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1

Part of an Excellence Ph.D. Course

Politecnico di Torino – June 27th, 2012

A talk on:

Transport of colloids and nanoparticles in saturatedporous media for environmental remediation

Rajandrea SETHI, Tiziana TOSCO and GROUNDWATER ENGINEERING GROUP

DIATI – Politecnico di Torino

DITAG

2

ZVI Permeable reactive barrier

2

3

Degrades

� Transformation and immobilization of inorganiccontaminants� Degradation of organiccontaminants

4

TCE degradation pathways

3

5

MillimetricMillimetricMillimetricMillimetric ironironironiron NanoscaleNanoscaleNanoscaleNanoscale ironironironiron

0.25 0.25 0.25 0.25 – 2 mm2 mm2 mm2 mm 15 15 15 15 – 100 100 100 100 nmnmnmnm

Use of ZVI to remediate contaminated

aquifers

Fre

yri

a e

t al. 2

007

6

ZVIPlume treatment

0.25 – 2 mm

� Installation:

� High costs

� Difficult, depth <30m

� Standard practice

MZVI & NZVI

Source & plume treatment

15 nm → 100 µm

� Installation:

� Low costs

� Injected, depth < 70m

� Under development

ZVI vs MZVI & NZVI

4

7

High specific surface area1 kg of nanoscale iron = 2 x Stadio Olimpico (Roma)

∼30000 m2

FESEM (Tecnogranda)

8

Degradation kinetics

� Degradation kinetics:� dove k pseudocinetica del I ordine [T-1], kSA cinetica all’unità di SA e cFe [LT-1], kMcinetica all’unità di cFe [L3M-1T-1], SSA superficie specifica [L2M-1], cFeconcentrazione di ferro per volume di acqua [ML-3], cTCE concentrazione del contaminante.

( ) ( ) TCEFeSATCEFeMTCETCE ccSSAkcckkc

dt

dc⋅⋅⋅−=⋅⋅−=−=

Fe0 + RCl + H+→ RH + Fe2+ + Cl-

5

9

MZVI & NZVI: suspension

stability

MZVI(1-100 µm)

relevant mass,

high density

NZVI(15–100 nm)

particle – particle

attraction

gravitational sedimentation aggregation (single domain)

10

NZVI: aggregation

� The application is hindered by aggregation

6

11

MZVI(1-100 µm)

relevant mass,

high density

NZVI(15–100 nm)

particle – particle

attraction

MZVI & NZVI: suspension

stability

sedimentation & aggregation

� Reactivity:

□ Lower, due to reduced surface area

� Injection:

□ Sedimentation during pumping and inside the wells

□ Reduced radius of influence

� Transport:

□ Filtered/strained in the porous medium, reduced contact with contaminants

12

NZVI: Thermodynamic stabilization

� Modification of surface properties: low concentrations of

polymers adsorbed on particles surface providing:

� Electrostatic stabilization:

repulsive forces due to the surface

charge of the polymer layer

□ short-ranged

□ affected by ionic strength

� Steric stabilization:

repulsion due to osmotic

and elastic forces

□ long-ranged if MW is high

□ indifferent to ionic strength

IS

With polimer

No polimer

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13

MZVI & NZVI: stabilization

� Stabilization: via addition of green polymers (guar gum and xanthan gum)

1. GREEN: natural origins from the seed of the guar

plant

2. INEXPENSIVE: Sigma-Aldrich: 44.60 €/kg

Commercial: ~2 €/kg

3. COMMERCIALLY AVAILABLE: food industry

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NZVI: Thermodynamic stabilization

� DLS measurements (guar gum 0.5 g/l):

Decrease of the hydrodynamic radius Reduced aggregation

0 1000 2000 3000 4000

200

300

400

500

Initial Particle Size

Initial Particle Size

Bare Particles

Particles in solution of Guar Gum 0.5 g/L

10mM NaCl

Radiu

s (

nm

)

Time (s)154 mg/l 231 mg/l

0

100

200

300

400

500

600

Hydro

dyna

mic

Ra

diu

s (

nm

)

Particle Concentration (mg/L)

Bare particles

MRNIP

Guar gum-coated particles

Tiraferri, A.; Chen, K.L.; Sethi, R.; Elimelech, M. Reduced aggregation and sedimentation of zero-valent iron nanoparticles in the presence of guar gum. Journal of Colloid and Interface Science 2008, 324(1-2), 71-79.

8

15

MZVI: Kinetic stabilization

� Modification of fluid properties: reduced frequency of

particle collisions.

� Shear-thinning solution of xanthan, guar gum (3-10 g/l)

Comba, S.; Dalmazzo, D.; Santagata, E.; Sethi, R. Rheological characterization of NZVI suspensions for injection in porous media.Journal of Hazardous Materials (submitted) 2010.

