Separation of volatile and non-volatile aerosol fractions by thermodesorption: instrumental development and applications

An instrument to remove volatile material from aerosol particles by thermal desorption is presented. The thermodesorber consists of a heated tube, whe re volatile material is desorbed from the particles, and a water or air-coo led tube, consisting of activated charcoal. This last tube removes desorbed material and thus prevents it from re-adsorbing onto particles. Although d esigned for measuring particulate emissions from combustion processes it ca n also be applied to atmospheric aerosols. After theoretical and experiment al determination of thermodesorber operating characteristics (temperature p rofile, losses, removal of desorbed material), examples of applications in several fields are given. Examples of atmospheric measurements at several r emote and urban sites are presented. In combustion technology, the thermode sorber is applied to remove all volatile materials, allowing separation of volatile species and the non-volatile core (mainly elemental carbon) of com bustion particles. Finally, the thermodesorber is used to study adsorption and desorption processes of polycyclic aromatic hydrocarbons on particles. (C) 2001 Elsevier Science Ltd. All rights reserved.