Some aspects of the adsorption of glyphosate and its degradation products on montmorillonite
The most worldwide used herbicide is glyphosate, phosphonomethylglycine (PMG). Consequently, a significant amount of PMG, its metabolites (sarcosine, SAR, and aminomethylphosphonic acid, AMPA) and the degradation product, methylphosphonic acid (MPA), reaches the soil, which acts as final sink. Becau...
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2018
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_09441344_v25_n18_p18138_Flores http://hdl.handle.net/20.500.12110/paper_09441344_v25_n18_p18138_Flores |
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paper:paper_09441344_v25_n18_p18138_Flores2023-06-08T15:53:43Z Some aspects of the adsorption of glyphosate and its degradation products on montmorillonite Aminomethylphosphonic acid Glyphosate Methylphosphonic acid Montmorillonite Sarcosine Surface adsorption sites adsorption amino acid chemical compound concentration (composition) degradation herbicide metabolite montmorillonite pH aluminum silicate bentonite clay glycine glyphosate herbicide adsorption analogs and derivatives analysis Argentina chemistry soil soil pollutant theoretical model Adsorption Aluminum Silicates Argentina Bentonite Glycine Herbicides Models, Theoretical Soil Soil Pollutants The most worldwide used herbicide is glyphosate, phosphonomethylglycine (PMG). Consequently, a significant amount of PMG, its metabolites (sarcosine, SAR, and aminomethylphosphonic acid, AMPA) and the degradation product, methylphosphonic acid (MPA), reaches the soil, which acts as final sink. Because clays are one of the most reactive components of soils, expansive clays such as montmorillonite (Mt) are used to retain agriculture contaminants with some success. In this work, as a preliminary step for the evaluation of the risk that PMG, SAR, AMPA, and MPA occurrence could have on the environment, their adsorption on Mt surface was performed. The adsorption process was analyzed at constant adsorbate concentrations and two pH values to take into account the different protonation states of the amino group. DTA, XRD, zeta potential measurements, and XPS were used to identify the interactions or association mechanisms with the clay surface, the entry of adsorbates into the Mt interlayer, and electric charge changes on the Mt surface, and evaluate the acid-base surface complex constants, respectively. The interlayer thickness in acid media indicated that adsorbates are able to enter the interlayer in planar form. Besides, for the Mt-PMG sample, some PMG molecules could be also inserted as a bilayer or with a tilt angle of 52.4° in the interlayer. However, in alkaline media, the interlayer thickness indicated that the adsorbate arrangement differed from that of acidic media where PMG and MPA could have more than one orientation. The surface complex deprotonation constants were determined for the =NH+2 ⇆ =NH+H+ process, being 3.0, 5.0, and 7.3 for PMG, AMPA, and SAR, respectively. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature. 2018 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_09441344_v25_n18_p18138_Flores http://hdl.handle.net/20.500.12110/paper_09441344_v25_n18_p18138_Flores |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Aminomethylphosphonic acid Glyphosate Methylphosphonic acid Montmorillonite Sarcosine Surface adsorption sites adsorption amino acid chemical compound concentration (composition) degradation herbicide metabolite montmorillonite pH aluminum silicate bentonite clay glycine glyphosate herbicide adsorption analogs and derivatives analysis Argentina chemistry soil soil pollutant theoretical model Adsorption Aluminum Silicates Argentina Bentonite Glycine Herbicides Models, Theoretical Soil Soil Pollutants |
| spellingShingle |
Aminomethylphosphonic acid Glyphosate Methylphosphonic acid Montmorillonite Sarcosine Surface adsorption sites adsorption amino acid chemical compound concentration (composition) degradation herbicide metabolite montmorillonite pH aluminum silicate bentonite clay glycine glyphosate herbicide adsorption analogs and derivatives analysis Argentina chemistry soil soil pollutant theoretical model Adsorption Aluminum Silicates Argentina Bentonite Glycine Herbicides Models, Theoretical Soil Soil Pollutants Some aspects of the adsorption of glyphosate and its degradation products on montmorillonite |
| topic_facet |
Aminomethylphosphonic acid Glyphosate Methylphosphonic acid Montmorillonite Sarcosine Surface adsorption sites adsorption amino acid chemical compound concentration (composition) degradation herbicide metabolite montmorillonite pH aluminum silicate bentonite clay glycine glyphosate herbicide adsorption analogs and derivatives analysis Argentina chemistry soil soil pollutant theoretical model Adsorption Aluminum Silicates Argentina Bentonite Glycine Herbicides Models, Theoretical Soil Soil Pollutants |
| description |
The most worldwide used herbicide is glyphosate, phosphonomethylglycine (PMG). Consequently, a significant amount of PMG, its metabolites (sarcosine, SAR, and aminomethylphosphonic acid, AMPA) and the degradation product, methylphosphonic acid (MPA), reaches the soil, which acts as final sink. Because clays are one of the most reactive components of soils, expansive clays such as montmorillonite (Mt) are used to retain agriculture contaminants with some success. In this work, as a preliminary step for the evaluation of the risk that PMG, SAR, AMPA, and MPA occurrence could have on the environment, their adsorption on Mt surface was performed. The adsorption process was analyzed at constant adsorbate concentrations and two pH values to take into account the different protonation states of the amino group. DTA, XRD, zeta potential measurements, and XPS were used to identify the interactions or association mechanisms with the clay surface, the entry of adsorbates into the Mt interlayer, and electric charge changes on the Mt surface, and evaluate the acid-base surface complex constants, respectively. The interlayer thickness in acid media indicated that adsorbates are able to enter the interlayer in planar form. Besides, for the Mt-PMG sample, some PMG molecules could be also inserted as a bilayer or with a tilt angle of 52.4° in the interlayer. However, in alkaline media, the interlayer thickness indicated that the adsorbate arrangement differed from that of acidic media where PMG and MPA could have more than one orientation. The surface complex deprotonation constants were determined for the =NH+2 ⇆ =NH+H+ process, being 3.0, 5.0, and 7.3 for PMG, AMPA, and SAR, respectively. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature. |
| title |
Some aspects of the adsorption of glyphosate and its degradation products on montmorillonite |
| title_short |
Some aspects of the adsorption of glyphosate and its degradation products on montmorillonite |
| title_full |
Some aspects of the adsorption of glyphosate and its degradation products on montmorillonite |
| title_fullStr |
Some aspects of the adsorption of glyphosate and its degradation products on montmorillonite |
| title_full_unstemmed |
Some aspects of the adsorption of glyphosate and its degradation products on montmorillonite |
| title_sort |
some aspects of the adsorption of glyphosate and its degradation products on montmorillonite |
| publishDate |
2018 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_09441344_v25_n18_p18138_Flores http://hdl.handle.net/20.500.12110/paper_09441344_v25_n18_p18138_Flores |
| _version_ |
1768544458907844608 |