Sulfosulfuron Incorporated in Micelles Adsorbed on Montmorillonite for Slow Release Formulations

Abstract

Slow release formulations of the anionic herbicide sulfosulfuron (SFS) were prepared by incorporating it in micelles of an organic cation octadecyltrimethylammonium, which adsorb on the clay-mineral montmorillonite. The fraction of SFS adsorbed on the micelle-clay complex reached 98%, whereas for monomer-clay complexes, its adsorption was insignificant. Fluorescence studies showed surface contact between the micelles and the clay surface. The rate of SFS release from the micelle-clay formulations in aqueous suspensions was slow (<1%, 72 h). Spraying SFS formulations on a thin soil layer in a funnel, followed by irrigations (50 mm), resulted in complete elution of SFS from the commercial formulation (dispersible granular) versus 4% from the micelle-clay formulation. A plant bioassay in Rehovot soil showed that these respective formulations yielded 23 and 65% of shoot growth inhibition of foxtail. Consequently, the slow release micelle-clay formulations of SFS yield significantly reduced leaching and enhanced biological activity, thus providing environmental and agricultural advantages.

Identification of Residues of Sulfosulfuron and its Metabolites in Subsoil-dissipation Kinetics and Factors Influencing the Stability and Degradation of Residues from Topsoil to Subsoil Under Predominant Cropping Conditions

“…Water movement modified by sorption and transformation processes apart from soil physical and chemical properties mainly influences herbicide transport and accumulation in soils and ground water. The mobility of residues in subsoil thus depends on the adsorption and desorption characteristics (Undabeytia, Mishael, Nir, Papahadjopoulus Stenberg, Rubin, Morillo et al, 2003;Mishael, Undabeytia, Rabinovitz, Rubin, & Nir, 2003). The residues adsorbed on the soil surface are vulnerable for sunlight exposure resulting their photochemical degradation.…”

Structural effects of organobentonites on controlled release of pretilachlor

“…Bentonite is a natural material containing montmorillonite as a major constituent and has been considered as a potential adsorbent or carrier for many chemicals due to the high specific surface area and particular surface properties (Zhu et al, 2003b;Xu and Zhu, 2007;Paiva et al, 2008;Ijagbemi et al, 2009). Bentonite has been used in CRF of insecticides and herbicides, and has succeeded in reducing the leaching of active ingredients in soil (Polubesova et al, 2001(Polubesova et al, , 2003Mishael et al, 2002Mishael et al, , 2003Rytwo et al, 2005Rytwo et al, , 2008Li et al, 2009;Singh et al, 2009Singh et al, , 2010. However, the intrinsic hydrophilicity of bentonite makes it an ineffective sorbent for hydrophobic organic molecules.…”

“…Mepiquat (Polubesova et al, 2001), berberine (Rytwo et al, 2005(Rytwo et al, , 2008 and quaternary ammonium surfactants (Mishael et al, 2002(Mishael et al, , 2003Polubesova et al, 2003) have turned out to be effective modifying agents to increase the adsorption capacity of bentonite towards several herbicides and reduce the leaching in soil. However, knowledge about the structural effects on the controlled release of pesticide from organobentonite is still very limited.…”

Factors Affecting the Design of Slow Release Formulations of Herbicides Based on Clay-Surfactant Systems. A Methodological Approach

“…It has been previously reported that incorporation of active ingredients in the micelles and vesicles formed by surfactant molecules which adsorbed on clays, such as montmorillonite, provided a slow release system [14]–[16]. The fraction of the pesticide encapsulated in surfactant-clay complexes prolonged their action.…”