OVERVIEW Introduction of Nanofiltration(NF) NF Application - in - - PDF document

1st Korea-US Nano Forum

• 2003. 10. 14

Kew-Ho Lee

Membrane and Separation Research Center Korea Research Institute of Chemical Technology TEL) 82-42-860-7240 FAX) 82-42-861-4151 E-mail) khlee@krict.re.kr

PROGRESS OF NANOFILTRATION MEMBRANES PROGRESS OF NANOFILTRATION MEMBRANES

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OVERVIEW

• Introduction of Nanofiltration(NF)
• NF Application
• in Aqueous system
• in Non-aqueous system
• NF Membranes developed in KRICT
• Fouling resistant membrane
• Solvent resistant membranes
• Summary

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Application range of various membrane process

KRICT Membrane & Separation Research Center low molecu- lar range 0.001 1.0 100,000 500,000 virus proteins yeast cells ultrafiltration microfiltration Particle size µm nm Molecular weight Solute Mmebrane separation process atomic/ ionic range macro particle range 100 200 1000 aqueous salt metal ion sugar microsolutes dialysis electrodialysis diffusion dialysis reverse osmosis gas separation pervaroration high molecu- lar range micro particle range 1.0 1000 10.0 10,000 0.1 100 0.01 10 colloidal silica bacteria nanofiltration KRIC T

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Nanofiltration

Pore size < 2 nm Skin Layer < 1 µm

Monovalent Salts Undissociated acids

Reverse Osmosis Ultrafiltration Microfiltration

Divalent Salts, Dissociated acids Small organic molecules ( 2 > nm ) Macromolecules Virus Suspended particles Water

NANOFILTRATION (NF) MEMBRANES – Membranes whose performance is in between those of

UF and RO ( MWCO: 200-1000 g/mole)

– Good rejection of multivalent ions or organic materials

with low molecular weight

– Low Operating pressure

Schematic drawing of separation of ions by negative nanofiltration membranes Schematic drawing of separation of ions by negative nanofiltration membranes

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– – – – – – – – – – – – + – + 2– 2– porous swollen

Feed Filtrate Retentate Membrane Spacer

(a) Plate type module (b) Spiral-wound type module

Membrane modules

Filtrate Feed Membrane Retentate Filtrate

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Progress in NanofiltrationMembranes

Reverse Osmosis membranes Nanofiltration membranes High flux & Low fouling RO membranes High flux & Low fouling NF membranes NF membranes for Non-aqueous solvent system Chlorine resistant NF membranes

Functionalized NF membranes

Porous ultrafiltration membrane Impregnation Immersion and reaction Aqueous solution (amine) Organic solution (acylchloride) Composite membrane Thin polyamide layer

Preparation of composite polyamide membrane

Polypiperazineamide; NF membrane

NH HN

+

COCl COCl

• r

COCl COCl COCl NF-40(FilmTec); NTR-7250, NTR-729(Nitto Denko); UTC-20/50/60(Toray)

Polyamide; RO & NF membrane

+

COCl COCl

• r

COCl COCl COCl NH2 NH2 KRIC T

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NH2 NH2

+

Diol

+

Camphor sulfonic acid Toluene sulfonicacid Aqueous solution

Significant flux enhancement due to the surface roughness increase High flux RO & NF membranes

Low fouling RO & NF membranes High flux RO & NF membrane Coating neutral polymers or inorganic material Fouling resistance due to the surface charge blocking Solvent resistant NF membranes Cross-linked PAN UF membrane Coating silicone Solvent resistant against almost all solvents; Large pore (400 – 700Da) Kyriat weizmann; MPF series

1 2 3 4 5 20 40 60 80 100

NaCl Rejection (%) Flux (m

3/m 2day)

Progress of NF membranes

1990 2000 RO

NF90 NF270 NF40

(FilmTec , Hydranautics , SaeHan) (FilmTec , Hydranautics , SaeHan) (FilmTec )

225 psi; 2000 ppm NaCl

KRICT KRICT

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EXTENSION OF NF APPLICATION

NF Membranes

Pharmaceutical Industry P u l p I n d u s t r y Surface Water Treatment Drinking Water Treatment Fine Chemical Industry F

• d

I n d u s t r y T e x t i l e I n d u s t r y P r

• d

u c t i

• n
• f

P u r e w a t e r

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NF for Aqueous System

• A. Drinking and Process Water Treatment

– Water softening and Pure water production – Potable Water Production_ – Surface and Ground water Treatment

• B. Wastewater Treatment

– Oily Wastewater – Removal of Dye, VOC and Heavy Metals – Chemical plant Wastewater – Textile and Pulp Wastewater

• C. Food Industry

– Desalting of cheese whey and sea food processing – Concentration of fruit juice – Yeast Production

