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Effect of Bacterial Polysaccharide Colonizing Environmental Surface on

the Affinity and Deposition of Nanoparticles

Yuliya Dzumedzey, J. Labille, C. Santaella, B.Cathala,

C. Moreau

CEREGE, Aix-Marseille Université, CNRS, Aix-en-Provence, France

BIA INRA, Nantes, France

LEMIRE, CEA, CNRS, Aix-Marseille Université, St-Paul-lez-Durance, France

1Safer and Ecodesign Research and Education applied to NAnomaterial DEvelopment

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Problematic

Porous media

Water

Sediments

Suspended grains

NPs

Biofilms

(EPS)

Fate in the aqueous

environment

Nanoparticles (NPs) interact with particulate matter in

aqueous environment

Mineral collectors are usually coated with biofilms

Biofilm – filtrating layer retaining or repelling NPs

What is the effect of organic coating on the collector

on the affinity and deposition of NPs?

NPs exposure

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Effect of organic coating on the

collector on the NPs deposition

SiO2

1) Attachment

3) Diffusion

inside

2) RepulsionElectrostatic

interactions

NPs

3

EPS

SiO2

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Approach

Parameters variable

(10-5M NaCl – 10-2M NaCl)

Favorable Unfavorable

NPsTiO2 – positively

charged (8 nm)PAA-TiO2 – negatively

charged (70 nm)

pH 3 pH 3 & 5.6pH

Soligel, bacterial polysaccharide (EPS):

negatively charged

Bare SiO2: negatively charged

Ionic strength 10-3M NaCl

Collector surface

4

+ –

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Experimental Approach

AFM after dipping

QCM-D in flow mode

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TiO2 deposition (by QCM-D)

Increased affinity

Deposited

mass,

mg/m2

0,5133

2,1872

3,186

8,673

Fre

quency,

Hz

6

Dzumedzey et al. submitted in Nanoimpact

Favorable deposition:

pH 3

TiO2 NP (+)

Collector (-)

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TiO2 deposition (by AFM)

EPS Substrate

7

NaCl-free solution 10-3M NaCl solution

Scratch holeScratch hole

Topography mode

Phase mode

Heig

ht pro

file

Surface coverage 12 % Surface coverage 40 %

Favorable deposition:

pH 3

TiO2 NP (+)

Collector (-)

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TiO2 deposition (by AFM)

SiO2 Substrate

8

NaCl-free solution 10-3M NaCl solution

Scratch hole Scratch hole

Topography mode

Phase mode

Heig

ht pro

file

Surface coverage 39 % Surface coverage 100 %

Favorable deposition:

pH 3

TiO2 NP (+)

Collector (-)

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Surface Coverage of TiO2 NP vs IS

25

30

35

40

45

50

1.00E-07 1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02

ZetaPoten

al,m

V

NaClConcentra on(mol/l)9

AFM overestimates surface density because of limited

resolution

Higher affinity for SiO2 (0.49 (-) per nm2 than for EPS

(0.14 (-) per nm2)

IS locally screens electrostatic repulsions between NPs

near the substrate

Higher affinity

Dzumedzey et al. submitted in Nanoimpact

Favorable deposition:

pH 3

TiO2 NP (+)

Collector (-)

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Sticking Efficiency of TiO2 NP vs IS

10

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

1.00E-07 1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00

Sckingefficien

cy

NaClConcentra on(mol/l)

EPS

SiO2

Sticking efficiency of NPs to collector calculated from deposition rate

2 regimes of NPs deposition:

limited by the sticking reaction

limited by transport

Limited by

sticking reaction

Limited by

transport

Favorable deposition:

pH 3

TiO2 NP (+)

Collector (-)

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Approach

Parameters variable

(10-5M NaCl – 10-2M NaCl)

Favorable Unfavorable

NPsTiO2 – positively

charged (8 nm)PAA-TiO2 – negatively

charged (70 nm)

pH 3 pH 3 & 5.6pH

Soligel, bacterial polysaccharide (EPS):

negatively charged

Bare SiO2: negatively charged

Ionic strength 10-3M NaCl

Collector surface

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+ –

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Unfavorable Conditions

pH 3 – lower deposition & reversibility pH 5.6 – higher deposition & reversibility

Highly swollen EPS

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NPs injection

NPs-free electrolyte

injection NPs injection

2 processes drive the NPs deposition: irreversible interactions & physical catchment

Dzumedzey et al. submitted in Nanoimpact

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Conclusions Physicochemical conditions influence strongly the mode

of NP deposition.

Under attractive interaction, higher deposition and

deposition rate were observed on the mineral collector

in comparison with the EPS coated collector in the

same conditions.

The NP deposit density increased with the ionic

strength for both collector surface types (EPS coated &

SiO2).

The thickness analysis of the NP deposit on the

substrate revealed that multilayer was never formed.

Under repulsive electrostatic interactions, a weak and

partially reversible NP deposition was measured.

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Thank you for your attention!

Acknowledgements

This work is a contribution to the Labex Serenade (no ANR-11-LABX-0064) funded by the

“Investissements d'Avenir” French Government program of the French National Research

Agency (ANR) through the A*MIDEX project (no ANR-11-IDEX-0001-02).

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