Organo-Clay Formulations of the Hydrophobic Herbicide Norflurazon Yield Reduced Leaching

Abstract

The study aimed to reduce leaching of the hydrophobic herbicide norflurazon (4-chloro-5-methylamino-2-(R,R,R)-trifluoro-m-tolylpyridazin-3-(2H)-one) by adsorbing it on clays or organoclays. The surface of the clay mineral montmorillonite was modified from hydrophilic to hydrophobic by preadsorbing it with organic cations, of which thioflavin-T (TFT) at a loading corresponding to 5 / 8 of the cation-exchange capacity of the clay mineral yielded the highest affinity of adsorption of norflurazon. Pillared clay (PC) used without organic cations exhibited enhanced affinity for norflurazon adsorption, much higher than that of montmorillonite or sepiolite. Fourier transform infrared (FTIR) results showed interactions between aromatic moieties of preadsorbed TFT and the herbicide. Stronger interaction of the herbicide with a clay mineral or organo-clay corresponded to its slower release. Formulations prepared on the basis of montmorillonite-TFT and PC were more effective in reducing herbicide leaching in soil columns in comparison to the commercial formulation, whereas the herbicidal efficiencies were comparable.

Mobility and efficacy of 2,4-D herbicide from slow-release delivery systems based on organo-zeolite and organo-bentonite complexes

“…[16] Various surfactant-mineral complexes have been tested for preparing SRFs of different herbicides such as norflurazon, [19,20] acetochlor, [21] fenuron, [22] metolachlor [23] and diuron. [24] Very few attempts have been made to synthesize and evaluate SRFs of 2,4-D using organo-minerals.…”

Effects of organoclays on soil eubacterial community assessed by molecular approaches

“…As regards soil, organoclays have been proposed for decontamination purposes [16][17][18] and also as carriers for the controlled release of pesticides to reduce the leaching process in soil and minimize the risk of ground water contamination [19][20][21][22]. The mobility of pesticides in soil is reduced by hydrophobic and polar interactions between the agrochemical and the alkyl chains of the organoclay.…”

“…The mobility of pesticides in soil is reduced by hydrophobic and polar interactions between the agrochemical and the alkyl chains of the organoclay. Undabeytia et al [19] developed controlled release formulations of the herbicide norflurazon by using organoclays. They modified the surface of the clay mineral montmorillonite from hydrophilic to hydrophobic by preadsorbing it with organic cations.…”

Significance of the long-chain organic cation structure in the sorption of the penconazole and metalaxyl fungicides by organo clays

“…In the past years, organo clays or clay minerals modified exchanging their inorganic cations by quaternary ammonium cations, with chains with a high number of carbon atoms have been proposed as sorbents of industrial organic contaminants and pesticides with the purpose to immobilise these compounds [1][2][3][4][5][6][7], to remove pesticides from water [8][9][10], to develop slow release pesticide formulations [11][12][13], or to examine the potential bioavailability [14,15] and the photostabilization of sorbed pesticides [16,17].…”