WO2012149141A1 - Membrane d'osmose directe dotée d'un support à base de polymères mélangés - Google Patents

Membrane d'osmose directe dotée d'un support à base de polymères mélangés Download PDF

Info

Publication number
WO2012149141A1
WO2012149141A1 PCT/US2012/035188 US2012035188W WO2012149141A1 WO 2012149141 A1 WO2012149141 A1 WO 2012149141A1 US 2012035188 W US2012035188 W US 2012035188W WO 2012149141 A1 WO2012149141 A1 WO 2012149141A1
Authority
WO
WIPO (PCT)
Prior art keywords
membrane
support layer
polyaniline
polysulfone
film
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US2012/035188
Other languages
English (en)
Inventor
Eric M. V. HOEK
Mary L. Lind
Greg R. GUILLEN
Mavis C.y. WONG
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
University of California Berkeley
University of California San Diego UCSD
Original Assignee
University of California Berkeley
University of California San Diego UCSD
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by University of California Berkeley, University of California San Diego UCSD filed Critical University of California Berkeley
Publication of WO2012149141A1 publication Critical patent/WO2012149141A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/56—Polyamides, e.g. polyester-amides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/002—Forward osmosis or direct osmosis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/02—Details relating to pores or porosity of the membranes
    • B01D2325/0283—Pore size
    • B01D2325/02833—Pore size more than 10 and up to 100 nm
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/04—Characteristic thickness
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/20—Specific permeability or cut-off range
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/30—Chemical resistance
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
    • Y02A20/124—Water desalination
    • Y02A20/131—Reverse-osmosis

Definitions

  • Osmosis is a spontaneous process that occurs whenever two solutions of different chemical potentials are separated by a semi-permeable membrane (i.e., permeable to water but not the solutes).
  • Engineered osmotic processes known as forward osmosis (FO) or direct osmosis, pressure-retarded osmosis (PRO) and reverse osmosis (RO) are depicted visually in Figure 1. Relatively dilute "feed” and concentrated “brine” (RO) or “draw” (FO/PRO) solutions are not in equilibrium.
  • RO processes water permeates from the brine solution through membrane into the dilute solution because the applied hydraulic pressure greatly exceeds the osmotic pressure difference ( ⁇ » ⁇ ).
  • PRO processes a hydraulic pressure is applied, but sufficiently below the osmotic pressure such that water spontaneously diffuses from the feed into the brine ( ⁇ ⁇ ⁇ ).
  • FO processes offer great potential for use in hydration bags for hiking, mountaineering and the military, osmotic pumps in microfluidic devices, small molecule dialysis and drug delivery, as well as biomolecule and fruit juice concentration.
  • Large-scale processes like FO desalination and water purification and osmotic power production by PRO are not yet commercially viable.
  • FO applications large and small - better performing osmotic membranes are needed to (1 ) enhance performance or (2) enable commercial viability.
  • asymmetric composite RO membrane structures e.g., polyamide, polysulfone, polyester
  • the invention relates to semi-permeable forward osmosis (FO) membranes having exceptional water permeability, salt selectivity, internal mass transfer and high pH (or chemical) stability.
  • FO forward osmosis
  • the invention relates to a semi-permeable osmotic membrane having an osmosis-driven water permeability of from about 0.01 gfd/psi to about 0.10 gfd/psi ( 10 " 12 m/Pa-s to 10 " " m/Pa-s), for example about 0.05 gfd/psi to about 0.10 gfd/psi.
  • the semipermeable osmotic membrane can also have a sodium chloride permeability of less than 10 "7 m/s , such as, for example, a sodium chloride permeability of 10 "7 m/s to 10 "8 m/s.
  • the semipermeable osmotic membrane can also have a support membrane with deionized water contact angle below 20 degrees.
  • the semi-permeable osmotic membrane can also have up to 50% porosity through the volume of support membrane (flat sheet and hollow fiber) and support fabric (flat sheet only).
  • the semi-permeable osmotic membrane can also have a stability for at least about 1 year under continuous exposure to pH of 10 to 13 (i.e., for the ammonia-carbon dioxide draw solution) and periodic exposure to pH ⁇ 1 or pH > 13
  • the invention relates to a method for preparing a semi-permeable osmotic membrane, the method comprising polymerizing a semi-permeable film onto a hydrophilic or blended polymeric support layer.
  • the invention relates to products produced by the disclosed methods.
  • the invention relates to a method for osmosis-driven separation, the method comprising creating an osmotic pressure gradient across a semi-permeable osmotic membrane comprising a film polymerized on a blended support layer.
  • Figure 1 illustrates FO, PRO, and RO processes.
  • Figure 2 shows SEM images of standard TFC-RO membrane cross-section and skin layer.
  • Polysulfone layer + fabric support is -150 ⁇ and the skin layer is ⁇ 0.05-0.25 ⁇ .
  • Figure 3 shows SEM images of cross-section and skin layer of the HTI-CTA membrane. Total thickness of the fabric-embedded polymer film is -100 ⁇ , while the skin layer is -10 ⁇ .
  • Figure 4 illustrates driving force profiles, expressed as water chemical potential, ⁇ ⁇ , for osmosis through (a) CTA membrane, (b) a TFC membrane operating in PRO-mode, and (c) a TFC membrane operating in FO-mode.
  • FIG. 5 is a plot of commercial CTA and TFC membrane performance when tested in FO and RO operating modes.
  • Figure 6 shows the ratio of hindered-to-bulk diffusivity as a function of support membrane porosity.
  • Figure 7 is an illustration relating composite membrane permeability to support membrane skin layer pore size and porosity.
  • Figure 8 is a plot of permeability ratio changes resulting from changes in skin layer thickness and support membrane skin layer porosity assuming a fixed support membrane skin layer pore size of 50 nm.
  • Figure 9 is a plot of permeability ratio changes resulting from changes in support membrane skin layer pore size (rl) and porosity assuming a fixed coating film thickness of 100 nm.
  • Figure 10 illustrates (a) individual support membrane skin layer "unit cells” as well as multiple unit cells considering (b) large skin layer pores and (c) small skin layer pores.
  • Figure 1 1 is a plot of (a) specific water flux (observed flux per unit applied pressure) and (b) observed salt rejection as a function of support membrane skin layer pore size and porosity.
  • Figure 12 Illustrates internal and external mass transfer limitations for (a) ideal FO membranes, (b) the CTA FO membrane, and (c) a conventional TFC RO membrane (operated in FO-mode).
  • Figure 13 shows plots of water flux versus (a) support membrane macrovoid porosity, (b) support membrane thickness assuming 50% porosity, (c) thin film water permeability (Pw) with 50% porosity and 40 ⁇ thick support, and (d) versus feed/draw (bulk) solution osmotic pressure difference.
  • Figure 14 shows SEM images of UF membranes containing blend ratios of PANi:PSf of (a) 1 :0, (b), 3: 1 , (c) 2:2, (d) 1 :3, and (e) 0: 1. From left to right, images are of membrane surface (left), entire membrane cross-section (middle), and high magnification close-up of skin layer pores.
  • FIG. 15 shows experimentally determined water (P w ) and salt (P s ) permeability coefficients for commercial CTA/TFC membranes and 3 generations of UCLA composite FO membranes tested in FO-mode.
  • UCLA FOl , F02, and F03 membranes represent polyamide coated membranes with 0: 1 (pure PSf), 2:2 and 1 :3 PANi:PSf blend ratios, which correspond to images (e), (c), and (d) in Fig. 14, respectively.
  • Figure 16 shows grey-scale SEM surface image of PANi membrane (left) converted to black and white image (right) to determine membrane pore size and porosity.
  • Figure 16 was originally published by R. Guillen, et al. (J. Mater. Chem. 2010, 20, 4621-4628).
  • Figure 17 shows PAN PSf composite membranes.
  • Figure 1 8 shows FT1R spectra for polyaniline-polysulfone blend membranes.
  • Figure 19 shows plan view time sequence SEM images of PANi-PSf blend membranes exposed to a focused ion beam.
  • Figure 20 shows the water permeability and salt permeability for preliminary PSf and PANi-blended TFC membranes compared to CTA membrane.
  • Figure 21 shows the water permeability and salt permeability of PANi-blended TFC membranes using isopar and hexane as the organic solvent compared to the CTA membrane when tested in forward osmosis experiments.
  • Ranges can be expressed herein as from “about” one particular value, and/or to "about” another particular value. When such a range is expressed, another aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. For example, if the value “ 10" is disclosed, then “about 1 0" is also disclosed.
  • a residue of a chemical species refers to the moiety that is the resulting product of the chemical species in a particular reaction scheme or subsequent formulation or chemical product, regardless of whether the moiety is actually obtained from the chemical species.
  • an ethylene glycol residue in a polyester refers to one or more -OCH2CH2O- units in the polyester, regardless of whether ethylene glycol was used to prepare the polyester.
  • a sebacic acid residue in a polyester refers to one or more -CO(CH 2 )gCO- moieties in the polyester, regardless of whether the residue is obtained by reacting sebacic acid or an ester thereof to obtain the polyester.
  • compositions of the invention Disclosed are the components to be used to prepare the compositions of the invention as well as the compositions themselves to be used within the methods disclosed herein. These and other materials are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these materials are disclosed that while specific reference of each various individual and collective combinations and permutation of these compounds may not be explicitly disclosed, each is specifically contemplated and described herein. For example, if a particular compound is disclosed and discussed and a number of modifications that can be made to a number of molecules including the compounds are discussed, specifically contemplated is each and every combination and permutation of the compound and the modifications that are possible unless specifically indicated to the contrary.
  • compositions disclosed herein have certain functions.
  • TFC reverse osmosis membranes comprise a -100 ⁇ thick non-woven polyester fabric supporting a ⁇ 50 ⁇ thick porous polysulfone membrane (Figure 2a), which is then coated with a -50-250 nm thick, very dense polyamide film.
  • the nanoscale polyamide film provides a highly productive and selective skin layer, but the composite membrane suffers from extremely high "internal concentration polarization" thereby greatly reducing productivity when used in FO processes.
  • the underlying porous support membrane and fabric hinders the diffusion of solutes due to their relatively low- porosity, which lowers the effective osmotic driving force across the membrane limiting water permeation.
  • RO membranes are formed as flat sheets or hollow fibers comprising an ultra-thin polyamide film coated over a porous polysulfone support membrane (S.H. Chen, et al. J. Appl. Polym. Sci. 83 (2002) 1 1 12; R.J. Petersen, J. Membr. Sci. 83 (1993) 81 ).
  • the selective polyamide barrier layer is formed in situ by polycondensation reaction of poly functional amine and acid chloride monomers at the interface of two immiscible solvents.
  • a polyfunctional amine is dissolved in water and a polyfunctional acid chloride is dissolved in apolar organic solvents like hexane, naptha, cyclohexane, freon, or isoparrafin (M.M. Chau, US Patent 5,271 ,843, 1993 ; H. Hachisuka, K. US Patent 6,413,425, 2002; S. Verissimo, et al., J. Membr. Sci. 264 (2005) 48).
  • DMF reacts with an acyl chloride to produce an amidinium chloride, which is relatively unreactive toward aromatic amines. Later the amidinium chloride hydrolyzes to a carboxylate group, which inhibits cross-linking and produces more negative charge and higher water flux.
  • Such additives include, but are not limited to, IPA, DMSO, HMPA and acetone.
  • DMSO dimethyl sulfoxide
  • aqueous solution may further contain a surfactant or organic acids like camphor sulfonic acid (CSA) improve absorption of the amine solution in the support(M.A. Kuehne, et al., Environ. Prog. 20 (2001 ) 23; J.E. Tomaschke US Patent 4,872,984, 1989).
  • CSA camphor sulfonic acid
  • MPD-TMC film thickness and morphology are not intrinsically related to water permeability. The lack of correlation between film thickness and water permeability suggest the entire film thickness does not determine the pressure drop across composite RO membranes. Rather, permeation may occur at a "dense inner barrier layer" and the visible surface morphology is an un fortunate byproduct of the polymerization reaction. Interestingly film thickness and surface area strongly correlate with salt permeability, which suggests mass transfer (and external concentration polarization) may be influenced by RO membrane surface morphology.
  • reaction and curing conditions that produce optimal separation performance tend to produce relatively rough, hydrophobic membrane surfaces.
  • Polyamide interfacial composite membranes are the most popular commercial form of reverse osmosis (RO) and nanofiltration ( F) membranes.
  • RO reverse osmosis
  • F nanofiltration
  • composite RO and NF membranes are now commonly employed in water purification applications such as desalinati on of brackish and ocean water, fresh water softening and organic removal, iiltrapure water pr oduction, and advanced wastewater purification (L. Raghuraman, Desalin. 91 ( 1993) 1 55- 162; F.E. Sanders, et al., Desalin. 103 (1995) 133 to l 45; M.
  • interfacial composite membranes are formed over porous supports by in sit u polycondensation of polyfunctional amine and acid chloride monomers at the interface of t wo immiscible solvents (R.J. Petersen, J. Membr. Sci. 83 ( 1993) 81 to 150).
  • Factors influenc ing the physicochemical properties (chemical structure, physical morphology, interfacial prop erties, and separation performance) of composite RO membranes include: support membrane structure and chemistry, monomer structures and concentration, polar and apolar solvent sele ction, catalysts and other additives, reaction temperature and time, curing temperature and ti me, and other post treatments.
  • porous support structures for polya mide composite membranes were prepared from polymers like polysulfone, polyethersulfone, polycarbonate, polyphenylene oxides, poly(styrenecoacrylonitrile), poly(phthalazinone ether sulfone ketone) (PPESK), polyacrylonitrile, pol etherimide, polypropylene and others by con ventional phase inversion techniques (J. Wei, et al, J. Membr. Sci. 256 (2005) 1 1 6 to 121 ; IC . imet al., J. Polym.
  • polysulfone appears to be the most popular polymer for fabricating composite RO membranes because it is widely available, relatively cheap, easy to process, and is fairly stabl e against thermal, mechanical, chemical and bacterial attack. Note that polysul fone is relativ ely hydrophobic compared to most of the other polymers.
  • the porous support membrane provides a mechanical layer on which to build the composite structure and should be biologically, chemically, mechanically, and thermally stable.
  • the morphology and chemistry of the support layer may influence the formation of the ultrathin polyamide layer.
  • cellulosic materials have very poor biological, chemical, mechanical and thermal stability; in fact, they rapidly hydrolyze and dissolve in water at neutral pH or higher. These same issues - low water permeability, salt selectivity and stability - plagued early RO membrane technology based on cellulosic polymers. It is well known that cellulosics are unstable at high temperature and pH, whereas polyamides and polysulfones have much better pH and temperature stability, which in combination with their high flux and selectivity explains their dominance in RO applications.
  • the ultra-thin skin layer of the TFC membrane produces higher permeability and selectivity
  • the low-porosity polysu lfone support membrane causes dilutive internal concentration polarization, which decreases water permeability to about ⁇ 1 OX below the CTA membrane.
  • the CTA membrane utilizes the entire driving force for transport, but offers extremely high hydraulic resistance to water permeation because it is so thick (recall Figure 4a)
  • a TFC RO membrane with the dense skin layer facing the feed solution in FO-mode is lim ited by draw solute dilution inside the porous support (recall Figure 4c).
  • Hindered diffusion in a porous media arises from the excluded volume occupied by the solid fraction of the media (e.g., the solid polymer phase of the support membrane).
  • the porosity of TFC-RO membrane supports is less than -20%, so the diffusivity is hindered to less than -5% of the bulk diffusion coefficient for a salt (Figure 6).
  • FO membrane designs begin from the perspective that the support membrane porosity should be as large as possible while maintaining requisite mechanical integrity and stability.
  • Ap is the trans-membrane hydraulic pressure
  • Ac is the concentration difference across the membrane
  • R universal gas constant
  • T absolute temperature) which converts units of molar concentration into units of osmotic pressure
  • P w and P s are the apparent water and solute permeability coefficients.
  • Ap is much larger than ⁇ , so the water flux is in the same direction as the salt flux; however, in FO processes, Ap is much smaller than n, so the water flux is in the opposite direction as the salt flux (recall Figure 1 ).
  • an osmotic membrane can be made more selective for water over salt by increasing either the diffusion selectivity (DJD S ) or solubility selectivity (S w /S s ), which requires changing the physical structure or chemical nature of the membrane, respectively.
  • DJD S diffusion selectivity
  • S w /S s solubility selectivity
  • TFC membrane performance must be tied to both selective coating film and porous support layer properties. This is not a new concept in membrane science; a simplified version of a previously developed mechanistic model has been adapted herein H. Lonsdale; et al. (Membrane processes in industry and biomedicine: proceedings 1 971 , 101 - 122).
  • the effective diffusion path length through the coating film is a direct function of the size and number of pores in the support membrane skin layer - the very top layer of the support membrane on which the coating film rests (Figure 7a).
  • the overall composite membrane structure is more permeable.
  • a minimum salt rejection is fixed, but the maximum salt rejection is produced by decreasing porosity and increasing pore size ( Figure 1 l a); in contrast, a maximum water flux is fixed and is produced by decreasing support membrane pore size and increasing porosity ( Figure 1 l b).
  • This mechanism explains one aspect of the classic trade-off relationship between high flux and high rejection.
  • TFC membranes with porous supports suffer from both internal and external concentration polarization-based mass transfer limitations when operated in FO-mode.
  • the ideal osmotic membrane is a thin, dense film without a porous supporting structure ( Figure 12a); hence, only external mass transfer and film
  • a simplified model of osmotic membrane transport is used here to i llustrate the relationship between TFC membrane permeability (TV), support membrane macrovoid porosity ( m ) and thickness (S m ), and water flux through the membrane. Assuming perfect rejection (to simplify this analysis), osmotic flux is described by
  • TFC osmotic membrane permeability represents the combined effects of support membrane skin layer pore size and porosity plus the coating film structure.
  • high-performance osmotic membranes are desirably composite structures comprising: ( 1 ) Support membrane skin-layers with: Small pore size (r p ⁇ 1 0-25 nm; to support 50-250 nm thick coating films), Highly porous ( ⁇ ⁇ ⁇ 20-30%; to decrease path length for diffusion), Hydrophobic 70 °; to prevent the polyamide coating film from filling support membrane pores as it interfacially polymerizes as described by Ghosh et al. (J. Membr. Sci.
  • compositions and methods demonstrate the abil ity to fine-tune performance of a new class of TFC-FO membranes.
  • These first generation materials can comprise a polyamide thin film polymerized in situ over porous support membranes comprising different blends of polyaniline and polysulfone polymers.
  • the polyaniline- polysulfone blend membranes can be prepared by phase inversion of the polymer mixtures on top of a polyester nonwoven fabric.
  • PANi-PSf blend ultrafiltration membrane thickness, macrovoid porosity and orientation, skin layer pore size and porosity, and hydrophilicity (Figure 14, Table 1 ) have been shown to vary as a function of PANi content (G.R. Guillen et al.
  • the- invention uses novel polyaniline-polysulfone (PANi-PSf) blends in the structure supporting a thin polyamide film where the majority of the separation occurs. These novel blends modify the structure and hydrophilicity of the pores in the support membrane. After the PANi-PSf blend is cast onto a non-woven polyester support, it is then coated with a polyamide thin film to enable the membrane to reject salt ions.
  • PANi-PSf polyaniline-polysulfone
  • This membrane structure can be used in developing FO-based desalination, water purification, drug delivery and PRO osmotic power production processes.
  • polyaniline alters the structure of polysulfone supports by introducing macrovoids within the support structure, increasing the porosity of the membrane and thereby increasing the water flux through the membrane.
  • a poiyamide thin film on the PANi-PSf support an active layer at which t he majority of solute rejection occurs.
  • the invention is suited for any FO or PRO applications, but specifically in FO processes in which the solutions are caustic (pH > 10).
  • This innovative FO membrane structure is stable under basic conditions (pH > 10) whereas the existing commercial CTA membrane degrades within 24 hours under basic conditions.
  • the PANi-PSf supported membrane with a poiyamide thin fi lm coating is proven to have relatively constant performance before and after a base bath (pH > 13) for longer than 48 hours.
  • the invention relates to a semi-permeable nanostructured osmosis membrane comprising a polymer film polymerized on a blended support layer.
  • a semi-permeable nanostructured osmosis membrane comprising a polymer film polymerized on a blended support layer.
  • such a membrane can have an asymmetric structure of three layers: a top t hin film active layer (e.g., interfacially polymerized film), a middle polymer support (e.g., blended support layer), and a bottom fabric (e.g., polyester) support.
  • the invention relates to a semi-permeable forward osmosis (FO) membrane comprising having a permeability of from about 0.01 gfd/psi to about 0.10 gfd/psi.
  • the FO membrane can also have a stability for at least about 1 year under periodic exposure to pH ⁇ 1 or pH > 13.
  • the membrane is compatible with "ammonia - carbon dioxide draw solution"(also referred to herein as a "draw solution”) FO process conditions.
  • the membrane is compatible with continuous exposure to an operating temperature range of from about 5 °C to about 60 °C.
  • the operating temperature can be about 50 °C.
  • the membrane has a selectivity (R,) of at least about 99.5% for NaCl, >99.9% for draw solute.
  • the semi-permeable forward osmotic membrane can also have a salt, such as a sodium chloride, permeability (P s )of less than 10 "7 m/s , such as a sodium chloride permeability of 10 "7 m/s to 10 "8 m/s.
  • a salt such as a sodium chloride, permeability of about 0.5-1 .0x 10 " m/s.
  • the permeable forward osmotic membrane can also have a support membrane with deionized water contact angle below 40 degrees.
  • the - permeable forward osmotic membrane can also have a support membrane with deionized water contact angle below 20 degrees.
  • the semi-permeable osmotic membrane can also have up to 50% porosity through the volume of support membrane (flat sheet and hollow fiber) and support fabric (flat sheet only).
  • the semi-permeable osmotic membrane can also have a stability for at least about 1 year under continuous exposure to pH of 10 to 13 (i.e., for the ammonia-carbon dioxide draw solution) and periodic exposure to pll ⁇ 1 or pH > 13
  • the membranes can be highly permeable, 0.05-0. 1 0 gfd/psi, be highly selective (draw solute P s ⁇ 0.5- 1.0x l 0 "8 m/s), be smooth, have a super-hydrophilic (#* ⁇ 40 °), uncharged interface (i. e. , fouling/cleaning), the composite membrane can have a stability for years when exposed to Periodic exposure to pH ⁇ 1 or > 13 and 1 -2 ppm HOC1 (cleaning and biogrowth control), Continuous exposure to 5 ⁇ T ⁇ 60 °C (tolerance to environmental and operational temp swings).
  • the membrane comprises a polymeric support layer, and a film polymerized on the support layer.
  • the polymeric support layer comprises a blend of two or more polymers.
  • the support layer comprises polysulfone.
  • the support layer comprises polyaniline. I n a further aspect, the support layer comprises a blend of polysulfone and polyaniline.
  • the support layer comprises at least about 50% polysulfone. In a further aspect, the support layer comprises less than about 50% polyaniline. In a further aspect, the support layer comprises from about 50:50 polyaniline/polysulfone to about 25 :75 polyaniline/polysulfone.
  • the support layer comprises from about 40:60 polyaniline/polysulfone to about 20:80 polyaniline/polysulfone. In a further aspect, the support layer comprises about 1 :3 polyaniline/polysulfone.
  • the film has: cross-sectional thickness of from about 50nm to about 250nm, permeability of from about 0.01 gfd/psi to about 0.10 gfd/psi, and surface water contact angle of ⁇ 0 W ) of greater than about 70°.
  • the membrane comprises: a polymeric support layer having: skin- layer average pore size r p ) of from about 10 nm to about 25 nm, skin-layer porosity (s m ) of from about 20% to about 30%, skin-layer surface water contact angle of ( ⁇ 3 ⁇ 4,) of greater than about 70°, cross-sectional thickness ( ⁇ 5 m ) of less than about 50 ⁇ , cross-sectional porosity (£ ⁇ , utilizat) of greater than about 50%, cross-sectional macrovoid alignment substantially vertical (r m ⁇ 1), and cross-sectional surface water contact angle of (dw) of less than about 40°; and a film polymerized on the support layer, the film having: cross-sectional thickness of from about 50 nm to about 250 nm, permeability of from about 0.01 gfd/psi to about 0.10 gfd/psi, and surface water contact angle of ⁇ 9 W ) of greater than about 70°.
  • the membrane comprises a polyaniline/polysulfone blend support layer having: skin-layer average pore size (r p ) of from about 10 nm to about 25 nm, skin- layer porosity (f m ) of from about 20% to about 30%, skin-layer surface water contact angle of (6? w ) of greater than about 70°, cross-sectional thickness ( ⁇ , adjective) of less than about 50 ⁇ , cross- sectional porosity (£ ⁇ personally,) of greater than about 50%, cross-sectional macrovoid alignment substantially vertical (r m ⁇ 1 ), and cross-sectional surface water contact angle of (0 » ,) of less than about 40°, such as less than 20°.
  • the support layer comprises about 1 :3 polyaniline/polysulfone.
  • the film comprises at least one of a polyamide, a polyether, a polyether-urea, a polyester, or a polyimide or a copolymer thereof or a mixture thereof.
  • the film comprises a polyamide.
  • the polyamide comprises residues of a phthaloyl halide, a trimesoyl halide, or a mixture thereof.
  • the polyamide comprises residues of diaminobenzene, triaminobenzene, or piperazine or a mixture thereof.
  • the film comprises an aromatic polyamide.
  • the film comprises residues of a trimesoyl halide and residues of a diaminobenzene.
  • the film comprises an interfacially polymerized aromatic polyamide.
  • the membrane is compatible with "ammonia - carbon dioxide" FO process conditions, and comprises an about 1 :3 polyaniline/polysulfone blend support layer having: skin-layer average pore size (r p ) of from about 10 nm to about 25 nm, skin-layer porosity (£occasion,) of from about 20% to about 30%, skin-layer surface water contact angle of (0 W ) of greater than about 70°, cross-sectional thickness (S m ) of less than about 50 ⁇ , cross- sectional porosity (f OT ) of greater than about 50%, cross-sectional macrovoid alignment substantially vertical (r m ⁇ 1 ), and cross-sectional surface water contact angle of (0 W ) of less than about 40°; and a polyamide film interfacially polymerized on the support layer, the film having: cross-sectional thickness of from about 50nm to about 250nm, permeability of from about 0.01 gfd/psi to about 0. 10 gf
  • the FO membranes are more stable in a draw solution than a CTA membrane.
  • the FO membrane can be more stable in a draw solution at pH > 13 than a CTA membrane.
  • the FO membrane can be more stable in a draw solution at pH 1 1 - 13 than a CTA membrane.
  • the FO membrane can be more stable in a draw solution at pH 9- 1 1 than a CTA membrane.
  • the FO membrane can be more stable in a draw solution at pH 7-9 than a CTA membrane.
  • the FO membrane can have a draw solution stability of at least about 60 hrs in pH > 13.
  • the FO membrane can have a draw solution stability of at least about 96 hrs in pH > 13.
  • the FO membrane can have a draw solution stability of at least about 1 week in pH > 13.
  • the FO membrane can have a draw solution stability of at least about 1 month in pH > 1 3.
  • the FO membrane can have a draw solution stability of at least about 3 months in pH > 13.
  • the FO membrane can have a draw solution stability of at least about 6 months in pH > 13.
  • the FO membrane can have a draw solution stability of at least about 1 year in pH > 13.
  • the FO membrane can have a draw solution stability of at least about 3 years in pH > 13.
  • the FO membrane can have a draw solution stability of at least about 5 years in pH > 13.
  • the FO membrane can have a draw solution stabi lity of at least about 1 week in pH 1 1 - 13.
  • the FO membrane can have a draw solution stability of at least about 3 months in pH 1 1 - 13.
  • the FO membrane can have a draw solution stability of at least about 6 months in pH 1 1 -13.
  • the FO membrane can have a draw solution stability of at least about 1 year in pH 1 1 - 13.
  • the FO membrane can have a draw solution stability of at least about 3 years in pH 1 1 - 13.
  • the FO membrane can have a draw solution stability of at least about 5 years in pH 1 1 - 13.
  • the FO membrane can have a draw solution stability of at least about 3 months in pH 9- 1 1.
  • the FO membrane can have a draw solution stability of at least about 6 months in pH 9- 1 1.
