Photocatalytic degradation of atrazine using suspended and supported TiO2

The degradation of 6-chloro-N-2-ethyl-N-isopropyl-1,3,5-triazine-2,4-diamine (atrazine) by heterogeneous photocatalysis using suspended and supported TiO2 is reported. The influence of reaction parameters such as catalyst and atrazine concentrations, pH, light intensity and temperature has been investigated and the optimal conditions for the abatement of atrazine have been identified. The primary degradation and the total mineralization of atrazine have been monitored by high performance liquid chromatography (HPLC) and total organic carbon (TOC), respectively. Atrazine got destroyed in both suspended and supported systems, but its complete mineralization is not observed, probably due to the formation of cyanuric acid as a stable product. The activation energy for the degradation reaction of atrazine is determined as 2.6 kcal mol(-1). The efficiencies of photodegradation in both suspended and supported systems (the latter in a 150 ml flow reactor) are compared and the results indicate that the catalytic activity of TiO(2)is not affected when it is immobilized using a functionalized polymer. It is observed that the durability of the supported catalyst activity is reduced after six or seven runs, but it could be fully re-activated by a simple heat treatment at 480 degreesC for 1 h. The findings clearly suggest that immobilized photocatalysts could indeed be developed for photocatalysis, without compromising on the activity of the primary catalyst particles. (C) 2004 Elsevier B.V. All rights reserved.