Quantification and risk assessment of organic products resulting from non‐thermal plasma removal of toluene in nitrogen

Abstract

A health-related index (HRI) was introduced to assess the health risks associated with these organic products. The HRI was not correlated with the removal efficiency (η), with higher η possibly yielding higher HRI, associated with higher health risks. Specific input energy (SIE) was a key factor affecting the formation of the observed organic products and their HRI values. We conclude that in practical applications, SIE, HRI, and η must be balanced.

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

“…The presence of these products, in spite of the fact that air and oxygen were not purposedly admitted in the reaction system, is attributed to residual oxygen, which efficiently quenches excited nitrogen species, as discussed later, and makes oxidation highly competitive. Experiments were run to investigate the effects of a few process variables on the obtained product distribution, namely (i) the N 2 flow rate, which was tested at 50, 75, and 100 ml/min; (ii) the treatment time, which was set at 30, 75, 100, and 150 min; and (iii) the process gas nature and composition, which were tested using N 2 /argon mixtures, as argon allows to ignite plasma at relatively low applied voltages [ 17 ] and might favor molecular nitrogen dissociation. [ 18 ] All these experiments produced results that are not significantly different from those reported in Figure 2.…”

“…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.…”

“…[ 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. Based on these observations, we decided to investigate the possibility to synthesize benzonitrile and other valuable C–N‐containing organic chemicals from liquid toluene using a DBD in N 2 at room temperature and atmospheric pressure to generate reactive nitrogen species and inject them into the liquid.…”

Application of proton transfer reaction mass spectrometry for the assessment of toluene removal in a nonthermal plasma reactor

“…Proton transfer reaction mass spectrometry has been applied in some studies related to VOC removal using different techniques, such as photocatalytic oxidation, vacuum ultraviolet photolysis, and wet scrubbing coupled with the photo‐Fenton reaction . Recently, a laboratory‐developed proton transfer time‐of‐flight mass spectrometry (PTR‐TOFMS) instrument was used to investigate toluene removal by NTP in our laboratory . Although valuable results were obtained, there are still some problems that must be solved.…”

“…31 Recently, a laboratory-developed proton transfer time-of-flight mass spectrometry (PTR-TOFMS) instrument was used to investigate toluene removal by NTP in our laboratory. 14,32 Although valuable results were obtained, there are still some problems that must be solved.…”