Wen Jie Zhang

Photocatalytic Degradation of Methyl Orange on Y Zeolite Supported TiO2

The photocatalytic activity of TiO2/Y photocatalyst was investigated. The experimental results showed that the activity of TiO2/Y photocatalyst prepared by sol-gel method was greatly affected by calcination temperature and the nature of Y-zeolite. Photocatalytic degradation efficiency increased with increasing content of TiO2 on NaY zeolite and reached its maximum rate of 12.4% when TiO2 content was 90%. When TiO2 content was in the range of 50% to 90% , the activity of TiO2/HY was better than pure TiO2. The activity of TiO2/FeY was comparatively low in the TiO2 content range of 50-90%. The enhancement of photocatalytic activity of TiO2 after loading on Y zeolite is not appreciable, indicating that Y type zeolite is not a promising support for TiO2 prepared by sol-gel method.

Study on Environmental Materials with Pore Size and Photocatalytic Activity of Porous TiO2-Al2O3 Photocatalyst

A novel porous TiO2-Al2O3 composite as a kind of environmental material was prepared by sol-gel method. The pore size distribution is not even in the whole pore size range. When pore size is 7.049 nm, the maximum pore volume of the material is 0.06627 cm3·g-1. The average pore size for the material is 14.56 nm and the total pore volume is 0.3945 cm3·g-1, as calculated from BJH method. Photocatalytic degradation of methyl orange can be regarded as following first order kinetic reaction. After 90 min of reaction, methyl orange degradation on the material was 77.0% and the total dye decoloration rate was 95.1%, containing both adsorption and photocatalytic degradation. The intensities of both peaks in visible and UV regions decreased sharply during photocatalytic degradation process.

Photoelectrocatalytic Properties of Porous TiO2 Films Prepared Using ODA as Template

The functions of applied potential to the photoelectrocatalytic degradation process of methyl orange were investigated. When using 0.05 M NaCl and under different applied potentials, the degradation rate increased obviously with increasing applied potential. When the applied potential was between 0.6 V-1.0 V, the degradation rate was enhanced drastically. The detected current values got larger as the applied potential increased from 0 up to 1.2 V. There was no direct electro-degradation to the dye in the solution. The applied potential and the irradiated light had synergetic effect when they were applied to the solution at the same time. While after irradiation for 0 to 60 min, with the increasing reaction time, methyl orange absorption peak intensity shrank obviously. The azo and benzene groups in methyl orange degraded totally under photocatalytic process.

Some Influencing Factors on Photocatalytic Activity of TiO2 Film Prepared Using Sol-Gel Method

Subscript text TiO2 film was deposited on glass substrate by a sol-gel process. The influences of the SiO2 layer, distance between lamp and solution, and air flow rate were investigated. Methyl orange can be hardly degraded under UV light exposure alone. The adsorption rate of methyl orange on TiO2 film is negative after 25 min of stirring. Although distance between the lamp and the solution varies from 5.5 cm to 7.5 cm, the degradation rates decline slightly. There is nearly no influence of air flow rate on the entire degradation ability of the photocatalyst. SiO2 film coated on microscope glass slide has no photocatalytic activity under UV irradiation. In prior to deposit TiO2 film onto the surface of the glass substrate, a SiO2 thin layer is coated. The results indicate that the TiO2 film with SiO2 layer has much better photocatalytic activity that the film without SiO2 layer.

Porous TiO2-Al2O3 Photocatalyst: The Effects of Calcination Time

Porous TiO2-Al2O3 composite materials were prepared through sol-gel method after calcination at 500 oC for different time. FT-IR spectra of porous TiO2-Al2O3 composite materials revealed that the samples are composed of Al2O3 and TiO2. The sample calcinated for 2.5 h had the maximum specific area of 128.9 m2•g-1. High pore volume and average pore size were possessed by the samples calcinated for 1 h and 3 h. While being calcinated at 500 oC, photocatalytic activities of the materials increased at first and then dropped down with the increasing calcination time. The sample calcinated for 3 h showed the maximum activity of 35%.

