Enhancing microfluidic separation of magnetic nanoparticles by - - PowerPoint PPT Presentation

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Enhancing microfluidic separation of magnetic nanoparticles by molecular adsorption

• J. Queiros Campos1, L. Checa Fernandez1,2, Ch. Hurel1, C. Lomenech1,
• G. Godeau1, A. Bee3, D. Talbot3, P. Kuzhir1

1 Université Côte d’Azur, INPHYNI 2 University of Granada, Dep. Applied Physics 3 Sorbonne Univeristé, PHENIX

Water purification with magnetic nanoparticles

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Advantage of nano before micro  increased specific area Colloidal scale:

charged colloid Pollutant molecule

Molecular scale:

SIROFLOC process

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Magnetic interactions between nanoparticles phase separation

H

N S

Magnet et al. Phys. Rev. E (2012), (2014)

How to separate nanoparticles from water desite strong Brownian motion

To get phase separation multicore nanoparticles of d30 nm Ezzaier et al. Nanomaterials (2018) (high cost syntheis with low issue)

• O. Sandre

Nanoclusters of d60 nm Orlandi et al. Phys. Rev. E (2016) – release of physisorbed surfactant Frka-Petesic et al. JMMM (2009) – use of block co-polymers

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We need to use single-core magnetic nanoparticles of d=8 nm (cost-effective synthesis, large issue, high specific area) Fe2O3 + + + + counter-ion (micropollutant) Fe2O3 + + + + + repulsion

Basic hypothesis: progressive

counter-ion adsorption decreases colloidal stability In the absence of field: Primary aggregation d In the presence of field:

H

Secondary (field-induced) aggregation  efficient magnetic separation Impossible to separate nanoparticles of d=8 nm by moderate magnetic field gradients If we want to extracte charged micropollutant…

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Objective: how does the surface coverage by counter-ions affect primary/secondary aggregation and magnetic separation

MB Adsorption isotherme

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-Fe2O3 Na -Fe2O3 Na

Citrate ion

water

Methylene blue (MB) pH7

q

No field

_ max

46%

ads ads

C C q   

Primary aggregation

• I. Primary aggregation at zero field

Model micropollutant

No needles Needles x4

• II. Secondary (field-induced) aggregation

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0.5 mm q=32% q=9% q=18% H=2.5 kA/m No aggregation without MB

No needles Needles

q

x4

• II. Secondary (field-induced) aggregation

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0.5 mm q=32% q=9% q=18% H=2.5 kA/m

q

H=2.5 kA/m j = 0.15%

D0 for q=18% Driving force: initial supersaturation

j j D   Zubarev and Ivanov PRE (1997); Ezzaier et al, J. Chem Phys. 2017

2 3/7

a few min

diff

d D 



 D 

Characteristic time: q  D0  More intense field- induced aggregation Faster aggregation with q  No aggregation without MB

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Can we further accelerate the field-induced aggregation

250 µm

H

1/3 1 max 2 diff

V d D  



     D    

Acceleration with  Diffusive boundary layer approach (Pe>>1): See poster by Maxime Raboisson Michel Process governed by Péclet number

convection diffusion

diff

LD Pe D   

L D  Rotating aggregates « collide » with free particles and absorbe them quickely

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• III. How efficient is magnetic separation of

nanoparticles with adsorbed MB?

To benefit from field-induced aggregation: Travel time > Aggregation timescale (a few min)

• utlet

inlet PDMS mould glass slide micro-channel micro-pillar magnetic field flow

H=18 kA/m

time flow

j=0.16% Q=30 µl/min q=32%

200 µm

No any separation without adsorbed MB Smart tool to visualize magnetic separation

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Naked pillars 10 µl/min 30 µl/min

H=18 kA/m

q=9% q=18% q=32% flow

200 µm

/

h m NP

F u d Ma F µ M H   

q

• 2. Deposite volume  with  of q

 Magnetic separation is strongly enhanced with MB adsorption

• 1. Nanoparticle deposite volume  with the  of speed

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Capture efficiency:

2 1 capt proj

J D Ma J d



        

aggregates micropillar Jcapt Jproj u Lc Aggregate thickness (aggregates grow when travelling before arriving to micropillar):

traveling time

c

L D f u        

q

With  amount q of MB  supersaturation D0  and capture efficiency 

0.82 1.57

Ma   D Ezzaier et al, Nanomaterials (2018)

More quantitatively:

flow zoom

Primary aggregation (zero field)

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Summary

Fe2O3 + + + + Fe2O3 + + + + + electrostatic repulsion 

H

Secondary (field-induced) aggregation efficient magnetic separation

flow

Primary aggregation (zero field)

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Summary

Fe2O3 + + + + Fe2O3 + + + + + electrostatic repulsion 

H

Secondary (field-induced) aggregation efficient magnetic separation

flow

Queiros Campos et al, to be submitted

Similar scenario of magnetic separation enhancement with protein adsorption onto iron oxides (vast biomedical applications)

Frustrated?.. Some more microfluidics…

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Fabrication by electroplating (collaboration: FEMTO-ST, Besançon)

Separation on micro-pillar arrays

glass Ni pillar 50 µm

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Disassembling Plexiglass channel PDMS pillars with iron particles (C. Claudet, Y. Izmailov, INFNI)

inlet

• utlet

PDMS mould glass slide PDMS micro- channel PDMS micro- pillar magnetic field flow

Permanent PDMS channel

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Shape of the nanocluster deposits

H=6 kA/m

time flow

f=0.3% u=1.88 m/s

Naked pillars 7x10-4 m/s 2x10-4 m/s

H

H=13.5 kA/m, f0=0.3% and t=60 min

Ezzaier et al,

• J. Magn. Magn.
• Mater. (2018)

Orlandi et al, PRE (2016)

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Shape of the nanocluster deposits

H=6 kA/m

time flow

f=0.3% u=1.88 m/s

Naked pillars 7x10-4 m/s 2x10-4 m/s

H

H=13.5 kA/m, f0=0.3% and t=60 min

Ezzaier et al,

• J. Magn. Magn.
• Mater. (2018)

Orlandi et al, PRE (2016)

Thank you! Merci!

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Constant charge in our working range of surface coverage by MB

• Domain correlation between

heterogeneously adsorbed H-aggregates?

• Zipping by short-ranged p-stacking

interactions between MB molecules? At const charge and const Debye length electrostatic repulsion ≈ const with q Fe2O3 + + + + + Na Na Na Na Na + MB … at least in the Debye-Hückel limit Why do the nanoparticles aggregate with MB adsorption if they keep the same electrostatic repulsion? Fe2O3 + + + + + effective charge = const Why constant charge despite MB adsorption?

Nanoparticle suspension

• II. Field-induced phase separation

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gas liquid gas liquid

µ µ p p       

Binodal decomposition Dipolar coupling parameter

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2

p

H V kT   

Volume fraction Hynninen, PRL 2005

H

Lower bound of the phase separation At F=0.1%vol. nanoparticles of d=30 nm aggregate at B>5mT

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Femto-ST LPMC

Electroformage

Bio-analyse: ADN, protéines, hormones, médicaments

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Fabrication de la cellule microfluidique pour la séparation magnétique

Micropillar

( ) 1 exp ut s t sm s L m f             F    

[Tien&Ramaro (2007)]

ln

in

• ut

j j  

in

j

• ut

j deposit area micropillar area s 

u

Deposit area S

Dynamics of separation

Sm



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Governing parameter

2

/

h m

F v d Ma F µ H   

Mason number

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Progressive desorption of Na+ with MB adsorption 1.3±0.3 Na desorbe for 1 MB adsorbed

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