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Chemical reactions in ventilation systems: Ozonolysis of monoterpenes
Umeå University, Faculty of Science and Technology, Department of Chemistry.
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Chemicals in indoor air, either emitted from a source or from a reaction, have been suggested to cause ill health in buildings. However, no clear correlations between exposure and health effects have been made.

In this thesis we studied the reaction between monoterpenes, a group of biogenic unsaturated C10 hydrocarbons, and ozone. Ozonolysis of monoterpenes was used as model reactions for unsaturated compounds in ambient air. Also the products formed from these reactions have been suggested as important participants in the occurrence of discomfort and ill health in buildings.

To enable a reliable and sensitive measurement of ppb-ppt levels of monoterpenes and the formed products in the presence of ozone an evaluation of available scrubber materials was made. Potassium iodide was shown to remove ambient levels of ozone and have a recovery of >95% for all monoterpenes and formed products included in the investigation.

Experimental conditions showed to have a large impact on the initial steps of the ozonolysis, and also on the composition of the formed products. We showed that water plays an important and complex role both in the initial stage of ozonolysis of ∆3-carene and in the formation and composition of products from the ozonolysis of ∆-pinene. The use of experimental design facilitated the evaluation of the investigated reactions. We showed that the formation of OH radicals could be studied using multiple linear regression models and that the presence or absence of OH radicals had a profound impact on the formation of many of the formed products. We also made an observation of the lack of formed OH radicals in the ozonolysis of limonene and discussed probable causes of this observation.

Despite the short reaction times and the ambient levels of ozone and monoterpenes used in our experiments we showed that a number of oxidation products were formed, and that the reaction rate is significantly increased in a ventilation system. This formation is underestimated by theoretical calculations and leads to high amounts of known irritants in the indoor air. We showed that theoretical calculations underestimate the formation of these oxidation products 3-13 times, depending on ventilation system and monoterpene.

Place, publisher, year, edition, pages
Umeå: Umeå universitet , 2003. , 61 p.
Keyword [en]
Environmental chemistry, Monoterpene, Ozone, OH Radical, Ozonolysis, Ventilation, Potassium Iodide, Experimental Design, Heat Exchanger
Keyword [sv]
Miljökemi
National Category
Environmental Sciences
Identifiers
URN: urn:nbn:se:umu:diva-97ISBN: 91-7305-511-5 (print)OAI: oai:DiVA.org:umu-97DiVA: diva2:145241
Public defence
2003-10-03, KB3B1, KBC, Umeå, 13:00
Opponent
Supervisors
Available from: 2003-09-10 Created: 2003-09-10 Last updated: 2012-05-22Bibliographically approved
List of papers
1. Ozone Removal in the Sampling of Parts per Billion Levels of Terpenoid Compounds: An Evaluation of Different Scrubber Materials
Open this publication in new window or tab >>Ozone Removal in the Sampling of Parts per Billion Levels of Terpenoid Compounds: An Evaluation of Different Scrubber Materials
2001 (English)In: Environmental Science & Technology, Vol. 35, no 7, 1458-62 p.Article in journal (Refereed) Published
Abstract [en]

Some reactive volatile organic compounds (VOCs) are prone to degradation during sampling in an ozone-rich environment. A wide variety of different chemicals have been used to remove the ozone prior to sampling, but the possibility of interference by such chemicals with the sampled VOCs has not been thoroughly examined. In the present investigation, the retention/degradation of four terpenes (-pinene, -pinene, 3-carene, and limonene) and isoprene together with some of their oxidation products (-pinene oxide, nopinone, 4-acetyl-1-methylcyclohexene (AMCH), methylglyoxal, and methacrolein) has been studied, using various ozone-removing chemicals in an attempt to evaluate their potential as ozone scrubbers in the sampling of ambient air. The chemicals included in this first screening and their ozone-removing capacity are as follows: KI, MnO2, and Na2SO3 removed ozone for more than 24 h when exposed to 73-78 ppb (150-160 g/m3) at a sampling flow rate of 500 mL/min. Silanized poly(1,4-phenylene sulfide) (PFS) removed ozone for 5 h, unsilanized PFS removed ozone for 1 h and 50 min, and Na2S2O3 removed ozone for 20 min. The recovery of the selected compounds with the different scrubbers was >95% for all compounds for KI; >95% for the terpenes oxidation products; >90% for the terpenes and isoprene for PFS; >90% for the terpenes and isoprene for MnO2 on copper nets, Na2SO3, and Na2S2O3; and <90% for the terpenes and isoprene for carulite (a commercial mixture between MnO2, CuO, and Al2O3), CuO, and indigo carmine.

