Introduction - uni-due.de...Funded by: Synthesis and Characterization of Efficient Polyamide Thin...
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Funded by: www.uni-due.de/zwu/iwatec Synthesis and Characterization of Efficient Polyamide Thin Film Nanocomposite Membranes M. M. Elleithy 1 Ahmed S. G. Khalil 2,3,4 ; A. Essawi 1 , R. Ghannam 4 , A. Ramadan 1 ; M. Ulbricht 2 1: American University in Cairo, Egypt 2: Technical Chemistry II, University of Duisburg-Essen, Germany 3: Fayoum University, Egypt 4: Egypt Nanotechnology Center, Egypt Introduction Thin film composite (TFC) membranes hold superior advantages of higher solute rejection and water fluxes. These superior properties were established via preparation of the membrane into two separate procedures each of which results in a separate layer holding its key feature. Firstly, high flux support layer is fabricated, followed by application of polyamide (PA) thin film which contributes crucially to the membrane solute rejection. For the stability of the PA layer, surface for PA application should preferentially have small sized pores 1 . Consequently, this work was dedicated for fabrication of isotropic support with suited surface pore size and low resistance (high water flux) through combining VIPS and NIPS Processes. Accordingly, a former work conducted by Ulbricht et. al. 2 was adopted, where a sponge-like membrane structure was prepared and showed hydraulic permeability exceeding its comparative commercials by then. • PES casting solutions were prepared with different compositions entailing the effect of PES content along with: 1. (NMP) organic solvent N-methyl-2-pyrrolidone. 2. (Plu®) triblock copolymer Pluronic® 6400 as a hydrophilic additive. 3. (TEG) non-solvent Triethylene glycol. •Fabrication parameters were studied and characterization was done to confirm and elucidate the variations. •General composition coding for casting solutions: PES wt% /NMP wt% /TEG wt% /Plu wt% = P wt% /N wt% /T wt% / Pl wt% • Support layer with relatively small sized pores at the bottom surface along with sufficient hydraulic permeability was successfully fabricated and will be a good candidate for thin film composite membrane with molded surface. • Prospective work is to apply and test the stability of PA layer and overall final membrane performance. Contact: Mohamed Elleithy, American University in Cairo, New Cairo Campus, [email protected] References 1: P.S. Singh, S.V. Joshi, J.J. Trivedi, C.V. Devmurari, A. Prakash Rao, P.K. Ghosh, Probing the structural variations of thin film composite RO membranes obtained by coating polyamide over polysulfone membranes of different pore dimensions, J. Membr. Sci. 278 (2006) 19–25. 2: H. Susanto, M. Ulbricht, High performance polyethersulfone microfiltration membranes having high flux and stable hydrophilic property. J. Membr. Sci. 342 (2009) 153–164. 3: H. Susanto, M. Ulbricht, Characteristics, performance and stability of polyethersulfone ultrafiltration membranes prepared by phase separation method using different macromolecular additives.J. Membr. Sci. 327 (2009) 125–135. Result discussion Decrease in the membrane hydraulic permeability with increasing the RH exposure degree; attributed to the significant reduction in pore size. (Fig. 5a). Inverse proportionality between pore size and RH. The higher saturation of atmosphere with vapor reduces time available for pore growth with rapid pre-precipitation. (Fig. 5b). Driven from H 1 NMR, Plu® entrapment was higher at 80% RH exposure; as rapid pre-precipitation lowered the leakage in coagulation bath. However, no significant effect is shown for Plu® content; thus, further increase of PES content was coupled with sacrificing Plu®. (Fig. 6, 7) Successful further reduction in pore size with maintaining cross sectional morphology was achieved by the increase in PES content. (Fig. 8a, b). PES with variant concentrations (10- 15wt%) NMP (30wt%) +TEG (55wt%) +Plu® (up to 5wt%) Clear Casting solution after Stirring Film casting (with vapor induced phase separation 3 ) Humidity (30-80% RH) Humidity exposure (1-5 min.) Membrane characterization Cross sectional morphology (SEM) Pore size distribution (Capillary