north american membrane society poster
TRANSCRIPT
www.buffalo.edu
0.8
0.85
0.9
0.95
1
0 500 1000 1500 2000 2500
Nor
mal
ized
Rej
ectio
n
ppm.h chlorine
Thiol-ene Polymer Networks for Reverse OsmosisShawreen Shah, Kaipin Huang, Norman Ng and Haiqing LinDepartment of Chemical and Biological Engineering, University at Buffalo (SUNY), Buffalo, NY 14260, USA
Overview
Conclusion and Future Work
Drawback of Current RO Membranes
Approach: Thiol-Ene Based Polymer Networks
Conclusion: Highly crosslinked thiol-ene polymers and thin film composite membranes based on these polymers have been successfully prepared and characterized.
Future Work: • Optimize composite membranes and evaluate salt rejection using a dead-end
filtration system and a crossflow filtration system.
Laboratory of InNovative
Membranes at UB
Composition
Density(g/cm3)
Fractional Free Volume
Water Sorption Sol-Gel Percent
Without solvent*
With solvent*
Without solvent*
With solvent*
Without solvent*
With solvent*
Without solvent*
With solvent*
T1+E1 1.2 1.2 0.16 0.16 2.4% 2.6% 1.6% 0%
T1+E2 1.3 1.3 0.12 0.12 2.2% 2.3% 1.2% 0%
T2+E1 1.3 1.3 0.12 0.12 2.8% 2.7% 1.6% 0%
T2+E2 1.3 1.3 0.15 0.15 1.9% 2% 0.2% 0%
Reverse Osmosis (RO) system(Δp > Δ)
Δp = pressure differenceΔ = osmotic pressure difference
Salt Rejection:
C2: salt concentration in the permeateC1: salt concentration in the feed
)( pAJW
10011
2
CCR
Current RO membranes are subjected to chlorine oxidation, leading to higher water flux and lower salt rejection.
Thiol monomers T1: T2:
Ene monomers E1: E2:
Objective: To design and develop thiol-ene polymer based reverse osmosis membranes and study structure/property correlation.
Advantage of Thiol-Ene Polymers: • Highly crosslinked and homogenous• Versatile with many choices of monomers• Easy to prepare and immune from oxygen inhibition
Approach: • Novel polymers are prepared using multifunctional thiols and enes. • Polymers are characterized using FTIR-ATR, density and fractional free
volume measurements, and water sorption measurements.• Thin film composite membranes are prepared on commercial microporous
substrates for reverse osmosis applications.
Flux evaluation:
• Thiol-ene polymer networks are immune to oxidation, and hence chlorine is not expected to degrade the membrane.
A series of thiol-ene polymers were synthesized by UV photopolymerization.
Monomers used:
The reaction is initiated by exposure to UV light and proceeds via free radical polymerization.
Thin Film Composite MembranesThin film composite membranes were prepared by coating prepolymer solution on commercial microporous supports such as polyacrylonitrile (PAN).
A dead end membrane filtration system was designed and built to test pure water flux across thin film composite membranes.
Acknowledgement
The selective layer of commercial RO membranes is comprised of highly crosslinked aromatic polyamide.
We thank School of Engineering and Applied Sciences at University at Buffalo for their financial support.
• Greenlee, Lawler, Freeman, Marrot, Moulin, Water Res., 43 (2009) 2317-2348..• Ju, McCloskey, Sagle, Wu, Kusuma, Freeman, J. Membr. Sci., 307 (2008) 260-267
Characterization of Polymer Films
Photo of a thiol-ene polymer film
Fundamental of Reverse Osmosis
1000 1500 2000 2500 3000
PolymerEneThiol
Wavenumber (cm -1)
Pore-penetrationIncrease viscosity
Decrease thickness
PEO-Filler
DCM-Solvent
Ideal coating
0.8
1
1.2
1.4
1.6
0 500 1000 1500 2000 2500
Nor
mal
ized
Flu
x
ppm.h chlorine
• Thiol-ene reactions have fast polymerization rates, high conversion, network homogeneity and offer versatility in thiol and ene selection.
0
10
20
30
40
50
60
70
80
Con
tact
Ang
le
TxE
y + 0.1% PEO
TxE
y+0.35% PEO
+ 50% DCMT
xE
y+0.35% PEO
+ 90% DCM
T1E2T1E1 T2E1 T1E1 T1E2 T2E1T1E2T2E1 T1E1PAN 30
Increasing the solvent content in the prepolymer solution increases the water permeance in the thin film composite membranes.
SEM image of T1E2 + 0.35% PEO + 90% DCMDense polymer structure on the surface.
Membranes of thiol-ene polymers show hydrophilicity.
Polymer network formation
Salt
* 50% Solvent content in prepolymer solutions
* Lowe, Poly. Chem., 2010, 1, 17-36
* Wu, Liu, Yu, Liu, Gao, J. Membr. Sci., 352 (2010) 76-85
0
0.2
0.4
0.6
0.8
1
0 5 10 15 20
Perm
eanc
e (L
/m2 x
hr x
bar
)
Pressure (bar)
T1E1 + 0.35% PEO + 90% DCM
T1E2 + 0.35% PEO + 90% DCM
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0 5 10 15 20
Perm
eanc
e (L
/m2 x
hr x
bar
)
Pressure (bar)
T1E1 + 0.35% PEO + 50% DCM
T1E2 + 0.35% PEO + 50% DCM
Lin et al., Ind. Eng. Chem. Res., 2013, 52 (31), 10820