Guar gum

solution

water

High viscosity at

low shear rate

↓

Reduced

sedimentation

& aggregation

Low viscosity at

low shear rate

↓

Easily injected

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� Sedimentation curves for MZVI in guar gum (5.5 g/l) proved increased stability:

Sedimentation curves

MZVI: Kinetic stabilization

MZVI in water

MZVI in guar gum

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17

Column tests: experimental

setup

� Column transport tests:� Packed column:

□ L = 0.46 m, din = 2.5 cm, n = 0.49

□ Q = 6.74 ·10-4 l/s

� Sand (Sibelco & Dorsilit):

□ d50 = 0.69 mm

□ Silica, K-feldspar (minor)

� Particles (20 g/l):

□ MZVI (Basf)

□ NZVI (Toda Kogyo corp.)

� Steps:

□ Injection (particles+dispersant)

□ Flushing (water)

� Dispersant during injection:

□ Water (DI)

□ Xanthan (3 g/l) in DI or 12.5 mM

manometer

susceptimeter

column

IN

OUT

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Column tests: experimental setup

� Column transport tests:� Packed column:

□ L = 0.46 m, din = 2.5 cm, n = 0.49

□ Q = 6.74 ·10-4 l/s

� Sand (Sibelco):

□ d50 = 0.69 mm

□ Silica, K-feldspar (minor)

� Particles (20 g/l):

□ MZVI (Basf)

□ NZVI (Toda Kogyo corp.)

� Steps:

□ Injection (particles+dispersant)

□ Flushing (water)

� Dispersant during injection:

□ Water (DI)

□ Xanthan (3 g/l) in DI or 12.5 mM

MZVI

dc = 1.1 µmComp.: 98.4% Fe0

0.69% C0.66% N

NZVIdc = 70 nmComp.: 35% Fe0

65% Fe3O4

10

19

Time (s)

0 2000 4000 6000 8000

0

0.2

0.4

0.6

0.8

1

Column tests: experimental

setup

� Column transport tests:� Packed column:

□ L = 0.46 m, din = 2.5 cm, n = 0.49

□ Q = 6.74 ·10-4 l/s

� Sand (Sibelco):

□ d50 = 0.69 mm

□ Silica, K-feldspar (minor)

� Particles (20 g/l):

□ MZVI (Basf)

□ NZVI (Toda Kogyo corp.)

� Steps:

□ Injection (particles+dispersant)

□ Flushing (water)

� Dispersant during injection:

□ Water (DI)

□ Xanthan (3 g/l) in DI or 12.5 mM

INJECTION FLUSHING

MZVI or NZVI

+ water

water or xanthan 3 g/l

(7 or 26 PVs) (26 or 15 PVs)

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� Iron concentrations measured with susceptibility sensors� Linear correlation between measured susceptibility and particle

concentration

□ Breakthrough curves

□ Total concentration profiles

Column tests: concentration measurements

Dalla Vecchia, E.; Luna, M.; Sethi, R. Transport in Porous Media of Highly Concentrated Iron Micro- and Nanoparticles in the Presence of Xanthan Gum. Environmental Science & Technology 2009, 43(23), 8942-8947.

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21

Column tests: experimental

results

� Continuous in-line measurement of iron concentration at column outlet:

non destructive measurement

MZVI NZVI

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Column tests: experimental results

� Concentration profiles after injection (before flushing): non

destructive measurement

NZVI

MZVI

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Modeling approach: key aspects

� Key aspects:

1. Particle interactions with the porous matrix

□ Physical filtration/straining

□ Physical-chemical interactions: blocking, ripening

2. Clogging:

□ Influence of particle deposits on porous medium properties

□ Coupled problem

3. Viscosity of the dispersant fluid

□ Shear-thinning behavior

□ Darcy’s law for non-Newtonian fluids

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Modeling approach: (1) Particle-porous medium interactions

� Modified ADE accounts for interaction mechanisms:Then...

First...

filtration/

straining

physical-chemical

interactions

( )( )

( )

( )( )

0

,

b

m m m

b

s cc q c D

t t x x x

sf c s

t

ρε ε

ρ

∂∂ ∂ ∂ ∂ + + − =

∂ ∂ ∂ ∂ ∂

∂= ∂

Cle

an

bed

Rip

en

ing

Blo

ckin

g

mec

hanism

smec

hanism

smec

hanism

smec

hanism

s

Str

ain

ing

Str

ain

ing

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Modeling approach: (2) Clogging

� Clogging: Deposited particles reduce porosity and

permeability:

V , g g

ε V , g g

εV ,

g gε

Tosco, T.; Sethi, R. Transport of non-Newtonian suspensions of highly concentrated micro- and nanoscale iron particles in porous media: a modeling approach. Environmental Science & Technology (submitted) 2010.

