DYNAMICS OF WATER CONFINED IN GEL FORMED DURING GLASS ALTERATION AT A PICOSECOND SCALE

Transcription

1 DYNAMICS OF WATER CONFINED IN GEL FORMED DURING GLASS ALTERATION AT A PICOSECOND SCALE Diane Rébiscoul a, Ibrahim Matar Briman a, Olivier Diat b, Julien Cambedouzou b, Patrick Jollivet a, Jean-Marc Zanotti c, Philippe Barboux d,stéphane Gin a a Laboratoire du Comportement à Long Terme des matrices de conditionnement CEA- Marcoule, France b CEA, Marcoule Institute for Separative Chemistry, CEA-Marcoule,France c Léon Brillouin Laboratory, CEA-Saclay, France d LCMCP, Chimie ParisTech, Paris, France PAGE 1

2 CONTEXT OF NUCLEAR WASTE French concept from ANDRA R7T7 glass secondary phases Glass surface gel Φ( RN) α M Source term verrealtéré = t, S r ( t, S ) ds dt Glass alteration rate Surface in contact with water Geologic time scale verre Study of the glass alteration Predictive Modeling Storage performance assessment

3 CONTEXT AND GOAL Rate laws and kinetics models of glass alteration generally take into account the properties of the gel trough a diffusion coefficient and some thermodynamic data arising from measurements in diluted media (D, Ci, K) Frugier P et al, J. of Nucl. Mat. 2008; 380: 8-21 Grambow B, J. of Nucl. Mat. 2001; 298: What is the validity of such parameters in the gel? Solution water Gel pores < 5 nm elements glass set of confined media Water + ions = leachate Cailleteau et al, Nature Materials 2007 ; 7: D H2O QENS and NMR m².g -1 1H 2 O-2DMSO m².g -1 2H 2 O-1DMSO 24 MAI x τ H2O in H 2 O = τ H2O in DMSO 2H 2 O-1DMSO Lowest SiO 2 dissolution rate x H2O Probing confined water dynamics in porous gel can provide a better understanding of water transport mechanisms and chemical reactivity in such confined media

4 SCIENTIFIC APPROACH 1) Impact of pore size and pore surface composition Models materials Complex composition (glass = 35 metal oxides) Secondary phases at the gel surface Porosity gradient Inactive R7T7 glass MCM41 + grafting H 2 O 2 < Ø < 2.7 nm Si-OH Al-OH Zr-OH 2) Impact of ions Models materials filled of leachate Leachate = ions + water 3) Case of gel formed during glass alteration Gels coming from the alteration of simplified glasses (SiO 2 /B 2 O 3 /NaO/CaO/X, with X=Al 2 O 3 or ZrO 2 )

5 MODELS MATERIALS PhD of I. Matar Briman I. Matar Briman, et al. Phys. Chem. C 2012, 116, I. Matar Briman, et al. Procedia Earth and Planetary Science, accepted Schematic concept of Hydrolytic Sol Gel (HSS) grafting method. α OH Reference Precursors Number of grafting cycle MCM-41-0 MCM Si-2 Si(OCH 3 ) 4 2 MCM Si-3 Si(OCH 3 ) 4 3 Goal Pore size effect Log I dvp/dr (cm 3.g -1.nm -1 ) SAXS patterns BJH Pore size distribution MCM-41 MCMSi-2 MCMSi-3 MCMAl-3 MCMZr Q (nm -1 ) MCM-41 MCMSi-2 MCMSi-3 MCMAl-3 MCMZr-3 Reference Si-OH / Al-OH / Zr-OH Pore diameter (nm) Wall thickness (nm) Vp (cm 3 /g) SSarea (m 2 /g) MCM MCMSi-2 MCM-Si MCM Al-3 Al(OC 2 H 5 ) 3 3 Pore surface composition effect MCM Zr-3 Zr(OC 2 H 5 ) Tevap of water ( C) OH/nm² (hydrolyzed) MCMAl (330 C) MCMZr (330 C) Pore diameter (nm)

6 MATERIALS FILLING I. Matar Briman, et al. Phys. Chem. C 2012, 116, I. Matar Briman, et al. Procedia Earth and Planetary Science, accepted Filling with water Filling with leachate (H) leachate (L) RH = 86 % at 25 C (saturated KCl solution) 24 hours in dessicator glass Alteration of a simplified glass SiO 2 /B2O 3 /Na 2 O/Al 2 O 3 /CaO S/V=2000 cm C in pure water during 35 days Model gels 48 hours at 20 C RH = of 86 % at 25 C (saturated KCl solution) Solution analysis Solution composition (g/l) D (nm) Si B Na Ca Al ion/nm ² ion/nm 3 ph (Chess) Leachate < (measured) MCMSi-2 porosity MCMAl-3porosity MCMZr-3 porosity concentrations in pores > concentrations in leachate

7 QENS ANALYSIS I. Matar Briman, et al. Phys. Chem. C 2012, 116, K λ=5.2 Å 140 µev 4.5 ps Sum over Q QENS time-of-flight spectometer, LLB - MIBEMOL one Lorentzian function 1 Γt ( Q) S( Q, ω) = π Γ ²( Q) + ω² t I (a.u.) 10 7 Q = 2.0 A Q = 1.63 A Q = 1.39 A Q = 0.92 A w (mev) Γ t ( Q) = D Q² t brownian diffusion Dt =( ) x 10-9 m².s-1 τ = ps hdtq² Γt ( Q) = 1+ D Q²τ t t jump diffusion Dt = ( ) x 10-9 m².s-1 τ = ps Singwi, K.S.; Sjolander, A.; Phys. Rev. 1960, 119, low impact of the confinement, the pore surface and the ions on Dt

