a discussion of polymer functionality of polymer application in...a discussion of polymer...

A DISCUSSION OF POLYMER FUNCTIONALITY

FOR SCALE AND CORROSION CONTROL

AWT ONLINE SEMINAR - JUNE 9TH 2011

PRESENTER - MIKE STANDISH

PRESENTATION OBJECTIVES

Discuss the Fundamental Mechanisms of Mineral Scale

Control with Polymers

Survey the Existing Commercial Polymer Landscape

Provide Application Guidance for Polymer Selection

Copyright 2011 Mike Standish


Deposit Control

Mechanism

Threshold Inhibition

Crystal Habit

Modification

Stabilization

Dispersion

Chelation

Sequestration

FUNCTIONALITY OF POLYMERS

INTERCONNECTED FUNCTIONALITY

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Mechanism

Threshold Inhibition

Crystal Habit

Modification

Stabilization

Dispersion

Chelation

Sequestration


CONNECTED FUNCTIONALITY

Polymers Control Scale by Multiple Mechanisms

The Mechanisms are Related and Connected

The Functionality Exhibited Makes Polymers:

Versatile

Sensitive to Design

Composition

Molecular Weight

Emphasized Functional Feature


MECHANISMS

AND

DEFINITIONS

THRESHOLD INHIBITION

Threshold Inhibition is defined as maintaining of solubility of

an otherwise insoluble salt beyond its saturation limits using

an additive at sub-stoichiometric levels - Standish

Threshold Inhibition is generally viewed as a temporary

effect.

Duration of Inhibition is related to:

• Driving force for precipitation

• Efficacy of Inhibitor

• Water Impurities (both dissolved and suspended)

• Frequency of Additive Dosage

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SEQUESTRATION

Sequestration – complexation of a metal ion such that

the ion does not retain its original reactive properties.

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"sequester." Online Etymology Dictionary. Douglas Harper, Historian. 07 Jun. 2011. <Dictionary.com

http://dictionary.reference.com/browse/sequester>.

Origin:

sequester

late 14c., from O.Fr. sequestrer (14c.), from L.L. sequestrare "to place in safekeeping," from L. sequester "trustee, mediator," probably originally

"follower," related to sequi "to follow" (see sequel). Meaning "seize by

authority, confiscate" is first attested 1510s.

CHELATION

A Chelate is a coordination compound in which a central metal ion such as Fe2+ is attached by coordinate links to two or more non-metal atoms in the same molecule, called ligands – Condensed Chemical Dictionary

Polymers act as chelates with most muti-valent ions due to their multiple binding sites.

In common vernacular, the term chelate tends to imply a more permanent or substantive relationship between the ion and the ligand (i.e. EDTA)

Chelation in common water treatment terms refers to stoichiometric relationships between the metal ion and the ligand.

Polymers, of the type we discuss, do not meet the common vernacular definition as their association is generally temporary.

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TYPICAL VIEWS OF CHELATES

+ M 2+

EDTA Divalent Metal Metal – EDTA

Complex

- Multiple Coordination Sites

- 1:1 Stoichiometry

TYPICAL VIEWS OF CHELATES

http://illumin.usc.edu/_images/pictures/ii9_168_edta.png

Ca2+ + EDTA4- → CaEDTA2-

POLYMERS CHELATE METALS

Google Images

DEFINITION - STABILIZATION

Can have two meanings with respect to polymer interactions

with metal ions:

• Colloidal – Precipitation occurs but polymer prevents

agglomeration of particles beyond 1 micron in size. These

particles are thus stabilized via electrostatic interactions with

the polymer.

• Typically are not visible (exception iron)

• Stabilization can fail due to physical or chemical changes in

the fluid.

• A synonym for sequestration where the coordination complex

is typically referred to prevention of precipitation where

inhibition is not the defined mechanism (i.e. iron, calcium

phosphate, zinc….)

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DEFINITION - CRYSTAL HABIT

MODIFICATION

Crystal Habit is generally defined as the normal size and shape of a precipitated substance in a given set of environmental conditions.

Crystal growth is dynamic. Crystalloids that do not grow properly tend to redissolve.

Polymers and other materials such as phosphonates can modify the size and shape of mineral crystal habits.

• CaCO3 > Cax(PO4)y , BaSO4>>> CaSO4

Crystal Habit Modification is the basis for scale control using polymers

• Threshold Inhibition

• Deposition Tendency

• Surface Adherence

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COMMON CRYSTAL HABITS

Calcite Anhydrite Barite

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http://web.mst.edu/~jswitzer/images/boxes.jpg Deposit Control

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CALCITE

http://www.minerva.unito.it/Chimica&Industria/Dizionario/Supplementi01/SEM/CalciteSEM.JPG Deposit Control

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CALCIUM SULFATE

Google Images

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TRICALCIUM PHOSPHATE

Google Images

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BARIUM SULFATE

Google Images

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© 1993 FMC Corporation – Belclene ® 200 Brochure

Now BWA Water Additives

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POLYMER INDUCED CRYSTAL

MODIFICATION

HOW?


