Preparation Of TiO 2 And Modified TiO 2 Mesoporous Microspheres And Their Photocatalytic And Antibacterial Properties

Photocatalytic oxidation technology of semiconductor with diverse advantages such as low energy consumption, simple operation, mild reaction conditions, full use of solar energy etc., is expected to become an important way to solve the problem of energy and environment in the 21 st century. Titanium?IV? dioxide?TiO₂? has attracted increasing attention because of its high efficiency, low-cost, and non-toxicity. In particular, nano TiO₂ power has been applied in various applications such as water and soil treatment, air purification, photocatalytic disinfection etc., due to its excellent photocatalytic performance. Howerver, nanoparticles often encounters practical problems such as deactivation caused by aggregation, difficulty in separation and collection etc., which increased the cost of sewage treatment.Large particles of TiO₂ with mesoporous structure provides one way to solve the collection problem after use without sacrifice of photocatalytic performance due to the large specific area of mesoporous structure.Herein, mesoporous TiO₂ and modified mesoporous TiO₂ microspheres were prepared via solvothermal process. The thesis is composed of the following parts:?1? Synthesis and characterization of mesoporous TiO₂ microspheres. Tetrabutyl titanate?TBOT? as Ti source was hydrolyzed and crystallized in media composed of acetic acid and ethanol, in which esterification catalyzed by TBOT occurred to in-situ “controlled water release”. Sample with 1.05 mL TBOT and 1.5: 8.5 ratio of acetic acid to ethanol has good morphology regularity with moderate particle size?D=0.85 ?m, PDI=0.005? and large surface area?148.2 m2/g?. After 140 min UV irradiation, the degradation rate of rhodamine B?RhB? is 70.76%.?2? Synthesis and characterization of mesoporous Ag/ TiO₂ microspheres. Under the condition of high temperature, Silver nitrate?AgNO₃? as Ag source was reduced by ethanol to form Ag nanoparticles?NPs? embedded evenly in the TiO₂ microspheres. Sample with 0.2 wt% of Ag content has the best photocatalytic performance with five times of rate constant than that of the unmodified TiO₂. After 140 min UV irradiation, the degradation rate of RhB is 99.76%, Additionally, under the dark condition, the minium inhibition concentration?MIC? and the minium bactericidal concentration?MBC? of the sample with 10 wt% of were 15 mg/L, 20 mg/L against E. coli, and 10 mg/L, 80 mg/L against S. aureus respectively, which showed more outstanding antibacterial performance than colloidal Ag NPs.?3? Preparation and properties of Fe³⁺/ TiO₂ microspheres. Iron nitrate nonahydrate?Fe?NO₃?₃·9H₂O? was used as the source of the metal ions for the modification of TiO₂ via “one-pot” route. A series of composite particles with different sizes were prepared via adjusting the dosage. XRD, XPS and TEM results showed that Fe element was in the form of Fe-O-Ti solid solution with TiO₂. The degradation rate of RhB is reduced with the increase of doping amount. And the samples show no antibacterial effect to both E. coli and S. aureus in the antibacterial test under the dark condition.