Study On UV And Photocatalytic Inactivation Performance Of Bioaerosols

Bioaerosols are widely concerned because they can carry and spread harmful microorganisms and cause potential harm to human health.UV irradiation and photocatalytic oxidation are two fast and effective methods to control bioaerosol.In this study,the device usd for UV/photocatalytic inactivation was improved.A mechanical dynamic model based on photo reaction process was established to fit the experimental data and simulate the inactivation efficiency of UV irradiation.The inactivation performance of UV/photocatalysis on different microorganisms was systematically explored and the mechanism of these two methods was compared.In additional,a new two-dimensional material,MXene,and Ti O₂ with exposed{001}facets was used as photocatalyst,which was supported on porous polyurethane sponge.Supporting methods,characterization,and reactivity test were carried out.UV irradiation could effectively inactivate E.coli in bioaerosols.The inactivation efficiency of different UV wavalthgth follows the order UVD>UVC>UVA.And the inactivation efficiency of UVD and UVC reaches 3 lg and 2 lg,respectively when the residence time is 25 s.The inactivation efficiency increases with the increase of irradiation intensity,whereas the bacteria concentration has little effect on it.The dynamic model based on photochemical reaction principle had a good fitting with the experimental data.Interestingly,the bacteria after UVA and UVC inactivation could get reactivation repair,and the photo reactivation repair was more obsivious than dark repair.Two-dementional material-MXene,was successfully prepared by Li F etching and ultrasonic delamination.{001}Ti O₂ with 3.4%MXene content had the highest photocatalytic activity,which is 1.3 times higher than the pure{001}Ti O₂,and the band gap is reduced to 3.0～3.2 e V.The catalyst was supported on the surface of PU sponge with 1%dipping solution with ethanol.The addition of photocatalysis can significantly improve the inactivation performance.The inactivation efficiency of E.coli under UV365 and UV254 were 0.4 lg and2.5 lg,respectively,with residence time of 4.27 s and relative humidity of 95%.The inactivation efficiencies increased to 2.5 lg and 3.4 lg,respectively,when photocatalysis was added.The inactivation efficiency of UV/photocatalysis on different bacteria or states followed the order E.coli>B.subtilis>spore of B.subtilis,and 95%>70%>30%under different relative humidity.Increasing residence time and light intensity also improved the inactivation efficiency to some extent.E.coli and B.subtilis showed no photo reactivation and dark repair after UV/photocatalytic inactivation.The bacteria even showed a continious decline trend under visible light.As for inactivation mechanism,UV irradiation mainly damages the DNA of microorganism,while photocatalysis could bring the inactivation by oxidizing cell structure,which makes it a more thorough method to inactivate microorginisum and a more promising way to be used.