CONCEPT OF SOLUBILITY AND

SATURATION

Driving Force (pH, Temperature)

Concentr

ation o

f Io

ns

Undersaturated

Metasable

Supersaturated

Saturated

Spontaneous

Precipitation

Precipitation

Occurs Over a

Long Period

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Adapted from Stumm and Morgan – Aquatic Chemistry Second Edition

MORE DEFINITIONS

Definition for SUPERSATURATED

A solution that contains a higher than saturation concentration of solute; slight disturbance or seeding causes crystallization of excess solute.

Definition for SATURATED

Describes a solution that has as much solute as possible.

Definition for METASTABLE

Of a body or system having a state of apparent equilibrium although capable of changing to a more stable or unstable state

CONCEPT OF SOLUBILITY AND

SATURATION

Driving Force (pH, Temperature)

Conce

ntr

ation o

f Io

ns

Undersaturated

Metasable

Supersaturated

Saturated

Incre

ase in O

rder

Ions in Random

Solution

Disordered Crystal

Lattice

Ordered Crystal

Lattice

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Adapted from Stumm and Morgan – Aquatic Chemistry Second Edition

CRYSTAL GROWTH STEPS

a) transport of solute to the crystal solution interface

b) absorption of the solute at the surface

c) incorporation of the crystal constituents into the lattice

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CRYSTAL FORMATION

Two way reaction

• Formation

• Dissolution

Growth Kinetics

• Diffusion-controlled Growth (dissolution)

• Interface-controlled Growth

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CRYSTAL FORMATION

Growth Kinetics Impacted by:

• ion concentration (at the interface)

• surface area

• turbulence

• adsorption rate

• “crystal poisons”

“Crystal Poisons” – Inhibit the spread of

monomolecular steps on the crystal surface by

becoming adsorbed on active growth sites.

• Foreign Inorganics

• Polymers, Phosphonates, Phosphates

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PAPER

EXPERIMENT

CALCITE CRYSTAL MODIFICATION WITH

POLYMERS


Nucleation Site


Nucleation Site


• 2D Representation of a 3D Event

• Each Dot Represents a Directional Growth Vector • Center Square Represents a Cubic Calcium Carbonate Lattice Section

• The Whole Grid Represents a Fully Formed Calcite Macro-Structure

Nucleation Site

Polymer


Nucleation Site

Polymer

Blocked Growth


Nucleation Site

Polymer

Blocked Growth

Crystal Lattice Formation


Nucleation Site

Polymer

Blocked Growth

Additional Polymer Interaction


Nucleation Site

Polymer

Blocked Growth

Lattice Dissolution


Freed Polymer Nucleation Site

Nucleation Site

Freed Polymer


IMPORTANCE OF CRYSTAL

MODIFICATION

Critical to Threshold Inhibition Mechanism

• Prevents Normal Crystal Growth

• Dissolution of Unstable “Crystaloids”

• Polymer “Freed” to Interact with other Forming Crystals (Sub-Stoichiometry)

Precipitated Crystals with Modified Habit…

• Reduced Area for Surface Attachment

• Reduced Deposition Amounts

• Easier Removal of Deposited Scale

• Weaker Attachment to Surface

• Compromised Macro Crystal Lattices


DEFINITION – PARTICULATE

DISPERSION

Particulate Dispersion (Formal) - A mixture of finely divided

particles, called the internal phase (often of colloidal size)

distributed in a continuous medium, called the external

phase.

Particulate Dispersion (Practical) – Suspension of

particulates in an aqueous solution.

• Inorganic

• Organic

• Mixture

Polymer composition and Mw are key determinants in

deriving functionality

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DRIVING FORCE

Driving Force for Mineral Scale Precipitation is a general term

used to refer to the severity of conditions (pH, temperature,

precipitating ion concentrations, contamination, corrosion,

evaporation……) that contribute of precipitation tendency of

a given compound.

Clearly not a specific term, rather a suggestion of degree or

potential.