Identifiers
urn:nbn:se:umu:diva-8876 (URN)doi:10.1021/es0001456 (DOI)
Available from: 2008-02-19 Created: 2008-02-19 Last updated: 2012-05-22Bibliographically approved
2. A study of the gas-phase ozonolysis of terpenes: the impact of radicals formed during the reaction
Open this publication in new window or tab >>A study of the gas-phase ozonolysis of terpenes: the impact of radicals formed during the reaction
2002 (English)In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 36, no 20, 3299-3308 p.Article in journal (Refereed) Published
Abstract [en]

The gas-phase ozonolysis of α-pinene, Δ3-carene and limonene was investigated at ppb levels and the impact of the ozone, relative air humidity (RH), and time was studied using experimental design. The amounts of terpene reacted varied in the different settings and were as high as 8.1% for α-pinene, 10.9% forΔ3-carene and 23.4% for limonene. The designs were able to describe almost all the variation in the experimental data and were also successful in predicting omitted values. The results described the effects of time and ozone and also showed that RH did not have a statistically significant effect on the ozonolysis. The results also showed that all three terpenes were affected by an additional oxidation of OH radicals and/or other reactive species. The results from the designs states that this additional oxidation was responsible for 40% of the total amount of α-pinene reacted, 33% of the total amount of Δ3-carene reacted and 41% of the total amount of limonene reacted at the settings 20 ppb terpene, 75 ppb ozone, 20% RH and a reaction time of 213 s. Additional experiments with 2-butanol as OH radical scavenger showed that the reaction with OH radicals was responsible for 37% of the total α-pinene reacted and 39% of the total Δ3-carene reacted at the same settings. The scavenger experiments also showed that there were no significant amounts of OH radicals formed during the ozonolysis of limonene. The results from the designs were also compared to a mathematical model in order to evaluate further the data.

Keyword
Monoterpenes, OH radicals, Relative humidity, Criegee intermediate, Experimental design
National Category
Meteorology and Atmospheric Sciences
Identifiers
urn:nbn:se:umu:diva-5652 (URN)10.1016/S1352-2310(02)00291-1 (DOI)
Available from: 2003-09-10 Created: 2003-09-10 Last updated: 2017-12-14Bibliographically approved
3. Effect of OH radicals, relative humidity, and time on the composition of the products formed in the ozonolysis of α-pinene
Open this publication in new window or tab >>Effect of OH radicals, relative humidity, and time on the composition of the products formed in the ozonolysis of α-pinene
2003 (English)In: Atmospheric Environment, Vol. 37, no 29, 4087-96 p.Article in journal (Refereed) Published
Abstract [en]

The gas-phase ozonolysis of α-pinene at ppb levels were studied and the effects of OH radicals formed in the reaction, the relative humidity (RH), and time on the products formed were investigated. Identified products were pinic acid, glyoxal, methyl glyoxal, norpinonic acid and a norpinonic acid isomer, pinonic acid, a C4 dicarbonyl, a C5 dicarbonyl, norpinon aldehyde, and pinon aldehyde. The different parameters effect on the formation of these products were evaluated using experimental design and multivariate modeling. Pinonic acid, norpinonic acid and its isomer, were not detected in the absence of OH radicals. The amounts of pinic acid, norpinon aldehyde, and pinon aldehyde all decreased in the absence of OH radicals. Glyoxal and methyl glyoxal were not affected.

The formation of pinonic acid decreased when the RH was increased. The formation of pinic acid, glyoxal, methyl glyoxal, and pinon aldehyde increased with increasing RH, while norpinon aldehyde was not affected. The implications of these observations and additional interaction effects are discussed, and a novel route of the formation of pinic acid is presented.

Keyword
Criegee intermediate, Experimental design, Monoterpenes, Pinic acid, Pinon aldehyde
Identifiers
urn:nbn:se:umu:diva-9215 (URN)doi:10.1016/S1352-2310(03)00522-3 (DOI)
Available from: 2008-03-11 Created: 2008-03-11 Last updated: 2012-05-22Bibliographically approved
4. The effect of mechanical ventilation systems on the chemistry in the supply air
Open this publication in new window or tab >>The effect of mechanical ventilation systems on the chemistry in the supply air
Show others...
(English)Article in journal (Refereed) Submitted
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-5654 (URN)
Available from: 2003-09-10 Created: 2003-09-10 Last updated: 2013-03-22Bibliographically approved

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