Aromatic VOC Removal by Formation of Microparticles in Pure Nitrogen Discharge Barrier Discharge

Abstract

The treatment of an oxygen‐free gaseous effluent polluted by an aromatic VOC in a discharge barrier discharge (DBD) was investigated. The gaseous mixture was prepared by diluting toluene in N2. The efficiency was investigated in terms of pollutant conversion and by‐product formation. With regard to the pollutant conversion, the destruction efficiency was comparable to that obtained when air was used. However, an original polymerisation mechanism was evidenced by the use of N2 in the DBD reactor. SEM analysis showed that toluene reacts in the DBD to form micrometric particles that can easily be removed by filtration. The polymerisation pathways were determined using GC/MS and XPS analysis. The respective roles of the nitrogenated active species and the hydrodynamics of the discharge are shown.

Plasma Reactivity and Plasma-Surface Interactions During Treatment of Toluene by a Dielectric Barrier Discharge

“…Trace of methanol (CH 3 OH) and acetic acid (CH 3 OOH) were detected, strengthening the proposal for reactions (54)(55)(56); methanol can also come from reaction (42), and the acetic acid from:…”

“…7 are plotted concentrations of C 2 H 2 , CH 4 , and HCN as functions of the HV-pulse frequency, for 400 ppm of toluene and a temperature of 50°C. These molecules have also been detected in other type of plasma reactors [24,29,54]. Their presence strengthens that toluene is dissociated in the plasma through, at least, two types of reactions: (i) abstraction of the methyl group, (ii) breaking of the benzene ring, as suggested for the first time by Urashima et al [55].…”

“…It has been proposed recently [54] that N-atoms could recombine with bi-radicals such as H°C = C 3 H 3 -C (CH 3 ) = C°H, followed by dissociation to give CN. However no data exists in the literature concerning either recombination processes of CN with aromatic radicals, or addition of N to bi-radicals.…”

Removal of gaseous toluene and submicron aerosol particles using a dielectric barrier discharge reactor

“…During DBD operation, a relatively low oxygen concentration (i.e. relatively high upstream toluene concentration) led to the formation of CO due to the incomplete oxidation reaction between the active species and toluene related molecules [22,23]. Hence, the CO 2 : CO 2 + CO ratio decreased with increasing upstream toluene concentration.…”

Nitrogen‐containing organic products from the treatment of liquid toluene with plasma‐activated N2 gas

“…The reactions of vaporized toluene in a dielectric barrier discharge (DBD) in pure nitrogen have been analyzed and discussed in fundamental studies on the degradation pathways of this organic pollutant in plasma‐based remediation processes. [ 15–17 ] Several toluene‐derived N‐containing organic reaction intermediates were observed in these studies, including benzonitrile, methyl pyridines, methyl benzonitriles, as well as HCN and low volatility, high mass polymerization products. [ 15–17 ] To the best of authors' knowledge, there are, however, no reports in the literature about plasma treatment of liquid toluene.…”