Polymer and Colloids Lab, Korea Institute of Science and Technology

고분자 분리막 및 자성이온교환수지

정범석 고분자하이브리드연구센터

한국과학기술연구원

고분자 환경 소재

고분자 분리막

고분자 분리막 (membrane) 기술 이란 ?기공 및 물리 , 화학 , 생물학적 특성을 이용해 혼합물로부터 특정 성분을 분리 , 농축 , 재이용하는 고분자 물질을 재료로 한 filter 로써 , 환경 /공업 분야 등 광범위한 영역에서 적용되고 있는 기술 .

수처리막 기능

내오염성 및 내화학성이 우수한 정밀여과막 및 한외여과막혼합 액체의 입자 분리 , 정제 및 재이용에 탁월한 효과

이용 분야

용수 처리 - 초순수 , 무균수 제조 , 해수 담수화 , 음료수폐수 처리 - 전착 도료 회수 , 오일폐수 분리 , 중수도재이용식품 공업 – 탈지유 농축 , 음료의 청정화바이오 산업 – 단백질 분리 농축 , 효소 정제

수처리막의 기능과 이용분야

100 m 10 m 1 m 0.1 m 0.01 m 0.001 m 0.0001 m

Reverse Osmosis

Nanofiltration

Microfiltration

Sand filter

Pollens Yeasts

Bacteria Viruses

Algea Organic macromolecules

Colloids Organic compounds

Dissolved saltsCa, Mg, Na

Ultrafiltration

분리막의 친수화 와 fouling

분리막 친수화 처리기술

* n

R

*C

n

OO

O

O O

O

* n

OOH

O

* n

OH

grafting

hydrolysis

Hydrophobic PE

Hydrophilic PE

( 예 ) 소수성 PE 막에 친수성 화학종 도입과정

polyolefin 계열 : PE, PP polyether 계열 : PSf,

PES polyacryl 계열 : PAN

분리막 표면처리 기법

대표적 수처리용 분리막 소재

Chemical modification Surface polymerization Polymer coating

친수성 고분자를 이용한 분리막 개발

분리막 소재용 고분자Polymers water

Cellulose Acetate (CA)

Structure

ROO

RO OR

O O R

RO

OR O

CH3

x

R= or H

N

x

O

CH3

CH3

O

O

x

N N N N

O

O O

O O

O

O

O x

CH3

x

CH3

CH3

O S OO

O

x

O SO

O x

F

x

FF

F

Polyacrylonitrile (PAN)

Polycarbonate (PC)

Polyimide (PI)

Polyproplene (PP)

Polysulfone (PSf)

Polyethersulfone (PES)

Polytetrafluoroethylene (PTFE)

59±3

57±3

78±1

79±2

83±2

82±2

92±2

117±2

Classification of Polymeric Membranes

porous

Symmetric

dense

Asymmetric

porous

macrovoid macrovoid with skin

porous with skin

Method for Polymeric Membrane Preparation

TIPS (Thermally Induced Phase Separation);Change in casting solution temperature.

Air-Casting and Evaporation; Evaporation of the volatile solvent in casting

solution. NIPS (Nonsolvent Induced Phase

Separation); Change in composition by the addition of

nonsolvent. Exposure to vapor or immersion in nonsolvent

bath.

finger-like sponge-like

• Typical morphology of asymmetric membranes

skin

sublayer

Asymmetric membrane formation

Polymer + solvent(s) Nonsolvent (bath)

Phase separation by immersion precipitation

Phase separation and membrane formation Phase inversion method (immersion precipitation method)• immersion of polymer solution into a coagulation medium• exchange of solvent with nonsolvent• phase separation occurs

P + S

NS

P + S

NS NS

S

binodal line

Polymer

NonsolventSolvent

composition path

Hollow Fiber Fabrication Process :

bore liquid

polymersolution

spinning nozzle

bore liquid polymer solution

Flat Sheet Fabrication Process :

polymersolution

porous support fabric

knife

Membrane morphology

Choice of solvent/nonsolvent pairs Polymer concentration Composition and temperature of gelation medium Composition and temperature of polymer solution

Thermodynamic parameters

Kinetic parameters

Exchange rate of solvent/non-solvent pairs Diffusion of polymer Coalescence of phase-separated domains

Membrane Morphology ; Solvent effect

(a) PI/DMSO 15wt% (b) PI/NMP 15wt%

Solution Viscosity

Concentration (wt%)

10 15 20

Vis

cosi

ty (

cP)

0

5000

10000

15000

20000

25000

30000

PI in DMSO PI in NMP

A

Phase Diagram

Water0 10 20

PI

0

10

20

NMP

80

90

100Water

0 10 20

PI

DMSO

80

90

100

binodal spinodal tie-linecloud pointcritical pointgelation point

Membrane Morphology; temperature effect (a) (b) (c)

(a) PI/NMP 19 wt% (b) PI/DMSO 15 wt% at 45OC solution (c) PI/DMSO 15 wt% at 30OC bath

Membrane Morphology ; cosolvent effect

CN

CH3

O

40/60 20/80 0/100

- Sponge-like finger-like as NMP content increases- Heat of mixing effect is clear

GBL/NMP: 100/0 80/20 60/40

CO

O

1-methyl-2-pyrrolidinone (NMP) -butyrolactone (GBL)

Membrane Morphology ; coagulation bath

Ratio of water/NMP is given by Vol/Vol.

10/1 10/2

10/3 10/4

Membrane Morphology: polymeric additives

PVP concentration: 5 wt%.

10k 360 k

40 k

Membrane Morphology ; additive effect

PVP: 0% 1% 3% 5% 8%

PI: 15 wt%, PVP 40k, solvent: NMP (high affinity with water)

macrovoid suppression

PI: 15 wt%, PVP 40k, solvent: GBL (low affinity with water)

macrovoid promotion

Membrane Morphology ; Inorganic addives

Nonsolvent: water/MeOH (2/1).

5 wt% LiCl3 wt% LiCl

5 wt% LiCl 5 wt% CaCl2 5 wt% MgCl21 wt% LiCl

Observation of phase separation

Optical microscope Recording to animation file Plotting depth vs. time

water drop

polymer solution

opticalmicroscope

3 sec 7 sec 11 sec 18 sec

※ An optical microscope snapshot of the progress of phase-separation

Phase separation ratePhase separation rate

- Diffusion process

- Decrease as GBL content increase

(effect of heat of mixing)

Solvent diffuse-out rateSolvent diffuse-out rate

polymer solution

D2O

polymer solution

D2O

Observation of solvent diffuse-out

- NMR spectroscopy

- Advantage in mixed-solvent system

- Measurement in different immersion time

- Plotting calculated value vs. time