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Transport of Small Molecules in Polymers:Overview of Research Activities
Benny D. FreemanDepartment of Chemical Engineering University of Texas at
Austin,
Office: CPE 3.404 and CEER 1.308B
Tel.: (512)232-2803, e-mail: [email protected]
http://www.che.utexas.edu/graduate_research/freeman.htm
http://membrane.ces.utexas.edu
September 2008
Develop fundamental structure/function rules to guide the preparation of high performance polymers or polymer-based materials for gas and liquid separations as well as barrier packaging applications.
Freeman Research Group Focus
• 18 Ph.D. students:– Gas Separations: Brandon Rowe, Victor Kusuma, Grant Offord,
Tom Murphy, James Kyzar, Katrina Czenkusch– Liquid Separations: Alyson Sagle, Bryan McCloskey, Hao Ju,
Yuan-Hsuan Wu, Lauren Greenlee, Liz Van Wagner, Wei Xie, Dan Miller, Joe Cook, Geoff Geise
– Barrier Materials: Richard Li, Kevin Tung
• 1 Postdoc: Dr. Claudio Ribeiro• Sponsors:
– NSF - 6 projects– DOE – 2 projects– Office of Naval Research - 1 projects– Sandia - 1 project
– Industrial sponsors: 3M, Air Liquide, Eastman Chemical, Kuraray, Kraton Polymers
Freeman Research Group Profile
• University of Texas:
– Don Paul (Chem. Eng.), Roger Bonnecaze (Chem. Eng.). Mukul Sharma (Petroleum Eng.), Des Lawler (Env. Eng.), Andy Ellington (Biochemistry)
• Prof. Eric Baer, Anne Hiltner, Dave Schiraldi (Case Western Reserve Univ.)
• Prof. Jim McGrath (Virginia Tech)
• Prof. Doug Kalika (Univ. of Kentucky)
• Prof. Todd Emrick (Univ. of MA, Amherst)
• Dr. Anita Hill (CSIRO, Melbourne, Australia)
• Prof. Giulio Sarti (Univ. of Bologna, Italy)
• Prof. Philippe Moulin (Univ. Paul Cézanne, Aix-en-Provence, France)
• Prof. Young Moo Lee (Hanyang Univ., Seoul, Korea)
Collaborations
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Spreading Water Shortage
Science 313, 1088-1090, 2006
• Over 1 billion people live without access to reliable drinking water.
• 2.3 billion people (41% of the Earth’s population) live in water stressed areas; expected to increase to 3.5 billion by 2025.
• Annual global costs in excess of $100 billion in medical costs and loss of productivity.
Magnitude of the Problem
Science 313, 1088-1090, 2006
7
Desalination Market
• Projected worldwide market for desalination- 2005: $1.0 billion- 2010: $3.0 billion- 2025: $12.0+ billionGlobal market growing at 12% annually, this growth rate is expected to continue or accelerate.
• Membrane processes, particularly reverse osmosis, will continue to take market share from thermal desalination, with 59% of the total new capacity being membrane based.
Water Desalination Report, 25 September 2006
(www.desalwater.com)
SEM image of GE AG membrane
Polyamide thin film composites on polysulfone support:
Conventional Reverse Osmosis Membrane
15-35Typical operating flux (L/m2hr)
99.5Average NaCl Rejection (%)
200Typical Feed Pressure (psig)
C N
O
H
C N
O
H
NC N
O H
C
O
H
C O
x y
C O
OH
Example: GE AG Brackish Water Desalination Membrane
300 nm
10
Why Chlorine is Used in Water Treatment
• Bacteria-laden untreated water kills more than 3.4 million people every year in developing countries.1
• Un-disinfected water causes biofouling of desalination membranes.
• Chlorine is the most economical disinfectant for deactivation of pathogenic microorganisms in drinking water.
• Over 98% of all water treatment facilities in the U.S. disinfect water with chlorine and chlorine-based products.
• But the problem is:
Chlorine degrades desalination membranes, reducing salt rejection and membrane lifetime.