Water Softening

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Feed water Acid treatment

Precipitation of dissolved salts (Si, Mn, Fe) : Foulants

Cartridge filter Feed pump NF NF Reject water Sulfate bicarbonate Chlorine treatment Product water

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Potable Water Production

Surface

• r ground water

Cartridge filters Feed pump Mixer

Scale inhibitor Sulfuric acid

NF NF Mixer

Sulfuric acid

NF Use as a irrigation Degasifiers (- H2S & CO2) Mixer Chlorine To distribute system KRIC T Me

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R e s e a r c h Ce n t e r

• A. Fine Chemical Industry

– The separation of organometallic catalysts – The separation of small molecular weight organics (300-

1000Da) or residual reactants produced from the synthesis in an

• rganic solvent-based systems
• B. Pharmaceutical Industry

– The separation of pharmaceuticals (300-1000Da) synthesized in

a variety of organic solvents via a multi-step synthetic route

• C. Vegetable Oil Industry

– The recovery of solvents used in the extraction of edible oil

processing

– The concentration of edible oil – The separation of denaturated oil (fatty acid) NF for Non-aqueous System

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N NF Membranes for Catalytic Reactor F for Non- aqueous System

Methanol/Substrate Solvent resistent NF-membrane H2-Gas CSTR Product

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Solvent (hexane) extraction Refined Oil UF UF or MF NF or RO Deodorization (N2)

Membrane method for vegetable oil purification

Removal of phospholipids Active Carbon Chlorophyll,Carotenoid Removal MeOH treatment

NF

Solvent (hexane) Recovery Fatty acid Dewaxing VP Hexane + N 2 Odoring material Water Oil, Fatty acid, hexane, Other small molecules Crude Oil MeOH Hexane N2 Odor

NF membranes studied in KRICT

• 1. Polyamide NF membranes (interfacial polymerization)

NF-90 : > 90% rejection of NaCl; underground water treatment NF-70 : > 70% ; underground water treatment NF-40 : > 40% ; surface water treatment NF-20 : > 20% ; surface water treatment Development trend : High flux and low fouling

• 2. Organic solvent-resistant NF membranes

Low swelling and high flux in organic solution High separation of small molecular solute in organic solution

• 3. PVA & Integrally skinned NF membranes

Low fouling and chlorine resistant

• Fouling
• A. Foulants

– Humic acid – Proteins – Colloids – Mineral salts – Surfactants – Silica

• B. Problems

– Increasing operation and maintenance costs – Deteriorating membrane performance – Shortening membrane

• C. Properties influencing fouling

– Surface structure (roughness, pore size) – Electrokinetic characteristics (ξ-potential) – Chemical property (hydrophobic-hydrophilic interaction)

Fouling-Resistant NF Membrane

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Support Membrane

– Polyamides

Piperazine & m-phenylene diamine Trimesoyl chloride

– Poly(vinyl alcohol)

Poly(vinyl alcohol) 0.05 wt% Glutaraldehyde

– Interfacial & Dip coating Method – Support membrane

Polysulfone MWCO 50kDa

– Other NF membranes

NF 70 NF 70/PVA

PVA-coated polyamide composite membrane

Polyamide PVA

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Change of membrane performance by PVA coating Change of membrane performance by PVA coating Rejection rate (%) PWF (m3/m2day) PEG 200 NaCl PA 2.9 60 8 PA/PVA (1) 2.6 72 13 NF-70 1.7 81 75 NF-70/PVA (3) 1.4 88 83

25 ° C; 200 psi

– Surface water treatment after microfiltration

Neutral polymer- or nano particle-coated polyamide composite membrane

10 20 30 40 50 60 70 80 90 100 110 0.5 0.6 0.7 0.8 0.9 1.0

Relative flux (F t/F0) Operating time (hr) NF-20 Fouling resistant NF

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ξ-potential of PVA-coated NF membranes ξ-potential of PVA-coated NF membranes

2 3 4 5 6 7 8 9 10 11

• 100
• 90
• 80
• 70
• 60
• 50
• 40
• 30
• 20
• 10

10 20 30

Zeta potential (mV) pH NF-70 NF-70/PVA(3) PA PA/PVA

Electro-phoretic method; pH 7.0; 0.01M NaCl

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AFM images of NF-70 & PVA/NF-70 membranes AFM images of NF-70 & PVA/NF-70 membranes

NF-70/PVA(3) NF-70/PVA(1) NF-70

Polymeric braid Thin Microporous Polymer Coating Layer (Thickness< 2 µm) Nano-Catalysts (Titania, Fe 2O3) Nano-size Pores Porosity : 40-50 % Size : 1-50 nm Integral multifunctional antifouling nano-complex- membranes that would be efficient for the treatment of the waste-water through nano-catalytic-reaction and separation