Adsorption Property and Photocatalytic Activity of Sol-Gel Prepared Porous TiO2 Using PEG1000 as Template

PEG1000 was used as a template to prepare porous TiO2 photocatalyst through sol-gel process. The amount of PEG1000 and calcination temperature and time were studied with respect to porous TiO2 activity. At the optimum adding amount of PEG1000, 30.0% of the initial methyl orange was degraded. Methyl orange adsorption on the porous TiO2 maintained less than 2% during the whole template content range. During the calcination temperature range from 400 oC to 600 oC and time range from 2 h to 5 h, the optimum degradation activity appeared to the sample calcinated at 500 oC for 4 h. Adsorption of the materials had no variation at different calcination temperatures and times, and was quite weak compared with degradation efficiencies. 96.2% of the initial methyl orange was degraded after 100 min of irradiation.

Photocatalytic Activity of TiO2/Ti Film Prepared by Sol-Gel Method on Methyl Orange Degradation

TiO2 film was deposited on titanium substrate by a sol-gel dip-coating process. Photocatalytic activities of the films prepared with and without template were compared. The TiO2 film deposited on Ti substrate obviously could not adsorb methyl orange on its surface and the titanium substrate had very weak activity under UV light irradiation. The TiO2 films prepared without the addition of PEG1000 were calcinated at 450 oC, 500 oC, 550 oC, and 600 oC and the film calcinated at 500 oC showed the optimum photocatalytic degradation activity. The addition of PEG1000 could promote degradation of methyl orange that can be attributed to the possible pore forming in the TiO2 film.

Photoelectrocatalytic Degradation of Methyl Orange on Porous TiO2 Film Electrode in NaCl Solution

Porous TiO2 films and smooth TiO2 films were fabricated by sol-gel dip-coating technique using titanium plate as support substrate. Photoelectrocatalytic (PEC) degradation of methyl orange was investigated in aqueous NaCl solution using the TiO2 films. PEC degradation efficiencies showed strong dependence on the concentrations of aqueous NaCl solutions and applied potentials. Photoelectrocatalytic activity of the porous TiO2 film was higher than that of the smooth TiO2 film at lower applied potential. 95.2% decolorization of the dye could be achieved in 50 minutes at applied potential of 0.6 V in 0.05 M NaCl solution on porous TiO2 films, while the efficiency was only 79.9% on smooth TiO2 films. Electrodegradation (ED) of these two film electrodes almost had no effect on methyl orange. Photocatalytic oxidation (PCO) degradation was 36.4% for the porous TiO2 thin film after 80 min, and 32.6% for the smooth TiO2 thin film during the same condition.

Effects of Calcination Time on Structure and Morphology of Porous TiO2-Al2O3 Material

Porous TiO2-Al2O3 composites were prepared through sol-gel method after calcination at 500 oC for different time. PEG1000 was used as a template and tetrabutyl titanate and aluminum isopropoxide were used as the precursors. The materials prepared under different calcination temperatures were all composed of anatase TiO2 and amorphous Al2O3. All the samples presented anatase TiO2 crystalline structure. There was no rutile TiO2 phase appearing in the patterns. Meanwhile, there were no noticeable diffraction peaks of any of crystalline phases of Al2O3. Calculated from Scherrer formula on (101) plane of the XRD patterns, crystallite sizes of anatase TiO2 were 10.06 nm, 10.55 nm, and 11.13 nm, respectively. The surfaces of the materials were very rough with long grooves on the surface. The materials were composed of large amorphous like matrix, along with some small particles laying on the surface.

PEG and ODA as Composite Templates to Prepare Porous TiO2 Films by Sol-Gel Method

Porous TiO2 films were prepared through dip-coating on glass substrates using composite templates of PEG and ODA. Photocatalytic activity of the photocatalyst was evaluated by measuring removal rate of aqueous methyl orange under UV light irradiation. The addition of composite templates had obvious influence on surface morphology of the films. Layered and porous structures formed in the surface due to the function of templates. When the amount of PEG in the composite template increased from 0.1 g to 1.9 g, adsorption edge of the films moved to longer wavelength region. When the amount of PEG increased to 1.0 g, there were sharp decrease of specific surface area and cumulative pore volume. The improving photocatalytic activity as a result of addition of PEG can be noticed.