# Online Monitoring of Molecular Processes in a Plasma Air Purifying System

Author(s) Schmid, Stefan, Meier, Lukas, Berchtold, Christian, Zenobi, Renato
Publication Type Journal Items, Publication Status: Published
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## Detailed Information

Title Online Monitoring of Molecular Processes in a Plasma Air Purifying System
Author(s) Schmid, Stefan
Meier, Lukas
Berchtold, Christian
Zenobi, Renato
Journal or Series Title Environmental science & technology
Volume Number 46
Issue Number 7
Start Page 4067
End Page 4073
ISSN 0013-936X
1520-5851
Publisher American Chemical Society
Publication Place Washington, DC
Publication Date 2012-04-03
Abstract Plasma air purifying systems present an interesting alternative to filters for purifying air. In this study, molecular processes in a commercially available ac driven plasma air purifier were studied in detail. This air purifier is supposed to reduce all air contaminants to small nontoxic molecules (e.g., H2O and CO2). However, degradation mechanisms ate not yet fully understood. In this study, we investigated the exhaust of the plasma air purifier to determine which degradation products are formed. An interface was designed and constructed to allow the direct coupling of the plasma air purifier's exhaust to a mass spectrometer. The compounds studied, primary and secondary amines, were introduced at a concentration of 1 ppmV. Contrary to our expectations, polymerization instead of degradation was observed. The higher the ac voltage applied (max. 9.0 kV) to the plasma air purifier, the higher the mass of the oligomer distribution. Side chain oxidation products as well as oligomers could be observed for all compounds tested. Starting with amines of low mass (m/z < 200), compounds of molecular masses above 1000 Da were observed in the plasma air purifier. Detailed analysis of the observed mass spectra as well as experiments with deuterated dibutylamine helped to unravel the mechanism taking place in the plasma air purifier. Nitrate anions generated in the plasma air purifier (presumably from N-2) are proposed to form ionic clusters with protonated amines.
DOI 10.1021/es2042492
Additional Notes Received 1 December 2011, Revised 9 February 2012, Accepted 15 March 2012, Published online 15 March 2012
Document Type Article
Publication Status Published
Language English
Assigned Organisational Unit(s) 03430
Organisational Unit(s)
NEBIS System Number 000033453
Source Database ID WOS-000302850400062
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@article{Schmd2012,
author = "Schmid, Stefan and Meier, Lukas and Berchtold, Christian and Zenobi, Renato",
title = "{O}nline {M}onitoring of {M}olecular {P}rocesses in a {P}lasma {A}ir {P}urifying {S}ystem",
journal = "Environmental science \& technology",
year = 2012,
volume = "46",
number = "7",
pages = "4067--4073",
month = apr,
}


E-Citations record created: Mon, 21 May 2012, 11:27:59 CET