TiO₂Induced Photocatalytic Activation Of Staphylococcus Aureus Under405nm LED Light Irradiation

In recent years, indoor air pollution and pathogens resistant are being increasinglyserious; people earnestly hope to apply a new indoor air purifying technology with highefficiency, energy-saving and without drug resistance. As a semiconductor material,Titanium dioxide （TiO₂） is of good biocompatibility and lows cost. Considerable inactivationability can be acquired when combining it with suitable light source, which will cause thephotocatalytic reaction. Therefore, people pay more and more attentions to the technology ofinduced photocatalytic inactivation for its broad application prospects. This thesis is basedon the principle of induced photocatalytic degradation. We study and validate the feasibilityof TiO₂combined with405nm LED light source as an inactivation technology.Photocatalytic reaction of nano-TiO₂can only work with the light whose wavelenth isshort than385nm. We have to fix it because UV light source is harmful to human, and itcosts too much but cannot work for a long time. In our work, we doped TiO₂with Nitrogen（N-TiO₂） as one processing method, and marked TiO₂with Carbon Quantum Dots（CQDs-TiO₂） as the other. Both of the two different methods made TiO₂work in thecondition of visible light, for the response spectrum red-shifted and photocatalytic reactioncan occur by wavelenth which is greater than390nm.In the qualitative experiment, both N-TiO₂and CQDs-TiO₂showed inducedphotocatalytic properties of visible region, which verifies the theory. In the quantitativeexperiment, Staphylococcus aureus （S.aureus） was chosen to be the target for its strongfatality and high drug resistance reaction. For N-TiO₂,we mainly focused on the relation-ship of concentration of material and bactericidal effect of S.aureus, as well as the differenceof TiO₂and N-TiO₂, using suspension reactor. For CQDs-TiO₂, using fixed-film reactor, wepaid attention to the relationship of the amount of CQDs and bactericidal effect of S.aureus.The results are as follows:Been radiated by LED with center wavelength of405nm,7W, N-TiO₂withconcentration of5g/l obtained the57%inactivation efficiency as the maximum, which is as4times as that of TiO₂’s. For the other method, the maximum is30%, which is obtained byCQDs-TiO₂with processed for8h, and this value is as2times as that of TiO₂’s. The results of two experiments showed that both N doped or marked CQDs, which isusing the upconversion effect, are able to make TiO₂work in the visible condition. LED isqualified for the light source in the induced photocatalytic inactivation system for itsenergy-saving, long working lift and non-hazardous. Since the two methods can be taken forTiO₂simultaneously, so they can be combined in the future to acquire better inducedphotocatalytic inactivation efficiency.