A study of the photocatalytic degradation of metamitron in ZnO water suspensions

The photocatalytic degradation of the herbicide metamitron in water using ZnO under Osram ULTRA-VITALUX® lamp light was studied. The effect of the operational parameters such as initial concentration of catalyst, initial metamitron concentration, initial salt concentration (NaCl, Na 2CO 3 and Na 2SO...

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Bibliographic Details
Published in:Desalination 2009-11, Vol.249 (1), p.286-292
Main Authors: Mijin, Dušan, Savić, Marina, Snežana, Perović, Smiljanić, Ana, Glavaški, Olivera, Jovanović, Mića, Petrović, Slobodan
Format: Article
Language:English
Subjects:
Adsorption
Applied sciences
Catalysis
Catalysts
Catalytic reactions
Chemical engineering
Chemistry
Chromatography
Degradation
Exact sciences and technology
General and physical chemistry
Herbicide
Herbicides
Inhibitors
Mathematical models
Metamitron
Photodegradation
Pollution
Rate constants
Reactors
Sodium chloride
Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
Zinc dioxide
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Summary:The photocatalytic degradation of the herbicide metamitron in water using ZnO under Osram ULTRA-VITALUX® lamp light was studied. The effect of the operational parameters such as initial concentration of catalyst, initial metamitron concentration, initial salt concentration (NaCl, Na 2CO 3 and Na 2SO 4) and pH was studied. The optimal concentration of catalyst was found to be 2.0 g/l. First-order rate constants were calculated for the uncatalysed reactions. On the base of the Langmuir–Hinshelwood mechanism, a pseudo first-order kinetic model was illustrated and the adsorption equilibrium constant and the rate constant of the surface reaction were calculated (0.119 l mg − 1 and 0.836 mg l − 1 min − 1 , respectively). The photodegradation rate was higher in acidic than in alkaline conditions. When salt effect was studied, it was found that sodium carbonate was the most powerful inhibitor used, while sodium chloride was the weakest one. A negligible inhibition was observed when the concentration of sodium chloride was 20 mM. The rate of photodecomposition of metamitron was measured using UV spectroscopy and HPLC, while its mineralization was followed using ion chromatography (IC), as well as total organic carbon (TOC) and total nitrogen (TN) analysis. Under the employed conditions, almost complete disappearance of 9 mg/ml of herbicide, 56% TOC and 34% TN removal, occurred within 4 h. The ion chromatography results showed that the mineralization led to ammonium, nitrite and nitrate ions during the process.
ISSN:0011-9164
1873-4464
DOI:10.1016/j.desal.2008.10.030