1Houston Chronicle, Jan.8, 2005 www.americanchemistry.com/chlorine/
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Membranes A-D: commercial polyamide membranes
Chlorine as hypochlorite pH > 8.5
Chlorine as hypochlorous acid pH < 5.5
T. Knoell, Ultrapure Water, April 2006, pp. 24-31
OCl- HOCl
Chlorine Attacks Desalination Membranes
0 3000 6000 9000 120000
10
20
30
40
50
60
70
80
90
100
Membrane A Membrane B Membrane C Membrane D
NaCl
reje
ctio
n (%
)
Chlorine exposure (ppm-hours)0 3000 6000 9000 12000
20
30
40
50
60
70
80
90
100
NaCl
reje
cton
(%)
Chlorine exposure (ppm-hours)
Membrane A Membrane B Membrane C Membrane D
12
Chlorinate(0.2-5 ppm)
Dechlorinate(Free chlorine
< 0.01 ppm)
Polyamidedesalinationmembrane
Rechlorinate(1-2 ppm)
Feed water
Product water
To protectmembranesfrom chlorine
Desalination 64 (1987) 411; Desalination 124 (1999) 251
Current Desalination Process
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Disulfonated Polysulfone Membranes Exhibit High Chlorine Tolerance
0 4000 8000 12000 16000
40
50
60
70
80
90
100
SW30HR(FilmTec)
BPS 40N
NaC
l rej
ectio
n (%
)
Chlorine exposure (ppm-hours)
BPS 40H
33 h16 h0 h 24 h8 h
Cross‐flowpH = 9.5Feed = 2000 ppm NaClPressure = 400 psigFlow rate = 0.8 GPMChlorine = 500 ppm
Hydrophilic block
Hydrophobic block
• High water permeability• High chlorine tolerance• Excellent fouling-resistance• Good reproducibility
S
O
O O
O
S
O
O O
O
SSO
O OH
O
OHO
14
Potential Desalination Process Using Chlorine-Tolerant Membranes
Chlorinate Newmembrane
Feedwater
Productwater
Extend membrane lifetime Simplify maintenance and operationProcess intensificationCost savings via elimination of dechlorination required by current membranes
Copolymer Synthesis by Nucleophilic Aromatic Substitution
S
O
O
ClClS
O
O
ClCl
NaO3S SO3Na
OH Ar OH
CH3
CH3
CF3
CF3
O S
O
O
O
SO3HHO3S
Ar O S
O
O
O Ar
+
140 oC / 4 h 190 oC / 24 h
+
K2CO3
NMP / Toluene
Ar =
n 1-n
H2SO4
x
Hydrophilic Hydrophobic
Harrison, W.L.; Wang, F.; Mecham, J.B.; Bhanu, V.A.; Hill, M.; Kim, Y.S.; McGrath, J.E. J. Polym. Sci., Part A: Polym. Chem. 2003, 41, 2264-2276.
140 ºC/4 h165 ºC/48 h
K2CO3, TolueneDMAc
Acidification
16
Material Design Options
S ClClO
O
SO3Na
NaO3S
Key monomer
Dow Water Solutions Launches Joint Development Partnership With Virginia Tech and University of Texas at Austin
Multi-year joint development agreement will develop oxidation-resistant reverse osmosis membranes
Edina, MN - August 26, 2008
Dow Water Solutions, a business unit of The Dow Chemical Company (Dow) and global leader in water purification, seawater desalination, contamination removal and water reuse solutions, has reached a multi-year joint development partnership with Virginia Polytechnic Institute and State University (Virginia Tech) and University of Texas at Austin (UT). Under the agreement, Dow Water Solutions will collaborate with Virginia Tech and UT on the research and development of oxidation-resistant reverse osmosis membranes.
"We're thrilled to be partnering with an industry leader such as Dow Water Solutions," said Dr. Benny Freeman, Kenneth A. Kobe and Paul D. and Betty Robertson Meek & American Petrofina Foundation Centennial Professor of Chemical Engineering, University of Texas at Austin. "It's an exciting alliance bringing together the vast engineering knowledge of our universities with Dow's existing industry expertise, resulting in breakthrough membrane chemistry."
Dr. James McGrath, University Distinguished and Ethyl Corporation Professor of Chemistry, Virginia Polytechnic Institute and State University, added, "This partnership is a positive step forward for the advancement of science. Through innovation, research and hard work, our joint development will present endless opportunities to deploy advanced membrane technologies, meaning greater water purification and management to the world."
This joint partnership will tackle one of the toughest technical challenges in the water desalination industry, developing oxidation-resistant, or chlorine-resistant, reverse osmosis membranes that will simplify the water treatment process and convert highly-contaminated waters into potable water sources.
