Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/31/1999
Publication Date: N/A
Technical Abstract: Sorption of imidacloprid on organic saturated octadecylammonium, C18, and dioctadecyldimethylammonium, DOD, and inorganic (Fe) saturated montmorillonites which have high (SAz) and low (SWy) layer charge, has been investigated. Sorption isotherms were fitted to the Freundlich equation. Imidacloprid-montmorillonite complexes were studied by X-ray diffraction and FT-IR techniques. Imidacloprid sorption coefficients, Kf, decreased in the order C18SWy>C18SAz>FeSWy>DODSWy >=DODSAz. The low layer charge and saturation by primary alkylammonium cation facilitated sorption of imidacloprid in the interlayer of the smectite, which is corroborated by the increase in basal spacing observed in X-ray diffractograms and by the presence of shifted absorption bands in FT-IR spectra. Low layer charge facilitates the opening of the silicate layer and sorption between charged sites by hydrophobic interactions, whereas primary alkylammonium enables the formation of polar bonds with imidacloprid molecules. Imidacloprid sorption on FeSWy montmorillonite appears to be sorption by cation exchange as a result of the high surface acidity of the clay.