Enhancing microfluidic separation of magnetic nanoparticles by - PowerPoint PPT Presentation

Enhancing microfluidic separation of magnetic nanoparticles by molecular adsorption J. Queiros Campos 1 , L. Checa Fernandez 1,2 , Ch. Hurel 1 , C. Lomenech 1 , G. Godeau 1 , A. Bee 3 , D. Talbot 3 , P. Kuzhir 1 1 Université Côte d’Azur, INPHYNI 2 University of Granada, Dep. Applied Physics 3 Sorbonne Univeristé, PHENIX 1

Water purification with magnetic nanoparticles Colloidal scale: charged colloid SIROFLOC process Molecular scale: Pollutant molecule Advantage of nano before micro  increased specific area 2

How to separate nanoparticles from water desite strong Brownian motion Magnetic interactions between nanoparticles  phase separation S H N Magnet et al. Phys. Rev. E (2012), (2014) multicore nanoparticles of d  30 nm Ezzaier et al. Nanomaterials (2018) (high cost syntheis with low issue) To get phase separation 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 3

We need to use single-core magnetic nanoparticles of d=8 nm ( cost-effective synthesis, large issue, high specific area) Impossible to separate nanoparticles of d=8 nm by moderate magnetic field gradients If we want to extracte charged micropollutant … Basic hypothesis : progressive + + counter-ion adsorption decreases + + colloidal stability + Fe 2 O 3 Fe 2 O 3 + + repulsion d + + counter-ion (micropollutant) In the absence of field: Primary aggregation H In the presence of field: Secondary (field-induced) aggregation  efficient magnetic separation 4

Objective : how does the surface coverage by counter-ions affect primary/secondary aggregation and magnetic separation 5

I. Primary aggregation at zero field Na Na Methylene blue (MB) Citrate ion  -Fe 2 O 3  -Fe 2 O 3 water Model micropollutant pH  7 No field MB Adsorption isotherme q C q    ads 0 46% C ads _ max Primary aggregation 6

II. Secondary (field-induced) aggregation Needles No needles x4 q =18% q =32% q =9% No aggregation without MB H =2.5 kA/m 0.5 mm 7

II. Secondary (field-induced) aggregation Needles q No needles D 0 for q =18% x4 q =18% q =32% q =9% No aggregation without MB q H =2.5 kA/m H=2.5 kA/m j = 0.15% 0.5 mm Driving force : initial supersaturation j  D  j  0 0 More intense field- q  D 0  induced aggregation 2 d    D  Characteristic time : 3/7 a few min 0 D Faster aggregation with q  8 diff Zubarev and Ivanov PRE (1997); Ezzaier et al, J. Chem Phys. 2017

Can we further accelerate the field-induced aggregation  Rotating aggregates « collide » with free particles and absorbe them quickely L D Process governed by H Péclet number  convection LD   Pe diffusion D diff Diffusive boundary layer approach (Pe>>1): 1/3   250 µm V d      D 1 max   0  2 D   diff Acceleration with  See poster by Maxime Raboisson Michel 9

III. How efficient is magnetic separation of nanoparticles with adsorbed MB? magnetic field inlet outlet Smart tool to visualize magnetic separation flow PDMS mould glass slide micro-channel micro-pillar To benefit from field-induced aggregation : Travel time > Aggregation timescale (a few min) j =0.16% H =18 kA/m q =32% Q=30 µl/min flow 200 µm time No any separation without adsorbed MB 10

q =9% q =18% q =32% Naked q pillars 200 µm 10 µl/min H=18 kA/m 30 flow  µl/min F u d /   h Ma F µ M H m 0 NP 1. Nanoparticle deposite volume  with the  of speed 2. Deposite volume  with  of q  Magnetic separation is strongly enhanced with MB adsorption 11

More quantitatively: aggregates micropillar flow J capt J proj u zoom L c Capture efficiency: 2   J D    capt   1  Ma   q J d proj Aggregate thickness (aggregates grow when travelling before arriving to micropillar):   L   c D f traveling time     u Ma    D 0.82 1.57 0 Ezzaier et al, Nanomaterials (2018) With  amount q of MB  supersaturation D 0  and capture efficiency  12

Summary + + + + flow + Fe 2 O 3 Fe 2 O 3 + + + + electrostatic repulsion  efficient magnetic separation H Secondary (field-induced) aggregation Primary aggregation (zero field) 13

Summary + + + + flow + Fe 2 O 3 Fe 2 O 3 + + + + electrostatic repulsion  efficient magnetic separation Queiros Campos et al, to be submitted H Similar scenario of magnetic separation enhancement with protein adsorption onto iron oxides (vast biomedical applications) Secondary (field-induced) aggregation Primary aggregation (zero field) 14

Frustrated?.. Some more microfluidics … 15

Separation on micro-pillar arrays Fabrication by electroplating (collaboration: FEMTO-ST, Besançon) Ni pillar  50 µm PDMS pillars with iron particles (C. Claudet, Y. Izmailov, IN F NI) magnetic field outlet glass inlet flow PDMS Disassembling Plexiglass channel mould glass slide PDMS micro- PDMS micro- pillar channel Permanent PDMS channel 16

Shape of the nanocluster deposits H =6 kA/m f =0.3% u=1.88 m/s Ezzaier et al, Orlandi et al, flow J. Magn. Magn. PRE (2016) Mater. (2018) time H =13.5 kA/m, f 0 =0.3% and t =60 min Naked pillars 7x10 -4 m/s H 2x10 -4 m/s 17

Shape of the nanocluster deposits H =6 kA/m f =0.3% u=1.88 m/s Ezzaier et al, Orlandi et al, flow J. Magn. Magn. PRE (2016) Mater. (2018) Thank you! time Merci! H =13.5 kA/m, f 0 =0.3% and t =60 min Naked pillars 7x10 -4 m/s H 2x10 -4 m/s 18

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Why constant charge despite MB adsorption? Na + MB Na + + + Na + + Fe 2 O 3 + Fe 2 O 3 + + + + Na Na effective charge = const Constant charge in our working range of surface Why do the nanoparticles aggregate with coverage by MB MB adsorption if they keep the same electrostatic repulsion? • At const charge and const Debye length Domain correlation between electrostatic repulsion ≈ const with q heterogeneously adsorbed H-aggregates? Zipping by short-ranged p -stacking • … at least in the Debye-Hückel limit interactions between MB molecules? 20

II. Field-induced phase separation H Binodal decomposition   Nanoparticle suspension  µ µ gas liquid    p p  gas liquid Hynninen, PRL 2005 Dipolar coupling parameter  2 H V   0 p 2 kT Volume fraction Lower bound of the phase separation At F =0.1%vol. nanoparticles of d=30 nm aggregate at B>5mT 21

Electroformage Femto-ST LPMC Bio-analyse : ADN, protéines, hormones, médicaments 22

Fabrication de la cellule microfluidique pour la séparation magnétique 23

Dynamics of separation Deposit area S S m deposit area s  micropillar area u  Micropillar j     f  ut   0 in        j ln s t ( ) sm 1 exp j in F out j   s L   m out [Tien&Ramaro (2007)]  F / v d   h Ma Governing parameter Mason number 2 F µ H m 0 24

1.3±0.3 Na desorbe for 1 MB adsorbed Progressive desorption of Na + with MB adsorption 25

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