flow porometer) Chemical composition (H 1 NMR) Hydraulic permeability (Dead-end stirred Amicon cell) a) b) c) Fig.1: SEM images for P 10% /N 30% /T 55% /Pl 5% . At 1min. exposure to 30% RH, (a) Cross-sectional, (b) top surface and (c) bottom surface. Fig.2: SEM images for P 10% /N 30% /T 55% /Pl 5% . At 1min. exposure to 80% RH, (a) Cross-sectional, (b) top surface and (c) bottom surface. Fig.3: SEM images for P 13% /N 30% /T 55% /Pl 2% . At 1min. exposure to 80% RH, (a) Cross-sectional, (b) top surface and (c) bottom surface. Fig.4: SEM images for P 15% /N 30% /T 55% . At 1min. exposure to 80% RH, (a) Cross-sectional, (b) top surface and (c) bottom surface. a) b) c) a) b) c) a) b) c) Method 0 5000 10000 15000 20000 25000 30000 35000 40000 30% 1min 30% 5min 80% 1min 80% 5min P10%/N90% P10%/N30% /T60% P10%/N30% /T55%/Pl5% Hydraulic permeability (L/m2/hr/bar) Hydraulic permeability RH% Exp. time 0 0,1 0,2 0,3 0,4 0,5 0,6 30% 1min 30% 5min 80% 1min 80% 5min P10%/N90% P10%/N30%/ T60% P10%/N30%/ T55%/Pl5% Max. pore size distribution (micron) RH% Exp. time Fig. 5: (a) Hydraulic permeability and (b) Max. pore size distribution. (a) (b) Plu/PES% (H1NMR) 0 5 10 15 20 25 30 35 1min 5min 30% 80% Fig. 7: Relative content of Plu for P 10% /N 30% /T 55% /Pl 5% RH (30% ,80% )for (1,5) min. 0 5000 10000 15000 20000 25000 30000 35000 40000 9 10 11 12 13 14 15 16 17 RH 30% RH 80% Hydraulic permeability (L/m2/hr/bar) PES content wt% Hydraulic permeability 0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4 0,45 0,5 9 10 11 12 13 14 15 16 17 Pore size (μm) PES content wt% RH 30% RH 80% PES content vs. Pore size Fig. 8: (a) Hydraulic permeability and (b) Max. pore size distribution. (a) (b) Proton peaks for aromatic PES Proton peaks for Plu methyl group Fig. 6: H1NMR chart for P 10% /N 30% /T 55% /Pl 5% 80% 1 min. Showing the integration of respective proton peaks. Conclusion
Transcript of Introduction - uni-due.de...Funded by: Synthesis and Characterization of Efficient Polyamide Thin...
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www.uni-due.de/zwu/iwatec
Synthesis and Characterization of Efficient Polyamide Thin Film Nanocomposite Membranes
M. M. Elleithy1
Ahmed S. G. Khalil2,3,4; A. Essawi1, R. Ghannam4, A. Ramadan1; M. Ulbricht2
1: American University in Cairo, Egypt 2: Technical Chemistry II, University of Duisburg-Essen, Germany 3: Fayoum University, Egypt 4: Egypt Nanotechnology Center, Egypt
Introduction Thin film composite (TFC) membranes hold superior advantages of higher solute rejection and water fluxes. These superior properties were established via preparation of the membrane into two separate procedures each of which results in a separate layer holding its key feature. Firstly, high flux support layer is fabricated, followed by application of polyamide (PA) thin film which contributes crucially to the membrane solute rejection. For the stability of the PA layer, surface for PA application should preferentially have small sized pores1. Consequently, this work was dedicated for fabrication of isotropic support with suited surface pore size and low resistance (high water flux) through combining VIPS and NIPS Processes.
Accordingly, a former work conducted by Ulbricht et. al.2 was adopted, where a sponge-like membrane structure was prepared and showed hydraulic permeability exceeding its comparative commercials by then.
• PES casting solutions were prepared with different compositions entailing the effect of PES content along with: 1. (NMP) organic solvent N-methyl-2-pyrrolidone. 2. (Plu®) triblock copolymer Pluronic® 6400 as a hydrophilic additive. 3. (TEG) non-solvent Triethylene glycol. •Fabrication parameters were studied and characterization was done to confirm and elucidate the variations. •General composition coding for casting solutions:
PESwt%/NMPwt%/TEGwt%/Pluwt% = Pwt%/Nwt%/Twt%/ Plwt%
• Support layer with relatively small sized pores at the bottom surface along with sufficient hydraulic permeability was successfully fabricated and will be a good candidate for thin film composite membrane with molded surface. • Prospective work is to apply and test the stability of PA layer and overall final membrane performance.
