Experimental Study On Inactivation Of Spores By Pulsed Plasma Jet Array

Under the epidemic background,disinfection and sterilization have become an important part of epidemic prevention work.Non-thermal plasma(NTP),as one non-selective technology,has attracted much attention in fields of disinfection and sterilization due to its high efficiency,low temperature,and safe while operation.In this work,the Staphylococcus aureus and Bacillus subtilis were selected as the target to evaluate the effect of sterilization.Two kinds of homemade 4×4 and 9×9 channel reactors were used to generate plasma jet,which were powered by a pulsed power supply.The effect of discharging process on jet structure,and inactivation efficiency was investigated,which explored the possibility for the scaling up of plasma jet.The main contents and conclusions of this paper are as follows:(1)With helium as the background gas,the 4×4 channel jet operated stably under the voltage ranging from 6 kV to 15 kV,frequency ranging from 1 kHz to 15 kHz,flow rate ranging from 5 L/min to 15 L/min.The lengthen of 4×4 and 9×9 channel jet could obtain more than 4 cm and 6 cm,respectively.Other gas or vapor introduced could abundant the kinds of active species.And the temperature of jet was kept low level between 16-19℃ without obvious burning and electric shock during operation.(2)The effect of parameters was discussed during the inactivation of bacterial spores by 4×4 channel jet.Results found that the high efficiency was achieved after jet treatment,and there was almost no bacterial in the area of jet contact.The increase of working voltage and pulse frequency,the prolongation of treatment time,and the appropriate flow rate of carrier gas are beneficial to the inactivation of spores.Compared with Ar-jet,He-jet had the better behaviors,which could weaken after the introduction of 1%O2 or 0.07%vapor.That might attribute to the electric features change,leading to sterilization ability reduction.(3)Based on 4×4 channel jet,the 9×9 channel jet was employed to discuss the effect of parameters,finding that the 9X9 channel jet enlarged the area of plasm,kept the sterilization efficiency,and consume lower energy during the same condition.(4)Electron microscope characterization was used to analyze the spore biofilm structure affected by jet,exhibiting that the biofilm was broken and contents flowed out,which might cause the spore inactivation.