( ) sAAsAc

b

cρ

ρθ+=

0

( ) snss

bm

ρ

ρε −=↓ porosity

( )2

3

A

nCsK =

↑ surface area

↓ permeability

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� Xanthan or guar gum gel (shear-thinning)

→ non-Newtonian fluid

Cross model:

Extended Darcy’s law:

Modeling approach: (3) Non-Newtonian viscosity

( )xmm ccf ,,γµ &=

( )( ) x

p

cc

sKq

xmm

m∂

∂−=

,,γµ &

Comba, S.; Dalmazzo, D.; Santagata, E.; Sethi, R. Rheological characterization of NZVI suspensions for injection in porous media.Journal of Hazardous Materials (submitted) 2010.

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Modeling approach: coupled model

E-MNM1Dhttp://areeweb.polito.it/ricerca/groundwater/software/EMNM1D.ht

ml

� Model structure:

� Implementation:� Finite differences, 1D

� Evolution of MNM1D model for colloid transport

Transport

equations

Darcy’s law

Permeability

coefficient

Fluid viscosityMedium porosity

Tosco, T.; Sethi, R. Transport of non-Newtonian suspensions of highly concentrated micro- and nanoscale iron particles in porous media: a modeling approach. Environmental Science & Technology (submitted) 2010.

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� Download:www.polito.it/groundwater/software

E-MNM1D:www.polito.it/groundwater

( )( ) x

p

cc

sKq

xmm

m∂

∂−=

,,γµ &

Darcy’s law:

( )( )

( )[ ] ( )c

mm

mxm

mxmmmc

cccc

χγλ

µµµγµ

&

&

⋅+

−+=

∞

∞1

,,,

,0,

,

( ) ( )ssK

q

m

mm

εαγ γ=&

Fluid viscosity:

( ) snss

b

mρ

ρε −=

Porosity:

( ) ( )0

2

0

0

3

K

sAA

A

n

ssK

c

bc

m

+

=

ρ

ρϑ

ε

Permeability:

Transport equations:

( ) ( )

( ) ( ) ( ) ( )

( ) ( )

( )

−

+=

∂

∂

−+=∂

∂

=

∂

∂

∂

∂−

∂

∂+

∂

∂+

∂

∂+

∂

∂

=

∂

∂

∂

∂−

∂

∂+

∂

∂

22,

50

2,

2

11,111,

1

21

1

1

1

1

0

0

skcd

xk

t

s

skcsAkt

s

x

cD

xcq

xt

s

t

sc

t

x

cD

xcq

xc

t

dbamb

dbamb

mmbb

m

xmxmxm

ρερ

ρερ

ερρ

ε

εε

β

β

E-MNM1D

Tosco, T.; Sethi, R. Transport of non-Newtonian suspensions of highly concentrated micro- and nanoscale iron particles in porous media: a modeling approach. Environmental Science & Technology 2010.

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Modeling approach: information

from experimental data

� Pressure drop

at column ends clogging&

viscosity

� Outlet

particle

concentration

Depositiondynamics

� Concentration

profiles after

injection

Time (s)0 2000 4000 6000 8000

0

0.2

0.4

0.6

0.8

1

Time (s)

0

0.2

0.4

0.6

0.8

1

0 2000 4000 6000 8000

x (m)0.1 0.2 0.3 0.4 0.5

1

1.5

2

2.5

3

3.5

4

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Modeling approach: fitting of experimental data

MZVI NZVI

Tosco, T.; Sethi, R. Transport of non-Newtonian suspensions of highly concentrated micro- and nanoscale iron particles in porous media: a modeling approach. Environmental Science & Technology (submitted) 2010.

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Permeability changes

� Changes in permeability are manly due to changes in surface area:

( ) ( )0

2

0

0

3

K

sAA

A

n

ssK

c

bc

m

+

=

ρ

ρϑ

ε

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E-MNM radial and spherical geometry

� Accounts for variable:� flow velocity� viscosity� attachment and detachment coefficients

� EEEE----MNMMNMMNMMNM (Enhanced Micro- and Nanoscale transport Model):� Homogeneous permeation;� Radial and spherical geometry.

