Passive collector

from Wikipedia, the free encyclopedia
Passive collector for nitrogen dioxide in Osnabrück

A passive collector or passive collector is a measuring device that collects the component to be measured without supplying energy. Passive collectors are used to monitor indoor and outdoor air as well as to determine water quality.

functionality

Passive collectors are usually designed as partially closed cylinders or tubes. The component to be measured reaches a carrier substance which acts as a sink and which can act as an absorbent or adsorbent through sedimentation , diffusion or permeation . In the case of gaseous substances, sedimentation does not play a role. The measuring component is often chemically bound so that the difference in concentration between the environment and the carrier substance remains the same as the driving force during the measurement.

Passive collectors have the advantage that they are network-independent and can therefore also be used in remote locations or in locations where there is not enough space for measuring containers, such as in narrow street canyons

Passive collector for gases

The sampling times of passive samplers for gases are in the range of weeks. The collectors can - depending on the component to be measured - be stored before and after sampling for a period of several months. Pay attention to the storage temperature.

Air pollutants that can be measured with passive collectors include

Measurement uncertainties when measuring with passive collectors can be caused by numerous factors. This includes in particular changing wind speeds during sampling, but also difficulties in laboratory analysis. With passive collectors for sulfur dioxide, for example, there is also the risk that an unstable complex will be formed.

Passive collector for liquids

In the past, water samples were often sampled, usually as a scoop sample. This means that fluctuations in water quality were only insufficiently recorded. Passive collectors, on the other hand, provide an average concentration over a longer period of time. In the case of non-polar substances present in low concentrations, the use of water samples can quickly mean that the collection and processing of large volumes is essential in order to achieve sufficient detection strength and distance from the blank value . On the other hand, passive collectors can collect the equivalent of up to several liters of water per day, which means that exposure over a longer period of time leads to increased detection strength and a significant difference to the blank value.

The pollutants in the water that can be measured with passive collectors include

Application examples

With the passive collection of dust deposits in a calm cylinder, particles sediment on a transparent acceptor surface. The acceptor surface is then evaluated using a light microscope . Particles with an aerodynamic diameter of 2.5  µm are almost completely recorded.

To determine the pollution of the outside air with nitrogen dioxide, this is reacted with triethanolamine . To this end, nitrogen dioxide diffuses through the diffusion path of the passive collector and reaches metallic nets or cellulose fiber filters, which serve as a carrier for the triethanolamine. The nitrite formed during the reaction is extracted after the end of the collection phase and then analyzed by means of colorimetry and ion chromatography .

literature

Individual evidence

  1. ^ A b Franz Joseph Dreyhaupt (Ed.): VDI-Lexikon Umwelttechnik. VDI-Verlag Düsseldorf 1994, ISBN 3-18-400891-6 , p. 901.
  2. ↑ a b Markus Hangartner: Use of passive collectors for various pollutants in the outside air. In: Commission for keeping the air clean in the VDI and DIN (ed.): Current tasks of measurement technology in air pollution control. VDI-Verlag Düsseldorf 1990, ISBN 3-18-090838-6 , pp. 515-526.
  3. ↑ Gert Jakobi, Horst Römmelt, Herbert Werner, Manfred Kirchner: Immission measurements of traffic-related air pollutants in a forest in the windward and lee of a motorway in southern Bavaria. In: Hazardous substances - cleanliness. Air . 69, No. 4, 2009, ISSN  0949-8036 , pp. 150-154.
  4. ↑ Air quality and vehicle propulsion. VDI status report December 2018, p. 5., available at vdi.de (registration required)
  5. ↑ Markus Hangartner: Determination of the measurement uncertainty in passive collector systems. In: Hazardous substances - cleanliness. Air. 66, No. 1/2, 2006, ISSN  0949-8036 , pp. 58-61.
  6. ↑ a b DIN EN ISO 5667-23: 2011-06 water quality ; Sampling; Part 23: Instructions for the use of passive samplers in surface water (ISO 5667-23: 2011); German version EN ISO 5667-23: 2011. Beuth Verlag, Berlin, p. 4.
  7. ↑ M. Zennegg, E. Vermeirssen, P. Schmid: Measurement of PCB and dioxins in rivers. Evaluation of the practicability of sediment analyzes and measurements by means of passive collectors in the water phase to localize emission sources. Federal Office for the Environment . Environmental Knowledge No. 1639, 2016, p. 46.
  8. ↑ VDI 2119: 2013-06 Measurement of Immissions; Sampling of atmospheric particles> 2.5 µm on an acceptor surface with the passive collector Sigma-2; Light microscopic characterization and calculation of the number sedimentation rate and the mass concentration (ambient air measurements; Sampling of atmospheric particles> 2.5 µm on an acceptor surface using the Sigma-2 passive sampler; Characterization by optical microscopy and calculation of number settling rate and mass concentration). Beuth Verlag, Berlin, pp. 8-11.
  9. ↑ DIN EN 16339: 2013-11 outside air; Determination of the concentration of nitrogen dioxide using a passive collector; German version EN 16339: 2013. Beuth Verlag, Berlin, p. 7.