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Levard C, Masion A, Rose J, Doelsch E, Borschneck D, Olivi L, Chaurand P, Dominici C, Ziarelli F, Thill A, Maillet P, Bottero JY. Synthesis of Ge-imogolite: influence of the hydrolysis ratio on the structure of the nanotubes. Phys Chem Chem Phys 2011; 13:14516-22. [DOI: 10.1039/c1cp20346k] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Thoral S, Rose J, Garnier JM, Van Geen A, Refait MP, Traverse A, Fonda E, Nahon D, Bottero JY. XAS study of iron and arsenic speciation during Fe(II) oxidation in the presence of As(III). Environ Sci Technol 2005; 39:9478-85. [PMID: 16475325 DOI: 10.1021/es047970x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The speciation of As and Fe was studied during the oxidation of Fe(II)-As(III) solutions by combining XAS analysis at both the Fe and As K-edges. Fe(II) and As(III) were first hydrolyzed to pH 7 under anoxic conditions; the precipitate was then allowed to oxidize in ambient air for 33 h under vigorous stirring. EXAFS analysis at the As K-edge shows clear evidence of formation of inner-sphere complexes between As(III) and Fe(II), i.e., before any oxidation. Inner-sphere complexes were also observed when Fe became sufficiently oxidized, in the form of edge-sharing and double-corner linkages between AsIIIO3 pyramids and FeIIIO6 octahedra. XAS analyses at the Fe K-edge reveal that the presence of As(III) in the solution limits the polymerization of Fe(II) and the formation of green rust and inhibits the formation of goethite and lepidocrocite. Indeed, As(III) accelerates the Fe(II) oxidation kinetics and leads to the formation of nanosized Fe-As subunits of amorphous aggregates. These observations, rather than a presumed weaker affinity of As(III) for iron oxyhydroxides, might explain why As(III) is more difficult to remove than As(V) by aerating reducing groundwater.
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Affiliation(s)
- S Thoral
- CEREGE UMR 6635 CNRS-Université Paul Cézanne Aix-Marseille III, IFR PMSE 112, Europôle Méditerranéen de l'Arbois, 13545 Aix-en-Provence, France
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Vilomet JD, Veron A, Ambrosi JP, Moustier S, Bottero JY, Chatelet-Snidaro L. Isotopic tracing of landfill leachates and pollutant lead mobility in soil and groundwater. Environ Sci Technol 2003; 37:4586-4591. [PMID: 14594365 DOI: 10.1021/es010245r] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Here we provide evidence of the capability of stable lead isotopes to trace landfill leachate in a shallow groundwater. The municipal landfill we have investigated is located in southeastern France. It has no bottom liner, and wastes are placed directly on the ground. Stable lead isotopes allow the characterization of this landfill leachate signature (206Pb/207Pb = 1.189 +/- 0.004) that is clearly different from that of the local atmosphere (206Pb/207Pb = 1.150 +/- 0.006) and crustal lead (206Pb/207Pb = 1.200 +/- 0.005). Piezometers located in the direct vicinity of the landfill generally display this contaminant imprint. The landfill plume is monitored up to 1000 m downgradient of the landfill, in very good agreement with evaluation from chloride concentration. Meanwhile, 206Pb/207Pb ratios measured at a piezometer located 4600 m downgradient of the landfill suggest a contamination by the landfill plume. This result shows that the complexity of a pollutant plume dispersion in this shallow groundwater system requires several independent tracers to clearly resolve origin and transport pathways for contaminants. Furthermore, seasonal rainfall variation for this Mediterranean mixed Quaternary alluvion reservoir and the use of KCl fertilizers might favor an efficient remobilization of atmospheric lead in plowed soils and its transfer into groundwater as shown by lead isotope systematics.
