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Interactions of Carbaryl with homoionic montmorillonite
AbstractAdsorption and catalytic degradation of the insecticide Carbaryl on montmorillonite self-supporting films (Upton, Wyoming) saturated with different cations (Al3+, Ca2+, Cu2+, Na+) was studied using thin-layer chromatography, X-ray diffraction, infrared and mass spectroscopy techniques. Carbaryl is adsorbed at room temperature by a coordination bond, through a water bridge, between the CO group and the exchangeable cation. X-ray diffraction patterns showed that the molecule is always intercalated in the smectite layers except for Na-montmorillonite. On moderate heating (90°C for 30 h) the Carbaryl adsorbed on Cu- and Al-montmorillonite decomposes to CO2, N-methylammonium cation, and 1-naphthol and polymerization products, di- and tri-condensate of 1-naphthol, are formed. By contrast for Ca- and Na-montmorillonite systems no degradation of Carbaryl was observed on heating at 90°C for 30 h. The Carbaryl decomposition can be ascribed to the concurrent effect, enhanced by dehydration, of the stronger polarizing power of Cu2+ and Al3+ ions and the acidity of the residual solvation water.
Interactions of Carbaryl with homoionic montmorillonite
AbstractAdsorption and catalytic degradation of the insecticide Carbaryl on montmorillonite self-supporting films (Upton, Wyoming) saturated with different cations (Al3+, Ca2+, Cu2+, Na+) was studied using thin-layer chromatography, X-ray diffraction, infrared and mass spectroscopy techniques. Carbaryl is adsorbed at room temperature by a coordination bond, through a water bridge, between the CO group and the exchangeable cation. X-ray diffraction patterns showed that the molecule is always intercalated in the smectite layers except for Na-montmorillonite. On moderate heating (90°C for 30 h) the Carbaryl adsorbed on Cu- and Al-montmorillonite decomposes to CO2, N-methylammonium cation, and 1-naphthol and polymerization products, di- and tri-condensate of 1-naphthol, are formed. By contrast for Ca- and Na-montmorillonite systems no degradation of Carbaryl was observed on heating at 90°C for 30 h. The Carbaryl decomposition can be ascribed to the concurrent effect, enhanced by dehydration, of the stronger polarizing power of Cu2+ and Al3+ ions and the acidity of the residual solvation water.
Interactions of Carbaryl with homoionic montmorillonite
Fusi, P. (Autor:in) / Ristori, G.G. (Autor:in) / Franci, M. (Autor:in)
Applied Clay Science ; 1 ; 375-383
28.04.1986
9 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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