Contact: Mohamed Elleithy, American University in Cairo, New Cairo Campus, [email protected]
References
1: P.S. Singh, S.V. Joshi, J.J. Trivedi, C.V. Devmurari, A. Prakash Rao, P.K. Ghosh, Probing the structural variations of thin film composite RO membranes obtained by coating polyamide over polysulfone membranes of different pore dimensions, J. Membr. Sci. 278 (2006) 19–25. 2: H. Susanto, M. Ulbricht, High performance polyethersulfone microfiltration membranes having high flux and stable hydrophilic property. J. Membr. Sci. 342 (2009) 153–164. 3: H. Susanto, M. Ulbricht, Characteristics, performance and stability of polyethersulfone ultrafiltration membranes prepared by phase separation method using different macromolecular additives.J. Membr. Sci. 327 (2009) 125–135.
Result discussion Decrease in the membrane hydraulic permeability with increasing the RH exposure degree; attributed to the significant reduction in pore size. (Fig. 5a). Inverse proportionality between pore size and RH. The higher saturation of atmosphere with vapor reduces time available for pore growth with rapid pre-precipitation. (Fig. 5b). Driven from H1NMR, Plu® entrapment was higher at 80% RH exposure; as rapid pre-precipitation lowered the leakage in coagulation bath. However, no significant effect is shown for Plu® content; thus, further increase of PES content was coupled with sacrificing Plu®. (Fig. 6, 7) Successful further reduction in pore size with maintaining cross sectional morphology was achieved by the increase in PES content. (Fig. 8a, b).
PES with variant concentrations (10-
15wt%)
NMP (30wt%) +TEG (55wt%) +Plu® (up to
5wt%)
Clear Casting solution after
Stirring
Film casting (with vapor
induced phase separation 3)
Humidity (30-80% RH)
Humidity exposure (1-5 min.)
Membrane characterization
Cross sectional morphology (SEM)
Pore size distribution (Capillary flow porometer)
Chemical composition (H1NMR)
Hydraulic permeability (Dead-end stirred Amicon
cell)
a) b) c) Fig.1: SEM images for
P10%/N30%/T55%/Pl5%. At
1min. exposure to 30% RH, (a) Cross-sectional, (b) top surface and (c) bottom surface.
Fig.2: SEM images for
P10%/N30%/T55%/Pl5%. At 1min.
exposure to 80% RH, (a) Cross-sectional, (b) top surface and (c) bottom surface.
Fig.3: SEM images for
P13%/N30%/T55%/Pl2%. At
1min. exposure to 80% RH, (a) Cross-sectional, (b) top surface and (c) bottom surface.
Fig.4: SEM images for
P15%/N30%/T55%. At 1min.
exposure to 80% RH, (a) Cross-sectional, (b) top surface and (c) bottom surface.
a) b) c)
a) b) c)
a) b) c)
Method
0
5000
10000
15000
20000
25000
30000
35000
40000
30%1min
30%5min
80%1min
80%5min
P10%/N90%
P10%/N30%/T60%
P10%/N30%/T55%/Pl5%H
ydra
ulic
per
mea
bili
ty
(L/
m2
/hr/
bar
)
Hydraulic permeability
RH% Exp. time
Pore size distributions
0
0,1
0,2
0,3
0,4
0,5
0,6
30%1min
30%5min
80%1min
80%5min
P10%/N90%
P10%/N30%/T60%
P10%/N30%/T55%/Pl5%
Max
. po
re s
ize
dis
trib
uti
on
(
mic
ron
)
RH% Exp. time
Fig. 5: (a) Hydraulic permeability and (b) Max. pore size distribution.
(a) (b)
Plu
/PES
%
(H1
NM
R)
0
5
10
15
20
25
30
35
1min 5min
30%
80%
Fig. 7: Relative content of Plu for P10%/N30%/T55%/Pl5% RH (30% ,80% )for (1,5) min.
0
5000
10000
15000
20000
25000
30000
35000
40000
9 10 11 12 13 14 15 16 17
RH 30%
RH 80%
Hyd
rau
lic p
erm
eab
ility
(
L/m
2/h
r/b
ar)
PES content wt%
Hydraulic permeability
0
0,05
0,1
0,15
0,2
0,25
0,3
0,35
0,4
0,45
0,5
9 10 11 12 13 14 15 16 17
Pore
siz
e (µ
m)
PES content wt%
RH 30%
RH 80%
PES content vs. Pore size
Fig. 8: (a) Hydraulic permeability and (b) Max. pore size distribution.
(a) (b)
Proton peaks for aromatic PES Proton peaks for
Plu methyl group
Fig. 6: H1NMR chart for P10%/N30%/T55%/Pl5% 80% 1 min. Showing the integration of respective proton peaks.
Conclusion
