The degradation of aqueous phenol solutions by pulsed positive corona discharges

Abstract

The Advanced Oxidation Process pulsed corona discharges have been utilized for the degradation of phenol in aqueous solution. The pulsed positive corona discharges are struck in the ambient gas phase over the solution. Experiments have been performed using both an air and argon atmosphere. Phenol conversion and the production of major oxidation products in the solution have been determined, using ion-exclusion chromatography with UV absorbance and conductivity detectors in series. The corona pulse energy has been measured from voltage and current waveforms using capacitive current correction. Oxidation products are polyhydroxybenzenes and carboxylic acids. Even though phenol conversion efficiencies by pulsed positive corona discharges in air and argon are similar, the degradation pathways are different.

Degradation of organic dyes in water by electrical discharges

“…This can be explained by the electronegative character of oxygen. A similar behaviour was observed by Hoeben et al [16] for a corona discharge generated above the water surface in various gaseous atmospheres: oxygen, air and argon. The pulse duration was shorter in argon as compared to oxygen.…”

“…Electrical discharges in water or at the water-gas interface have been investigated as well for the degradation of various organic compounds [2,[9][10][11][12][13][14][15][16][17][18]. Gas phase ozone concentrations up to 3000 ppmv and liquid phase hydrogen peroxide concentrations up to 2.5 mmol/l were reported [19,20].…”

“…The main reactions responsible for free radical production and termination in the case of electrical discharges in water, as well as their rate constants are summarized in [21]. Experimental work on the decomposition of several molecules: phenol [2,9,10,14,[16][17][18], trichloroethylene [12], nitrobenzene [11], organic dyes [2,[13][14][15], using electrical discharges was carried out on laboratory scale.…”

Degradation of phenolic compounds in water by non-thermal plasma treatment

“…7, a) are catechol, hydroquinone, 1,4-benzoquinone, and 2-nitrophenol, along with trace amounts of formic and acetic acids. Among possible chemically active species which contribute to the degradation of phenols in the gasliquid phase NTP, OH radicals and ozone are expected to be the most important species, and these species are proposed to be generated above the water surface by the coronal discharge [10,19]. Oxidation by OH radicals has been previously shown to be the primary step in the degradation of phenol by the liquid phase discharge [10,17,20,21].…”

Induction of cell growth arrest by atmospheric non-thermal plasma in colorectal cancer cells

“…When a substrate is treated with cold plasma, chemical reactions were induced, generated by active radicals (Kim et al, 2008). Generation of atmospheric plasmas is not restricted to the gas phase: a well-known type is an underwater corona discharge, which has attracted much attention as a cheap and environmentally safe means for cleaning polluted water (Hoeben et al, 2000). In addition, a vacuum system is not required for cold plasma, making it possible to use in nanotechnology and biomedicine applications (Shashurin et al, 2008).…”