Glyphosate adsorption on montmorillonite: An experimental and theoretical study of surface complexes
In this study we perform X-ray diffraction and XPS analysis to study the adsorption of the herbicide glyphosate on montmorillonite. Structures of the surface complexes are proposed based on the XPS and XRD patterns and explored using molecular modeling techniques. Adsorption isotherms showed multist...
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todo:paper_01691317_v50_n2_p167_Khoury2023-10-03T15:06:55Z Glyphosate adsorption on montmorillonite: An experimental and theoretical study of surface complexes Khoury, G.A. Gehris, T.C. Tribe, L. Torres Sánchez, R.M. dos Santos Afonso, M. Adsorption Clay mineral Glyphosate Herbicide Montmorillonite Adsorption energies Aluminol Amino moiety Basal spacing Bidentate complexes External surfaces Glyphosates Herbicide glyphosate High concentration Interlayer spaces Internal surfaces Macroscopic behaviors Mineral interactions Molecular modeling techniques Monodentates Montmorillonite Multi-step Negative values PH dependence pH value Phosphonates Presence of water Silanol groups Surface complex Theoretical models Theoretical study Water molecule XPS XPS analysis XRD patterns Adsorption Complexation Dyes Herbicides Minerals Molecules Silicate minerals Weed control X ray diffraction X ray diffraction analysis X ray photoelectron spectroscopy Clay minerals adsorption computer simulation concentration (composition) experimental mineralogy glyphosate isotherm microstructure montmorillonite numerical model pH theoretical study X-ray diffraction X-ray spectroscopy In this study we perform X-ray diffraction and XPS analysis to study the adsorption of the herbicide glyphosate on montmorillonite. Structures of the surface complexes are proposed based on the XPS and XRD patterns and explored using molecular modeling techniques. Adsorption isotherms showed multistep profiles at all pHs studied, indicating the adsorption on aluminol and/or silanol groups of the external surface and in the interlayer space. PMG intercalation was indicated by the XRD patterns. The increase of the basal spacing as a function of the number of water molecules in the calculations indicated the appropriateness of the theoretical model to simulate macroscopic behaviors of the water/clay mineral interactions. Final conformations of the system determined by molecular mechanics indicated that the charged amino moiety was attracted by the negative surfaces of the interlayer space in absence or presence of water molecules, with marked pH dependence. Negative values of the estimated adsorption energies at all pH values studied suggested that glyphosate molecules were adsorbed via the amino moiety or through monodentate or bidentate complexes formed between the phosphonate moiety and the internal surfaces of the clay mineral, explaining the basal spacing changes at high concentrations of PMG. © 2010 Elsevier B.V. Fil:Tribe, L. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_01691317_v50_n2_p167_Khoury |
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Universidad de Buenos Aires |
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I-28 |
| repository_str |
R-134 |
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Adsorption Clay mineral Glyphosate Herbicide Montmorillonite Adsorption energies Aluminol Amino moiety Basal spacing Bidentate complexes External surfaces Glyphosates Herbicide glyphosate High concentration Interlayer spaces Internal surfaces Macroscopic behaviors Mineral interactions Molecular modeling techniques Monodentates Montmorillonite Multi-step Negative values PH dependence pH value Phosphonates Presence of water Silanol groups Surface complex Theoretical models Theoretical study Water molecule XPS XPS analysis XRD patterns Adsorption Complexation Dyes Herbicides Minerals Molecules Silicate minerals Weed control X ray diffraction X ray diffraction analysis X ray photoelectron spectroscopy Clay minerals adsorption computer simulation concentration (composition) experimental mineralogy glyphosate isotherm microstructure montmorillonite numerical model pH theoretical study X-ray diffraction X-ray spectroscopy |
| spellingShingle |
