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Manganese dioxide nanoparticles-silver-Y zeolite as a nanocomposite catalyst for the decontamination reactions of O, S-diethyl methyl phosphonothiolate
Dastafkan, K.; Sadeghi, M. & Obeydavi, A.
Abstract
The decontamination reactions of O,S-diethyl
methyl phosphonothiolate, as an agricultural organophosphorous
pesticide onto 20 wt% loaded manganese
dioxide nanoparticles-silver-Y zeolite as a nanocomposite
catalyst in different solvents, were evaluated and monitored
by means of gas chromatography–flame ionization detector
and gas chromatography–mass spectrometry. Prior to the
reaction, the catalyst was synthesized in three steps: at first,
sodium-Y zeolite was prepared by hydrothermal method;
then, silver-Y zeolite was prepared from sodium-Y zeolite
using ion exchange procedure; and finally, manganese
dioxide nanoparticles were synthesized by in situ impregnation
method by pouring the pre-prepared silver-Y zeolite
into manganese(II) nitrate solution and loaded as 20 wt%
onto silver-Y zeolite structure. The formation of the synthesized
units and final nanocomposite catalyst was verified
through scanning electron microscopy, X-ray
diffraction, atomic absorption spectrometry and Fourier
transform-infrared spectroscopy techniques. Gas chromatography
chromatograms showed that O,S-diethyl methyl
phosphonothiolate was decontaminated perfectly by the
catalyst in n-heptane solvent after 8 h, at room temperature,
while chloroform and isopropanol solvents and other
reaction times gave lower decontamination results. Moreover,
gas chromatography–mass spectrometry chromatograms
confirmed the formation of ethyl methyl phosphonic
acid as a major and final product, which exemplifies the
role of hydrolysis reaction during the degradation progress.
Keywords
Decontamination; O, S-diethyl methyl phosphonothiolate; Manganese dioxide nanoparticles-silver-Y zeolite; Nanocomposite catalyst; Degradation; Ethyl methyl phosphonic acid
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