INTERACTION OF PHOSMET WITH MONTMORILLONITE

Publisher Website
Google Scholar
Abstract
In order to contribute to the understanding of soil-phosmet (0,0-dimethyl S-(N-phthalimidomethyl) dithiophosphate) interactions, we studied the interaction mechanism of this organophosphorus pesticide with montmorillonite. The study was carried out in an organic medium using x-ray diffraction and infrared spectroscopy. Phosmet forms definite and stable interlayer complexes with montmorillonite of 16.05-angstrom basal spacing. The expansion is not affected by the hydration status of the clay, the time of contact, or the concentration of the phosmet solution for concentrations equal or superior to 5 percent. The nature of the interlayer cations affects the expansion. The shifts of the P=S and C=O stretching frequencies in the infrared spectra, as a function of the interlayer cation and hydration status of the complexes, indicate that phosmet molecules interact with the interlayer cations through both the oxygen atom of the C=O group and the sulfur atom of the P=S group. In the latter case, this interaction occurs directly or indirectly, according to the hydration status of the complex. According to these results and the dimensions of the phosmet molecule, the complex is monolayer. The possible orientation of the organic molecules within the interlayer space is suggested. In order to contribute to the understanding of soil-phosmet (0,0-dimethyl S-(N-phthalimidomethyl) dithiophosphate) interactions, we studied the interaction mechanism of this organophosphorus pesticide with montmorillonite. The study was carried out in an organic medium using x-ray diffraction and infrared spectroscopy. Phosmet forms definite and stable interlayer complexes with montmorillonite of 16.05-angstrom basal spacing. The expansion is not affected by the hydration status of the clay, the time of contact, or the concentration of the phosmet solution for concentrations equal or superior to 5 percent. The nature of the interlayer cations affects the expansion. The shifts of the P=S and C=O stretching frequencies in the infrared spectra, as a function of the interlayer cation and hydration status of the complexes, indicate that phosmet molecules interact with the interlayer cations through both the oxygen atom of the C=O group and the sulfur atom of the P=S group. In the latter case, this interaction occurs directly or indirectly, according to the hydration status of the complex. According to these results and the dimensions of the phosmet molecule, the complex is monolayer. The possible orientation of the organic molecules within the interlayer space is suggested. © Williams & Wilkins 1980. All Rights Reserved.

This publication has 4 references indexed in Scilit: