WO2015012766A1 - Thin film composite membranes for pervaporation - Google Patents

Thin film composite membranes for pervaporation Download PDF

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Publication number
WO2015012766A1
WO2015012766A1 PCT/SG2014/000349 SG2014000349W WO2015012766A1 WO 2015012766 A1 WO2015012766 A1 WO 2015012766A1 SG 2014000349 W SG2014000349 W SG 2014000349W WO 2015012766 A1 WO2015012766 A1 WO 2015012766A1
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polymeric
layer
thin film
gutter
ceramic support
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PCT/SG2014/000349
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French (fr)
Inventor
Gui Min SHI
Tai-Shung Chung
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National University Of Singapore
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D69/00Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12Composite membranes; Ultra-thin membranes
    • B01D69/1214Chemically bonded layers, e.g. cross-linking
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D69/00Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12Composite membranes; Ultra-thin membranes
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D67/00Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002Organic membrane manufacture
    • B01D67/0006Organic membrane manufacture by chemical reactions
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D67/00Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0079Manufacture of membranes comprising organic and inorganic components
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D67/00Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0079Manufacture of membranes comprising organic and inorganic components
    • B01D67/00791Different components in separate layers
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D69/00Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/10Supported membranes; Membrane supports
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D69/00Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/10Supported membranes; Membrane supports
    • B01D69/108Inorganic support material
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D69/00Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12Composite membranes; Ultra-thin membranes
    • B01D69/125In situ manufacturing by polymerisation, polycondensation, cross-linking or chemical reaction
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D69/00Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12Composite membranes; Ultra-thin membranes
    • B01D69/125In situ manufacturing by polymerisation, polycondensation, cross-linking or chemical reaction
    • B01D69/1251In situ manufacturing by polymerisation, polycondensation, cross-linking or chemical reaction by interfacial polymerisation
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D71/00Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/02Inorganic material
    • B01D71/024Oxides
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D71/00Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/02Inorganic material
    • B01D71/024Oxides
    • B01D71/025Aluminium oxide
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D71/00Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06Organic material
    • B01D71/56Polyamides, e.g. polyester-amides
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D71/00Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06Organic material
    • B01D71/58Other polymers having nitrogen in the main chain, with or without oxygen or carbon only
    • B01D71/60Polyamines
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D71/00Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06Organic material
    • B01D71/58Other polymers having nitrogen in the main chain, with or without oxygen or carbon only
    • B01D71/60Polyamines
    • B01D71/601Polyethylenimine
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D71/00Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06Organic material
    • B01D71/70Polymers having silicon in the main chain, with or without sulfur, nitrogen, oxygen or carbon only
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D71/00Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06Organic material
    • B01D71/70Polymers having silicon in the main chain, with or without sulfur, nitrogen, oxygen or carbon only
    • B01D71/701Polydimethylsiloxane
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D71/00Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06Organic material
    • B01D71/76Macromolecular material not specifically provided for in a single one of groups B01D71/08 - B01D71/74
    • B01D71/82Macromolecular material not specifically provided for in a single one of groups B01D71/08 - B01D71/74 characterised by the presence of specified groups, e.g. introduced by chemical after-treatment
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2323/00Details relating to membrane preparation
    • B01D2323/40Details relating to membrane preparation in-situ membrane formation
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D61/00Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/36Pervaporation; Membrane distillation; Liquid permeation
    • B01D61/362Pervaporation

Definitions

  • Pervaporation is a process for separating a mixture of liquids by vaporization through a non-porous membrane.
  • an asymmetric membrane e.g., a thin film composite (TFC) membrane
  • TFC thin film composite
  • Dehydration of industrial solvents (e.g., ethanol and isopropanol) by pervaporation is more economical than conventional distillation.
  • a TFC membrane formed of a thin film layer and a porous support is typically exposed to a high temperature and various chemicals. Swelling of the porous support resulting from the exposure damages the thin film layer and undermines its pervaporation performance. Thus, it is critical that a porous support be rigid, thermal stable, and chemical resistant.
  • Ceramic materials are well suited for making porous supports for their excellent properties, e.g., strong mechanical strength, thermal stability, and high chemical resistance. Yet, a TFC membrane made of a ceramic support has a thick thin film layer, resulting in poor pervaporation performance.
  • This invention provides a TFC membrane including a ceramic support that swells minimally.
  • the membrane has an unexpectedly high separation performance. In other words, it possesses an unexpectedly high flux rate and separation factor, even at an elevated temperature. As such, it is suitable for use in a pervaporation process.
  • a TFC membrane that includes a ceramic support, a polymeric gutter layer bonding covalently or non-covalently onto the ceramic support, and a thin film layer bonding covalently onto the polymeric gutter layer.
  • the ceramic support has a thickness of 1 to 10000 ⁇ (preferably, 50- 1000 ⁇ , and, more preferably, 100-300 ⁇ ) and a pore size of 1 to 200 nm
  • the ceramic support include, but are not limited to, a-alumina, titania, zirconia, and a
  • a polyelectrolyte having an amine functional group e.g., PDA
  • PEI polyethyleneimine
  • Examples of a polyelectrolyte can be found in Krasemann et al., Self-assembled polyelectrolyte multilayer membranes with highly improved pervaporation separation of ethanol/ water mixtures, J. Membr. Sci. 181 (2001) 221— 228.
  • the thin film layer having a thickness of 10 to 1000 nm (preferably, 20-500 nm, and, more preferably, 50-100 nm), can be made of a polyamide covalently bonding to the polymeric gutter layer via an ester bond or an amide bond.
  • the TFC membrane includes a ceramic support made of a-alumina, a polymeric gutter layer made of PEI, and a thin film layer made of poly(m-pheylenediamine trimesoyl amide) covalently bonding to the polymeric gutter layer via an amide bond.
  • the ceramic support is a tube that has an outer diameter of 0.1 to 100 mm and an inner diameter of 0.05 to 95 mm, the polymeric gutter layer bonding onto the inner surface of the tube.
  • the TFC membrane of this invention further includes a sealing layer that bonds to the thin film layer.
  • the sealing layer which can be made of polydimethylsiloxane (PDMS), has a thickness of 1 to 250 nm (preferably, 5-100 nm, and, more preferably, 10-40 nm).
  • Another aspect of this invention relates to a method of preparing the above- described TFC membrane.
  • the method includes the following steps: (i) providing a ceramic support having a thickness of 1 to 10000 ⁇ and a pore size of 1 to 200 nm, (ii) coating a polymer on a surface of the ceramic support to form a polymeric gutter layer having a thickness of 1 to 10000 nm, and (iii) forming by interfacial polymerization a thin film layer having a thickness of 10 to 1000 nm and bonding covalently onto the polymeric gutter layer.
  • the TFC membrane thus formed has a ceramic support, a polymeric gutter layer, and a thin film layer.
  • the ceramic support can be made of a-alumina, titania, zirconia, or a combination thereof;
  • the polymeric gutter layer can be made of PDA or a polyelectrolyte having an amine functional group; and the thin film layer can be made of a polyamide.
  • Poly(m-pheylenediamine trimesoyl amide, an example of a polyamide, is typically formed via interfacial polymerization between
  • phenylenediamine MPD
  • trimesoyl chloride TMC
  • the above-described method can include a step of coating a sealing layer onto the thin film layer.
  • a sealing layer onto the thin film layer. Examples of the polymer used for the sealing layer are enumerated above.
  • the TFC membrane of this invention includes a ceramic support, which swells minimally and maintains the stability of the membrane in a pervaporation process. It has a flux rate of 6.0 kgm “ h " and a separation factor of greater than 1000 at 80 °C for pervaporation dehydration of isopropyl alcohol (IP A).
  • the flux rate J is determined by the following equation:
  • subscripts and j refer to water (i.e., component i) and IPA (i.e.,
  • y w and x w are the weight fractions of a component in the permeate and feed, respectively. They are analyzed using a Hewlett-Packard GC 7890 with a HP-INNOWAX column and a TCD detector.
  • the permeance Pj/1 is determined in the same manner.
  • the membrane selectivity c3 ⁇ 4 is defined by the equation below:
  • a ceramic tube made of a-alumina is prepared to serve as a ceramic support.
  • the outside of the tube is wrapped with tape.
  • the inner surface of the tube is coated with either PDA or a
  • the polyelectrolyte coating is performed by dipping a ceramic tube in a polyelectrolyte coating solution for 1 min, followed by blowing air into the ceramic tube to remove excess polyelectrolyte coating solution. The dip-coating process is repeated once to ensure the formation of a polyelectrolyte layer on the inner surface of the ceramic tube. Afterwards, the tube having a polymeric gutter layer bonded onto its inner surface is dried in a vacuum oven at 100 °C for 10 min.
  • a polyamide thin film layer is coated onto the polymeric gutter layer via the interfacial polymerization reaction between MPD and TMC.
  • the PDA- or polyelectrolyte-coated ceramic tube is first immersed in an MPD solution for 10 min, followed by blowing air into the tube to remove excess MPD solution.
  • the tube is then immersed in a TMC solution for 2 min, followed by heating at 65 °C for 10 min to facilitate interfacial polymerization between MPD and TMC to form a polyamide thin film layer.
  • the TFC membrane thus prepared has a ceramic support, a polymeric gutter layer bonding covalently or non-covalently onto the ceramic support, and a thin film layer bonding covalently onto the polymeric gutter layer.
  • the TFC membrane can be immersed in a PDMS solution for 3 min to form a sealing layer bonded to the thin film layer.
  • Ceramic tubes purchased from Inocep® a-alumina tube M20 (outside diameter 3.7 mm, inside diameter 2.7 ⁇ 0.1mm, and average pore size 20 nm, supplied by Hyflux SIP Pte Ltd.) were cut into shorter tubes each having a length of about 15 cm. These shorter tubes, each used as a ceramic support, were ultrasonically washed in deionized (DI) water for 20 min before coating either PDA or PEI on their inner surfaces to form a polymeric gutter layer.
  • DI deionized
  • each of the ceramic tubes was wrapped with Teflon tape to ensure that only the inner surface of the tubes was coated.
  • the PEI coating was performed by dipping a ceramic tube for 1 min in a PEI coating solution (10 g/L), which was prepared by dissolving hyperbranched PEI (Sigma-Aldrich molecular weight 60,000 g/mol) in DI water, followed by blowing air into the tube to remove excess PEI solution. The dip-coating process was repeated once to ensure the formation of a PEI film on the inner surface of the ceramic tube.
  • the ceramic tubes each having a polymeric gutter layer bonded onto its inner surface, were dried in a vacuum oven at 100 °C for 10 min.
  • a polyamide thin film layer was then coated onto the polymeric gutter layer via the interfacial polymerization reaction between MPD and TMC.
  • the PDA- or PEI-coated ceramic tube was immersed in an MPD (Sigma-Aldrich) 2 wt% solution for 10 min, followed by blowing air into the tube to remove the excess MPD solution.
  • the tube was immersed in a TMC (Sigma-Aldrich) 0.1 wt% solution for 2 min and then subjected to heat treatment at 65 °C for 10 min, thereby forming a polyamide thin film layer covalently bonding to the polymeric gutter layer via an amide bond.
  • TFC membranes having the PDA coating thus prepared were designated as "PDA-IP” and those having the PEI coating were designated as “PEI-IP.”
  • PDA-IP and PEI-IP membranes were immersed in a PDMS (Sylgad® 184) n-hexane solution for 3 min to form a sealing layer bonded to the thin film layer and they were stored for at least 24 h for the sealing layers to cure.
  • the PDA-IP and PEI-IP membranes coated with PDMS were designated as "PDA- IP-PDMS” and "PEI-IP-PDMS,” respectively.
  • EXAMPLE 2 Characterization of TFC membranes having a ceramic support
  • the membrane morphology of the TFC membranes i.e., PDA-IP-PDMS and PEI-IP-PDMS membranes prepared in Example 1 , was observed by using a JSM- 6700F field emission scanning electron microscope (FESEM).
  • FESEM images show that the TFC membranes had a ridge-and-valley structure, which is a typical morphology for those prepared by interfacial polymerization. Also, the images show a continuous polyamide thin film layer with a thickness of about 100 nm, but not a polymeric gutter layer made of PDA or PEI.
  • XPS X-ray photoelectron spectrometer
  • Ceramic-IP a TFC membrane which only included a ceramic support and a thin film layer, was used as a control in the study.
  • IP A/water 85/15 wt % was used, which was maintained at 20 1/h for each membrane.
  • the permeate pressure was maintained at ⁇ 2 mbar by a vacuum pump. Retentate and permeate samples were collected after the membranes were kept under these conditions for at least 2 h.
  • the flux rate and separation factor were determined for each membrane following the equations described above. Table 1 below lists the results.
  • PEI-IP had a higher separation factor than that of PDA-PI (220 vs. 110), which is consistent with the observations with the AFM images that the polymeric gutter layer made of PEI yielded a much smoother surface than that made of PDA
  • Table 1 also show significant improvement in pervaporation performance for TFC membranes having a PDMS sealing layer.
  • PEI-IP-PDMS exhibited a much higher separation factor (2800 vs. 220) and only a less than 20% drop in the flux rate (2.19 vs. 2.7), implicating that the PDMS sealing layer effectively sealed defects of a TFC membrane.
  • the PDA-IP -PDMS did not exhibit much improvement over PDA-IP possibly due to too many surface defects (observed with the AEM images) that could not be effectively sealed by PDMS.
  • PEI-IP 40 1.31 3350 10,561 2.87 3678

Abstract

Disclosed is a thin film composite membrane that includes a ceramic support having a thickness of 1 to 10000 µm and a pore size of 1 to 200 nm, a polymeric gutter layer having a thickness of 1 to 10000 nm and bonded covalently or non-covalently onto the ceramic support, and a thin film layer having a thickness of 10 to 1000 nm and bonded covalently onto the polymeric gutter layer. Also disclosed are methods of preparing the above-described thin film composite membrane.

Description

THIN FILM COMPOSITE
MEMBRANES FOR PERVAPORATION
BACKGROUND OF THE INVENTION
Pervaporation (or pervaporative separation) is a process for separating a mixture of liquids by vaporization through a non-porous membrane. Typically, an asymmetric membrane, e.g., a thin film composite (TFC) membrane, is employed for pervaporation dehydration applications. Dehydration of industrial solvents (e.g., ethanol and isopropanol) by pervaporation is more economical than conventional distillation.
During pervaporation, a TFC membrane formed of a thin film layer and a porous support is typically exposed to a high temperature and various chemicals. Swelling of the porous support resulting from the exposure damages the thin film layer and undermines its pervaporation performance. Thus, it is critical that a porous support be rigid, thermal stable, and chemical resistant.
Ceramic materials are well suited for making porous supports for their excellent properties, e.g., strong mechanical strength, thermal stability, and high chemical resistance. Yet, a TFC membrane made of a ceramic support has a thick thin film layer, resulting in poor pervaporation performance.
There is a need to develop a high-performance TFC membrane having a ceramic support for use in pervaporation of industrial solvents.
SUMMARY OF THE INVENTION
This invention provides a TFC membrane including a ceramic support that swells minimally. The membrane has an unexpectedly high separation performance. In other words, it possesses an unexpectedly high flux rate and separation factor, even at an elevated temperature. As such, it is suitable for use in a pervaporation process.
One aspect of this invention relates to a TFC membrane that includes a ceramic support, a polymeric gutter layer bonding covalently or non-covalently onto the ceramic support, and a thin film layer bonding covalently onto the polymeric gutter layer. The ceramic support has a thickness of 1 to 10000 μηι (preferably, 50- 1000 μηι, and, more preferably, 100-300 μιη) and a pore size of 1 to 200 nm
(preferably, 5-100 nm, and, more preferably, 10-40 nm). Examples of the ceramic support include, but are not limited to, a-alumina, titania, zirconia, and a
combination thereof.
The polymeric gutter layer has a thickness of 1 to 10000 nm (preferably, 20- 1000 nm, and, more preferably, 50-500 nm) and can be made of polydopamine (PDA) or a polyelectrolyte having an amine functional group, e.g.,
polyethyleneimine (PEI). Examples of a polyelectrolyte can be found in Krasemann et al., Self-assembled polyelectrolyte multilayer membranes with highly improved pervaporation separation of ethanol/ water mixtures, J. Membr. Sci. 181 (2001) 221— 228.
The thin film layer, having a thickness of 10 to 1000 nm (preferably, 20-500 nm, and, more preferably, 50-100 nm), can be made of a polyamide covalently bonding to the polymeric gutter layer via an ester bond or an amide bond.
In one embodiment, the TFC membrane includes a ceramic support made of a-alumina, a polymeric gutter layer made of PEI, and a thin film layer made of poly(m-pheylenediamine trimesoyl amide) covalently bonding to the polymeric gutter layer via an amide bond.
In another embodiment of the TFC membrane, the ceramic support is a tube that has an outer diameter of 0.1 to 100 mm and an inner diameter of 0.05 to 95 mm, the polymeric gutter layer bonding onto the inner surface of the tube.
Optionally, the TFC membrane of this invention further includes a sealing layer that bonds to the thin film layer. The sealing layer, which can be made of polydimethylsiloxane (PDMS), has a thickness of 1 to 250 nm (preferably, 5-100 nm, and, more preferably, 10-40 nm).
Another aspect of this invention relates to a method of preparing the above- described TFC membrane. The method includes the following steps: (i) providing a ceramic support having a thickness of 1 to 10000 μιη and a pore size of 1 to 200 nm, (ii) coating a polymer on a surface of the ceramic support to form a polymeric gutter layer having a thickness of 1 to 10000 nm, and (iii) forming by interfacial polymerization a thin film layer having a thickness of 10 to 1000 nm and bonding covalently onto the polymeric gutter layer. The TFC membrane thus formed has a ceramic support, a polymeric gutter layer, and a thin film layer.
As disclosed above, the ceramic support can be made of a-alumina, titania, zirconia, or a combination thereof; the polymeric gutter layer can be made of PDA or a polyelectrolyte having an amine functional group; and the thin film layer can be made of a polyamide. Poly(m-pheylenediamine trimesoyl amide, an example of a polyamide, is typically formed via interfacial polymerization between
phenylenediamine (MPD) and trimesoyl chloride (TMC).
The above-described method can include a step of coating a sealing layer onto the thin film layer. Examples of the polymer used for the sealing layer are enumerated above.
The details of the invention are set forth in the description below. Other features, objects, and advantages of the invention will be apparent from the description and from the claims.
DETAILED DESCRIPTION
The TFC membrane of this invention includes a ceramic support, which swells minimally and maintains the stability of the membrane in a pervaporation process. It has a flux rate of 6.0 kgm" h" and a separation factor of greater than 1000 at 80 °C for pervaporation dehydration of isopropyl alcohol (IP A).
Both the flux rate and the separation factor of a TFC membrane can be measured in a laboratory scale pervaporation study described in Shi et ah, Dual-layer PBI/P84 hollow fibers for pervaporation dehydration of acetone, AIChE J., 58 (2012) 1133-1145.
The flux rate J is determined by the following equation:
AT
wherein Q is the total mass transferred over time t and A is the membrane area. The mass of permeate is weighed by using a Mettler Toledo balance. The separation factor β is defined as follows:
wherein subscripts and j refer to water (i.e., component i) and IPA (i.e.,
component j), respectively; yw and xw are the weight fractions of a component in the permeate and feed, respectively. They are analyzed using a Hewlett-Packard GC 7890 with a HP-INNOWAX column and a TCD detector.
The permeance Pj/1 of a membranes, expressed in GPU (1 GPU = 1 10"6 cm3 (STP)/cm2 s cm Hg), is determined as follows:
^ J ix .Pr' -y.P") wherein , and Jt are the membrane permeability and flux rate of component /', respectively, / is the membrane thickness, and xt are the permeate mole fraction and the feed mole fraction of component i, respectively, Pp is the total pressure at the permeate side, P at is the partial vapor pressure of component i at the feed side, and yt is the activity coefficient. Both Pfat and y, are obtained from the AspenTech Process Modeling V7.2.
The permeance Pj/1 is determined in the same manner.
The membrane selectivity c¾ is defined by the equation below:
-ML
Described below is an exemplary procedure for preparing a TFC membrane of this invention.
First, a ceramic tube made of a-alumina is prepared to serve as a ceramic support. To ensure that the subsequent coating only occurs on the inner surface of each tube, the outside of the tube is wrapped with tape.
Next, the inner surface of the tube is coated with either PDA or a
polyelectrolyte having an amine functional group to form a polymeric gutter layer. After a PDA coating solution is prepared, the PDA coating is conducted under ambient conditions for 24 h.
The polyelectrolyte coating is performed by dipping a ceramic tube in a polyelectrolyte coating solution for 1 min, followed by blowing air into the ceramic tube to remove excess polyelectrolyte coating solution. The dip-coating process is repeated once to ensure the formation of a polyelectrolyte layer on the inner surface of the ceramic tube. Afterwards, the tube having a polymeric gutter layer bonded onto its inner surface is dried in a vacuum oven at 100 °C for 10 min.
Finally, a polyamide thin film layer is coated onto the polymeric gutter layer via the interfacial polymerization reaction between MPD and TMC. The PDA- or polyelectrolyte-coated ceramic tube is first immersed in an MPD solution for 10 min, followed by blowing air into the tube to remove excess MPD solution. The tube is then immersed in a TMC solution for 2 min, followed by heating at 65 °C for 10 min to facilitate interfacial polymerization between MPD and TMC to form a polyamide thin film layer.
The TFC membrane thus prepared has a ceramic support, a polymeric gutter layer bonding covalently or non-covalently onto the ceramic support, and a thin film layer bonding covalently onto the polymeric gutter layer.
Further, the TFC membrane can be immersed in a PDMS solution for 3 min to form a sealing layer bonded to the thin film layer.
The specific examples below are to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever. Without further elaboration, it is believed that one skilled in the art can, based on the description herein, utilize the present invention to its fullest extent. All publications cited herein are incorporated by reference in their entirety.
EXAMPLE 1 : Preparation of TFC membranes having a ceramic support
Ceramic tubes purchased from Inocep® a-alumina tube M20 (outside diameter 3.7 mm, inside diameter 2.7 ± 0.1mm, and average pore size 20 nm, supplied by Hyflux SIP Pte Ltd.) were cut into shorter tubes each having a length of about 15 cm. These shorter tubes, each used as a ceramic support, were ultrasonically washed in deionized (DI) water for 20 min before coating either PDA or PEI on their inner surfaces to form a polymeric gutter layer.
Prior to the coating process, each of the ceramic tubes was wrapped with Teflon tape to ensure that only the inner surface of the tubes was coated.
After a PDA coating solution (2 g/L) was prepared by dissolving dopamine hydrochloride (Sigma-Aldrich) in tris-buffer at PH = 8.5, the PDA coating was conducted under ambient conditions for 24 h.
On the other hand, the PEI coating was performed by dipping a ceramic tube for 1 min in a PEI coating solution (10 g/L), which was prepared by dissolving hyperbranched PEI (Sigma-Aldrich molecular weight 60,000 g/mol) in DI water, followed by blowing air into the tube to remove excess PEI solution. The dip-coating process was repeated once to ensure the formation of a PEI film on the inner surface of the ceramic tube.
After the PDA or PEI coating, the ceramic tubes, each having a polymeric gutter layer bonded onto its inner surface, were dried in a vacuum oven at 100 °C for 10 min.
A polyamide thin film layer was then coated onto the polymeric gutter layer via the interfacial polymerization reaction between MPD and TMC. First, the PDA- or PEI-coated ceramic tube was immersed in an MPD (Sigma-Aldrich) 2 wt% solution for 10 min, followed by blowing air into the tube to remove the excess MPD solution. Next, the tube was immersed in a TMC (Sigma-Aldrich) 0.1 wt% solution for 2 min and then subjected to heat treatment at 65 °C for 10 min, thereby forming a polyamide thin film layer covalently bonding to the polymeric gutter layer via an amide bond.
The TFC membranes having the PDA coating thus prepared were designated as "PDA-IP" and those having the PEI coating were designated as "PEI-IP." Finally, PDA-IP and PEI-IP membranes were immersed in a PDMS (Sylgad® 184) n-hexane solution for 3 min to form a sealing layer bonded to the thin film layer and they were stored for at least 24 h for the sealing layers to cure. The PDA-IP and PEI-IP membranes coated with PDMS were designated as "PDA- IP-PDMS" and "PEI-IP-PDMS," respectively. EXAMPLE 2: Characterization of TFC membranes having a ceramic support
The membrane morphology of the TFC membranes, i.e., PDA-IP-PDMS and PEI-IP-PDMS membranes prepared in Example 1 , was observed by using a JSM- 6700F field emission scanning electron microscope (FESEM). The FESEM images show that the TFC membranes had a ridge-and-valley structure, which is a typical morphology for those prepared by interfacial polymerization. Also, the images show a continuous polyamide thin film layer with a thickness of about 100 nm, but not a polymeric gutter layer made of PDA or PEI.
To evaluate the roughness and topology of the surface of the membranes, an atomic force microscope (AFM, Agilent Technology, USA) in contact mode was employed. The AFM images indicated that the polymeric gutter layers made of PEI yielded a much smoother surface than that made of PDA. Note that a smoother surface of the polymeric gutter layer leads to less defects in the polyamide thin film layer later formed. As confirmed by pervaporation performance below, PEI-IP- PDMS membranes had higher flux rates than PDA-IP-PDMS membranes.
In addition, an X-ray photoelectron spectrometer (XPS, Kratos XPS System- AXIS His- 165 Ultra) was utilized to assess the surface roughness of layers in the TFC membranes, the results of which show that the polymeric gutter layer made of PDA or PEI was not continuous owing to the rough inner surface of original ceramic tubes.
EXAMPLE 3: Pervaporation performances of TFC membranes have a ceramic support
A study was conducted to assess the pervaporation performances of TFC membranes PDA-IP, PEI-IP, PDA-IP-PDMS, and PEI-IP-PDMS prepared in Example 1. Ceramic-IP, a TFC membrane which only included a ceramic support and a thin film layer, was used as a control in the study.
A feed solution of IP A/water (85/15 wt %) was used, which was maintained at 20 1/h for each membrane. The permeate pressure was maintained at < 2 mbar by a vacuum pump. Retentate and permeate samples were collected after the membranes were kept under these conditions for at least 2 h. The flux rate and separation factor were determined for each membrane following the equations described above. Table 1 below lists the results.
Table 1. Pervaporation performances of TFC membranes (Feed: IP A/Water 85/15 Wt%
at 50°C).
Membrane Flux rate Water in Separation
(kgm' 1) permeate factor
(wt%) (water/IP A)
Ceramic-IP 3.40 76.0 27.8
PDA-IP 2.85 95.4 110
PEI-IP . 2.70 97.5 220
PDA-IP-PDMS 2.55 97.6 233
PEI-IP-PDMS 2.19 99.7 2800
The results show that, when used for dehydration of IP A at 50 °C, both PDA- IP and PEI-IP membranes exhibited unexpectedly higher separation factors than that of the Ceramic-IP membrane (110 and 220 vs. 27.8) while they had about the same flux rates (2.70 - 3.40). The gain in pervaporation performance of PDA-IP and PEI- IP over Ceramic-IP was clearly attributed to a polymeric gutter layer which was missing from Ceramic-IP. Having a polymeric gutter layer bonded onto the ceramic support, both PDA-IP and PEI-IP had a polyamide thin film layer bonding covalently on the polymeric gutter layer, thus contributing to high-performance in
pervaporation.
Note that PEI-IP had a higher separation factor than that of PDA-PI (220 vs. 110), which is consistent with the observations with the AFM images that the polymeric gutter layer made of PEI yielded a much smoother surface than that made of PDA
The results in Table 1 also show significant improvement in pervaporation performance for TFC membranes having a PDMS sealing layer. For example, compared to PEI-IP, PEI-IP-PDMS exhibited a much higher separation factor (2800 vs. 220) and only a less than 20% drop in the flux rate (2.19 vs. 2.7), implicating that the PDMS sealing layer effectively sealed defects of a TFC membrane. However, the PDA-IP -PDMS did not exhibit much improvement over PDA-IP possibly due to too many surface defects (observed with the AEM images) that could not be effectively sealed by PDMS.
EXAMPLE 4: Temperature effects on the pervaporation performances of various
TFC membranes
A study was conducted to assess the performances of PDA-IP-PDMS and PEI-IP-PDMS membranes when pervaporation was carried out at 40, 50, 60, and 80°C. The results are shown in Table 2 below.
Table 2. Temperature effects on the pervaporation performances of TFC
membranes (Feed: IPA/Water 85/15 wt%)
TFC Feed Flux Rate Separation Water Selectivity
Figure imgf000010_0001
PDA-IP 40 1.68 414 13,416 29.5 454.6
-PDMS 50 2.55 233 12,289 47.0 261.3
60 3.70 90 10,810 105.3 102.7
80 6.40 71 9755 118.1 82.62
PEI-IP 40 1.31 3350 10,561 2.87 3678
-PDMS 50 2.19 2800 10,768 3.43 3140
60 3.10 2000 9595 4.20 2282
80 6.05 1396 9917 6.10 1625 The results indicate that, with the increase in temperature, the separation factors decreased significantly while the flux rates increased also significantly for both PDA-IP-PDMS and PEI-IP-PDMS membranes. At 80 °C, the flux rate of the PEI-IP-PDMS membrane was unexpectedly high, i.e., 6.05 kgm"2h , and its separation factor remained unexpectedly high, i.e., 1396.
Note that a flux rate of 6.05 kgm"2h_1 is higher than that of eight reported TFC membranes that exhibited satisfying separation factors, i.e., 160 or higher. See Table 3 below. This superior performance of the PEI-IP-PDMS membrane in a pervaporation process can be attributed to having (i) a ceramic support that resists temperature or chemical-induced swelling, (ii) a polymeric gutter layer, (iii) a polyamide thin film layer, and (iv) a sealing layer.
The results demonstrate that the TFC membranes having a ceramic support thus prepared are most suitable for dehydration of industrial solvents in a pervaporation process.
Table 3. Literature comparison of pervaporation performances of TFC Membranes known to have a polymeric support
Membrane ■ Feed Temperature Flux rate Separation Reference compositions (°C) (kg/m2h) factor
(wt%/wt%)
IP/polyacrylonitrile Ethanol/water (90/10) 25 -1.75 -600 [1]
IP/Torlon IP A/water (85/15) 50 1.28 624 [2]
IP/polyetherimide IPA/water (85/15) 50 3.5 278 [3]
Polyvinyl alcohol Ethyl acetate /water 60 1.05 633 [4] (PVA)/alumina (95/5)
Polyimide P84 n-butanol/water 95 -1.20 -1000 [5] /y-alumina (95/5)
PVA-chitosan/alumina Ethyl acetate 50 2.22 500 [6]
/water (92/8)
PVA/y-alumina IPA/water (95/5) 80 -1.00 -160 [V] poly(acrylic Ethanol/water (95/5) 30 0.54 1168 [8] acid)/alumina
Polyelectrolyte Ethanol/water (94/6) 65 18.40 8.2 [9] /alumina
IP/a-alumina IPA/water (85/15) 80 6.05 1396 This study
References listed in Table 3:
[1] Huang et al., Interfacially polymerized thin-film composite polyamide
membranes: Effects of annealing processes on pervaporative dehydration of aqueous alcohol solutions, Sep. Purif. Technol 72 (2010) 40^47.
[2] Zuo et al., Molecular design of thin film composite (TFC) hollow fiber
membranes for isopropanol dehydration via pervaporation, J. Membr. Sci., 405-
406 (2012) 123-133.
[3] Zuo et al, Novel organic-inorganic thin film composite membranes with
separation performance surpassing ceramic membranes for isopropanol dehydration, J. Membr. Sci., 433 (2013) 60-71.
[4] Xia et al., Dehydration of ethyl acetate-water mixtures using PVA/ceramic
composite pervaporation membrane, Sep. Purif. Technol., 77 (2011) 53-59. [5] Kreiter et al., Hightemperature pervaporation performance of ceramic-supported polyimide membranes in the dehydration of alcohols, J. Membr. Sci., 319 (2008) 126-132.
[6] Zhu et al., Preparation of ceramic-supported poly(vinyl alcohol)-chitosan
composite membranes and their applications in pervaporation dehydration of organic/water mixtures, J. Membr. Sci., 349 (2010) 341-348.
[7] Petes et al., Ceramic-supported thin PVA pervaporation membranes combining high flux and high selectivity; contradicting the flux-selectivity paradigm, J.
Membr. Sci., 276 (2006) 42-50.
[8] Cao et al., A novel hydrophilic polymer-ceramic composite membrane 1 Acrylic acid grafting membrane, J.Membr. Sci., 312 (2008) 15-22.
[9] Chen et al., Organic-inorganic composite pervaporation membranes prepared by self-assembly of polyelectrolyte multilayers on macroporous ceramic supports, J.
Membr. Sci., 302 (2007).
OTHER EMBODIMENTS
All of the features disclosed in this specification may be combined in any combination. Each feature disclosed in this specification may be replaced by an alternative feature serving the same, equivalent, or similar purpose. Thus, unless expressly stated otherwise, each feature disclosed is only an example of a generic series of equivalent or similar features.
Further, from the above description, one skilled in the art can easily ascertain the essential characteristics of the present invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. Thus, other embodiments are also within the claims.

Claims

What is claimed is:
1. A thin film composite (TFC) membrane comprising
a ceramic support having a thickness of 1 to 10000 μηι and a pore size of 1 to 200 nm,
a polymeric gutter layer having a thickness of 1 to 10000 nm, and
a thin film layer having a thickness of 10 to 1000 nm,
wherein the polymeric gutter layer bonds covalently or non-covalently onto the ceramic support and the thin film layer bonds covalently onto the polymeric gutter layer.
2. The TFC membrane of claim 1, wherein the ceramic support is made of a- alumina, titania, zirconia, or a combination thereof.
3. The TFC membrane of claim 2, wherein the ceramic support is made of a- alumina.
4. The TFC membrane of claim 1, wherein the polymeric gutter layer is made of polydopamine or a polyelectrolyte having an amine functional group.
