Study On Atmospheric Pressure Jet Plasma Sterilization Effect

Plasma activated water has been received extensive attention as an emerging means ofdecontamination and disinfection.Research shows that reactive species such as OH enter the liquid and undergo a series of biochemical reactions with the biofilm,eventually leading to cell death.Therefore,it is especially important to diagnose reactive species in plasma and explore the interaction mechanism between plasma and bacteria.In this thesis,an atmospheric pressure needle-ring electrode plasma jet generator was used to generate plasma for activating water.The physicochemical properties of plasma activated water.such as: conductivity,oxidation-reduction potential,pH,liquid temperature and the reactive species in gas-liquid phase plasma jet.Have been diagnosed using optical emission spectroscopy approach the killing effect of plasma activated water on Escherichia coli was investigated under the different treatment conditions and storage conditions.The objective of the study is to investigate the inactivated the mechanism of reactive species to Escherichia coli in gas-liquid phase plasma.(1)A plasma jet device was designed and built to generate plasma activated water.The needle-ring electrode structure was used in the experiment to form a three-dimensional movable structure.It was integrated to the emission spectral diagnosis system to realize the detection of reactive species.(2)In the aseptic laboratory,the activation and culture of Escherichia coli,the preparation of medium and the inactivation of Escherichia coli by plasma activated water were completed.(3)The interaction mechanism reactive species and Escherichia coli was explored by used optical emission spectroscopy technology in plasma.The treatment time was from 0 to40 min,and the injection power and frequency were fixed at 0.4 W.9.4 KHz.The mechanism of action of Escherichia coli and reactive species was discussed.(4)The plasma activated water was prepared by He discharge under different power conditions.It was stored at 4 ?and 25 ? for 1 h,respectively.The injection power was from0 to 2.0 W and the treatment time was 10 min.The mechanism of producing and inactivating Escherichia coli in two storage conditions of reactive species was studied.Research the killing reasons of Escherichia coli.(5)The physicochemical properties of plasma activated water: electrical conductivity,oxidation-reduction potential,pH value,liquid temperature were investigated.The results were discussed under the condition of variable power and variable preservation.