Adsorption Clay mineral Glyphosate Herbicide Montmorillonite Adsorption energies Aluminol Amino moiety Basal spacing Bidentate complexes External surfaces Glyphosates Herbicide glyphosate High concentration Interlayer spaces Internal surfaces Macroscopic behaviors Mineral interactions Molecular modeling techniques Monodentates Montmorillonite Multi-step Negative values PH dependence pH value Phosphonates Presence of water Silanol groups Surface complex Theoretical models Theoretical study Water molecule XPS XPS analysis XRD patterns Adsorption Complexation Dyes Herbicides Minerals Molecules Silicate minerals Weed control X ray diffraction X ray diffraction analysis X ray photoelectron spectroscopy Clay minerals adsorption computer simulation concentration (composition) experimental mineralogy glyphosate isotherm microstructure montmorillonite numerical model pH theoretical study X-ray diffraction X-ray spectroscopy Khoury, G.A. Gehris, T.C. Tribe, L. Torres Sánchez, R.M. dos Santos Afonso, M. Glyphosate adsorption on montmorillonite: An experimental and theoretical study of surface complexes |
| topic_facet |
Adsorption Clay mineral Glyphosate Herbicide Montmorillonite Adsorption energies Aluminol Amino moiety Basal spacing Bidentate complexes External surfaces Glyphosates Herbicide glyphosate High concentration Interlayer spaces Internal surfaces Macroscopic behaviors Mineral interactions Molecular modeling techniques Monodentates Montmorillonite Multi-step Negative values PH dependence pH value Phosphonates Presence of water Silanol groups Surface complex Theoretical models Theoretical study Water molecule XPS XPS analysis XRD patterns Adsorption Complexation Dyes Herbicides Minerals Molecules Silicate minerals Weed control X ray diffraction X ray diffraction analysis X ray photoelectron spectroscopy Clay minerals adsorption computer simulation concentration (composition) experimental mineralogy glyphosate isotherm microstructure montmorillonite numerical model pH theoretical study X-ray diffraction X-ray spectroscopy |
| description |
In this study we perform X-ray diffraction and XPS analysis to study the adsorption of the herbicide glyphosate on montmorillonite. Structures of the surface complexes are proposed based on the XPS and XRD patterns and explored using molecular modeling techniques. Adsorption isotherms showed multistep profiles at all pHs studied, indicating the adsorption on aluminol and/or silanol groups of the external surface and in the interlayer space. PMG intercalation was indicated by the XRD patterns. The increase of the basal spacing as a function of the number of water molecules in the calculations indicated the appropriateness of the theoretical model to simulate macroscopic behaviors of the water/clay mineral interactions. Final conformations of the system determined by molecular mechanics indicated that the charged amino moiety was attracted by the negative surfaces of the interlayer space in absence or presence of water molecules, with marked pH dependence. Negative values of the estimated adsorption energies at all pH values studied suggested that glyphosate molecules were adsorbed via the amino moiety or through monodentate or bidentate complexes formed between the phosphonate moiety and the internal surfaces of the clay mineral, explaining the basal spacing changes at high concentrations of PMG. © 2010 Elsevier B.V. |
| format |
JOUR |
| author |
Khoury, G.A. Gehris, T.C. Tribe, L. Torres Sánchez, R.M. dos Santos Afonso, M. |
| author_facet |
Khoury, G.A. Gehris, T.C. Tribe, L. Torres Sánchez, R.M. dos Santos Afonso, M. |
| author_sort |
Khoury, G.A. |
| title |
Glyphosate adsorption on montmorillonite: An experimental and theoretical study of surface complexes |
| title_short |
Glyphosate adsorption on montmorillonite: An experimental and theoretical study of surface complexes |
| title_full |
Glyphosate adsorption on montmorillonite: An experimental and theoretical study of surface complexes |
| title_fullStr |
Glyphosate adsorption on montmorillonite: An experimental and theoretical study of surface complexes |
| title_full_unstemmed |
Glyphosate adsorption on montmorillonite: An experimental and theoretical study of surface complexes |
| title_sort |
glyphosate adsorption on montmorillonite: an experimental and theoretical study of surface complexes |
| url |
http://hdl.handle.net/20.500.12110/paper_01691317_v50_n2_p167_Khoury |
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