5. The TFC membrane of claim 4, wherein the polymeric gutter layer is made of polyethyleneimine .
6. The TFC membrane of claim 1 , wherein the thin film layer is made of a polyamide covalently bonding to the polymeric gutter layer via an ester bond or an amide bond.
7. The TFC membrane of claim 6, wherein the thin film layer is made of poly(m-pheylenediamine trimesoyl amide) covalently bonding to the polymeric gutter layer via an amide bond.
8'. The TFC membrane of claim 7, wherein the ceramic support is made of a- alumina, the polymeric gutter layer is made of polyethyleneimine.
9. The TFC membrane of claims 1, wherein the ceramic support is a tube that has an outer diameter of 0.1 to 100 mm, an inner diameter of 0.05 to 95 mm, and an inner surface, the polymeric gutter layer bonding onto the inner surface.
10. The TFC membrane of claim 9, wherein the ceramic support is made of a- alumina, titania, zirconia, or a combination thereof, the polymeric gutter layer is made of polydopamine or a polyelectrolyte having an amine functional group, and the thin film layer is made of a polyamide covalently bonding to the polymeric gutter layer via an ester bond or an amide bond.
11. The TFC membrane of claim 10, wherein the ceramic support is made of a- alumina, the polymeric gutter layer is made of polyethyleneimine, and the thin film layer is made of poly(m-pheylenediamine trimesoyl amide) covalently bonding to the polymeric gutter layer via an amide bond.
12. The TFC membrane of claim 1, further comprising a sealing layer that bonds to the thin film layer, the sealing layer having a thickness of 1 nm to 250 nm.
13. The TFC membrane of claim 12, wherein the ceramic support is made of a- alumina, titania, zirconia, or a combination thereof, the polymeric gutter layer is made of polydopamine or a polyelectrolyte having an amine functional group, and the thin film layer is made of a polyamide covalently bonding to the polymeric gutter layer via an ester bond or an amide bond.
14. The TFC membrane of claim 12, wherein the sealing layer is made of polydimethylsiloxane.
15. The TFC membrane of claim 14, wherein the ceramic support is made of a- alumina, the polymeric gutter layer is made of polyethyleneimine, and the thin film layer is made of poly(m-pheylenediamine trimesoyl amide) covalently bonding to the polymeric gutter layer via an amide bond.
16. A method of preparing a TFC membrane of claim 1, the method comprising: providing a ceramic support having a thickness of 1 to 10000 μηι and a pore size of 1 to 200 nm,
coating a polymer on a surface of the ceramic support to form a polymeric gutter layer having a thickness of 1 to 10000 nm, and
forming by interfacial polymerization a thin film layer bonding covalently onto the polymeric gutter layer, the thin film layer having a thickness of 10 to 1000 nm.
17. The method of claim 16, further comprising coating a sealing layer onto the thin film layer.
18. The method of claim 17, wherein the ceramic support is a tube that has an outer diameter of 0.1 to 100 mm, an inner diameter of 0.05 to 95 mm, an outer surface, and an inner surface, the polymeric gutter layer bonding onto the inner surface.
19. The method of claim 18, further comprising coating a sealing layer onto the thin film layer, wherein the ceramic support is made of a-alumina, titania, zirconia, or a combination thereof, the polymeric gutter layer is made of poly dopamine or a polyelectrolyte having an amine functional group, and the thin film layer is made of a polyamide covalently bonding to the polymeric gutter layer via an ester bond or an amide bond. '
20. The membrane of claim 19, wherein the ceramic support is made of a- alumina, the polymeric gutter layer is made of polyethyleneimine, the thin film layer is made of poly(m-pheylenediamine trimesoyl amide) covalently bonding to the polymeric gutter layer via an amide bond, and the sealing layer is made of polydimethylsiloxane.
PCT/SG2014/000349 2013-07-24 2014-07-24 Thin film composite membranes for pervaporation WO2015012766A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4705545A (en) * 1984-06-01 1987-11-10 Uop Inc. Thin film polymer blend membranes
EP0703819B1 (en) * 1993-06-15 1998-05-13 Uop Inc. Method of making composite gas separation membranes
US20100224555A1 (en) * 2007-09-21 2010-09-09 Hoek Eric M V Nanocomposite membranes and methods of making and using same
WO2013006288A1 (en) * 2011-07-01 2013-01-10 International Business Machines Corporation Thin film composite membranes embedded with molecular cage compounds

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4705545A (en) * 1984-06-01 1987-11-10 Uop Inc. Thin film polymer blend membranes
EP0703819B1 (en) * 1993-06-15 1998-05-13 Uop Inc. Method of making composite gas separation membranes
US20100224555A1 (en) * 2007-09-21 2010-09-09 Hoek Eric M V Nanocomposite membranes and methods of making and using same
WO2013006288A1 (en) * 2011-07-01 2013-01-10 International Business Machines Corporation Thin film composite membranes embedded with molecular cage compounds

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