8 QENS ANALYSIS I. Matar Briman, et al. Phys. Chem. C 2012, 116, EISF 2 Ielastic 3 j = 1 ( QR) Volino, F.; Dianoux, A.J. Mol. Phys. 1980, 41, I elastic + I quasi elastic EISF M ( Q) = f + (1 f ) QR f Free water Reference D (nm) R(Å) f Bulk MIBEMOL ± ± 0.02 MCM ± ± 0.01 MCMSi ± ± 0.01 MCM-Si ± ± 0.02 MCMAl ± ± 0.02 MCMZr ± ± 0.01 coordination bonds 1 H-MAS-NMR and DSC Free water Dt close to Dt bulk interfacial water f depends on pore surface No ions effect For pore size lower than 2.3 nm water dynamics mostly depends on the surface composition than the pore size

9 SCIENTIFIC APPROACH 1) Impact of pore size and pore surface composition Models materials Complex composition (glass = 35 metal oxides) Secondary phases at the gel surface Porosity gradient MCM41 + grafting H 2 O Si-OH Al-OH Zr-OH 2 < Ø < 2.7 nm 2) Impact of ions Models materials filled of leachate Leachate = ions + water 3) Case of gel formed during glass alteration Gels coming from the alteration of simplified glasses (SiO 2 /B 2 O 3 /NaO/CaO/X, with X=Al 2 O 3 or ZrO 2 )

10 ALTERED GLASSES Glass and gel composition Solution analysis Elementary molar ratio Retention factor in gel Si B Na Ca Zr Al O Si Na Ca Zr Al Zr/Ca glass Zr glass Al/Ca glass Al glass S. Indris et al, Physical Review B 71 (2005) S/V=80 cm C Ca effect Glass with Zr Glass with Al Is there also an effect on water dynamics at a ps time scale?

11 QENS ANALYSIS QENS time-of-flight spectometer, FOCUS -SINQ (PSI) Sum over Q 300 K λ=4.3 Å 90 µev 10 ps Zr/Ca glass vanadium glass 7 days 21 days 65 days one Lorentzian function Zr glass vanadium glass 7 days 21 days 65 days S (Q,w) 0.01 S (Q,w) E-3 1 Γt ( Q) S( Q, ω) = π Γ ²( Q) + ω² t 1E-3 S (Q,w) 1E Al/Ca glass w (mev) vanadium ref 7 days 21 days 67 days Strong impact of Al S (Q,w) 1E Al glass w (mev) vanadium glass 7 days 21 days 65 days 1E-3 1E-3 1E w (mev) 1E w (mev)

12 QENS ANALYSIS EISF 2 Ielastic 3 j = 1 ( QR) Volino, F.; Dianoux, A.J. Mol. Phys. 1980, 41, I elastic + I quasi elastic EISF M ( Q) = f + (1 f ) QR EISF Zr/Ca glass 7 and 21 days 65 days MCMZr-3 EISF Zr glass 65 days 7 and 21 days MCMZr bulk Q (A -1 ) Reference time (days) R(Å) f Bulk FOCUS ± ± ± ± 0.2 bulk Q (A -1 ) Zr/Ca glass ± ± 0.2 f AG > f MCMZr ± ± ± ± 0.2 Zr glass ± ± ± ± 0.2 MCMZr-3-2.1± ± 0.2

13 QENS ANALYSIS 0.8 Zr/Ca glass jump diffusion model bulk 0.8 Zr glass jump diffusion model bulk days 0.6 Γ (mev) days 65 days τ t Γ (mev) days 21 days 7 days τ t 0.2 Dt AG = = m².s Q² (A -2 ) hdtq² Γt ( Q) = 1+ D Q²τ t 0.2 Dt AG = = m².s -1 t Q² (A -2 ) 0.8 Grafted MCM41 Γ (mev) jump diffusion model Dt AG = = m².s -1 MCMSi2 MCMSi3 MCMZr3 MCMAl MAI PAGE 13 Q² (A -2 ) τ t Dt AG = Dt MGels Dt bulk Other type of dynamics at low Q? Very local motion?

14 QENS ANALYSIS Residence time τ Presence of Ca binding of H 2 O molecules in strong complexes Behrens H et al, 2000 enhance the gel network Effect of gel composition and morphology and/or ions in pores? SAXS and ads-des N 2 analysis are on going 24 MAI 2013 PAGE 14

15 CONCLUSION At a picosecond scale: -Models materials have helped to understand the effect of pore surface composition: for pore size lower than 2.3 nm water dynamics mostly depends on the surface composition than the pore size -No ions effect on water dynamics in Models materials -Altered glass :strong effect of gel composition on fixed proton amount and residence time

16 OUTLOOK QENS Relaxometry NMR Pulse Field Gradient NMR TOF-SIMS/ tracers Reflectometry Our «No man s land» time 10-9 m².s m².s -1 <D<10-20 m².s -1 A student? LCLT team Thank you for your attention