Unpublished data

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Reagent delivery

(reactive zones)

� Injection methods:� Gravity� Fracturing

□ Hydraulic□ Pneumatic

� Jetting� Pressure Pulse Technology� Direct push

� Soil mixing

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Direct push system

� Hydraulically-powered machines� Environmental sampling (soil, gas, groundwater)� Grouting and reagents injection

www.carsico.it

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35

Direct push system

Pumps and injection tips

� High pressure (69-127 bar) suitable for viscous fluids� Average pumping rates� Injection (Top-down or bottom-up)

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Recirculation

Sethi

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37

Field injection of MZVI

� FP7 AQUAREHAB� Injection 16/11/2011� Site description (Belgium):

� Contamination of chlorinated hydrocarbons� Sandy-loam aquifer� Injection depth: 8.5 – 10.5 m� 5 injection points

TCE

TCA

clayey sand

coarse

sand

7m

20m

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Field injection of MZVI

� Fracturing injection:� Direct push system (Geoprobe GS200)� High pressure bottom-up injection (10-40 bar)

� Sospension:� MZVI: D50 = 50 µm, 50 g/l� Guar gum: 6 g/l� Volume: 1.6 m3

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39

Field injection of MZVI

� Installazione della rete di monitoraggio:

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Conclusions

� Stability:� Guar gum and xanthan (green biopolymers) provide thermodynamic and

kinetic stabilization:

□ MZVI: sedimentation prevention

□ NZVI: aggregation and sedimentation prevention

� Transport in porous media:� Transportability: guar gum & xanthan increase breakthrough concentration

� Modeling: successful modeling of particle transport with

□ Extension of Darcy’s law for non-Newtonian fluids

□ Changing of hydrodynamic parameters due to clogging

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Projects and Acknowledgements

� The work was partially funded by the EU Research

project (VII Framework Program) “AQUAREHAB –

Development of rehabilitation technologies and

approaches for multipressured degraded waters and the

integration of their impact on river basin management” –

project coordinator Dr. L. Bastiaens (VITO, Belgium)

� Acknowledgement to:

� DITAG, Politecnico di Torino: Alberto Tiraferri, Elena Dalla Vecchia, Michela Luna, Francesca Gastone, Xue Dingqui, Silvia Comba, Francesca Messina, Matteo Icardi

� DISAT, Politecnico di Torino: Daniele Marchisio, Barbara Bonelli,

Federica Lince, Francesca Freyria

� INRIM, Torino: Marco Coisson

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References

� Tosco T, Bosch J, Meckenstock RU, Sethi R. Transport of ferrihydrite nanoparticles in saturated porous media: role of ionic strength and flow rate.Environ Sci Technol. 2012 Apr 3;46(7):4008-15� Freyria F.S.; Bonelli B.; Sethi R.; Armandi M.; Belluso E.; Garrone E. (2011). Reactions of Acid Orange 7 with Iron Nanoparticles in Aqueous Solutions. In: JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES, vol. 115 n. 49, pp. 24143-24152. - ISSN 1932-7447� Tosco, T.; Tiraferri, A.; Sethi, R. Ionic Strength Dependent Transport of Microparticles in Saturated Porous Media: Modeling Mobilization and Immobilization Phenomena under Transient Chemical Conditions. Environmental Science & Technology 2009200920092009, 43(12), 4425-4431.� Tosco, T.; Sethi, R. MNM1D: a numerical code for colloid transport in porous media: implementation and validation.American Journal of Environmental Sciences 2009200920092009, 5(4), 517-525.� Tosco, T.; Sethi, R. Transport of non-Newtonian suspensions of highly concentrated micro- and nanoscale iron particles in porous media: a modeling approach. Environmental Science & Technology (submitted) 2010201020102010.� Tiraferri, A., T. Tosco, e R. Sethi (2010), Transport and Retention of Microparticles in Packed Sand Columns at Low and Intermediate Salinities: Experiments and Mathematical Modeling. Environmental Earth Sciences (submitted) 2010201020102010.� Tiraferri, A.; Chen, K.L.; Sethi, R.; Elimelech, M. Reduced aggregation and sedimentation of zero-valent iron nanoparticles in the presence of guar gum. Journal of Colloid and Interface Science 2008200820082008, 324(1-2), 71-79.� Tiraferri, A.; Sethi, R. Enhanced transport of zerovalent iron nanoparticles in saturated porous media by guar gum. J Nanopart Res 2009200920092009, 11(3), 635-645.� Dalla Vecchia, E.; Coisson, M.; Appino, C.; Vinai, F.; Sethi, R. Magnetic Characterization and Interaction Modeling of Zerovalent Iron Nanoparticles for the Remediation of Contaminated Aquifers. Journal of Nanoscience and Nanotechnology 2009200920092009, 9(5), 3210-3218.� Comba, S.; Dalmazzo, D.; Santagata, E.; Sethi, R. Rheological characterization of NZVI suspensions for injection in porous media. Journal of Hazardous Materials (submitted) 2010201020102010.� Dalla Vecchia, E.; Luna, M.; Sethi, R. Transport in Porous Media of Highly Concentrated Iron Micro- and Nanoparticles in the Presence of Xanthan Gum. Environmental Science & Technology 2009200920092009, 43(23), 8942-8947.