WorldCat Identities

Drot, Romuald

Overview
Works: 3 works in 4 publications in 1 language and 4 library holdings
Publication Timeline
Key
Publications about  Romuald Drot Publications about Romuald Drot
Publications by  Romuald Drot Publications by Romuald Drot
Most widely held works by Romuald Drot
Sorption des ions U(VI) et Eu(III) à l'interface solution -solides phosphatés : étude structurale et mécanismes by Romuald Drot ( Book )
2 editions published in 1998 in French and held by 2 WorldCat member libraries worldwide
LA MIGRATION DES RADIONUCLEIDES STOCKES EN SITES GEOLOGIQUES PROFONDS EST FORTEMENT REGIE PAR LES PROCESSUS DE SORPTION (NOTAMMENT SUR LA BARRIERE OUVRAGEE). UNE CONNAISSANCE FINE DE CES MECANISMES EST NECESSAIRE. LA DEMARCHE QUE NOUS PRESENTONS CONSISTE A DEFINIR EXPERIMENTALEMENT LES EQUILIBRES MIS EN JEU AVANT DE MODELISER LES DONNEES DE RETENTION. CERTAINS PHOSPHATES SONT CANDIDATS EN TANT QU'ADDITIFS A LA BARRIERE OUVRAGEE. NOUS AVONS CONSIDERE TH#4(PO#4)#4P#2O#7, ZRP#2O#7 ET ZR#2O(PO#4)#2 QUI PERMETTENT D'ETUDIER SEPAREMENT L'INFLUENCE DES GROUPEMENTS PO#4 ET P#2O#7. LES IONS EU(III) ET U(VI) SIMULENT LE COMPORTEMENT DES ACTINIDES TRIVALENTS ET HEXAVALENTS. APRES SYNTHESE, LES SOLIDES ONT ETE CARACTERISES PAR DIFFRACTION DES RAYONS X, SPECTROSCOPIE IR ET MICROANALYSE PAR SONDE ELECTRONIQUE. DES MESURES ELECTROCINETIQUES ONT REVELE UN COMPORTEMENT AMPHOTERE DES SITES DE SURFACE ET LA SPECTROFLUORIMETRIE LASER A MONTRE QU'AUCUN PHENOMENE DE DIFFUSION DU CATION SORBE DANS LE SUBSTRAT N'AVAIT LIEU. XPS ET SPECTROFLUORIMETRIE LASER ONT MONTRE QUE ZRP#2O#7 N'ADMET QU'UN SEUL TYPE DE SITES (P#2O#7), ALORS QUE TH#4(PO#4)#4P#2O#7 ET ZR#2O(PO#4)#2 PRESENTENT DEUX SITES DISTINCTS (PO#4/P#2O#7 ET PO#4/OXO, RESPECTIVEMENT). EN MILIEU KNO#3 0,5 M ET POUR UN TYPE DE SITE, LA SPECTROFLUORIMETRIE LASER A REVELE LA PRESENCE DE DEUX COMPLEXES DE SURFACE POUR U(VI) (SORPTION DE UO#2#+#2 ET DE UO#2NO#+#3) ET D'UN SEUL POUR EU(III) (SORPTION DE EUNO#2#+#3) ; LES ENTITES SORBEES FORMENT DES COMPLEXES DE SPHERE INTERNE BIDENTATES (EXAFS). LA SIMULATION DES COURBES DE TITRAGES POTENTIOMETRIQUES DE SUSPENSIONS DE CHACUN DES SOLIDES A L'AIDE DU CODE FITEQL (CAPACITE CONSTANTE) A CONDUIT AUX VALEURS DES CONSTANTES D'ACIDITE DE SURFACE. LES EQUILIBRES DE SORPTION ETANT DEFINIS, NOUS AVONS CALCULE LES CONSTANTES CORRESPONDANTES PAR SIMULATION DES ISOTHERMES DE SORPTION, EN RESPECTANT LES DIFFERENTES CONTRAINTES TIREES DE L'ETUDE STRUCTURALE
Etude thermodynamique de la sorption de l'uranyle sur la monazite et la magnétite by Olivia Félix ( )
1 edition published in 2012 in French and held by 1 WorldCat member library worldwide
The migration of radiotoxic elements in the geosphere is mainly regulated by chemical parameters which control the partitioning of the elements between mineral phases and aqueous solutions. Variation in temperature may affect the retention properties of a mineral surface and requires a careful investigation in order to understand the radionuclides behavior in the geosphere. In this way, the interaction mechanisms between uranium(VI) and two minerals (LaPO4 and Fe3O4) have been studied. In a first step, the monazite (LaPO4) has been chosen as methodological solid in order to clearly define all the different stages needed to completely characterize the influence of temperature on the sorption phenomena. To reach that goal, three media, more or less complexants towards aqueous uranyl and the mineral surface, have been considered. Physico-chemical as well as surface acid-base properties of the solid surface have been studied by considering three electrolytes (NaClO4, NaNO3 and Na2SO4) and temperatures ranged from 25°C to 95°C. The point of zero charge has been found to be identical for perchlorate and nitrate media (pHPZC=2.1) but it was found to be one pK unit higher for the sulfate medium indicating a sorption of the background electrolyte ions. The reaction heats associated to the hydration of the solid have been measured by using microcalorimetry and the nature of the reactive surface sites has been determined by carrying out Time-Resolved Laser-Induced Fluorescence Spectroscopy (TRLFS). On the basis of these experimental constraints, the titration curves obtained for the monazite suspensions were fitted by using the Constant Capacitance Model and the 1-pK model was preferred to characterize the surface charge evolution, due to the limited number of adjustable parameters. The surface protonation constants being determined, the behavior of U(VI) towards the monazite surface in the three electrolytes has been investigated. On the basis of both U(VI) speciation in solution and the results of a structural study carrying out by using TRLFS together with calorimetric measurements, the sorption edges have been modeled and the corresponding sorption constants determined. Since these values take into account a wide number of experimental results (both structural and thermodynamical ones) they appear to be accurate and could be extrapolated more confidently to other physico-chemical conditions. The experimental approach being validated with the methodological solid, preliminary tests have been carried out to study uranyl sorption onto a second substrate, the magnetite, more relevant than monazite in the field of radionuclides migration in the geosphere
Le défi énergétique by Christine Azémar ( Visual )
1 edition published in 2012 in French and held by 1 WorldCat member library worldwide
 
Audience Level
0
Audience Level
1
  Kids General Special  
Audience level: 0.50 (from 0.00 for Etude ther ... to 1.00 for Sorption d ...)
Associated Subjects
Languages
French (4)