Reductive dechlorination of atrazine catalyzed by metalloporphyrins.
Atrazine (2-chloro-4-(ethylamine)-6-(isopropylamine)-s-triazine) is a widely used herbicide which is considered a persistent groundwater contaminant. Its selective transformation mediated by cobalt or nickel porphyrins was studied in aqueous solutions at room temperature and ambient pressure. Several metalloporphyrins were examined as catalysts for the reaction and all yielded the same reaction, transforming atrazine solely to the seldomly reported form 2,4-bis(ethylamine)-6-methyl-s-triazine. The reaction involves dechlorination and migration of a methyl group to yield a symmetric product. Nickel 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin tetra(p-toluenesulfonate) (TMPyP) was activated by nanosized zero-valent iron (nZVI) while cobalt porphyrins (TMPyP, 5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphine-(TP(OH)P) and 4,4',4'',4'''-(porphine-5,10,15,20-tetrayl)tetrakis (benzenesulfonic acid)-(TBSP)) were activated by titanium(III) citrate as the electron donor. The effect of pH on atrazine transformation was demonstrated for the catalytic system of TP(OH)P-Co/Ti(III) citrate. Finally, a comparison of the reactivities of cobalt TMPyP and TP(OH)P was given and the differences discussed.
Nelkenbaum
Elza
E
Department of Environmental Sciences and Energy Research, Weizmann Institute of Science, Rehovot 76100, Israel.
Dror
Ishai
I
Berkowitz
Brian
B
D001280:Atrazine / Q000737:chemistry*; D002384:Catalysis; D002713:Chlorine / Q000737:chemistry*; D019343:Citric Acid / Q000737:chemistry; D003035:Cobalt / Q000737:chemistry; D052918:Environmental Restoration and Remediation; D006540:Herbicides / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D008665:Metalloporphyrins / Q000737:chemistry*; D009532:Nickel / Q000737:chemistry; D010084:Oxidation-Reduction; D013056:Spectrophotometry, Ultraviolet; D014874:Water Pollutants, Chemical / Q000737:chemistry*
D006540:Herbicides; D008665:Metalloporphyrins; D014874:Water Pollutants, Chemical; C419387:titanium citrate; D019343:Citric Acid; D003035:Cobalt; D002713:Chlorine; D009532:Nickel; D001280:Atrazine