Membrane Process

Prof. Chung-Hak Lee School of Chemical and Biological Engineering

Seoul National University, Seoul, Korea

URL: http://wemt.snu.ac.kr

Membrane Process

References: 1) Norman N. Li, A.G. Fane, W.S. Wisnton Ho, Takeshi Matsuura (2008), Advanced Membrane Technology and Applications, John Wiley & Sons, Inc. 2) Cheryan, M. (1998), Ultrafiltration and Microfiltration Handbook, Technomic Publishing Company, Inc. 3) Mulder,M. (1996), Basic Principles of Membrane Technology, 2nd Edition, Kluwer Academic Publishers. 4) Faisal I.Hai, Kazuo Yamamoto. Chung-Hak Lee (2014), Membrane Biological Reactors, International Water Association.

Chapter 1-1. Definition of Membrane 1-2. Classification of Membrane Processes 1-3. Historical Development 1-4. Classification of Filter (Membrane)

Chapter 1 Introduction

1-1. Definition of Membrane separation Processes

WHAT IS A MEMBRANE?

i) A region of discontinuity interposed between two phases Hwang & Kammermeyer (1975)

ii) A phase that acts as a barrier to prevent mass movement, but allows restricted and/or regulated passage of one or more species. Lakshminarayanaiah (1984)

It can mean almost anything even air.

Membrane can be gaseous, liquid, solid or combination of these. better definition

- Conventional Filtration : Separation of solid, immiscible particles from liquid or gaseous streams.

- Membrane Filtration : Extends this application further, e.g., separation of dissolved solids in liquid streams and separation of gas mixtures.

Conventional vs. Membrane Filtration

Chapter 1-1. Definition of Membrane 1-2. Classification of Membrane Processes 1-3. Historical Development 1-4. Classification of Filter (Membrane)

Chapter 1 Introduction

1-2. Classification of Membrane Processes

-The membrane has the ability to transport one component more readily than other because of differences in physical and/or chemical properties between the membrane and the permeating components. - Transport through the membrane takes place as a result of a driving force acting on the individual components in the feed.

-In many cases, the permeation rate through the membrane is proportional to the driving force

J = - A dX/ dx A : phenomenological coefficient dX/dx : driving force (temp., pressure, concentration, etc.)

-Phenomenological equations cane also be used to describe not only mass flux but heat flux, volume flux, momentum flux and electrical flux.

Phenomenological Equations

J = - A dX/ dx A : phenomenological coefficient dX/dx : driving force (temp., pressure, concentration, etc.) A = Diffusion coefficient (mass flux, Ficks law)) = permeability coefficient (volume flux, Darcys law)) = thermal diffusivity (heat flux, Fouriers law) = kinetic viscosity (momentum flux, Newtons law) = electrical conductivity (electrical flux, Ohms law)

Phenomenological Equations

J = - A dX/ dx A : phenomenological coefficient dX/dx : driving force (temp., pressure, concentration, electrical potential, etc.)

- In using such equation, the transport process is considered as being macroscopic and the membrane as a black box. - For a pure component permeating through a membrane, it is possible to employ linear relations to describe transport. - However, two or more components permeate simultaneously, such relations cannot be generally employed since coupling phenomena may occur in the fluxes and forces.

Phenomenological Equations

Phases divided by membrane

Some Membrane Processes and Driving Forces

Chapter 1-1. Definition of Membrane 1-2. Classification of Membrane Processes 1-3. Historical Development 1-4. Classification of Filter (Membrane)

Chapter 1 Introduction

1-3. Historical Development of Membranes

Historical Development of Membranes

1748 : French, Abb Nollet - Demonstrated semi-permeability for the first time - He placed spirits of wine in a vessel, the mouth of which was closed with an animal bladder and immersed in pure water. Because it was more permeable to water than to wine, the bladder swelled and sometimes even burst.

1855 : Fick

- He published his phenomenological laws of diffusion, which we still use today as a first-order description of diffusion through membrane. - He prepared and studied some of the earliest artificial semi-permeable membranes. (collodion ; ether-alcohol solution of cellulose nitrate)

1861 : T. Graham - Grahams law of diffusion in gases - He made some of the first measurements of dialysis through synthetic membranes. - He discovered that rubber exhibits different permeabilities to different gases. Father : gas separations via membranes.

1860-1887 : Traube, Pfeffer, Vant Hoff

- They manufactured precipitated membrane.

- Osmotic pressure and diffusion phenomena were measured quantitatively Vant Hoff equation.

Historical Development of Membranes

1907-1918 : Bech hold, Zsigmondy - They developed methods for controlling the membrane pore size, principally with collodion membrane

1911 : Donnan

- He studied the distribution of macromolecular and micromolecular charged species across the semi-permeable membranes. - Donnan Distribution Law still finds use in our understanding of equilibrium phenomena in Donnan Dialysis and in coupled transport

1930s : Teorell, Meyer, Sievers

-Theory of transport across neutral and fixed-charge membrane. It formed the basis for our current understanding of both electro- dialysis membranes and modern membrane electrodes.

