Particle Technology- Membranes and Colloids
-
Upload
the-engineering-centre-for-excellence-in-teaching-and-learning -
Category
Education
-
view
2.449 -
download
3
description
Transcript of Particle Technology- Membranes and Colloids
![Page 1: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/1.jpg)
Membranes & ColloidsChapters 4 & 13 in Fundamentals
Professor Richard Holdich
[email protected] Course details: Particle Technology, module code: CGB019 and CGB919, 2nd year of study.
Watch this lecture at http://www.vimeo.com/10202852
Visit; http://www.midlandit.co.uk/particletechnology.htm
for further resources.
![Page 2: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/2.jpg)
Membranes & Colloids
Types, configurations and permeate flux
Surface and internal fouling Polarisation flux models &
enhancement Colloidal interaction – DLVO
theory
![Page 3: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/3.jpg)
Introduction
![Page 4: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/4.jpg)
Particle size - colloids
Bacteria 0.2 to 8 microns viruses 0.05 to 0.5 microns colloidal silica 0.02 to 1 micron macromolecules 0.01 to 0.5 microns ions <0.01 microns no concentration limit in MF & UF
processes
![Page 5: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/5.jpg)
Membrane types
Microfiltration• 0.05 to 10 microns generally
Ultrafiltration• 1 to 50 nano-metres
Nanofiltration & Reverse Osmosis
![Page 6: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/6.jpg)
Membrane cartridges
![Page 7: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/7.jpg)
Cells - unstirred and stirred
![Page 8: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/8.jpg)
Filter Media - Pressure
start
Medium
Rm
Po
P
v1
later
Medium
Rm
Po
P
v2
![Page 9: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/9.jpg)
Crossflow filtration
![Page 10: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/10.jpg)
Crossflow filtration
![Page 11: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/11.jpg)
Flux variation and resistance
Resistances to membrane filtration:
![Page 12: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/12.jpg)
Flux variation and resistance
Darcy’s law:
At
V
kL
P 1
d
d
Darcy’s law modified:
Jk
LP
)( mC RR
PJ
![Page 13: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/13.jpg)
Flux variation and resistance
Darcy’s law:
)( mC RR
PJ
J is permeate flux, in conventional units of litres per metre squared of membrane area per hour. It is the same as superficial velocity.
![Page 14: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/14.jpg)
Crossflow filtration
![Page 15: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/15.jpg)
Permeate flux decay
![Page 16: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/16.jpg)
Filtration fundamentals
Why can’t we simply measure Rm for each medium?Ideal
Filtrate
Bridgingover pores
Filter m edium
Filter cake
sharp interface m edium /cake - uniform spheresin cake easy to m odel
![Page 17: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/17.jpg)
Membranes & Colloids
Types, configurations and permeate flux
Surface and internal fouling Polarisation flux models &
enhancement Colloidal interaction – DLVO theory
![Page 18: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/18.jpg)
Filter Media - Pore Size?
What do we mean by pore size?
![Page 19: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/19.jpg)
Filter Media - Pore Size?
Metal fibre microfiltration medium - rated at 3 microns
![Page 20: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/20.jpg)
Filter Media - Pore Size!
Equivalent pore size
![Page 21: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/21.jpg)
Membrane media - PTFE
0.2 micron rated membrane filter
![Page 22: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/22.jpg)
Membrane internal fouling?