Graph Prepared using French Creek Software’s WaterCycle® Program

POLYMER

LANDSCAPE


EXAMPLES OF COMMERCIALLY

AVAILABLE POLYMER TYPES


Polyacrylates (PAA or NaPAA)– Typical MW 1,000 – 5,000 daltons

SMBS – Sodium Metabisulfite/Sodium Persulfate

IPA – Isopropanol/Sodium Persulfate Mercaptain – Thioglycolic Acid, 2-mercaptoethanol, 3-mercaptoproprionic acid

Hypophosphite IPA Solvent Polymerization

Other Organic Solvent Polymerization

Maleic Homopolymers and Copolymers – Typical MW 500 – 3,500 daltons

Polymaleic Acid (PMA) – Organic Solvent Polymerization

Polymaleic Acid (PMA) – Aqueous Polymerization Maleic/Ethyl Acrylate/Vinyl Acetate (MA/EA/VA)Copolymer

Acrylic Maleic (AA/MA) Copolymers Acrylic Maleic Non-Ionic (AA/MA/NI) Copolymers

Poly-expoxy-Succinic Anhydride Hompolymers (PESA)




Polymethacrylates (PMA)– Typical MW 6,000 – 30,000 daltons

SMBS – Sodium Metabisulfite/Sodium Persulfate

APS – Ammonium Persulfate Mercaptain – Thioglycolic Acid, 2-mercaptoethanol, 3-mercaptoproprionic acid

Acrylamide Copolymers (ACM) – Typical MW 2,000 – 5,000 daltons

Hydrolyzed Polyacrylamide …..Acrylic/Acrylamide Copolymer

Copolymerized Acrylic Acid/Acrylamide Copolymer




Sulfonated Copolymers – Typical MW 2,000 – 20,000 daltons

Acrylic Acid/2-Acrylamido 2-Methylpropane Sulfonic Acid Copolymers (AA:AMPS) Acrylic Acid/2-Acrylamido 2-Methylpropane Sulfonic Acid/t-butyl acrylamide Copolymer (AA:AMPS:t-BAM)

Acrylic Acid/2-Acrylamido 2-Methylpropane Sulfonic Acid/Non-Ionic Copolymer (AA:AMPS:NI) Acrylic Acid/2-Acrylamido 2-Methylpropane Sulfonic Acid/Hypophosphite Copolymer

Acrylic Acid/2-Acrylamido 2-Methylpropane Sulfonic Acid/Sodium Styrene Sulfonate Copolymer (AA:AMPS:SSS) Acrylic Acid/1-allyloxy-2-hydroylpropyl sulfonate (COPS) Copolymer (AA:COPS) Acrylic Acid/ammonium allyl polyethoxy sulfate (APES) Copolymer (AA:APES)

Acrylic Acid/allyl-oxy-benzene sulfonate (ABS) Copolymer (AA:ABS) Acrylic Acid/allyl-oxy-benzene sulfonate/methyl methacrylate/sodium methallyl sulfonate Copolymer (AA:ABS:MMA:SMS)

Sulfonated Styrene/Maleic Anhydride Copolymer (SS:MA) Sulfonated PolyStyrene Homopolymer (SPS) Acrylic Acid/Sodium Styrene Sulfonate Copolymer (AA:SSS)

AND SO ON……….

AMPS Monomer is a registered trademark of The Lubrizol Corporation

COMMERCIALLY AVAILABLE

POLYMERS….

Represents Over 90% of what YOU and YOUR Competitors

USE!

Significant COMMONALITIES EXIST!

Significant DIFFERENCES EXIST!

Very Important to Understand WHEN and HOW to Utilize

GENERICS versus SPECIALTIES


COMMONALITIES

Three Classes of Monomers Used

• Carboxylates

• Sulfonates

• Non-Ionics

Most polymers reacted in aqueous solvent

• Notable Exceptions (Certain Polymaleic Acids and IPA

PAA’s)

All produce random polymers

• Molecular weight distribution

• Monomer distribution

Majority Have Molecular Weights of <10,000 daltons


SIGNIFICANT DIFFERENCES

Combination of Monomers

Ratio of Monomers

Specific Molecular Weight Control

• Dispersivity

• Average Mw

Type of Initiator System Used

Polymerization Conditions

Quasi Polymer Architecture


ROLE OF MONOMER CLASSIFICATION

Carboxylic Acids

• Typical Polymer “Backbone”

• Usually the Majority Component

• Provide Base Functionality


• Earth Metal Chelation

• Solids Suspension

• Do Not Typically Stabilize Transition Metals

• Polyacrylic Acids are not Highly Stable to Ca++, Ba++

• Maleics are Highly Stable Due to Di-carboxylic Acid and

Electrostatic Repulsion


TYPICAL CARBOXYLIC ACID

MONOMERS



Sulfonic Acids

• Provide Brine and Hardness Stability

• Decrease Calcium Carbonate Efficacy

• Required to Add Functionality for

• Calcium Phosphate

• Iron Stabilization

• Zinc Stabilization

• Other Transition Metals (Mn, Cu, Ag)

• Increase Polymer Cost

• Typically Added at Levels Below 10 mole%


TYPICAL SULFONATED MONOMERS



Non-Ionics

• May be used as Spacers

• In-Situ Benefits during Polymerization

• Can add Quasi Architecture Capabilities

• Interact with Organics, Hydrophic Materials in Water

• Biodispersion Properties

• Increase Polymer Stability to Ions, Hardness


TYPICAL NON-IONIC MONOMERS

isobutylene


SIMPLIFIED MONOMER

FUNCTIONALITY CHART

CaCO3 CaSO4 Cax(PO4)y Iron Zinc Organic

s

Salt Stab

Carboxylate + + - - - - + MA

- AA

Sulfonate - + + + + - +

Conc.

