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Photocatalytic transformation and mineralization of 2,4,6-trinitrotoluene (TNT) in TiO2slurries

Authors
Journal
Water Research
0043-1354
Publisher
Elsevier
Publication Date
Volume
29
Issue
12
Identifiers
DOI: 10.1016/0043-1354(95)00136-9
Keywords
  • Tnt
  • Munitions Remediation
  • Photocatalysis
  • Tio2
  • Nitroaromatic
  • Sensitized Photocatalysis
Disciplines
  • Chemistry

Abstract

Abstract An analysis of the photodegradation of TNT in a TiO 2 slurry reactor is presented. The rates and extent of TNT transformation and mineralization are compared for photocatalytic and direct photolytic reactions under conditions of varying light energies and in the presence and absence of oxygen. Certain initial organic transformation products are identified for both photocatalytic and photolytic reactions. Nitrate, nitrite, and ammonium ions are analyzed and the possibility of semiconductor sensitization by colored compounds is considered. TNT was transformed rapidly under each set of photochemical conditions but destruction was faster and more complete with TiO 2 photocatalysis. Transformation by-products were destroyed readily under oxygenated photocatalytic conditions and were observed to be more refractory under direct photolytic conditions. Mass balances performed on carbon and nitrogen revealed that when the TiO 2 photocatalyst was utilized in the presence of oxygen and near u.v. radiation (λ > 340 nm) approx. 90% of the TNT was mineralized and 35% of the total nitrogen was recovered as ammonium ion after 120 min. Among the large number of organic transformation products produced photocatalytically, trinitrobenzoic acid, trinitrobenzene and trinitrophenol have been identified as oxidative intermediate species and dinitroaniline as a reduction product. The photocatalytic transformation of TNT appears to involve both oxidative and reductive steps and sensitization by colored compounds plays no detectable role in degradation.

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