Papers by Philippe Le Coustumer
Research Square (Research Square), Dec 3, 2023
Environmental Geochemistry and Health, 2008
<jats:title>Abstract</jats:title> <jats:p>Thorium Phosphate-Diphosphate (TPD) c... more <jats:title>Abstract</jats:title> <jats:p>Thorium Phosphate-Diphosphate (TPD) can be considered as a potential matrix for the immobilization of actinides and especially for the plutonium coming from dismantled nuclear weapons. The capability of this solid to form solid solutions by substitution of thorium by tetravalent uranium, neptunium or plutonium is rather high. The synthesis of sintered pellets of thorium-uranium(IV) phosphate-diphosphate was successfully performed. Their density reached 95–99% of the value calculated from XRD data. The open and closed porosities were equal to 2–3% each. The resistance of the TPD and derivative solid solutions to aqueous corrosion are also very good. Leaching tests of powdered samples containing tetravalent plutonium or uranium showed that the normalized dissolution rate remained low (between 10−5 and 10−6 g/(m2.d)) even in acidic media. For tetravalent actinides, the saturation of the leachate seems to be controlled by the precipitation of the thorium phosphate-hydrogenphosphate hydrate which solubility product was found to be KS,0°* = 10−66.6 ± 1. This very low value allows a supplementary delay of the actinides migration in the hypothesis of their release in the leachate from the matrix.</jats:p>
Chemistry of Materials, May 31, 2002
Taking into account some attractive properties of the thorium phosphate-diphosphate (Th 4 (PO 4) ... more Taking into account some attractive properties of the thorium phosphate-diphosphate (Th 4 (PO 4) 4 P 2 O 7), called TPD, we focused our research on its potential use as a ceramic for the long term storage of some radionuclides including trivalent and tetravalent actinides. In this objective, we already investigated with success several ways of preparation of the pure TPD and solid solutions with tetravalent actinides either by wet or dry chemical methods. In the field of nuclear applications and considering handling operations on the radioactive materials, the preparation of this compound in the ceramic form was developed. Therefore, a precursor of TPD was especially synthesized in order to get sintered samples after performing an uniaxial pressing at room temperature followed by a heat treatment at high temperature. The synthesis, the characterization, and the sintering procedure of the precursor are described in this paper. The influence of the heating temperature on the specific area of the powder is examined and then correlated with the granulometry and the densification of the solid. For all of the samples, the apparent and effective relative densities obtained are in the range of 87-99% of the value calculated from XRD data. Moreover, some physical properties such as thermal diffusivity, thermal conductivity, and specific heat were measured from room temperature up to 1000°C. The main results are given in this paper. Finally, the durability of the sintered TPD samples during leaching tests was studied. The apparent dissolution rates remain low even in very corrosive media (1.25(2) × 10-3 g d-1 in 5 M HNO 3 at 25°C) which shows that the TPD can be considered as a promising candidate for the immobilization of actinides and some fission products for a long-term storage.
Journal of Nuclear Materials, Dec 1, 2004
Several compositions of new precursor of thorium–uranium (IV) phosphate–diphosphate solid solutio... more Several compositions of new precursor of thorium–uranium (IV) phosphate–diphosphate solid solutions (Th4−xUx(PO4)4P2O7, called β-TUPD) were synthesized in closed PTFE containers either in autoclave (160°C) or on sand bath (90–160°C). All the samples appeared to be single phase. From XRD data and TEM observations, the diffraction lines matched well with that of pure thorium phosphate–hydrogenphosphate hydrate (TPHPH), Th2(PO4)2(HPO4)·H2O, which confirmed the
Physics and Chemistry of the Earth, Parts A/B/C, 2011
This study was conducted to appraise the quality of groundwater for irrigation and domestic water... more This study was conducted to appraise the quality of groundwater for irrigation and domestic water supply in the Ga West Municipality, Ghana. A total of 29 borehole water samples were collected for hydrogeochemical analysis and interpreted using hydrogeochemical plots and multivariate statistical analysis. The relative abundance of the major ions in the analyzed water samples were in the order Na + > Ca 2+ > Mg 2+ > K + and HCO 3-> Cl-> SO 4 2-. Trilinear Piper plot shows that Na-HCO 3-Cl and Na-Ca-HCO 3-Cl are the dominant water types in the area. The Ca 2+ and HCO 3 in these type of waters are primarily from dissolution of carbonate minerals whilst the Na + and Clmay have been input from water-rock interaction with granitic rocks, seawater intrusion, and anthropogenic activities in the watershed. All the analyzed physico-chemical parameters are within the acceptable limits of the World Health Organization (WHO) for drinking except TDS, total hardness, Na + , and Clwhich could be as a result of solid waste leachate and marine water intrusion. The samples have low to medium sodium hazard values with high to very high salinity hazard values when plotted on the Wilcox diagram. This suggests that the water is suitable for irrigation purposes with regard to sodium hazard but a mixing of the high salinity water with low salinity water is highly recommended prior to irrigation to reduce the salinity hazard in the area. However, if the crops are salt tolerant, then mixing is not necessary. Three factors explain 99.8% of the total variance and suggest that water-rock interaction is the most important factor that controls the groundwater chemistry. Besides, some contribution from agricultural activities and seawater
Cette étude démontre qu'en zone soudano-sahélienne, en année à pluviosité déficitaire, à différen... more Cette étude démontre qu'en zone soudano-sahélienne, en année à pluviosité déficitaire, à différentes échelles, plusieurs facteurs physiques, chimiques et anthropiques des sols régissent le report hydrique, part bénéfique du ruissellement représentant «une irrigation naturelle, complémentaire et simultanée à la pluie qui l'a générée en fonction des conditions topographiques et micro morphologiques avec transfert complémentaire de fertilité ». En condition pluviale, l'encroûtement décroissant le long du versant favorise l'infiltration du report hydrique dans les unités de sol en bas de pente. A l'échelle du champ, il est encore maximisé par le micromodelé concave, par une compaction profonde moins forte et par le labour. L'augmentation des nutriments est de 13,4 à 10% et en éléments fins de 16,3 à 12,5% respectivement sous labour et grattage. Cette maximisation du report hydrique provoque un drainage significatif très localement. Sur les périmètres irrigués la salinisation renforce les facteurs de formation des croûtes et le ruissellement, réduisant drastiquement la capacité d'infiltration des sols. Il en résulte une limitation des réserves en eau utile malgré l'irrigation non contraignante. Ceci provoque une sécheresse édaphique. Dans ces deux conditions culturales cette baisse drastique des stocks hydriques due à la formation d'un encroûtement conduit à la réduction voire à l'annulation du rendement des cultures. Ces résultats montrent la difficulté qu'ont les chercheurs à expliquer la complexité du comportement et du fonctionnement hydrique sur l'ensemble d'un versant et à l'intérieur du champ pour comprendre la variabilité des rendements. L'identification, à l'échelle de la parcelle et sur le versant, des causes du ruissellement et du report hydrique et d'en mesurer l'effet sur la modification des stocks hydriques sur de faibles distances est nécessaire pour conceptualiser un aménagement raisonné, innovant et efficace des flux de surface.
Nuclear Medicine and Biology, May 1, 2022
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Environmental Monitoring and Assessment, Sep 4, 2012
The research focuses on the monitoring of trace metals and pharmaceuticals as potential anthropog... more The research focuses on the monitoring of trace metals and pharmaceuticals as potential anthropogenic indicators of industrial and urban influences on surface water. This study includes analysis of tracers use for the indication of water pollution events and discussion of the detection method of these chemicals. The following criteria were proposed for the evaluation of indicators: specificity (physical chemical properties), variability (spatial and temporal), and practicality (capacity of the sampling and analytical techniques). The combination of grab and passive water sampling (i.e., diffusive gradient in the thin film and polar organic chemical integrated samplers) procedure was applied for the determination of dissolved and labile trace metals (Ag, Cd, Cr, Cu, Ni, Pb, and Zn) and pharmaceuticals (carbamazepine, diazepam, paracetamol, caffeine, diclofenac, and ketoprofen). Samples were analyzed using inductively coupled plasma mass spectrometry (MS; trace metals) and liquid chromatography-tandem MS electrospray ionization+/− (pharmaceuticals). Our results demonstrate the distinctive spatial and temporal patterns of trace elements distribution along an urban watercourse. Accordingly, two general groups of trace metals have been discriminated: "stable" (Cd and Cr) and "time varying" (Cu, Zn, Ni, and Pb). The relationship Cd≫Cu >Ag>Cr≥Zn was proposed as an anthropogenic signature of the industrial and urban activities pressuring the environment from point sources (municipal wastewaters) and the group Pb-Ni was discussed as a relevant fingerprint of the economic activity (industry and transport) mainly from non-point sources (runoff, atmospheric depositions, etc.). Pharmaceuticals with contrasting hydrochemical properties of molecules (water solubility, bioaccumulation, persistence during wastewater treatment processes) were discriminated on conservative, labile, and with combined properties in order to provide information on wastewater treatment plant efficiency, punctual events (e.g., accidents on sewage works, runoff), and uncontrolled discharges. Applying mass balance modeling, medicaments were described as relevant socioeconomic indicators, which can give a picture of main social aspects of the region.