Dependant

Non-Ionic +

Crystal

Mod. -

Threshold

Chelation

- +

(HPA)

+

(H2O-

Phobic Iron

Forms)

- + +


OTHER CONSIDERATIONS

Reaction Solvent

Polymerization Method

Molecular Weight Control

Monomer Combination

Monomer Ratio

Initiator System


AQUEOUS VERSUS NON-AQUEOUS

Impacts Monomer Selection

• Maleic Homopolymer

• Non-Ionics

• Organic Solvent

• Aqueous

• Co-Solvent

• Broader Monomer Selection for Aqueous

• Sulfonated Monomers

• Each Process Allows for Specific Process or Initiator Conditions

• Organic Aromatics

• Inorganics

• Cost Weighting

• Finished Product Purity


RANDOM POLYMERIZATION

Free Radical Polymerization

Inefficient Process

Little Direct Control

Empirical Learnings….Manufacturing Techniques


EFFECT OF

MOLECULAR WEIGHT

Polymerization Method Yields Broad Molecular Weight

Distribution

Mw versus Mn

• Dispersivity

Rules of Thumb for Mw

• <5,000 Threshold Inhibition

• >5,000 Dispersion

• ~106 Coagulation

• ~107 Flocculation


INITIATOR AND

POLYMERIZATION

SYSTEM IMPACT

Organic versus Inorganic Initiator Systems

Hypophosphite

Persulfate – Bisulfite

Organosulfur

H2O2

Temperature – Reactivity, Decomposition

Pressurized Reactions


MONOMER SELECTION AND

COPOLYMERIZATION RATIOS

Not an Exact Science

Typical Purposes

• Cost

• Desired Functionality

• Raw Material Sourcing Position

• Polymerization Practicalities

• Diminishing Return on Functionality

• Reactivity Ratios

• IP (Preventive….Novelty/Opportunity)


POLYMER

SELECTION

EXAMPLES


FUNCTIONALITY

RULES OF THUMB

Three Primary Functional Groups

• Carboxylates (acrylates, maleates)

• Sulfonates (AMPS, Sulfonated Styrene, Other Specialty)

• Non-ionics (acrylamide and derivatives, hydrophobes...)

Carboxylates

• Provide General Purpose Functionality

• Typical Backbone

• Good for Dispersion, CaCO3, CaSO4

Sulfonates

• Typically for Stabilization of Phosphate, Iron, and Zinc

• Add Electrolyte Stability

Non-ionics

• Extend Functionality to Include a Broader Range of Solids

• Can Change Polymer Configuration Properties

• Can be Effective for Stabilization Similar to Sulfonates


CALCIUM PHOSPHATE

STABILIZATION

Poor Performers

Best in Class

Moderate

Effectiveness

75:25 AA:AMPS

AA:AMPS:t-BAM

60:40 AA:AMPS AA:AMPS:SS

AA:AMPS:HYPO

AA:NI:ABS:SMS Highly

Effective

Low to Moderate LSI, Phosphate, pH

High to Severe LSI, Phosphate, pH

Surface Temperature

Polyacrylates

Polymaleates

Maleic Copolymers

Polymethacrylates

Phosphonates

Maleic Sulfonates


IRON STABILIZATION

Poor Performers

Best in Class

Moderate

Effectiveness

75:25 AA:AMPS

AA:AMPS:t-BAM 60:40 AA:AMPS

AA:AMPS:SS

AA:AMPS:HYPO

AA:NI:ABS:SMS

Highly

Effective

Low to Moderate Iron Concentration High Iron Concentration (>5ppm)

Polymaleates

Most Maleic Copolymers

Maleic:Sulfonate

Polyacrylates and Polymethacrylates can demonstrate particulate iron dispersion functionality

SS:MA


CONCLUSIONS

Multiple Functionalities Must Be Considered

Functionalities are Connected


• Stabilization

• Sequestration

• Crystal Modification

• Dispersion

• Chelation

Polymers are Engineered for Specific Purposes

• No Magic Bullet for All Scale Types

Vendor Relationship and Access to Experience Critical


CONTACT

INFORMATION

Mike Standish

56 N. Crest Road

Chattanooga, TN 37404

+1 423 316 9877

[email protected]

www.formulateonline.com


a discussion of polymer functionality of polymer application in...a discussion of polymer...

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