Sonolytic, photolytic, and photocatalytic decomposition of atrazine in the presence of polyoxometalates.
Aqueous solutions of atrazine [2-chloro-4-(isopropylamino)-6-(ethylamino)-s-triazine] (CIET) decompose upon illumination with a low-pressure Hg-arc lamp (254 nm). However, no decomposition takes place with lambda > 300 nm. On the other hand, addition of polyoxometalates (POM), PW12O40(3-) or SiW12O40(4-), into a solution of atrazine photodecomposes the substrate within a few minutes (cutoff fiter 320 nm). Ultrasound (US) treatment also decomposes aqueous solutions of atrazine within a few minutes. Both methods, sonolysis and photolysis with POM, give common intermediates, namely, 2-hydroxy-4-(isopropylamino)-6-amino-s-triazine (OIET), 2-chloro-4-(isopropylamino)-6-amino-s-triazine (CIAT), 2-chloro-4-amino-6-(ethylamino)-s-triazine (CAET), 2-hydroxy-4,6-diamino-s-triazine (OAAT), and 2-hydroxy-4-hydroxy-6-amino-s-triazine (OOAT) among others. The final products for both methods, US and photolysis with POM, were cyanuric acid (OOOT), NO3-, Cl-, CO2, and H2O. OOOT showed no signs of decomposition by sonication and/or photolysis with POM. It also resisted degradation upon photolysis with plain UV light (254 nm). However, it has been reported to decompose upon photolysis with lambda > 200 nm. Combination of US and photolysis with POM produces only a cumulative effect.
Hiskia
A
A
Institute of Physical Chemistry, NCSR Demokritós, 153-10 Athens, Greece.
Ecke
M
M
Troupis
A
A
Kokorakis
A
A
Hennig
H
H
Papaconstantinou
E
E
D001280:Atrazine / Q000737:chemistry*; D002384:Catalysis; D004787:Environmental Pollution / Q000517:prevention & control*; D006540:Herbicides / Q000737:chemistry*; D010782:Photolysis; D017973:Tungsten Compounds / Q000737:chemistry*; D014465:Ultrasonics; D000099294:Polyoxometalates
D001280:Atrazine; D006540:Herbicides; D017973:Tungsten Compounds; C102296:polyoxometalate I; D000099294:Polyoxometalates