title: Characterizing and designing polycation-clay nanocomposites as a basis for imazapyr controlled release formulations.
abstract: A novel controlled release formulation (CRF) of the herbicide imazapyr (IMP) was designed to reduce its leaching,which causes soil and water contamination. The anionic herbicide IMP was bound to polydiallyldimethylammonium-chloride (PDADMAC)-montmorillonite composites. PDADMAC adsorption reached a high loading of polymer, which resulted in charge reversal of the clay and promoted IMP binding. The composites were characterized by Fourier transform infrared, zeta potential, and X-ray diffraction measurements, indicating electrostatic interactions of the polycation with the surface, polycation intercalation in the clay and suggesting a configuration as loops and tails on the surface at high loadings. IMP binding to the composites is affected by polycation loading and flocculation. Upon adding high concentrations of IMP to a composite of 0.16 g/g, we obtained high herbicide loadings (66% active ingredient). IMP release from the CRFs applied on a thin layer of soil was substantially slower than its release from the commercial formulation (Arsenal). Accordingly, soil column bioassays indicated reduced herbicide leaching (nearly 2-fold) upon applying the CRFs while maintaining good herbicidal activity. The new PDADMAC-clay formulations are promising from the environmental and weed control management points of view.
authors.affiliation: Seagram Center for Soil and Water Sciences, Faculty of Agricultural, Food and Environmental Quality Sciences, Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors.forename: Adi
authors.initials: A
authors.lastname: Radian
authors.forename: Yael G
authors.initials: YG
authors.lastname: Mishael
mesh_terms: D000538:Aluminum Silicates; D000077215:Clay; D006540:Herbicides / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D053761:Nanocomposites; D009525:Niacin / Q000031:analogs & derivatives* / Q000737:chemistry; D011095:Polyethylenes / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*
chemical_list: D000538:Aluminum Silicates; D006540:Herbicides; D007093:Imidazoles; D011095:Polyethylenes; D000644:Quaternary Ammonium Compounds; C041004:poly-N,N-dimethyl-N,N-diallylammonium chloride; D009525:Niacin; C076656:imazapyr; D000077215:Clay