Reaktionen von Luftverunreinigungen im Bereich kleiner Konzentrationen – Bedeutung für Natur und Technik

Abstract

Reactions of pollutants that are present in the atmosphere in low concentrations are able to cause changes in the atmosphere expecially over industrial regions. Attempts were made to evaluate the effects of these reactions with mathematical models, e.g. on the ozone belt which surrounds the earth. It is elucidated that the results of predictions based on such model calculations are very much influenced by the boundary conditions which are allowed and by the model reactions which were considered. In particular this concerns changes in the ozone belt caused by halogenated hydrocarbons and by catalytic effects of NO_x.
A problem is still the elimination of pollutants that are present in waste gases only in the ppm-range because it is necessary to adapt every plant to its special problems. The limiting factors for the use of thermal combustion, catalytic gas cleaning, sorption and gas scrubbing are presented.
Kinetic investigations of the reactions of O(³P)-atoms and OH-radicals with C₂HCl₃ and C₂Cl₄ were presented as an example for the reactions and the degradation of chemicals in the atmosphere. A significant result is that the degradation of C₂Cl₄ should ensue predominantly by OH-radicals. Specified are the reaction channels and also the intermediate and final products which have been found.
The field of waste gas cleaning, especially waste gases which contain pollutants in the ppm-range, is represented by a new cleaning process. This process is working with bacteria suspensions as absorbent. Investigations concerning the reaction kinetics and process engineering fundamentals for absorption and biological degradation of propanal by bacteria cells of Pseudomonas fluorescens are described. For the design of such biological waste gas cleaning plants some instructions were derived from the measurement results.