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Mixing Of Latex Concentrate With Protein Solutions

A Combined PS / ZETA Study

Nikolaas De Jaeger

President International Fine Particle Research Institute (IFPRI)

Wilmington, DE-USA

PARCOTEC BVBA Hove Belgium

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IFPRI

Your Outlook on Particle Technology

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• A consortium/club of industrial members (20) Common interest in making, handling, measuring

particles Diverse - both in activities and location

• Membership fees fund global research programme Members define programme Strategic to meet long term goals Dynamic to reflect changing needs

• Target specific researchers to join the programme Work in strong partnership with researchers

• Research is Pre-competitive Aims to establish fundamental understanding

• Supports technical programme of c. $M 0.5 8 Full projects 2 Collaborations 3 Reviews

About IFPRI

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IFPRI Industrial Membership

Fine Chemical Syngenta

Pharmaceutical Merck Pfizer J&J, Jansen Pharma Eli Lily

Fast Moving Consumer Goods

Proctor & Gamble Unilever

Cosmetics L’ Oréal

Mineral Umicore

Equipment

Gen. Chemicals DSM Lafarge

Spec. Chemicals

UOP

Biotec Purac Novozymes

Arranged by Sector

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How IFPRI Works

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Dynamic - responds to Member Company needsManaged within 5 Subject Areas which have strong interactions and weak boundaries

Sols & DispersionsFlow / Separations

Dry Powder Flow

Characterization &Measurement

Particle Formation Size Reduction

Transition from wet to dry

Engineered Products

AttritionInterparticle

Forces

IFPRI Technical Programme

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System

Type

Project Objetives

Particle Flow & Handling Particle Formation & Modification

Measurement& Characterization

Dry System

s

Powder flow towards the real challenges

G. Tardos

NYCC Milling of organic materials

Yulong Ding

Leeds 3DCharacte-rization

E. Pierard

ULG

Dynamics & Rheology of Cohesive & Deformable Granular Materials

R. Behringer 

Univ.Duke

Powder Structure Control

F. Stepanek  

Univ. Prague

Wet System

s

Microstructures in Gelled Systems

M. SolomonE. Furst     

Univ.Michigan

Univ. Delaware

Granulationcontrol

Doyle UC SantaBarbara

Determina-tion of interaction forces between mineral surfaces at high ionic strength

V. Craig

AustralianNat.Univ.

Overview Project Portfolio

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General Introduction

• Mixing Colloidal Suspensions with polymer / protein solutions is a common operation while formulating Dispersed Materials

• Mixing also shows up during sample prep. for PSA

Danger: Bridging Floculation

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Flat-on adsorption

Solution

Adsorption of Polymers and Oligomers

Interface

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Random coil adsorption

Solution

Adsorption of Polymers and Oligomers

Interface

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Tails

Solution

Adsorption of Polymers and Oligomers

TrainsInterface

Loops

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Charged Polymer “Gelatin”

Ph 4.8 = IEP

Charged surface

min

expansion

Ph < IEP

Electrostatic

Ph > IEP

Hydrofobic

expansion

Schematic representation of gelatine adsorption on a charged surface

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Modification of Latex through Protein Adsorption

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Mixing Dispersions with Concentrated Polymer Solutions

Flocculation Mechanisms

1. Charge neutralisation

2. Bridging

3. Microparticles

4. Patchwise charge coagulation

5. Depletion

6. Floccuculation through sterically stabilised latices

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1. Charge Neutralisation

Mechanism: VDW attraction dominant

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2. Bridging

Mechanism: one polymer chain adsorbs on multiple particles

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Important Parameters

1. MW

2. Celec.

•Compression of double layer•Microbridging•Limitation of conformatios

3. pH

4. CColloid

6. Mixing Mode

5. PS and distribution

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3. Microparticles

Mechanism: Classical bridging + bridging via microparticles

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4. Patchwise Charge Neutralisation

Mechanism: Bridging + charge neutralisation

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5. DepletionMechanism: Osmotic pressure due to local differences in

polymer concentration and MW of polymer

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6. Flocculation Trough Latices

Mechanism: Bridging through sterically stabilised Latices

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Schematical Representation of the Effect of Polymers on the Stability of Dispersed

Particles

Bridging flocculation

Clow

Sterical stabilization

Cintermediate

Depletion flocculation

Chigh

Depletion stabilization

Chigher

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Bridging Flocculation in Practice

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0 0.01 0.02 0.03 0.04CE (g/100ml)

Particle size of P.E.A. (clean H+) in presence of gelatine (0.025%) and a poststabilising agent

NatrosolKX-4Melflux-ND-2Lomard

PS of P.E.A. (clean)

PS of P.E.A. origial

50

150

Mixing Dispersion / Polymer Solution

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Mixing Dispersion / Polymer Solution

Zeta potential of P.E.A. (clean H+) in presence of gelatine (0.025%) and a poststabilising agent

NatrosolKX-4Melflux-ND-2Lomard

Zetapotential of P.E.A. (clean)

Zetapotential of P.E.A. (clean) mixed with gelatine

-7.5

-5

-2.50 0.01 0.02 0.03 0.04

Concentration poststabilising agent (%)

Ze

ta p

ote

nti

al (

mV

)

-25

-50

-75

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Sherlock Holmes

One should not theorise before one has data, automatically one starts to twist data to suit theory instead of developing a theory to suit facts…

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CONCLUSIONS

• Mixing dispersion concentrates with Protein / Polymer Solutions is industrially not an easy task

• Bridging adsorption resulting in PS increase is a main problem

• Characterise both the protein and Particle concentrate

• How to avoid Bridging

Don’t add Prot. Sol. to the Dispersion Concentrate

Control pH & try to use a pH whereby the 2 colloids

have the same sign

Dilute Particle Concentrate before mixing

Add Poststab. to Particle Concentrate before mixing

Combined PS/Zeta measurements are an excellent

tool to choose the adequate nature and quantity

of the Poststab.

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Thank you