Disinfection Of Indoor Air With Needle Array Corona Discharge-nanophotocatalysis Coupling System

At present,under the environment of Novel Coronavirus pneumonia,indoor air purification and disinfection has become a prominent problem in the prevention and control.With regard to the existing technologies of air purification and disinfection,it is difficult to achieve purification and disinfection of air under the condition of high efficiency and no secondary pollution based on a single technology formed decontamination and disinfection process.Combined processes are the main direction in the development of disinfection technology for indoor air purification.Low temperature plasma technology shows unique advantages in many sterilization technologies because of its fast,efficiency and safety advantages.Nano-photocatalysis technology is widely used in the field of air pollution control because of the advantages of typical photocatalyst TiO₂,such as strong oxidation ability,strong availability,environment-friendly and non-toxic.At present,there are some drawbacks in using these two technologies alone in air purification and disinfection.The plasma-photocatalysis technology based on the combination of these two technologies has shown an attractive application prospects in indoor air purification and disinfection.In this thesis,the effect of needle array corona discharge-nanophotocatalysis coupling system on indoor air purification and disinfection was studied.Firstly,by investigating the number of needle electrodes,the spacing between needle and plate,the type of plate electrodes and the polarity of power supply for needle array corona discharge,the optimum conditions for building a discharge reactor were determined.The discharge reactor was constructed with negative corona,needle plate space of 8 mm,and plate electrode（hole diameter of 2 cm）.The coupling method between needle array corona discharge reactor and nanophotocatalyst was investigated.The needle array corona discharge synergistic nanophotocatalysis system was constructed by coating the Nano-Photocatalyst on the surface of the plate electrodes,and the experiment was carried out in a gas-free flow mode.Furthermore,we investigated the inactivation of E.coli by needle array corona discharge-nanophotocatalysis coupling system.The results show that the higher the applied voltage and the longer the discharge time,the better the sterilization effect.When the voltage is 6 kV,the sterilization rate can reach 100%in about 8 minutes,and the sterilization effect of negative corona is significantly higher than that of positive corona.The sterilization effect of synergistic system based on Ag/TiO₂ is better than that of corona discharge alone,while that of TiO₂ is the worst.Based on the needle array corona discharge-nanophotocatalysis coupling system as the core components,we also designed and constructed the air purification and disinfection machine prototype,and tested the particulate matter,pathogenic bacteria,influenza A virus and secondary pollutants produced during operation in a 30 m³ closed cabin.The results show that the air purification and disinfection machine has excellent purification and disinfection function for common indoor air pollutants,and the emission concentration of secondary pollutants fully meets the national standards.Finally,the Ag/TiO₂nanophotocatalyst was characterized by TEM,XRD and UV visible DRS,and the needle array corona discharge reactor was diagnosed by spectrum and the basic parameters of plasma were estimated.It was found that the increase of voltage would make the collision and energy transfer between particles in plasma more sufficient,crystal violet spectrophotometry was used to evaluate the formation and concentration of reactive oxygen species in the process of needle array corona discharge cooperating with Ag/TiO₂ system discharge;Then,through the comprehensive analysis of electrical,optical diagnosis and in-situ or non in-situ characterization technology,the mechanism of needle array corona discharge-nanophotocatalysis coupling system to purify disinfected air was discussed.