France
‘Ecole des Mines de Douai’ (EMD)
The ‘Ecole des Mines de Douai’ (EMD) is a higher education and research institute belonging to the Mines – Telecom Institute. EMD is organized into 5 teaching and research departments, including the Department of Atmospheric Science and Environmental Engineering (SAGE) (15 permanent researchers and PhD students) to which the French partner is part of. The research activities at the SAGE department are devoted to indoor and outdoor air quality, through instrumental development in gas and particle sampling and analysis, atmospheric reactivity experiments and, more recently, air cleaning technologies using photocatalysis and cold plasma techniques. The SAGE department has been behind the implementation of air quality monitoring networks in France in the 90’s through the development of chromatographic-based analytical methods. Strong expertise in atmospheric chemistry has also been acquired through the development of original reactors, notably an environmental simulation chamber coupled to the cavity ring-down spectroscopy (CRDS) for homogeneous gas phase kinetic studies where photo-stationary concentrations of HO2 radical have been measured in situ for the first time. The OzOA project will allow strengthening the heterogeneous chemistry approach that has been started a few years ago by the development of a laminar aerosol flow reactor.
Laminar flow reactor from EMD-SAGE
The cylindrical reactor (1 m length and 10 cm i.d.) has been designed to work with total flows of about 1 to 5 L min-1, corresponding to reaction times between 10 s and several minutes (~ 15 min). A mobile injector is used to introduce the reagents separately and ensure their rapid mixing into the Pyrex tube in a laminar flow regime at atmospheric pressure and room temperature. The laminar flow in the reactor ensures a stationary mode, enabling large volume to be sampled. The volume of the flow reactor may vary depending on the position of the sliding injection head, in order to watch the evolution of the reagents and products at various reaction times, and to estimate kinetic and mechanistic parameters. Considering a fixed distance between the movable injection head and the sampling point, different reaction times may also be achieved by changing the flow rate of the reactants in the reactor. The outlet analytical chain of the reactor includes an HR-ToF-AMS (High Resolution – Time-of-Flight – Aerosol Mass Spectrometer) to analyze the particulate phase, on-line mass spectrometers like a PTR-ToF-MS (Proton-Transfer-ToF-MS) and a selected ion flow tube MS (SIFT-MS) to identify gas-phase intermediates and on-line GC-MS after cryogenic preconcentration and thermodesorption. Additional off-lines techniques currently used in the laboratory will also be brought into play to broaden the analytical capacities: in-water sampling and IC-MS analysis (Ion Chromatography – Mass Spectrometry), Teflon or quartz filter sampling and UPLC-ToF-MS analysis (Ultrahigh Pressure Liquid Chromatography ToF-MS) for acidic, hydroxylated or nitrated species. A 10-m optical path length White-cell coupled to an FTIR spectrometer will be used to record IR spectra. The AMS measures in real time the average chemical composition of aerosols as a function of their size. Ozone traps (scrubbers) consisting of a dry coating of KI on the walls of a copper tube are used upstream of the cartridge sampling in order to prevent additional degradation processes of the VOCs by ozone during sampling and thermal desorption. An O3 analyzer monitors O3 levels in the reactor as well as the efficiency of the scrubber. Sampled cartridges are thermodesorbed and analyzed by gas chromatography coupled with mass spectrometry and FID detection.