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Affiliation(s)
- J D Vilomet
- CEREGE, U.M.R. 6635, CNRS/Université Aix-Marseille 3, B.P. 80, 13545 Aix en Provence Cedex 4, France
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Lambert S, Moustier S, Dussouillez P, Barakat M, Bottero JY, Le Petit J, Ginestet P. Analysis of the structure of very large bacterial aggregates by small-angle multiple light scattering and confocal image analysis. J Colloid Interface Sci 2003; 262:384-90. [PMID: 16256618 DOI: 10.1016/s0021-9797(03)00167-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2002] [Accepted: 02/05/2003] [Indexed: 11/23/2022]
Abstract
This work aims at developing a more accurate measurement of the physical parameters of fractal dimension and the size distribution of large fractal aggregates by small-angle light scattering. The theory of multiple scattering has been of particular interest in the case of fractal aggregates for which Rayleigh theory is no longer valid. The introduction of multiple scattering theory into the interpretation of scattering by large bacterial aggregates has been used to calculate the fractal dimension and size distribution. The fractal dimension is calculated from the form factor F(q) at large scattering angles. At large angles the fractal dimension can also be computed by considering only the influence of the very local environment on the optical contrast around a subunit. The fractal dimensions of E. coli strains flocculated with two different cationic polymers have been computed by two techniques: static light scattering and confocal image analysis. The fractal dimensions calculated with both techniques at different flocculation times are very similar: between 1.90 and 2.19. The comparison between two completely independent techniques confirms the theoretical approach of multiple scattering of large flocs using the Mie theory. Size distributions have been calculated from light-scattering data taking into account the linear independence of the structure factor S(q) relative to each size class and using the fractal dimension measured from F(q) in the large-angle range or from confocal image analysis. The results are very different from calculations made using hard-sphere particle models. The size distribution is displaced toward the larger sizes when multiple scattering is considered. Using this new approach to the analysis of very large fractal aggregates by static light multiple scattering, the fractal dimension and size distribution can be calculated using two independent parts of the scattering curve.
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Affiliation(s)
- S Lambert
- CEREGE, UMR 6635 CNRS/Aix-Marseille III, Europôle de l'Arbois BP 80, 13545 Aix-en-Provence cedex 05, France
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Bottero JY, Cases JM, Fiessinger F, Poirier JE. Studies of hydrolyzed aluminum chloride solutions. 1. Nature of aluminum species and composition of aqueous solutions. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100459a021] [Citation(s) in RCA: 348] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Bottero JY, Tchoubar D, Cases JM, Fiessinger F. Investigation of the hydrolysis of aqueous solutions of aluminum chloride. 2. Nature and structure by small-angle x-ray scattering. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100215a034] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Vilomet JD, Angeletti B, Moustier S, Ambrosi JP, Wiesner M, Bottero JY, Chatelet-Snidaro L. Application of strontium isotopes for tracing landfill leachate plumes in groundwater. Environ Sci Technol 2001; 35:4675-4679. [PMID: 11770770 DOI: 10.1021/es000169c] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We are evaluating strontium isotopes as alternative tracers of landfill leachate in groundwater. The municipal landfill studied here is located in southeastern France. This landfill has no bottom liner, and wastes are placed directly on the ground. Based on the evaluation of chloride concentration, the plume extends a maximum of 4,600 m. Strontium isotopic composition characterizes two sources: natural groundwater (87Sr/86Sr = 0.708175) and landfill leachate contamination (87Sr/86Sr = 0.708457). The evolution of mixing ratios obtained with strontium reveals a second source of groundwater contamination: fertilizers (87Sr/ 86Sr = 0.707859). These results suggestthat isotopic signatures can be used to provide useful information on sources of groundwater contamination where conventional water quality parameters may yield ambiguous results.
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Affiliation(s)
- J D Vilomet
- CEREGE, UMR, 6635 CNRS/Université Aix-Marseille 3, Aix en Provence, France
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Lambert S, Thill A, Ginestet P, Audic JM, Bottero JY. Structural Interpretations of Static Light Scattering Patterns of Fractal Aggregates. J Colloid Interface Sci 2000; 228:379-385. [PMID: 10926478 DOI: 10.1006/jcis.2000.6965] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A method based on static light scattering by fractal aggregates is introduced to extract structural information. In this study, we determine the scattered intensity by a fractal aggregate calculating the Structure and the Form factors noted, respectively, S(q) and F(q). We use the approximation of the mean field Mie scattering by fractal aggregates (R. Botet, P. Rannou, and M. Cabane, appl. opt. 36, 8791, 1997). This approximation is validated by a comparison of the scattering and extinction cross sections values calculated using, on the one hand, Mie theory with a mean optical index n) and, on the other hand, the mean field approximation. Scattering and extinction cross sections values differ by about 5%. We show that the mean environment of primary scatterers characterized by the optical index n(s) must be taken into account to interpret accurately the scattering pattern from fractal aggregates. Numerical simulations were done to evaluate the influence of the fractal dimension values (D(f)>2) and of the radius of gyration or the number of primary particles within the aggregates (N=50 to 250) on the scatterers' mean optical contrast (n(s)/n). This last parameter plays a major role in determining the Form factor F(q) which corresponds to the primary particles' scattering. In associating the mean optical index (n) to structural characteristics, this work provides a theoretical framework to be used to provide additional structural information from the scattering pattern of a fractal aggregate (cf. Part II). Copyright 2000 Academic Press.
