Title :
Fluorescence detection of hydroxyl radicals in water produced by atmospheric pulsed discharges
Author :
Li, S. ; Timoshkin, I.V. ; Maclean, M. ; Macgregor, S.J. ; Wilson, M.P. ; Given, M.J. ; Wang, T. ; Anderson, J.G.
Author_Institution :
Dept. of Electron. & Electr. Eng., Univ. of Strathclyde, Glasgow, UK
Abstract :
It has been proven that hydroxyl (OH) radicals can be generated by streamer discharges across water surfaces under ambient atmospheric conditions. Hydroxyl radicals have the highest oxidation capability amongst all oxygen-based reactive species, thus OH play an important role in oxidation of organic molecules and the bactericidal effects of plasma discharges. In this study, generation of hydroxyl radicals in water by pulsed streamer discharges was investigated. Terephthalic acid was used as a chemical probe as this acid is converted into 2-hydroxyterephthalic acid (HTA) by chemical reaction with OH radicals. The concentration of OH radicals was quantified by measuring the fluorescence light intensity generated by HTA molecules in water solutions. Both positive and negative pulsed discharges with different voltage levels were tested. Two different types of sample holder - non-conductive plastic dishes, and dishes lined with conductive aluminum foil - were used in order to investigate the effect of the discharge propagation path on the efficiency of OH production. The efficiency of OH production was measured as a function of: the distance between the needle electrode and the water surface; the magnitude and polarity of HV energization; and the total delivered charge. The obtained results will help in optimization of non-thermal plasma systems for chemical and biological decontamination.
Keywords :
antibacterial activity; decontamination; discharges (electric); fluorescence; oxidation; oxygen compounds; plasma applications; plasma diagnostics; sterilisation (microbiological); 2-hydroxyterephthalic acid; HTA molecules; HV energization magnitude; HV energization polarity; OH; OH production; OH radical concentration; ambient atmospheric conditions; atmospheric pulsed discharges; bactericidal effects; biological decontamination; chemical decontamination; chemical probe; chemical reaction; conductive aluminum foil; discharge propagation path; fluorescence detection; fluorescence light intensity; hydroxyl radicals; needle electrode; negative pulsed discharges; nonconductive plastic dishes; nonthermal plasma systems; organic molecules; oxidation; oxygen-based reactive species; plasma discharges; positive pulsed discharges; pressure 1 atm; pulsed streamer discharges; total delivered charge; voltage levels; water solutions; water surfaces; Chemicals; Discharges (electric); Electrodes; Fluorescence; Liquids; Plasmas; Transient analysis; Fluorescence; OH radicals; Streamer discharges;
Journal_Title :
Dielectrics and Electrical Insulation, IEEE Transactions on
DOI :
10.1109/TDEI.2015.005147