EFFECT OF ZN(II) ON ACID HYDROLYSIS OF METHYLPARATHION
ABSTRACT Methylparathion (O,O,-dimethyl O-4 nitrophenylphosphorotioate) kinetic transformation in presence of Zn(II) was studied at pH range from 2 to 7. Between pH 2-5 methylparathion degraded, but at pH 6 and 7 Zn(II) precipitated and the pesticide hydrolysis did not occur. The reaction was first order and the rate constant values were 3.38 x 10-2 h-1 (pH 2), 7.69 x 10-3 h-1 (pH 3), 1.31 x 10-2 h-1 (pH 4) and 1.02 x 10-2 h-1 (pH 5). Paranitrophenol appeared as the only electroactive product at all pH values. It is proposed that the main degradation pathway for methylparathion in acid medium was a hydrolysis reaction of the pesticide catalyzed by Zn(II), via an electrophilic mechanism.
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| Main Authors: | , , , |
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| Format: | Digital revista |
| Language: | English |
| Published: |
Universidad Nacional Autónoma de México, Centro de Ciencias de la Atmósfera
2006
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| Online Access: | http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0188-49992006000100021 |
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