Photochemical processes for atrazine degradation: Methodological approach

Numerous studies have been carried out on s-triazines, and more specificall y on atrazine, with the long-term objective of resolving the problems cause d by these herbicides removing them from drinking water. However, applicati ons have remained too limited. So far, processes based on photochemical deg radation have been little implemented. We, therefore, investigated the development of photochemical processes, emp hasizing their capacity to degrade triazine by photolytic and photocatalyti c mode. The study sought to assess the performance of these systems, Experi ments showed that according to a medium pressure mercury source (UV-Vis irr adiation), the photolytic degradation of atrazine was very efficient, with a best atrazine degradation half-life shorter than 5 min, The main degradat ion pathway was deshalogenation. The photocatalytic degradation of atrazine under irradiation over 290 nm in the presence of titanium dioxide was show n to be efficient too, with a half-life of about 20min. In this case an exp erimental design was conducted so as to assess the influence of various par ameters: pH, water medium, and amount of catalyst. There has been observati onal evidence for the efficiency of the processes investigated here and for potential technological developments as regards drinking water treatment. (C) 2001 Elsevier Science Ltd. All rights reserved.