of existing type of catalyst on photo degradation of organic compounds using sunlight, MB was degraded using solar energy with Ag/TiO2 fixed and suspended separately. Experimental results indicates that it has not much more advantages to degrade organic compounds with catalyst suspended in solution than fixed on somewhere in reactor under the condition of fixing the treating amount of solution per unit time, although the time needed by suspended catalyst is less than that by fixed catalyst for degrading MB to the same concentration. At first, the recovery processing of catalyst will increase the expense. Secondly, the time needed by fixing typeTiO2 will decrease by increasing the reaction area. So, it is necessary to set much more attention on the designing of sunlight photo catalytic reactor with fixing type catalyst. Key words: photo catalyst, sunlight, fix, suspend.