Nano catalysts coated NF membranes

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O2 O2 O2 O2 O2

light

O2 O2 O2 O2

Membrane

O2 O2 O2 O2 O2

Water Water Photo catalyst Non-degradable organics

NF membrane-coupled Photo Catalyst Reactor

• Easy to recover the catalysts
• Need low-fouling NF membrane

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O2 O2 O2 O2 O2

light

Membrane Membrane

O2 O2 O2 O2 O2

Water Water Photo catalyst Non-degradable organics

Nano catalysts-coated NF membrane reactor

• No need to recover the catalysts
• Low fouling by catalytic degradation of organics

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Commercial NF membrane for non-aqueous system

MPF series (Kyriat Weizmann): MWCOs of 700 and 400Da made with silicone Advantage: high flux to organic solvent Disadvantage: difficult to reduce pore size

Objectives of the present work

• Develop various types of NF membranes

which is stable in organic solvents

• Investigate the possibility to separate fatty acid

in methanol and acetone solution

Solvent Resistant NF Membranes

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– Polyamides

Piperazine & m-phenylene diamine Trimesoyl chloride

– Silicones

Polydimethylsiloxane (prepolymer A & cross-linker B)

– Interfacial & Dip coating Method – Support membrane

Phase inversion PAN/NMP (15/85 wt%) Coagulated in water

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Support Membrane

Silicone + Polyamide

Silicon Contained Polyamide NF Membranes

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0.0 0.5 1.0 1.5 2.0 2.5 3.0 40 60 80 100 120 140

Contact angle (

• )

Concentration of diamine (wt%)

0.0 0.5 1.0 1.5 2.0 40 60 80 100 120 140

Contact angle ( o ) Concentration of silicone (wt%)

3wt% diamine 0.25wt% diamine

Polyamide Polyamide Silicone-based polyamide Silicone-based polyamide

Contact angle of polyamide and silicone-contained polyamide NF membranes Contact angle of polyamide and silicone-contained polyamide NF membranes

Advanced angle of droplet formed by CCl4 in water

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SEM photographs of membrane surfaces SEM photographs of membrane surfaces Polyamide Silicone-based Polyamide

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Flux ratio of MeOH to water of polyamide membrane Flux ratio of MeOH to water of polyamide membrane

0.0 0.5 1.0 1.5 2.0 2 4 6 8 10

F

MeOH / FH

2O

Concentration of silicone (%)

3wt% diamine 0.25wt% diamine

Performance of silicone-contained PA NF membranes in aqueous and MeOH solution Performance of silicone-contained PA NF membranes in aqueous and MeOH solution

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0.0 0.5 1.0 1.5 2.0 0.0 0.5 1.0 1.5 2.0 3wt% diamine 0.25wt% diamine

Concentration of silicone (wt%) Water flux (m

3/m 2day)

80 85 90 95 100 3wt% diamine 0.25wt% diamine PEG 200 rejection rate (%) 0.0 0.5 1.0 1.5 2.0 0.0 0.5 1.0 1.5 2.0 3wt% diamine 0.25wt% diamine

Concentration of silicone (wt%) MeOH flux (m

3/m 2day)

80 85 90 95 100 3wt% diamine 0.25wt% diamine

Oleic acid rejection rate (%)

Concentrations of Diamines, 0.25 wt% Concentrations of Diamines, 0.25 wt%

Solvent flux (TMD) Silicone Conc. (wt%) H2O MeOH EtOH IPA acetone MEK Hexane 0.54 0.68 0.41 0.11 1.09 0.20

• 0.2

0.44 1.09 0.56 0.39 1.62 0.36 0.25 0.5 0.31 1.44 0.85 0.44 2.03 0.68 1.12 1.0 0.12 1.85 1.09 0.79 2.41 1.82 2.85 2.0 0.09 1.75 1.29 0.88 2.58 1.85 2.89

25 ° C; 200 psi

SUMMARY

• Nanofiltration (NF) is rapidly growing in liquid phase separation for the

removal of natural organic matter(NOM), multivalent salts, dyes, and small organic molecules.

• NF membranes with high flux, solvent resistance, and low fouling have been

developed for the extension NF application range

• Membrane fouling is influenced by the membrane surface properties,

such as surface roughness, charge and hydrophobic-hydrophilic properties and the PA membranes coated with a thin PVA layer or nano particles show very good fouling resistance

• For a non-aqueous NF system, solvent resistance of the membrane materials,

and solvent fluxes are key issues. NF membranes prepared by blending of polyamide and silicone polymer show high solvent flux and high rejection to small organic molecules.

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