HAL (Le Centre pour la Communication Scientifique Directe), 1999
This work presents a feasibility study for the revalorization of ultimate glassy wastes. A new pr... more This work presents a feasibility study for the revalorization of ultimate glassy wastes. A new process was used to convert these wastes into high value structural composite materials that can be used as brake friction materials. As significant amounts of vitrified domestic waste residues (20 to 60 wt%) were used to manufacture these composite materials, this revalorization process is particularly promising in the context of clean technologies and sustainable development as an alternative to the storage of wastes. Thus the aim of this study was to determine the feasibility of using glassy wastes as friction material in automotive brakes and, moreover, to assess whether this revalorization technique of ultimate wastes is both economical viable and environmentally friendly. Specific mechanical properties (friction, wear rate etc) were measured and appeared to be better than those of conventional commercial brake pads. To assess the environmental impact of these composite materials, risk assessment studies were conducted to evaluate the remobilization of hazardous species such as heavy metals that are concentrated in the wastes. Leaching tests were conducted to simulate the effects of weathering. The alteration solutions were analyzed by ICP-MS to evaluate the dissolution rate of the wastes matrix and the amount of heavy metals released. Thermal shock experiments were conducted with laser ablation and ICP-MS to monitor the secondary products rejected at high temperature. Reutilization of wastes for friction applications appeared to be an economically viable opportunity to converse and valorize ultimate glassy wastes respecting environmental regulations.
Microscopy and Microanalysis, Aug 1, 2001
Due to their ability to undergo a refractive index change (Δn) induced by appropriate UV irradiat... more Due to their ability to undergo a refractive index change (Δn) induced by appropriate UV irradiation and thermal development, Photo-Thermo-Refractive (PTR) glasses are candidate materials for use in optical applications such as hologram recording, optical data storage, or spectral filters. Although this induced index modulation (Δn) has been characterized in terms of its optical ramifications, glass scientists are working to understand more clearly, the underlying mechanisms associated with the photo-induced crystallization process. For example, the phase, concentration and size of crystals responsible for the induced index change, the diffusion and growth process leading to the resultant optical behavior, and the precise role of the active components of PTR glasses, has yet to be completely elucidated. Numerous techniques have been employed to address these questions and this paper reports results of sample preparation and analysis of PTR glasses using Transmission Electron Microscopy (TEM).
Talanta, Feb 1, 2020
Three methods of membrane separation by dead-end, tangential, and centrifugal ultrafiltration (UF... more Three methods of membrane separation by dead-end, tangential, and centrifugal ultrafiltration (UF) were considered in order to understand the physicochemical phenomena occurring during the preconcentration of the colloidal phase of soil water. The analytical approach used involved dynamic light scattering (DLS), transmission electron microscopy (TEM), determination of total organic carbon (TOC-metry) and mass spectrometry (ICP-MS). The mass amounts of the major components of the colloidal phase, i.e. Al, Fe and total organic carbon (TOC), as well as the mass amount of uranium considered as a trace element of environmental interest, were determined, both in soil water, and in the concentrates (i.e. retentates) and filtrates of this water obtained by the 3 methods tested. Dead-end ultrafiltration led to an enlargement of the size distribution towards larger sizes because of agglomeration/aggregation phenomena. This method also generated enrichment of concentrates, in particular in organic matter. The consequence was that large structures were observed coating or embedding the particles initially present individually dispersed in the test sample. The mass amounts of elements and TOC increased more importantly than expected, which confirmed the enrichment of the concentrates from the dissolved phase probably by sorption on colloidal objects. To a lesser extent similar effects were observed after tangential ultrafiltration. Such phenomena were not observed after centrifugal ultrafiltration. From a practical point of view, both tangential and centrifugal ultrafiltration proved to be both the most practical and the best suited for the preconcentration of soil water sample. Finally, centrifugal ultrafiltration has proved to be the best compromise given the preservation of colloidal particles and method practicality.
