Study Of Method And Application For UV-shielding Capacity Evaluation Of Nano-oxide

The ultraviolet(UV) radiation is the importance in human being' life, however, the excess UV radiation causes all kinds of dematosis, ageing and damage. As the environment has been damaged increasingly, people are likely to be exposed to an increasing dose of UV radiation. It is the time for humen to protect ourselves.The wide application of organic sunscreen has protect us from the excess UV radiation effectively, but its protection in UVA is not good enough. Scientists find the nano-oxide,like as titanium dioxide, zinc oxide and so on, have excellent capacity of UV-shielding and block all wave ultraviolet and more safer than the organics.Scientists also find the disadvantage of the nano-oxide, for example,they have photocataysis oxide capacity, they can not disperse in organics well. But they get a resolve through coating the nano-oxide with other oxides. So it provides a perspective for the nano-oxide application in sunscreen. This dissertation starts with the mechanism of nano-oxide UV-shielding and proposes two method for evaluation of UV-shielding: electroanalysis with the TiO₂ film sensor and flow injection analysis with thin lay photocell. Then at the last part of the dissertation we give a method of evluate the sunscreen. The following is the work in this dissertation.Chapter 1: IntroductionIn this chapter, the damage of the ultraviolet radiation, the characteristic of nano-oxide for UV-shielding, the coating on nano-titania and its application of sunscreen is reviewed.Chapter 2: The mechanism of nano-titanium dioxide for UV-shieldingWith the increasing of ultraviolet radiation on humen being, people has paid a great attention to the sun protection. However, the organics sunscreen has its defect so people add the nano-oxides to the sunscreen for improving the capacity of sun protection. The mechanism of nano-titanium dioxide has not been understood so far. In this chapter, we employed the photoelectroanalysis and resonance scattering analysis to study the mechanism of nano-titania for UV-shielding.Chapter 3: Nanostructured TiO2 film electrode and its application in UV-shielding Capacity Evaluation for nanometer oxidesIn this work, the nanostructured TiO2 film electrode was prepared by the sol-gel method and applied to evaluate the UV-shielding capacity of kinds of nanometer oxides. When the UV-light shines on the TiO2 layer, photocurrent linear to the light intensity is produced. By determining the reduction of this current caused by the addition of nanometer oxide, the UV shielding effect of the oxide was monitored and assessed. The method gave out the evaluation results for kinds of oxides in good accordance to the integrated absorbency achieved by UV/Vis spectrophotometer. But for its high assessing speed and sensitivity, this novel method shows to be a promising way for UV-shielding capacity evaluation.Chapter 4: Flow injection analysis and its application in UV-shielding Capacity Evaluation for nano-oxidesIn this chapter, we preparared TiO2/Ti electrode with anodic oxiding the titanium stick and evaluated the nano-oxides UV-shielding capacity. The result showed that the electrode had a sensitive and rapid response to the ultraviolet radiation. We also prepared the thin lay photocell with the new style electrode and jointed with the flow injection analysis. We compared kinds nano-oxides UV-shielding capacity. This method will offer people a new idea for thenano-oxides evaluation.Chapter 5: Study on the sunscreen in UV-shielding capacity and its applicationIt is a problem for consumer to tell the difference from the plenty of sunscreen cream, because the SPF can not indicate its capacity in UVA and UVB region. So it is urgent for government to constitute the rule about the evluation of sunscreen. The work in this chapter offered people a resolve to evluate the sunscreen and we studied the feasibility to evluate the sunscreen through the method of spectrophotography. At last we studied the application of nano-oxide for sunscreen.