![Page 23: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/23.jpg)
Membrane secondary membrane
![Page 24: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/24.jpg)
Membranes & Colloids
Types, configurations and permeate flux
Surface and internal fouling Polarisation flux models &
enhancement Colloidal interaction – DLVO theory
![Page 25: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/25.jpg)
Membrane models
![Page 26: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/26.jpg)
Rejection
R = 1 - Np/Nb
![Page 27: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/27.jpg)
Equilibrium flux response
![Page 28: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/28.jpg)
Membrane film theory
![Page 29: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/29.jpg)
Membrane simple circuit
![Page 30: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/30.jpg)
Membrane feed & bleed
![Page 31: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/31.jpg)
Diafiltration
![Page 32: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/32.jpg)
Diafiltration
Stirred tank displacement washing only:
)/exp( VJAtCC o
e.g. washing times given a flux rate of 50 l m-2 h-1 and tank volume of 1000 litres
Area (m2): 1 10 20t(hrs) C(ppm) C(ppm) C(ppm)0 500 500 5001 476 304 1842 452 184 684 409 68 96 370 25 1
![Page 33: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/33.jpg)
Membrane cleaning
![Page 34: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/34.jpg)
Membrane & other SLS
![Page 35: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/35.jpg)
Membrane surface filter
![Page 36: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/36.jpg)
Membrane surface filter - slots
![Page 37: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/37.jpg)
Membranes & Colloids
Types, configurations and permeate flux
Surface and internal fouling Polarisation flux models &
enhancement Colloidal interaction – DLVO
theory
![Page 38: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/38.jpg)
Colloidal interaction
Stokes’ law tells us about settling?
Increase diameter but decrease density – net enhanced rate
COAGULATION v
FLOCCULATION
![Page 39: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/39.jpg)
Colloidal interaction
Floc bed clarifier
![Page 40: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/40.jpg)
Electrical interaction
Surface –ve charge Fixed layer +ve ions Diffuse layer after… Shear layer Zeta potential –
measured by moving particle in field,
Typically -50 to 0 mV
![Page 41: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/41.jpg)
Van der Waal’s attraction
H
H
HH
A
s
s
ss
HA 2
ln)2(
)H2(1
12 = s
x
zH s
2
where AH is the Hamaker* constant for a given system and Hs is the ratio of the separation distance (z) between the particles and the particle radius.
So, in terms of particle diameter
*5x10-20 J for water
![Page 42: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/42.jpg)
Electrical repulsion
zΚzΚ
zΚxZZZZ
pR 2exp(1ln)(
exp(1
)exp(1ln2
82
2:2
1:2:1:
where the Zeta potential is used extensively above, together with the particle diameter, dielectric constant of the system and the Debye-Hückel function –which is a function of ionic conditions.
![Page 43: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/43.jpg)
Net forces - DLVO
Total
RAT
Dimensionless interaction energy
Tk B
T
Force
zF
d
d
![Page 44: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/44.jpg)
Net forces - DLVO
Curve 1 Primary minimum and maximum
Curve 2 Primary and Secondary
minimum Single maximum
Curve 3 Primary minimum
Which colloid is the most stable?
![Page 45: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/45.jpg)
Net forces - DLVO
Silting of estuaries Click image for
XLS
![Page 46: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/46.jpg)
Stokes’ settling equation
Colloid stability important in filtration and sedimentation.
Often assessed by the Zeta potential
Surface forces can predominate at iso-electric point.
![Page 47: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/47.jpg)
Membranes & Colloids
Types, configurations and permeate flux
Surface and internal fouling Polarisation flux models &
enhancement Colloidal interaction – DLVO theory
![Page 48: Particle Technology- Membranes and Colloids](https://reader033.fdocuments.net/reader033/viewer/2022042623/54bc1ea74a79594f698b4646/html5/thumbnails/48.jpg)
This resource was created by Loughborough University and released as an open educational resource through the Open Engineering Resources project of the HE Academy Engineering Subject Centre. The Open Engineering Resources project was funded by HEFCE and part of the JISC/HE Academy UKOER programme.
© 2009 Loughborough University
This work is licensed under a Creative Commons Attribution 2.0 License.
The name of Loughborough University, and the Loughborough University logo are the name and registered marks of Loughborough University. To the fullest extent permitted by law Loughborough University reserves all its rights in its name and marks which may not be used except with its written permission.
The JISC logo is licensed under the terms of the Creative Commons Attribution-Non-Commercial-No Derivative Works 2.0 UK: England & Wales Licence. All reproductions must comply with the terms of that licence.
The HEA logo is owned by the Higher Education Academy Limited may be freely distributed and copied for educational purposes only, provided that appropriate acknowledgement is given to the Higher Education Academy as the copyright holder and original publisher.