Modification,Loading And Characterization Of TiO₂ Photocatalyst

Photocatalytic oxidation technology was firstly realized in the 1970s, which is a new water treatment technology. TiO2 has been paid much attention as a representative photocatalyst. Much study found that TiO2 has not only the capability of treating waste water, but also a great potential in biological application. However, there is some obstacle in practical application of TiO2. Therefore, we made some modifying treatment to overcome the shortcomings of TiO2. All the researchs and results are as follows:(1) The experimental material Nd and I co-doped TiO2 (denoted as Nd-I-TiO2), which was synthesized by our laboratory in hydrolysis method, was immobilized on the pure aluminum piece through electrophoretic deposition. We discussed the influence factors on depositional film, such as the component of electrophoretic suspension, Zeta potential, electrophoretic voltage and electrophoretic time during electrophoretic deposition. Then the optimal content of component in electrophoretic suspension was as follows:0.03g Nd-I-TiO2 powder,0.08g PEG1000,3.2g boric acid solid powder and 80ml distilled water. After dissolving, the suspension was treated by ultrasonic in order to make Nd-I-TiO2 particles disperse uniformly. The Zeta potential was +6.06mV measured by iontophoretic instrument. Finally, under the 3V of electrophoretic voltage and 40min of electrophoretic time, the Nd-I-TiO2 film was deposited on Al piece, denoting as Nd-I-TiO2/Al. The result of visible-light photocatalytic degradating methylene blue solution showed that Nd-I-TiO2 still had quite good photocatalytic activity after loading on Al piece. Nd-I-TiO2/Al interacted with Escherichia coli (E. coli) under visible light. The absorbance, fluorescence microscopy and fluorescence polarization were measured. By CdSe/L-cysteine Quantum Dots(QDs) labeling, we can see the QDs enter the E. coli.,which indicating that Nd-I-TiO2/Al has damaging effect on E. coli. So the sample has great value in biological application.(2) TiO2 immobilized on activated carbon (AC) was prepared by sol-gel method, marked as TiO2/AC. And using deposition-precipitation method AgBr can deposite on the surface of TiO2/AC, then Ag/AgBr/TiO2/AC was synthesized. By the test of XRD, UV-vis diffuse reflectance and SEM-EDS, we character the four photocatalysts. Compared with TiO2, TiO2/AC and Ag/AgBr/TiO2, Ag/AgBr/TiO2/AC has the highest photocatalytic activity, which was evaluated by degradation of methylene blue under visible light. (3) The Ag/AgBr/TiO2/AC, TiO2, TiO2/AC and Ag/AgBr/TiO2 interacted with E. coli in order to compare the four biological activity of the four samples. Firstly, we can ascertain samples'bacteriostasis effect by absorbance test and halo test. In order to infer the mechanism of destroying E. coli, through ICP-AES the concentration of Ca2+ and Mg2+ was determined. Finally, after visible-light photocatalytic process the ATR-FTIR spectra of E. coli was measured by transform infrared spectrometer. Meanwhile, from the result Ag/AgBr/TiO2/AC has the highest photokilling E. coli activity.