DouAir (mobile photochemical reactor)

Energy Environment

DouAir is a mobile photochemical reactor that can be used (1) in the laboratory for homogeneous gas phase kinetic studies or (2) in the field to study the in-situ reactivity of an air mass. The advantage of this approach in the field is that it can eliminate emissions, from transport and other combinations, which can complicate the interpretation of purely chemical processes in ambient air.

A diagram of DouAir can be seen below in Figure 1 on left. The reactor is built with aluminium profile bars and all the panels and inner surfaces are covered with a fluorinated ethylene propylene (FEP) film, selected for its well-known characteristics of chemical inertia and transparency to solar radiation. The rectangular geometry (2.8 × 2.3 × 1.4 m) provides an internal volume of about 9 m3. For photochemical experiments, the reactor can be exposed directly to solar radiation during its deployment in the field or equipped with an artificial irradiation system in the laboratory consisting of 50 UVA lamps (365 nm, 40W, 1.2 m long). DouAir is covered with a tarpaulin for experiments without irradiation.

Diagram of the DouAir photochemical reactor (approx. 9 m3) (a) and detailed diagram of the front and rear plates (b)

The front plates on either side of the reactor connect the filling lines, pumping lines and sampling lines for a series of analysers used to monitor the key species during experiments on the oxidation of trace atmospheric compounds:

  • O3, NOx (NO and NO2) and water vapour analysers,
  • Proton-transfer-reaction time-of-flight mass spectrometers (PTR-MS), gas chromatographs (GC/FID-MS) and cartridge-based active sampling systems for volatile organic compounds,
  • Peroxy Radical Chemical Amplifier (PERCA) device for measuring peroxyl radicals HO2 and RO2,
  • Condensation particle counter (CPC) and scanning mobility particle sizer (SMPS),
  • METCON spectral radiometer for continuous actinic flux measurements (lamps in the laboratory or solar irradiation in the field).

The photos below show its use in the laboratory for kinetic studies on simplified chemical matrices and its use in the field to monitor the ageing of biogenic air mass.

DouAir deployment in the laboratory (image 1) and in the field (images 2 and 3), CERVOLAND 2018 measurement campaign in the Landes forest)


Labex CaPPA

Labex CaPPA

Labex CaPPA

Laboratory of Excellence on “Chemical and Physical Properties of Aerosols” (Labex CaPPA) The CaPPA laboratory of excellence won the second wave of the “Laboratories of Excellence” call for projects (2012) of the French Investments for the Future Program (PIA). It…

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