Plasma Electronics Laboratory Hanyang University, Seoul, Republic of Korea Bio-Decontamination of Water and Surfaces by DC Discharge in Atmospheric Air 임영민

Plasma Electronics Laboratory Hanyang University, Seoul, Republic of Korea 2 Contents Introduction Material and Methods –Discharge Experimental Set-up –Flowing Water-Discharges with Electrostatic Spraying –Agar Surface- Direct and Indirect Exposure to Plasma –Measurements of the Oxidative Stress Results and Discussion –Flowing Water Treatment Through the Stressed Electrode –Oxidative Stress Induced in Bacteria –Direct vs. Indirect Plasma Treatment Conclusions

Plasma Electronics Laboratory Hanyang University, Seoul, Republic of Korea 3 Introduction

Plasma Electronics Laboratory Hanyang University, Seoul, Republic of Korea 4 Introduction UV 는 고려하지 않는가 ? – 고려한다 하지만 Cold air discharge 에서 멸균 자외선 영역인 (220~280nm) 의 자외선이 잘 발생하지 않는다. 따라서 영향이 별로 크지 않을 것으로 예상된다. Atmospheric air plasma source –Streamer corona(SC) –Transient spark(TS) Characteristics of SC and TS –Nanosecond repetitive pulses –Non-equilibrium plasma

Plasma Electronics Laboratory Hanyang University, Seoul, Republic of Korea 5 Material and Methods Discharge Experimental Set-up 5-10mm gap

Plasma Electronics Laboratory Hanyang University, Seoul, Republic of Korea 6 Material and Methods Flowing Water-Discharges with Electrostatic Spraying -2 가지 플라즈마 소스를 이용, SC 와 TS. -8mm 의 gap, Water flow rate = 0.5mL/min 에서 실험을 진행. -Cold air discharge for easy application in ambient environment.

Plasma Electronics Laboratory Hanyang University, Seoul, Republic of Korea 7 Material and Methods Agar Surface- Direct and Indirect Exposure to Plasma -Direct and Indirect Exposure to Plasma -Case a) = direct exposure to plasma -Case b) = indirect exposure to plasma with UV -Case c) = Indirect exposure only with UV

Plasma Electronics Laboratory Hanyang University, Seoul, Republic of Korea 8 Material and Methods

Plasma Electronics Laboratory Hanyang University, Seoul, Republic of Korea 9 Material and Methods Measurements of the Oxidative Stress -Interaction of ROS with bacterial cell membranes + ROS Thiobarbituric acid reactive substance (TBARS)

Plasma Electronics Laboratory Hanyang University, Seoul, Republic of Korea 10 Results and Discussion Flowing Water Treatment Through the Stressed Electrode –TS 는 초기 미생물의 대략 3 log 정도 SC 는 1 log 정도 줄임. –E value(Joule per treated water volume and one log reduction of microbial population) – 열에 의한 멸균 효과는 고려하지 않는가 =>TS 에서 최대 약 10K 의 온도 상승효과, 치명적인 열 멸균 효과는 기대 없다.

Plasma Electronics Laboratory Hanyang University, Seoul, Republic of Korea 11 Results and Discussion Oxidative Stress Induced in Bacteria - UV source(Hg lamp, 254nm, 1min) for comparison. - UV 는 TBARS 을 만들지 않는다. 그럼에도 efficiency 는 매우 높음. - SC 와 TS 는 TBARS 를 만들어낸다.

Plasma Electronics Laboratory Hanyang University, Seoul, Republic of Korea 12 Results and Discussion Direct vs. Indirect Plasma Treatment -Indirect treatment 는 agar 의 중성종에 의한 제염 효과를 봄. -Void 가 treatment 후에도 주변과 비슷한 온도를 유지, 열에 의한 멸균효과는 무시. -Inactivated area 가 노출시간에 따라 증가하는 경향.

Plasma Electronics Laboratory Hanyang University, Seoul, Republic of Korea 13 Results and Discussion Direct vs. Indirect Plasma Treatment - 중성종의 dominant 한 영향 Direct exposure is much more stronger for 5s. At 15s, direct and indirect effects become more similar At 60s, there is very little difference between the direct and indirect. A crucial role of reactive neutral species.

Plasma Electronics Laboratory Hanyang University, Seoul, Republic of Korea 14 Results and Discussion

Plasma Electronics Laboratory Hanyang University, Seoul, Republic of Korea 15 Conclusions 대기압 방전 플라즈마인 SC 와 TS 를 이용한 흐르는 물과 Agar 표면에서의 효 과는 매우 효율적임이 입증되었다. ROS 의 역할이 TBARS method, Agar 표면에서 void 관찰로 확인 되었다. Direct, Indirect exposure 실험으로 60s 이상에서 동일한 효과를 내는 것을 관 찰, 제염에서 reactive neutral species 가 dominant 함을 보았다. Charged particle 은 short time exposure 에 큰 역할을 하고, neutral species (such as ROS) 는 longer exposure 에 큰 역할을 한다. SC 와 TS 의 UV 에 의한 제염 효과는 미비했다. Cold atmospheric air DC discharges can be efficiently used for bio decontamination of water and various surfaces!

Plasma Electronics Laboratory Hanyang University, Seoul, Republic of Korea 16 Reference

Plasma Electronics Laboratory Hanyang University, Seoul, Republic of Korea 17 Reference

Plasma Electronics Laboratory Hanyang University, Seoul, Republic of Korea 18 Reference From Plasma bio decontamination, medicine and food security. Eddited by Zdenko Machala, Karol Hensel and Yuri akishev