  • the FO membrane can have a draw solution stability of at least about 1 year in pH 9-1 1.
  • the FO membrane can have a draw solution stability of at least about 3 years in pH 9- 1 1 .
  • the FO membrane can have a draw solution stability of at least about 5 years in pH 9- 1 1 .
  • the FO membrane can have a draw solution stability of at least about 1 year in pH 7-9.
  • the FO membrane can have a draw solution stability of at least about 3 years in pH 7-9.
  • the FO membrane can have a draw solution stability of at least about 5 years in pH 7-9.
  • the support layer comprises two or more polymers.
  • the support layer comprises polysulfone.
  • the support layer comprises polyaniline.
  • the support layer comprises a blend of polysulfone and polyaniline.
  • the support layer is nonwoven.
  • the blend can comprise up to about 99% polysulfone.
  • the blend can comprise up to about 98%, up to about 97%, up to about 95%, up to about 90%, up to about 85%, up to about 80%, up to about 75%, up to about 70%, up to about 65%, up to about 60%, up to about 55%, up to about 50%, up to about 45%, up to about 40%, up to about 35%, up to about 30%, up to about 25%, up to about 20%, up to about 15%, up to about 10%, up to about 5%, up to about 98%, up to about 3%, up to about 2%, or up to about 1% polysulfone.
  • the blend comprises no polysulfone.
  • the blend can comprise up to about 99% polyaniline.
  • the blend can comprise up to about 98%, up to about 97%, up to about 95%, up to about 90%, up to about 85%, up to about 80%, up to about 75%, up to about 70%, up to about 65%, up to about 60%, up to about 55%, up to about 50%, up to about 45%, up to about 40%, up to about 35%, up to about 30%, up to about 25%, up to about 20%, up to about 15%, up to about 10%, up to about 5%, up to about 98%, up to about 3%, up to about 2%, or up to about 1 % polyaniline.
  • the blend comprises no polyaniline.
  • the blend can comprise up to about 99% polyaniline- polysulfone.
  • the blend can comprise up to about 98%, up to about 97%, up to about 95%, up to about 90%, up to about 85%, up to about 80%, up to about 75%, up to about 70%, up to about 65%, up to about 60%, up to about 55%, up to about 50%, up to about 45%, up to about 40%, up to about 35%, up to about 30%, up to about 25%, up to about 20%, up to about 15%, up to about 10%, up to about 5%, up to about 98%, up to about 3%, up to about 2%, or up to about 1 % polyaniline-polysulfone.
  • the blend can comprise polymers in addition to polyaniline and polysulfone.
  • the ratio of polyaniline to polysulfone can be, for example, 99: 1 , 98:2, 97:3, 95:5, 90: 10, 85: 1 5, 80:20, 75:25, 70:30, 65:35, 60:40, 55:45, 50:50, 45:55, 40:60, 35:65, 30:70, 25:75, 20:80, 1 5:85, 10:90, 5 :95, 3 :97, 2:98, or 1 :99.
  • POLYMER FI LM POLYMER FI LM
  • the film comprises at least one of a polyamide, a polyether, a polyether-urea, a polyester, or a polyimide or a copolymer thereof or a m ixture thereof.
  • the film comprises a polyamide.
  • the polyamide comprises residues of a phthaloyl halide, a trimesoyl halide, or a mixture thereof.
  • the polyamide comprises residues of diaminobenzene, triaminobenzene, or piperazine or a mixture thereof.
  • the film comprises an aromatic polyamide.
  • the film comprises residues of a trimesoyl halide and residues of a diaminobenzene.
  • the film has an average thickness of from about 50 nm to about 250 nm, from about 50 nm to about 200 nm, from about 100 nm to about 250 nm, or from about 100 nm to about 200 nm.
  • the film comprises an interfacially polymerized aromatic polyamide.
  • hydrophilicity can be described in terms of surface water contact angle (0 W ).
  • a membrane or a discrete part, portion, or section of a membrane
  • a surface water contact angle can be less than about 40°, less than about 35°, less than about 30°, less than about 25°, less than about 20°, less than about 15°, less than about 10°, or less than about 5°.
  • the membrane can have a surface water contact angle can be less than about 20°.
  • hydrophobicity can be described in terms of surface water contact angle (0 W ).
  • a membrane or a discrete part, portion, or section of a membrane
  • a surface water cont act angle can be greater than about 70°, greater than about 75°, greater than about 80°, greater than about 85°, greater than about 90°, or greater than about 95°.
  • cross-sectional alignment of macrovoids within the support layers can be described in terms of deviation from theoretical perpendicularity from the support layer surface.
  • the average cross-sectional macrovoid alignment is substantially parallel to the support layer surface.
  • cross-sectional alignment of macrovoids within the support layers is substantially vertical (r m ⁇ ⁇ ).
  • ⁇ , sacrifice is greater than 0.95, greater than 0.90, greater than 0.85, greater than 0.80, greater than 0.75, or greater than 0.70.
  • the invention relates to a method for preparin a semipermeable nanostructured osmosis membrane, the method comprising polymerizing a film onto a blended polymeric support layer.
  • polymerizing is performed interfacially.
  • the support layer comprises polysulfone.
  • the support layer comprises polyaniline.
  • the support layer comprises a blend of polysulfone and polyaniline.
  • the fi lm comprises at least one of a polyamide, a polyether, a polyether-urea, a polyester, or a polyimide or a copolymer thereof or a mixture thereof.
  • the film comprises a polyamide.
  • the support layer is produced by phase inversion of a polymer blend solution or suspension.
  • the invention comprises the steps of providing a polar mixture comprising a polar liquid and a first monomer that is miscible with the polar liquid; providing an apolar mixture comprising an apolar liquid substantially immiscible with the polar liquid and a second monomer that is miscible with the apolar liquid; and contacting the polar mixture and the apolar mixture at a temperature sufficient to react the first monomer with the second monomer, thereby interfacially-polymerizing the first monomer and the second monomer to form a polymer matrix film.
