Study On Multifunctional Sterilizer Based By Non-thermal And Atmospheric Pressure Plasma

Atmospheric pressure cold plasma is a kind of non-thermal and non-equilibrium plasma.The plasma is produced by the gas which is ionized by the external high-energy,such as high voltage,high electromagnetic fields,and radiation.Studies have shown that plasma can explode and kill the microorganism and destroy the chemical substances(such as ethanol,acetaldehyde,acetone,benzene,camphor,butane,mineral oils,organic chlorine,cyanides,sulfides,alkylate,etc.).It can change these substances into the harmless objects(carbon dioxide,steam and oxygen).Throughout the course of the reaction,the temperature will remain at 38℃-47℃.In recent years,the plasma sterilizers have been considered as the products of high efficiency and environmental protection features.According to the needs of practical application,we design and produce a multifunctional plasma sterilizer based on the theory of non-thermal and non-equilibrium,which has the functions of air disinfection,water disinfection and surface disinfection.And Under the simulated environmental conditions,the inactive efficacy of the sterilizer have been observed.The research results are as follows:1.Design and fabrication of multi-functional plasma sterilizerThis multifunctional combined plasma sterilizer consists of 3 sets of plasma-electrode,power supply,voltage regulator,temperature control,ventilation,gas transmission,function switch of the original composition.Gas output tube and surface disinfection probe(electrode)is outside of the host.The whole dimension of the sterilizer is 45cm*34cm*9cm,weighing about 5kg.The size of surface disinfection probe and multi-channel barrier discharge element are 20cm*12cm*11cm and 7.5cm*4cm respectively.The weight of the surface disinfection probe is 762 g and the distance is 4.5mm from the nearest surface disinfection.Water disinfection aeration stone of micro pores is 7.8cm in diameter,1.5cm in thickness and 122.7g in weight.We measured concentrations of hydroxyl radicals near the surface sterilized probe electrode and ozone in water of fenton reaction method and redox titration respectively.The production rate of hydroxyl radicals near the surface disinfection electrodes is 2.6124*10-7mol/min.The ozone concentration is 36mg/L after 30 min of disinfection.2.Observation of disinfection efficacy2.1 Air disinfectionIn the test of air sterilization,the killing rate of Staphylococcus Albus is more than 99.990% in the aerosol cans(1m3)of simulation for 60min(temperature:22℃-25℃,relative humidity:50%-55%).2.2 Water disinfectionThe results showed that the sterilizer can kill the Escherichia coli by 100% in 80 liters of simulate water for 10min(temperature:20℃-25℃).The sterilizer can also kill the Coliform bacteria in the natural water of 2L in 30min(The Yangtze River and Jialing River)completely.Cell culture test showed that the sterilizer can kill the Poliovirus-I in 500 ml water by the log values of 3.25(10min)、4.5(20min)、5.25(30min)in different times respectively.2.3 Surface disinfectionThe killing rate of Escherichia coli and Staphylococcus aureus are 100% at the distance of 4.5mm in 30 s by the plasma sterilizer.The killing rate of Bacillus Subtilis can be 100% after disinfection in 180 s.We also have observed the bacterial’ morphology by transmission electron microscope after the disinfection.After 20 s of disinfection,the fimbriae of Escherichia coli is shedding and it’s body is deformed and narrow.We also have found that the bacterial is degradating and its structure is broken and blurred.Staphylococcus aureus is relatively intact,but the shape is deformed.The arch structure outside cell wall is disappeared,the density of cell wall and the cell is decreased.These phenomena fully comfirmed the effect of plasma sterilization.Under simulated conditions of surface contamination,the killing rate of Aleurolyphus ovatus can be 90%-100% in 70s-80s(room temperature:20℃-25℃,sterilization temperature:35℃-43℃)at the distance of 4.5mm by the electrodes.