Simulation chamber studies

In this paper an overview of the application of simulation chamber studies to the photolysis of aldehydes is presented and a brief review of the kinetic and mechanistic data currently available is also provided. Finally, results from some of the first studies of tire photolysis of aromatic aldehydes in an outdoor simulation chamber are presented and discussed. 

Simulation Chamber Studies on the Photolysis of Aromatic Aldehydes... 

Simulation Chamber Study of the Oxidation of Acetic Acid by OH Radicals Detection of Reaction Products by CW-CRDS in the Near-Infrared Range... 

Simulation Chamber Study of the Oxidation of Acetic Acid by OH Radicals... 

Bossmeyer, J., T. Brauers, C. Richter, F. Rohrer, R. Wegener, and A. Wahner (2006), Simulation chamber studies on the NO3 chemistry of atmospheric aldehydes, Geophys. Res. Letters, 33, L18810/1-L18810/5. 

Carrasco, N., J.E. Doussin, M. O Connor, J.C. Wenger, B. Picquet-Varrault, R. Durand-Jolibois, and P. Carlier (2007a), Simulation chamber studies of the atmospheric oxidation of 2-methyl-3-buten-2-ol reaction with hydroxyl radicals and ozone under a variety of conditions J. Atmos. Chem., 56, 33-55. 

Considerable attention has been directed in determining the products from reactions of aliphatic hydrocarbons, aromatic compounds, and unsaturated compounds including biogenic terpenes that exhibit appreciable volatility. These studies have been conducted both in simulation chambers and using natural sunlight in the presence of NO. 

The success of these computer simulations must be rated as quite good. Figure 2-8 compares concentration-time measurements from a smog-chamber study of NO,-propylene-air with computer-calculated results based on the same initial conditions. The time dependences and absolute concentrations agree fairly well, but not perfectly. Note that the... 

Depending on meteorologic conditions, aerosol formation in the atmosphere is better approximated, but never fully simulated, by smog-chamber studies under either static (batch-reactor) or dynamic (flow-reactor) conditions. 

Products (and their mutagenicities) of the gas-phase reactions of these and other 2- to 4-ring PAHs (fluorene, naphthalene, etc.) carried out under simulated atmospheric conditions should be consistent with the nitroarenes and nitro-PACs that have been identified in ambient air. This criterion has been well established over the years in environmental chamber studies conducted in several laboratories (e.g., see reviews by Atkinson and Arey, 1994 and Arey, 1998a articles by Kamens et al., 1994 Fan et al., 1995 Feilberg et al., 1999a and references therein). 

The data shown in Figure 1 were used as a reference for the kinetic scheme formulated in this work 12). In this experiment a mixture of 2.23 ppm CsHe, 0.97 ppm NO, and 0.05 ppm NO2 in prepurified air (50% relative humidity) was irradiated at 31.5 db 2°C by simulated sunlight with an intensity corresponding to a rate of NO2 photodissociation in N2, ka, of 0.4 min The reactant concentrations used in this experiment are typical of smog chamber studies but are an order of magnitude higher than atmospheric levels. The implications of this will be discussed below. 

Carter, W. P. L. Environmental chamber studies of ozone formation potentials of VOCs. Presented at the NATO EST-ARW Workshop on Environmental Simulation Chambers Application to Atmospheric Chemical Processes, Zakopane, Poland, October 1-4 (2004b). 

The reactivity of NMP towards OH radicals was studied in the aqueous phase, under tropospheric conditions. The kinetic results show that the OH oxidation of NMP is fast compared to that of other WSOC, and thus should induce modifications of the composition of water droplets, due to the reaction products formed. A new experimental technique was developed to study the aqueous phase OH oxidation of NMP. A mass spectrometer was coupled to an aqueous phase simulation chamber, thus providing an on-line analysis of the solution. The mass spectrometer was equipped with an electrospray ionisation (ESI) unit and a triple quadrupole, which allowed ESI-MS, ESI-MS, and ESI-MS-MS analysis. The results proved that this experimental technique is highly promising, as it allowed us to detect the formation of 66 reaction products, of which 24 were positively identified. Based on the results obtained, a chemical mechanism has been suggested for the OH oxidation of NMP in the aqueous phase. The developed equipment can be used to study other molecules and other reactions of atmospheric interest. 

The present study reports the first coupling between a smog chamber and a CW-CRDS setup. After a successful evaluation the CW-CRDS setup in the laboratory (spectroscopic study of C2H2 around 1512 nm), this new analytical device permits us to follow the production of small molecules (CO, CO2, C2H2, HCOOH, etc.) and also of isotopic compounds (HDO, H2 0 for example) almost in "real time" during experiments on VOC degradation (oxidation or photolysis) in a simulation chamber. 

Karl M., Th. Brauers, H.-P. Dom, F. Holland, M. Komenda, D. Poppe, F. Rohrer, L. Rupp, A. Schaub and A. Wahner, Kinetic study of the OH-isoprene and Os-isoprene reaction in the atmosphere simulation chamber, SAPHIR, Geophys. Res. Lett. 31 (2004), L05117, doi 10.1029/2003GL019189. 

This paper describes a project that was designed to study the products from sunlight, ozone, HO radical, and NO3 radical-initiated reactions (the latest in the dark) of diesel emissions with the aid of an environmental simulation chamber, under realistic ambient conditions (dilution in the range of 1 300 - 1 400). The European Photoreactor in Valencia, Spain, (EUPHORE) which is currently one of the largest (approximately 200 m ) and best equipped outdoor simulation chambers in the world, is employed for this study. 

It has been demonstrated that atmospheric simulation chambers offer the unique possibility for studying the impact of real car exhaust under almost real-world conditions on tropospheric photosmog formation. 

Since the quality of simulation studies strongly depends on the question how exactly the chemical behaviour of the chamber itself is characterised, sensitive parameters urgently required for simulations have to be determined for each facility of the infrastructure (l objective). The dissemination of each result from such studies serves for a better interpretability of environmental chamber studies as a whole. 

The methodology of studying the effects of trace components in simulation chambers was developed for the assessment of the impact of phytotoxins on land vegetation. On the basis of the experimental studies in chambers and of the field studies, ecological standards have been formulated for the effect of atmospheric air pollution on land vegetation. 

Laboratory studies to study the oxidation of isoprene imder carefully controlled conditions, in particular using atmospheric simulation chambers, in order to corrfirm the presence of reaction products and the rates of competing channels. 

Karl M, Dom H-P, Holland F, Koppmann R, Poppe D, Rupp L, Schaub A, Wahner A (2006) Product study of the reaction of OH radicals with isoprene in the atmosphere simulation chamber SAPHIR. J Atmos Chem 55 167-187... 

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