Study On The Sterilization And Regulation Method Of ONOOH In Plasma-activated Water

A large number of primary active species are generated in the plasma,which will react with water to form secondary species,including H₂O₂,NO₃^-,andNO₂^-,then plasma-activated water(PAW)is obtained.At present,researchers at home and abroad have applied PAW to the field of sterilization,and put forward a variety of mechanisms to explain for its mechanism.Most are thought to be closely related to the reactive nitrogen and oxygen species in PAW and the complex chemical reactions involved,in which exists some speculations about the product ONOOH generated by the reaction of HNO₂ and H₂O₂.However,little research has been reported on the value of ONOOH in practical applications.At the same time,the discussion on how to increase the production and effective time of ONOOH through artificial regulation is of great significance for subsequent applications,but there are few relevant reports and studies at the present stage.Therefore,in this paper,through the detection of gas-liquid products and sterilization experiments,mainly aiming at the above problems,the characteristics of air plasma activated water under the structure of micro hollow cathode discharge(MHCD)and pulse needle water discharge are studied.The importance of ONOOH in the application and the method of prolonging its action time are deeply explored,which lays a foundation for promoting the efficient application of paw in the future.First of all,the detection methods applicable to different environmental conditions are found,including gaseous products,nitrate,nitrite and hydrogen peroxide in PAW.It provides guidance for the subsequent accurate determination of discharge plasma products.Secondly,under the condition of MHCD device,through the product characteristic detection and sterilization experiment,it is reflected that the sterilization of PAW is closely related to theNO₃^-,NO₂^-and H2O2 in the acid solution.At the same time,it is proved that the ONOOH produced by HNO₂ and H₂O₂ plays an important role in the process of sterilization,and its actual effective life is analyzed.The characteristics and mechanism of PAW are more deeply understood.What's more,the effect of PAW on spores reflects that the increase of voltage,treatment time and water content of working gas can effectively increase the output of ONOOH.Finally,using pulsed needle-to-water discharge,the plasma product is separated into two parts by blowing gas-liquid gap,which are respectively stored in the discharge chamber and the gas-washing bottle.In this system,because the solution in discharge chamber is neutral,H₂O₂ cannot react withNO₂^-,so both are detected and can be maintained for a longer time.And when used,it is mixed with the acidic solution in the gas bottle,led to the important product of ONOOH generated.Through the sterilization experiment,it is proved that PAW generated under this structure has obvious advantages,that is,the germination inhibition rate decreases slowly with the increase of storage time.In other words,using the advantages of the device to control the reaction of H₂O₂and HNO₂ is one of the effective methods to prolong the preservation time and effect of ONOOH.In addition,the variation of products under different gas flow conditions is also compared.It is found that gaseous and liquid products in discharge chamber or gas-washing bottle do not change monotonously with gas flow increasing.