  • miscible it is meant that the respective phases can mix and form a homogeneous mixture or dispersion at the relevant temperature and pressure. Unless otherwise specified, the relevant temperature and pressure are at room temperature and at atmospheric pressure. By “immiscible,” it is meant that the respective phases do not appreciably mix and do not appreciably form a homogeneous mixture at the relevant temperature and pressure.
  • Two liquids can be termed immiscible if neither liquid is appreciably soluble in the other liquid.
  • An example of two immiscible liquids is hexane and water.
  • the apolar liquid can be any apolar liquid known to those of skill in the art, typically, an apolar liquid of the invention is selected such that it is immiscible with a particular polar liquid used in a method of the invention.
  • the apolar liquid can comprise at least one of a C5 to C24 hydrocarbon.
  • the hydrocarbon can be an alkane, an alkene, or art alkyne.
  • the hydrocarbon can be cyclic or acyclic.
  • the hydrocarbon can be straight chain or branched.
  • the hydrocarbon can be substituted or unsubstituted.
  • the apolar liquid can comprise at least one of a linear hydrocarbon, a branched hydrocarbon, a cyclic hydrocarbon, naptha, heavy naptha, paraffin, or isoparaffin or a mixture thereof.
  • the apolar liquid comprises hexane. b. POLAR LIQUI D
  • the polar liquid can be any polar liquid known to those of skill in the art, typically, a polar liquid of the invention is selected such that it is immiscible with a particular apolar l iquid used in a method of the invention.
  • the polar liquid can comprise at least one of a C5 to C24 alcohol.
  • the alcohol can be an alkane, an alkene, or an alkyne.
  • the alcohol can be cyclic or acyclic.
  • the alcohol can be straight chain or branched.
  • the alcohol can be substituted or
  • the polar liquid comprises water.
  • the support membrane can comprise a polymer blend. That is, the support membrane can comprise two or more polymers.
  • the support membrane comprises polysulfone.
  • the support membrane comprises polyaniline.
  • the support membrane comprises a blend of polysulfone and polyaniline.
  • the support membrane is cast onto a nonwoven fabric. In a further aspect, the support membrane is cast into a woven fabric. d. MONOMERS
  • the polymer matrix of the invention is prepared by reaction of two or more monomers.
  • the first monomer is a dinucleophilic or a
  • each monomer can have two or more reactive (e.g., nucleophilic or electrophilic) groups. Both nucieophiles and electrophiles are well known in the art, and one of skill in the art can select suitable monomers for use in the methods of the invention.
  • the first and second monomers can be chosen so as to be capable of undergoing an interfacial polymerization reaction to form a polymer matrix (i. e., a three-dimensional polymer network) when brought into contact.
  • the first and second monomers can be chosen so as to be capable of undergoing a polymerization reaction when brought into contact to form a polymer product that is capable of subsequent crosslinking by, for example, exposure to heat, light radiation, or a chemical crosslinking agent.
  • a first monomer is selected so as to be m iscible with a polar liquid and, with the polar liquid, can form a polar mixture.
  • the first monomer can optionally also be selected so as to be immiscible with an apolar liquid.
  • the first monomer is a dinucleophilic or a polynucleophilic monomer.
  • the first monomer can comprise a diaminobenzene.
  • the first monomer can comprise m- phenylenediamine.
  • the first monomer can comprise a triaminobenzene.
  • the polar liquid and the first monomer can be the same compound; that is, the first monomer is not dissolved in a separate polar liquid.
  • a second monomer is selected so as to be m iscible with an apolar liquid and, with the apolar liquid, can form an apolar mixture.
  • the second monomer can optionally also be selected so as to be immiscible with a polar liquid.
  • the second monomer is a dielectrophilic or a polyelectrophilic monomer.
  • the second monomer can comprise a trimesoyl halide.
  • the second monomer can comprise trimesoyl chloride.
  • the second monomer can comprise a phthaloyl halide.
  • the apolar liquid and the second monomer can be the same compound; that is, the second monomer is not dissolved in a separate apolar liquid.
  • the difunctional or polyfunctional nucleophil ic monomer used in the present invention can have primary or secondary amino groups and may be aromatic (e.g., w-phenylenediamine, /?-phenyenediamine, 1 ,3,5-triaminobenzene, 1 ,3,4-triaminobenzene, 3,5-diaminobenzoic acid, 2,4-diaminotoluene, 2,4-diaminoanisole, and xylylenediamine) or aliphatic (e.g., ethylenediamine, propylenediamine, and /m(2-diaminoethyl)amine).
  • Suitable amine species include primary aromatic am ines having two or three amino groups, for example m-phenylene diamine, and secondary aliphatic amines having two amino groups, for example piperazine.
  • the amine can typically be applied to the
  • microporous support as a solution in a polar liquid, for example water.
  • the resulting polar mixture typically includes from about 0.1 to about 20 weight percent, for example from about 0.5 to about 6 weight percent, amine.
  • excess polar mixture may be optionally removed.
  • the polar mixture need not be aqueous but is typically immiscible with the apolar liquid.
  • difunctional or polyfunctional electrophilic monomer is preferably coated from an apolar liquid, although the monomer can optionally be delivered from a vapor phase (for monomers having sufficient vapor pressure).
  • the electrophilic monomer can be aromatic in nature and can contain two or more, for example three, electrophilic groups per molecule.
  • acyl halide electrophilic monomers because of the relatively lower cost and greater availability, acyl chlorides are generally more suitable than the
  • a suitable polyfunctional acyl halide is trimesoyl chloride (TMC).
