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Preparation and characterization of thin-film composite membrane with nanowire-modified support for forward osmosis process.

Low ZX, Liu Q, Shamsaei E, Zhang X, Wang H - Membranes (Basel) (2015)

Bottom Line: In FO mode, the ratio of water flux to reverse solute flux was also improved.The result shows that Zn2GO4 nanowire may be used as a modifier to the substrate to improve the quality of the polyamide layer on the substrate to improve the flux and selectivity, but not as effective in reducing ICP.This work demonstrates that the incorporation of nanomaterials to the membrane substrate may be an alternative approach to improve the formation of polyamide skin layer to achieve better FO performance.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemical Engineering, Monash University, Clayton VIC 3800, Australia.

ABSTRACT
Internal concentration polarization (ICP) in forward osmosis (FO) process is a characteristic problem for asymmetric thin-film composite (TFC) FO membrane which leads to lower water flux. To mitigate the ICP effect, modification of the substrates' properties has been one of the most effective methods. A new polyethersulfone-based ultrafiltration membrane with increased surface porosity and high water flux was recently produced by incorporating Zn2GeO4 nanowires. The composite membrane was used as a substrate for the fabrication of TFC FO membrane, by coating a thin layer of polyamide on top of the substrate. The substrate and the nanowires were characterized by a range of techniques such as SEM, XRD, and contact angle goniometry. The water permeability and molecular weight cut-offs (MWCO) of the substrate; and the FO performance of the TFC membrane were also determined. The Zn2GeO4-modified membrane showed ~45% increase in water permeability and NaCl salt rejection of 80% under RO mode. In FO mode, the ratio of water flux to reverse solute flux was also improved. However, lower FO flux was obtained which could be due to ICP. The result shows that Zn2GO4 nanowire may be used as a modifier to the substrate to improve the quality of the polyamide layer on the substrate to improve the flux and selectivity, but not as effective in reducing ICP. This work demonstrates that the incorporation of nanomaterials to the membrane substrate may be an alternative approach to improve the formation of polyamide skin layer to achieve better FO performance.

No MeSH data available.


Schematic diagram of bench-scale FO test system.
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membranes-05-00136-f009: Schematic diagram of bench-scale FO test system.

Mentions: Evaluation of FO membrane performance. The permeability and salt rejection of the FO membrane was determined by testing the membrane in RO mode using the same dead-end cell. The water permeability was obtained by applying transmembrane pressure of 15.51 bar. The salt rejection (R) was determined using 2000 ppm NaCl solution as the feed based on the conductivity measurements of the permeate and feed. The FO performance (water flux and reverse solute flux) of a membrane was evaluated using a bench-scale crossflow permeation FO cell, as shown in Figure 9. The active membrane area in the FO cell (modified Sterlitech CF042 crossflow cell, Kent, USA) is 12.25 cm2. Both the FS and DS were circulated at a fixed crossflow rate of 500 mL·min–1 on both sides of the membrane. NaCl solution was used as the draw solution, while DDI water was used as the feed. The FO water permeation flux (Jw; LMH) was determined by measuring the weight changes of the FS with a digital balance (A&D FZ-5000i, Tokyo, Japan) connected to a computer using the following equation:(3)Jw=ΔmρAΔtwhere Δm (g) is the mass of water permeated across the membrane in a predetermined time Δt (h) during the FO process. ρ is the density of water and A is the effective membrane surface area (m2). The reverse solute flux (Js; g·m–2·h–1) was determined from the conductivity measurement of the FS (WTW Cond 730 with conductivity probe LR 325/01, Weilheim Germany) using the following equation:(4)Js= Δ(CtVt)AΔtwhere Ct (g·L–1) and Vt (L) are the salt concentration and the volume of the feed, respectively. Effects of FS and DS on FO membrane performance were conducted by using different DS concentration (0.5 M, 1.0 M, and 2.0 M) for active-layer-facing-FS (AL-FS) orientations.