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Affiliation(s)
- S Lambert
- CEREGE, UMR 6635 CNRS/Aix-Marseille III, Europôle de l'Arbois BP 80, Aix-en-Provence Cedex 05, 13545, France
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Thill A, Lambert S, Moustier S, Ginestet P, Audic JM, Bottero JY. Structural Interpretations of Static Light Scattering Patterns of Fractal Aggregates. J Colloid Interface Sci 2000; 228:386-392. [PMID: 10926479 DOI: 10.1006/jcis.2000.6836] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Information on the size and structure of aggregates is critical in predicting the formation kinetics, settling velocities, and reactivity of particle aggregates. For some systems, however, accessing this information may be very difficult. Light scattering measurements are among the most useful techniques for accessing such information. In the case of large primary particles forming aggregates, the common Rayleigh approximation is not valid. Instead, Mie scattering must be used and multiple scattering must be accounted for. Moreover, size polydispersity and structure of aggregates are combined in the scattered intensity measurements. This work presents an experimental validation of a new theoretical approach for extracting information on both aggregate structure and size when multiple scattering cannot be neglected. The chemically controlled aggregation of 0.8-µm latex particles demonstrates the following: (1) Polydispersity effects prevent the interpretation of data to obtain structural information from the Structure factor S(q). (2) The calculated optical contrast decreasing during the aggregation can be correlated with the structural changes in the growing aggregates independently of size polydispersity. We have shown that a strict correlation can be obtained between the fractal dimension D(f) and the scatterers' mean optical contrast calculated at large scattering angles. (3) The changes in the Form factor (F(q)) due to multiple scattering when particles are close together yield a predicted structure that is in agreement with expected fractal dimension values and therefore S(q) can be described in term of both structure and size polydispersity. Copyright 2000 Academic Press.
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Affiliation(s)
- A Thill
- CEREGE, UMR 6635 CNRS/Aix-Marseille III, Europôle de l'arbois, Aix-en-Provence, 13545, France
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Abstract
Several assumptions are made when confocal scanning laser microscopy is used for the determination of the fractal dimension of aggregates. The purpose of this study is to experimentally show that one of these assumptions, which concerns the relation existing between the structure of an aggregate and that of its sections, is valid. A comparison between the structures of sections and reconstructed 3D edifices of latex aggregates shows that they are both directly related even in the case of relatively small aggregates. Copyright 1999 Academic Press.
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Affiliation(s)
- A Thill
- Europole Méditerranéen de l'Arbois, Les Milles Cedex, 13762, France
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Thill A, Veerapaneni S, Simon B, Wiesner M, Bottero JY, Snidaro D. Determination of Structure of Aggregates by Confocal Scanning Laser Microscopy. J Colloid Interface Sci 1998; 204:357-62. [PMID: 9698415 DOI: 10.1006/jcis.1998.5570] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The fractal dimension of a particle aggregate can provide fundamental information on the structure and origin of the aggregate. The analysis of large chemically homogeneous fractal objects has been achieved, but reliable methods of estimating the fractal dimensions of large and chemically heterogeneous aggregates are needed. To this end, we used confocal scanning laser microscopy in which thin optical sections of aggregates were obtained in order to calculate their 2D and ultimately 3D fractal dimensions according to the Mandelbrot theory. Fractal dimensions of 2.08 +/- 0.11 for a Brownian aggregation of latex particles and 2.25 +/- 0.12 for shear aggregation were determined using the confocal technique. These values are within the ranges for universality classes predicted for such aggregates and observed by previous investigators. Thus, this method appears to provide reliable estimates of the fractal dimension with particular utility in the characterization of aggregates composed of larger particles or complex materials where the fractal dimension may not be accessible by light-scattering measurements. The confocal method is used to analyze flocs of activated sludge material as one example of the application of this method to more complex, large (up to 500 µm), and chemically heterogeneous flocs. Copyright 1998 Academic Press.
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Affiliation(s)
- A Thill
- Laboratoire des Géosciences de l'Environnement, Centre Européen de Recherche et d'Enseignement de Géosciences de l'Environnement, Les Milles Cedex, 13762, France
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Saulnier F, Ferrero F, Bottero JY, Linden G. Variations de composition et nature de la fraction insoluble des lactosérums industriels. ACTA ACUST UNITED AC 1995. [DOI: 10.1051/lait:199517] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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