Partnership with Dow Water Solutions - World’s Largest Supplier of Desalination Membranes
Research in Water Purification Appears to be Gaining Traction in the Scientific Community
Gas Separation Applications Involving CO2
H2 Natural Gas Sweetening
Natural Gas Sweetening (CO2/CH4)
Syngas Purification (CO2/H2)
Advanced Food Packaging (CO2/O2)
JA
Membrane thickness
Upstream pressurepfeed
Downstream pressurepperm
l
Component AComponent B
pfeed > pperm
(1) Sorption on upstream side(2) Diffusion down partial pressure gradient(3) Desorption on downstream side
• Permeability of A ≡ PA = DA SA , where DA ≡ Diffusion coefficient of A SA ≡ Solubility coefficient of A
• Selectivity ≡ αA/B =PA
PB=
DA
DB
⎛
⎝⎜
⎞
⎠⎟
SA
SB
⎛
⎝⎜
⎞
⎠⎟
Mobilityselectivity
Solubilityselectivity
• Flux of A ≡ JA =PA (pfeed,A - pperm,A)
l
J. Membrane Sci.., 107, 1-21 (1995)
Gas Transport in Polymers: Solution-Diffusion Model
100
101
102
103
10-2 10-1 100 101 102 103 104
Glassy PolymersRubbery Polymers
H2 Permeability × 1010 [cm3(STP)cm/(cm 2 s cmHg)
Upper Bound
αH
2/N
2
The Upper Bound
Theory of the upper bound: B.D. Freeman, Macromolecules, 32(2), 375 (1999).
Design of Highly Permeable, Highly Selective Polymers
Candidate Structures
NN
O
O
X1
O
O
X2
OH
OH
• Soluble• High glass transition temperature (>350 oC)• Thermally stable polymers for photoresist• Non-linear optical (NLO) applications
Polyimides with Ortho-Positioned Functional Groups (PIOFG)
N
O
O
OH
N
O
OHO
N
O
O
OH
N
O
O
OH
N
O
+ CO2
• Temperature: 350 – 450 oC• Atmosphere: vacuum or inert• State: Film, fiber, and powder (solid state)
1. Vysokomol. Soyed. B9 (1967) 8732. Polymer 40 (1999) 3463
Polyimide
Polybenzoxazole Intermediate
Thermal Conversion of PIOFG
N NCF3
CF3
O
OO
OOH OH
F3C CF3
N
O
O
OH OH
F3C CF3
N
O
O
N N
O
O
OO
OOH OH
F3C CF3
N
O
O
N
O
O
OH OH
F3C CF3O
N
N
O
O
OH OH
F3C CF3O
O
PIOFG‐1
PIOFG‐2
PIOFG‐3
PIOFG‐4
PIOFG‐5
PIOFG Structures Considered
FFV FFV Increase (%) d-spacing (nm)
PIOFG-1 0.15965
0.548TR-1-450 0.263 0.600PIOFG-2 0.134
640.546
TR-2-450 0.219 0.606PIOFG-3 0.131
570.503
TR-3-450 0.205 0.611PIOFG-4 0.120
1020.539
TR-4-450 0.243 0.602PIOFG-5 0.148
280.560
TR-5-450 0.190 0.698
Change in Free Volume Due to Thermal Rearrangement
New Gas Separation Membrane Materials withPerformance Better than Conventional Membranes
Science, vol. 318, 12 October 2007, pp. 254-258.
Science, vol. 318, 12 October 2007, pp. 254-258.
O
O
O8
O
O
OH7
polyethylene glycol diacrylate n=14 (PEGDA)
polyethylene glycol acrylate n=7 (PEGA7)
polyethylene glycol methyl ether acrylate: n=8 (PEGMEA8)Lin, H., Kai, T., et al. Macromolecules 38, 8381-93 (2005)Kalakkunnath, S., Kalika, D.S., et al. Macromolecules 38, 9679-87 (2005)
O
O
O14
O
Crosslinked Poly(ethylene oxide) (XLPEO)
Lin et al., Science, 311, pp. 639-642 (2006).
Beating the Permeability-Selectivity Tradeofffor H2 Purification
CO2 Selective Materials
Commercial Availability
Using Nanocomposites to Enhance Membrane Separations
Last Name First Name Email AddressCook Joe [email protected] Katrina [email protected] Geoff [email protected] Lauren [email protected] Hao [email protected] Victor [email protected] James [email protected] Hua "Richard" [email protected] Bryan [email protected] Dan [email protected] Tom [email protected] Grant [email protected] Claudio [email protected] Brandon [email protected] Alyson [email protected] Kevin [email protected] Wagner Elizabeth [email protected] Wei [email protected] Yuan-Hsuan [email protected]
Student Contacts
For gas separation project, primary contacts are Brandon Rowe (main campus) and Claudio Ribeiro (Pickle campus).
For water purification project, contact Bryan McCloskey, Liz van Wagner, or Joe Cook (Pickle campus).
The Best Part of the Job