HAL (Le Centre pour la Communication Scientifique Directe), Mar 28, 2012
HAL (Le Centre pour la Communication Scientifique Directe), 2018
AFFInternational audienc
ACS Biomaterials Science & Engineering, Jun 30, 2022
Journal of Applied Polymer Science, May 26, 2020
In many applications, we monitor data obtained from multiple streaming sources for collective dec... more In many applications, we monitor data obtained from multiple streaming sources for collective decision making. The task presents several challenges. First, data in sensor networks, satellite transmissions, and many other fields are often of large volume, fast speed, and highly bursty nature. Second, because data are collected from multiple sources, it is impossible to offload classification decisions to individual data sources. Hence, the central classifier responsible for decision making is constantly under overloaded situations. In this paper, we study intelligent load shedding for classifying multi-source data. We aim at maximizing classification quality under resource (CPU and bandwidth) constraints. We use a Markov model to predict the distribution of feature values over time. Then, leveraging Bayesian decision theory, we use Bayes risk analysis to model the variances among different data sources in their contributions to classification quality. We adopt an Expected Observational Risk criterion to quantify the loss of classification quality due to load shedding, and propose a Best Feature First (BFF) algorithm that greedily minimizes such a risk. We also introduce an approximate BFF algorithm that reduces computation complexity. The effectiveness of the approach proposed is confirmed by several experiments on both synthetic and real-life data.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, Nov 1, 2017
The use of cerium dioxide manufactured nanoparticles (CeO2 MNPs) at a large scale in the industry... more The use of cerium dioxide manufactured nanoparticles (CeO2 MNPs) at a large scale in the industry, automotive and everyday products is resulting in a continuous emission and release of CeO2 MNPs to the aquatic environments. In such complex systems, MNPs interact with water components, including biopolymers, resulting in MNP coating which give a new environmental identity to the MNPs and greatly influence their fate, transport and biological impact. MNP surface properties, aggregation, media composition such as ionic composition and pH, strongly influence the importance of natural organic matter coating and coating stability with time. In our study, we are using alginate, a relevant surrogate of natural organic polysaccharides, to coat CeO2 MNPs under different conditions from ultrapure water to synthetic and natural waters. First, the most favourable conditions of alginate coating are defined and then the stability of this coating in changing pH condition is investigated. Then alginate coating impact, at variable alginate concentration, is studied in synthetic and natural waters and comparison is made with ultrapure water. The possible interaction mechanisms between alginate, CeO2, dissolved ions (in particular divalent cations) and natural inorganic compounds are discussed. Our finding demonstrates that alginate concentration, solution pH and presence of divalent cations are key parameters defining the stability and effect of alginate coating and that once formed the biopolymer coating is found irreversible with time and when changing the solution chemistry.
BioMed Research International, 2013
e synthesis of nanosized particles of Ag-doped hydroxyapatite with antibacterial properties is o... more e synthesis of nanosized particles of Ag-doped hydroxyapatite with antibacterial properties is of great interest for the development of new biomedical applications. e aim of this study was the evaluation of Ca 10− Ag (PO 4) 6 (OH) 2 nanoparticles (Ag:HAp-NPs) for their antibacterial and antifungal activity. Resistance to antimicrobial agents by pathogenic bacteria has emerged in the recent years and became a major health problem. Here, we report a method for synthesizing Ag doped nanocrystalline hydroxyapatite. A silverdoped nanocrystalline hydroxyapatite was synthesized at 100 ∘ C in deionised water. Also, in this paper Ag:HAp-NPs are evaluated for their antimicrobial activity against �ram-positive and �ram-negative bacteria and fungal strains. e speci�c antimicrobial activity revealed by the qualitative assay is demonstrating that our compounds are interacting differently with the microbial targets, probably due to the differences in the microbial wall structures.
HAL (Le Centre pour la Communication Scientifique Directe), 2018
AFFInternational audienc
European Microscopy Congress 2016: Proceedings, Dec 20, 2016
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Papers by Philippe Le Coustumer