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Adsorption mechanisms of imazamethabenz-methyl on homoionic montmorillonite

A. Pusino, A. Gelsomino and C. Gessa
Adsorption mechanisms of imazamethabenz-methyl on homoionic montmorillonite
Clays and Clay Minerals (June 1995) 43 (3): 346-352

Abstract

The adsorption of the herbicide imazamethabenz-methyl, a mixture of the two isomers methyl (+ or -)-2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-4-methylbenzoate (para isomer) and methyl (+ or -)-2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-methylbenzoate (meta isomer), from water onto Al (super 3+) -, Fe (super 3+) -, Ca (super 2+) -, K (super +) - and Na (super +) -montmorillonite was studied by analytical (HPLC) methods. The adsorption from an organic solvent was also investigated by spectroscopic (IR) and X-ray diffraction measurements. It was observed that, depending on the acidic properties of the exchangeable cations, two different mechanisms may take place. The first one, acting on Fe (super 3+) - and Al (super 3+) -clays, involves the protonation of the more basic nitrogen atom ofimidazolinone ring of the herbicide because of a proton transfer from the acidic metal-bound water, followed by adsorption on the clay surfaces. In this case, the clay surfaces have greater affinity for the meta than the para isomer, due to the extra-stabilization of the meta protonated form by resonance. The second mechanism, taking place on Ca (super 2+) -, K (super +) - and Na (super +) -clays, is hydrogen-bond formation between the ester carbonyl group of the herbicide and hydration water metal ions and is not affected by the structure of the isomers.


ISSN: 0009-8604
Coden: CLCMAB
Serial Title: Clays and Clay Minerals
Serial Volume: 43
Serial Issue: 3
Title: Adsorption mechanisms of imazamethabenz-methyl on homoionic montmorillonite
Affiliation: Universita di Reggio Calabria, Dipartimento di Agrochimica e Agrobiologia, Gallina, Italy
Pages: 346-352
Published: 199506
Text Language: English
Publisher: Clay Minerals Society, Clarkson, NY, United States
References: 25
Accession Number: 1995-068492
Categories: Geochemistry of rocks, soils, and sedimentsMineralogy of silicatesEnvironmental geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables
Secondary Affiliation: Universita di Bologna, ITA, Italy
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland
Update Code: 199524
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