Papers by Author: Wen Jie Zhang

Abstract: Boron doped TiO2 photocatalysts was prepared by sol-gel method. The influences of Boric acid amount, reaction time and calcination temperature on photocatalytic activity of the prepared B-TiO2 were studied. The boron doped TiO2 had small adsorption capacity. 38.8% of the initial methyl orange was degraded on the sample prepared with 1% B2O3 after 30 min of irradiation. After 120 min of irradiation, nearly 100% of the methyl orange was degraded on the material. Photocatalytic activities of the boron doped TiO2 materials increased from 400 oC up to 500 oC. After that, degradation activity decrease with further increase of calcination temperature in the range from 500 oC to 600 oC.

Abstract: Porous and smooth TiO2 film electrodes prepared by sol-gel method were used on methyl orange degradation by an electro-assisted photocatalytic degradation process. The results indicates that methyl orange was barely degraded under the potential alone, availing that potential under 1.8 V had no noticeable effect on removal of the dye. The porous film electrode showed better electro-assisted photocatalytic activity than the smooth film electrode when the potential was above 0.6 V. The porous film showed better activity than the smooth film in nearly all the concentration range except for the highest one. The porous film exhibited better activity than the smooth one.

Abstract: The effects of H2O2 addition to degradation efficiencies of TiO2 and the mixture of TiO2 and HZSM-5 were investigated. When H2O2 concentration increased from 2 mmol/l to 8 mmol/l, methyl orange decoloration rates increased from 41% up to 90%. TiO2 concentration was 100 mg/l and decoloration rates varied with increasing H2O2 concentration. Decoloration of methyl orange increased from 45.3% to 90.3% when H2O2 concentration increased from 2 mmol/l to 8 mmol/l. Total decoloration of the dye mainly came from oxidation of methyl orange by either oxidation of H2O2 and photocatalytic oxidation process. There was a maximum H2O2 concentration in methyl orange degradation when using mixture of TiO2 and HZSM-5.

Abstract: HZSM-5 was prepared from NaZSM-5 through treatment with NH4Cl. Adsorption and photocatalytic degradation of methyl orange was investigated as the factors of HZSM-5 amount and reaction time. Adsorption of methyl orange on the mixtures varied slightly in the range from 1% to 10% when using zeolite in the concentration up to 800 mg/l. Adsorption contributed a small percent in the total decoloration of methyl orange. With increasing HZSM-5 concentration in the solution, total decoloration rate changed in a wide range. The maximum decoloration value was obtained in HZSM-5 concentration of 104 mg/l. After 70 min of irradiation, methyl orange decoloration on the mixture reached 99.5%.

Abstract: A mixture of TiO2 and HZSM-5 zeolite was used for adsorption and photocatalytic degradation of an azo dye, Active Brilliant Red X-3B. ABR X-3B adsorption on HZSM-5 zeolite is quite small although the amount of HZSM-5 is as many as 0.5 g/l. Photocatalytic degradation of ABR X-3B on HZSM-5 is less than 5% after 90 min of irradiation. When the adding amount of HZSM-5 is 300 mg/l, the maximum decoloration rate on the mixture reaches 88.1% that is 22.7% more than that on pure TiO2. The variations of adsorption and photocatalytic degradation on the mixture are not large with changing of HZSM-5 amount from 0.05 g to 0.6 g.

Abstract: Porous and smooth TiO2 film electrodes prepared by sol-gel method were used on methyl orange degradation by an electro-assisted photocatalytic degradation process. When using the applied potential along, there was no obvious degradation of methyl orange whether using TiO2 film electrode prepared using PEG template or not. The largest difference between the two electrodes appears at potential of 0.7 V in 0.05 mol/l NaCl solution, and the porous electrode shows better degradation activity in electro-assisted photocatalytic degradation. When NaCl concentration was 0.07 mol/l, degradation rates on porous and smooth film electrodes were 51.16% and 32.35 %, respectively. After 100 min of irradiation, 90% of the methyl orange degraded on the porous TiO2 film electrode, and 79.87% of the methyl orange degraded on the smooth TiO2 film electrode.

Abstract: 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.

Abstract: Photoelectrocatalytic oxidation of methyl orange on TiO₂ films were investigated in KNO₃ solution. In the potential range up to 1.2 V, electro-degradation rates were fairly low that was less than 1%. Degradation rates on the two films were larger at higher potentials. The film prepared without PEG showed better activities than the film prepared with PEG during the whole range of potential. Methyl orange degradation rate increased with increasing KNO₃ concentration from 0 to 0.010 mol/l. After 120 min of irradiation, methyl orange degradation rate on the film with PEG was 89.5%, while degradation rate on the film without PEG was 92.0% after the same period.

Abstract: Aeration and pH of methyl orange solution were adjusted to investigate the influences on photocatalytic degradation activities of TiO₂/HZSM-5. Degradation rate was enhanced when applying air into the solution. When air flow rate increased from 0 to 150 ml/l, methyl orange degradation rate increased from 47% to 55%. Further increase of air flow rate had nearly no influence on degradation rate. Degradation rate performed strong dependence on pH value of methyl orange solution. Acidic situation was favorable for methyl orange degradation, whereas methyl orange degradation in basic situation was comparatively weak. Photocatalytic degradation of methyl orange decreased with increasing of pH value.

Abstract: When potential was less than 1.2 V, electro-degradation rate was not more than 1.2% on both the films prepared using PEG or not. The film prepared with addition of PEG showed better degradation rates in the whole potential range than the film prepared without using of PEG. The highest degradation rates existed at 1.1 V of applied potential for both of the film electrodes, where degradation rate on film with PEG was 93.6% and the rate was 92.2% on the film without PEG. Methyl orange degradation rates increased with increasing KCl concentration from 0 to 0.7 mol/l, while degradation rates dropped down at even higher potential. Degradation rates increased with prolonged irradiation time for both of the two film electrodes.