Pulsed underwater corona discharges as a source of strong oxidants: •OH and H2O2

Abstract

Because of undesirable side effects of chemical methods pulsed underwater corona discharges are emerging as a potential future advanced oxidation process (AOP) for water disinfection. In pulsed corona discharges a discharge channel is created, which contains a non-thermal plasma with a low degree of ionisation and low electron densities, but with electron energies of up to 10 eV. It has been demonstrated that electrons with this energy can dissociate water and oxygen molecules and produce various reactive radicals (*OH, H*, O*, HO2*), molecular species (H2O2, H2, O2), ultraviolet radiation and shock waves. It is supposed that the combination of all effects leads to a very efficient killing of microorganisms. To understand this in detail and to improve the efficiency of the overall system there is the need to develop suitable diagnostic methods for the quantitative determination of the various oxidants produced during the discharge. In this paper we present preliminary experimental results obtained with different chemical probes for *OH radicals, and H2O2 produced by pulsed corona discharges.

Oxidative DNA damage caused by pulsed discharge with cavitation on the bactericidal function

“…Thus, such concentrated OH radical will react each other with high efficiency, and then H 2 O 2 are generated. This finding is consistent with the results of a previous study [Gupta and Bluhm, 2007]. ROS localization is a key factor associated with cellular DNA damage.…”

“…When OH radical attacks the C-8 position of guanine, 8-hydroxy-7,8-dihydroguanyl radical is formed, which thereafter is converted to Fapy-G and 8-OH-G via reduction and oxidation reactions, respectively [Cadet et al, 2010]. Oxidative purine lesions induced by -irradiation probably contain 8-OH-G more abundantly than Fapy-G. On the other hand, the pulsed discharge could induce Fapy-G more abundantly than , and water radical ion (H 2 O + ) [Gupta and Bluhm, 2007;Jiang et al, 2014]. Reactive species such as OH radical, 1 O 2 , and O have very short half-lives.…”

“…These reactions seem to be generated on the boundary between plasma and water of the bubble [Jiang et al, 2014;Miichi et al, 2002;Shih and Locke, 2009]. H 2 O 2 generated in water by plasma seems to play an important role in a mechanism of the bactericidal effect [Sato et al, 1996], which is formed via the recombination of two OH radicals each other [Gupta and Bluhm, 2007;Sato et al, 1996]. Thus, the importance of ROS has been recently recognized for sterilization effect caused by the plasma, and some previous studies have quantitatively determined the yield of ROS formed via plasma by colorimetry with indicator chemicals, such as terephthalic acid [Bai et al, 2010;Sahni and Locke, 2006;Sato et al, 1996].…”

Water Purification by Plasmas: Which Reactors are Most Energy Efficient?

“…Free radicals react with the toxic organic compounds (RH), their intermediates (R • ) or with each other through reaction such as the following [24] Initial reaction rates for the formation of • OH and H 2 O 2 have been described in literature [45,46]. Highly reactive free radicals are lost during production of species like H 2 O 2 .…”

Nonthermal Plasma–Liquid Interactions in Food Processing: A Review

“…Corona discharges (Figure B) are one of the highly researched NTP discharge methods. Pulsed corona discharge is a potential alternative to the existing advanced oxidation processes in water treatment (Gupta & Bluhm, ) and it has been widely reported for its microbial inactivation efficiency in water (Abou‐Ghazala, Katsuki, Schoenbach, Dobbs, & Moreira, ; Sato, Ohgiyama, & Clements, ; Soušková et al., ; Šunka, ). Corona discharge could be produced by applying high‐voltage to a thin electrode or wire.…”