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Plasma Sci. Technol. ›› 2018, Vol. 20 ›› Issue (4): 044011.doi: 10.1088/2058-6272/aaa8da

• Plasma Biomedicine • Previous Articles     Next Articles

Influence of water content on the inactivation of P. digitatum spores using an air–water plasma jet

Youyi HU (胡友谊)1, Weidong ZHU (朱卫东)1,2, Kun LIU (刘坤)1, Leng HAN (韩冷)3, Zhenfeng ZHENG (郑振峰)1 and Huimin HU (胡慧敏)1   

  

  1. 1 The State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, No.174 Shazheng Street, Shapingba, Chongqing 400044, People’s Republic of China 2 Saint Peter’s University, Jersey City, NJ 07306, United States of America 3 The Citrus Research Institute, Chinese Academy of Agricultural Sciences, Chongqing 400712, People’s Republic of China
  • Received:2017-11-09 Published:2018-01-18
  • Supported by:

    This work was supported by National Natural Science Foundation of China (NSFC) under Grants No. 51407020, National Key Technology Research and Development Program of the Ministry of Science and Technology of China under Grants No. 2014BAC13B05 and Visiting Scholarship of State Key Laboratory of Power Transmission Equipment & System Security and New Technology (Chongqing University) No. 2007DA10512716404.

Abstract:

In order to investigate whether an air–water plasma jet is beneficial to improve the efficiency of inactivation, a series of experiments were done using a ring-needle plasma jet. The water content in the working gas (air) was accurately measured based on the Karl Fischer method. The effects of water on the production of OH (A2Σ+ –X2Πi) and O (3p5P–3s5S) were also studied by optical emission spectroscopy. The results show that the water content is in the range of 2.53–9.58 mg l-1, depending on the gas/water mixture ratio. The production of OH (A2Σ+ –X2Πi) rises with the increase of water content, whereas the O (3p5P–3s5S) shows a declining tendency with higher water content. The sterilization experiments indicate that this air– water plasma jet inactivates the P. digitatum spores very effectively and its efficiency rises with the increase of the water content. It is possible that OH (A2Σ+ –X2Πi) is a more effective species in inactivation than O (3p5P–3s5S) and the water content benefit the spore germination inhibition through rising the OH (A2Σ+ –X2Πi) production. The maximum of the inactivation efficacy is up to 93% when the applied voltage is -6.75 kV and the water content is 9.58 mg l-1.

Key words: air–water plasma jet, water content, inactivation efficiency, P. digitatum spores, OH (A2Σ+ –X2Πi), O (3p5P–3s5S)