Preparation and characterization of thin-film composite membrane with nanowire-modified support for forward osmosis process.

Low ZX, Liu Q, Shamsaei E, Zhang X, Wang H - Membranes (Basel) (2015)

Schematic diagram of bench-scale FO test system.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4384095&req=5

membranes-05-00136-f009: Schematic diagram of bench-scale FO test system.
Mentions: Evaluation of FO membrane performance. The permeability and salt rejection of the FO membrane was determined by testing the membrane in RO mode using the same dead-end cell. The water permeability was obtained by applying transmembrane pressure of 15.51 bar. The salt rejection (R) was determined using 2000 ppm NaCl solution as the feed based on the conductivity measurements of the permeate and feed. The FO performance (water flux and reverse solute flux) of a membrane was evaluated using a bench-scale crossflow permeation FO cell, as shown in Figure 9. The active membrane area in the FO cell (modified Sterlitech CF042 crossflow cell, Kent, USA) is 12.25 cm2. Both the FS and DS were circulated at a fixed crossflow rate of 500 mL·min–1 on both sides of the membrane. NaCl solution was used as the draw solution, while DDI water was used as the feed. The FO water permeation flux (Jw; LMH) was determined by measuring the weight changes of the FS with a digital balance (A&D FZ-5000i, Tokyo, Japan) connected to a computer using the following equation:(3)Jw=ΔmρAΔtwhere Δm (g) is the mass of water permeated across the membrane in a predetermined time Δt (h) during the FO process. ρ is the density of water and A is the effective membrane surface area (m2). The reverse solute flux (Js; g·m–2·h–1) was determined from the conductivity measurement of the FS (WTW Cond 730 with conductivity probe LR 325/01, Weilheim Germany) using the following equation:(4)Js= Δ(CtVt)AΔtwhere Ct (g·L–1) and Vt (L) are the salt concentration and the volume of the feed, respectively. Effects of FS and DS on FO membrane performance were conducted by using different DS concentration (0.5 M, 1.0 M, and 2.0 M) for active-layer-facing-FS (AL-FS) orientations.

Bottom Line: In FO mode, the ratio of water flux to reverse solute flux was also improved.The result shows that Zn2GO4 nanowire may be used as a modifier to the substrate to improve the quality of the polyamide layer on the substrate to improve the flux and selectivity, but not as effective in reducing ICP.This work demonstrates that the incorporation of nanomaterials to the membrane substrate may be an alternative approach to improve the formation of polyamide skin layer to achieve better FO performance.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemical Engineering, Monash University, Clayton VIC 3800, Australia.

ABSTRACT
Internal concentration polarization (ICP) in forward osmosis (FO) process is a characteristic problem for asymmetric thin-film composite (TFC) FO membrane which leads to lower water flux. To mitigate the ICP effect, modification of the substrates' properties has been one of the most effective methods. A new polyethersulfone-based ultrafiltration membrane with increased surface porosity and high water flux was recently produced by incorporating Zn2GeO4 nanowires. The composite membrane was used as a substrate for the fabrication of TFC FO membrane, by coating a thin layer of polyamide on top of the substrate. The substrate and the nanowires were characterized by a range of techniques such as SEM, XRD, and contact angle goniometry. The water permeability and molecular weight cut-offs (MWCO) of the substrate; and the FO performance of the TFC membrane were also determined. The Zn2GeO4-modified membrane showed ~45% increase in water permeability and NaCl salt rejection of 80% under RO mode. In FO mode, the ratio of water flux to reverse solute flux was also improved. However, lower FO flux was obtained which could be due to ICP. The result shows that Zn2GO4 nanowire may be used as a modifier to the substrate to improve the quality of the polyamide layer on the substrate to improve the flux and selectivity, but not as effective in reducing ICP. This work demonstrates that the incorporation of nanomaterials to the membrane substrate may be an alternative approach to improve the formation of polyamide skin layer to achieve better FO performance.

No MeSH data available.