Historical Development of Membranes

1927 : Satorius, Germany

- Membranes were manufactured commercially in small quantities.

1944 : Kolff

- He demonstrated Artificial Kidney as one of the first practical applications of dialysis.

1951 : Goetz

- He imprinted grid lines on filters to facilitate bacteria counting.

Historical Development of Membranes

Artificial Kidney

Dr. Kolff : Artificial Kidney

1957 : United States Public Health Service (USPH)

- Officially adopted the membrane filtration procedure for drinking water analysis.

Early 1950s : Samuel Yuster of U.C.L.A.

- He predicted that, based on Gibbs adsorption isotherm, it should be possible to produce fresh water from brine. (Shortage of H2O in California so came up with a desalination idea)

Historical Development of Membranes

Our species is the only creative species, and it has only one creative instrument, the individual mind and spirit of man. Nothing was ever created by two men. There are no good collaborations, whether in music, in art, in poetry, in mathematics, in philosophy. Once the miracle of creation has taken place, the group can build and extend it, but the group never invents anything. The preciousness lies in the lonely mind of a man. John Steinbeck, East of Eden, 1952

Samuel Yuster predicted that, based on Gibbs adsorption isotherm, it should be possible to produce fresh water from brine.

Gibbs Adsorption Isotherm

S = excess solute near the surface

C2 = concentration of solute

= surface tension = surface area

)(

2

2

CRTCS

=

- If a solute causes a decrease in surface tension [ ], there will be adsorption on the surface.

0)(2

C

- If a solute causes an increase in surface tension [ ], the solute avoids the surface region.

0)(2

C

2ln1

CRTS

=

)(2

2

CRTC

= a2 = 2C2

2 1 in dilute solution

(dyne/cm)

73

NaCl

C2H5OH

0 moles/L

Surface tension vs. concentration

- Unfortunately, most stuff we deal with, decrease surface tension.

- 2t ; need of appropriate size [2 x the thickness(t)] to get a water fall.

Reverse Osmosis

It caused the pores to shrink Better rejection

Asymmetry higher flux

1958-1960 : Sourirajan, Loeb

- They performed heat treatment (annealing) to expand the pores and thus increase flux. But exactly the opposite happened : heating contracted the pores. So then they took commercially available UF Membrane and performed the heat treatment 3rd row in Tab. 1.2

Birth of Asymmetric Membrane

Historical Development of Membranes

Journal of membrane science, 339, 1-4, 2009

Seawater Desalination by Reverse Osmosis (RO)

Total capacity of worldwide seawater desalination plants : > 30 million tons/day Total market growth rate : ~11%/year (Sea Water Reverse Osmosis: ~17%/year)

International Market Trends

= 1million m3/day (220MIGD)

North America

Central America

South America Australia

Asia Middle East (50%)

Europe

Africa

Source: Wangnick (2004)

Chapter 1-1. Definition of Membrane 1-2. Classification of Membrane Processes 1-3. Historical Development 1-4. Classification of Filter (Membrane)

Chapter 1 Introduction

Depth Filter : - Filtration or particle removal occurs within the depths of the filter material.

- A matrix of randomly oriented fibers or beads that are bonded together to form a tortuous maze of flow channel.

- Removal mechanisms : interception, inertial impaction, diffusion, etc.

Screen Filter : - Separation of particles by retaining them on its surface in much the same manner as a sieve.

- Having a defined pore size. Membrane filters fall into this category.

Depth filter vs. Screen filter

FILTERS

Depth Screen

Microporous Asymmetric (Skinned)

Isotropic Anisotropic Integrally skinned

Non-integrally skinned

1- 5. Classification of Filter (Membrane)

Depth Filter

Screen Filter

1) Grow-through of microorganisms is not as frequent a problem

2) Little danger of sloughing off (material migration)

3) Higher recovery of the retained material (microbial cell harvesting)

4) Little liquid hold-up

5) Pore size can be controlled.

Advantages of screen filter

Absolute vs. Nominal Rating

Microporous : - No skin. - Absolute rating (retain all the particles larger than that rating)

Isotropic : pores of uniform size throughout the body of the membrane.

Anisotropic : pores change in size from one surface of the membrane to the other.

Asymmetric : - A thin skin on the surface of membrane with supporting layer. - Nominal rating (MWCO above which a certain percentage of the solute will be retained by the membrane.

- Anisotropy and Asymmetry are (incorrectedly) used inter- changeably.

Microporous vs. Asymmetric

Integrally skinned : homogeneous skin and support layers Non-integrally Skinned: composite skin and support layers

* http://www.fluxxion.com

MF membrane (Fluxxion,Eindhoven, Netherlands)

MF membrane (Fluxxion,Eindhoven, Netherlands)

MF membrane (Isopore MINs Membrane, WEMT, SNU )

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