  • TMC trimesoyl chloride
  • the polyfunctional acyl halide can be dissolved in an apolar organic l iquid in a range of, for example, from about 0.01 to about 10.0 weight percent or from about 0.05 to about 3 weight percent, and delivered as part of a continuous coating operation.
  • Suitable apolar liquids are those which are capable of dissolving the electrophilic monomers, for example polyfunctional acyl halides, and which are immiscible with a polar liquid, for example water.
  • suitable polar and apolar liquids can include those which do not pose a threat to the ozone layer and yet are sufficiently safe in terms of their flashpoints and flammability to undergo routine processing without having to undertake extreme precautions.
  • Higher boiling hydrocarbons i.e., those with boiling points greater than about 90 °C, such as Cg -C24 hydrocarbons and mixtures thereof, have more suitable flashpoints than their C5 -C7 counterparts, but they are less volatile.
  • the reaction time is typically less than one second, but contact time is often longer, for example from one to sixty seconds, after which excess liquid may optionally be removed, e.g., by way of an air knife, water bath(s), dryer, and the like.
  • the removal of the excess polar m ixture and/or apolar mixture can be conveniently achieved by drying at elevated temperatures, e.g., from about 40 °C to about 120 °C, although air drying at ambient temperatures may be used, or by immersing into water at elevated temperatures, e.g., from about 40 °C to about 120 °C.
  • the invention relates to a method for osmotically-driven separation, the method comprising creating an osmotic pressure gradient across a semipermeable forward osmosis membrane comprising a film polymerized on a blended support layer.
  • the semi-permeable forward osmosis membrane exhibits a water permeability of about l , about 2x, or about 5x that of a commercial "CTA" membrane.
  • the semi-permeable forward osmosis membrane exhibits a salt passage of about 1 x, about 0.1 x, or about 2x that of a commercial "CTA" membrane.
  • purified water is produced.
  • electricity is produced.
  • Membranes comprising the compositions disclosed herein can be produced by a number of procedures known in the art. Typical processes and reagents known in the art include those described for example in Fan et al., J. Membr. Sci., 2008, 320, 363-371 ; Ball et al., Membr. Sci., 2000, 1 74, 1 61 - 1 76; Anderson et al., Science, 1991 ,252, 1412- 14 15; U.S. Patent No. 5,096,586; U. S. Provisional Patent Application No. 61 /260,365; WO
  • Phase inversion is a common method used to synthesize porous membranes. Polymers are controllably transformed from a liquid state to a solid state by this process. Solidification is initiated by the formation of two liquid phases from a single liquid phase.
  • phase inversion covers several specific techniques such as vapor phase precipitation, solvent evaporation, thermal precipitation, and immersion precipitation. Immersion precipitation is the most common technique used to produce phase inversion membranes (see, e.g. Mulder, M., Basic Principles of Membrane Technology. 2nd Edition ed.; Kluvver Academic Publishers: Dordrecht, The 25 Netherlands, 2003).
  • Factors that influence phase inversion membrane morphology include: (1 ) the choice of solvent/nonsolvent system; (2) the composition of the polymer solution, which includes the polymer selected, its concentration and molecular weight distribution plus addition of other polymers or nonsolvent; (3) the composition of the coagulation bath, which is generally limited to adding solvent up to the binodal; and (4) fi l m casting conditions such as polymer solution and coagulation bath temperature, film thickness, immersion in a non- solvent with low mutual affinity to the solvent or use of an evaporat ion step before immersing into the nonsolvent.
  • the latter two techniques of item (4) are generally used to produce integrally skinned membranes for gas separation, vapor permeation, or
  • Immersion precipitation membranes are typically formed by casting a polymer solution as a thin film on a support or by extruding a hollow fiber through a spinneret with an appropriate bore liquid.
  • the polymer solution, or dope is composed of polymer, solvent, and may contain some additives.
  • the cast thin film and support or extruded hollow fiber are immersed in a coagulation bath.
  • a coagulation bath consists of the nonsolvent and may contain additives. Solvent diffuses out of the polymer/solvent phase and into the coagulation bath while nonsolvent diffuses into the polymer/solvent phase.
  • the choice of solvent/nonsolvent system in porous membrane synthesis can be significant.
  • the polymer is typically soluble or easily dispersible in the chosen solvent.
  • a highly processable form of polyaniline was synthesized and used to form pure polyaniline and polyaniline-polysulfone ultrafiltration membranes by nonsolvent induced phase inversion. Blends containing up to 75% polyaniline were 10-20% more permeable than pure polysulfone membranes, while pure polyaniline membranes were 10 times more permeable and extremely hydrophilic.
  • a novel scanning electron microscope imaging technique was combined with characterization data and the Hagen— Poiseuille pore- flow model to elucidate that increasing polyaniline content increased the apparent membrane pore size and hydrophilicity, while decreasing skin layer thickness and porosity. Pure polyaniline membranes exhibited relatively larger, shorter pores that combined with the increased hydrophilicity to produce the observed separation performance enhancements.
  • PS f pure polysul fone
  • pure PANi and PANi-PSf blend membranes which indicate this highly processable form of polyaniline can open up new opportunities for engineering advanced membrane materials.
  • Ammonium peroxydisulfate (APS) Prod. No. A682, ACS grade, 98.0%
  • acetone Prod. No. 26831001 0, HPLC grade, 99.8%
  • sodium hydroxide Prod. No. S61 2
  • Aniline Prod. No. 1 0400, ACS grade, 99.5%
  • sulfuric acid Prod. No. 320501 , ACS grade, 95.0-98.0%
  • methanol Prod. No. 1 79957, laboratory grade, 99.6%
  • potassium bromide Prod. No. 221 864, FT-IR grade, 99%
  • polysulfone beads Prod. No.
  • Polymer solutions were prepared with PANi:PSf weight ratios of 1 :0 (pure polyanil ine), 3 : 1 , 1 : 1 , 1 :3, and 0: 1 (pure polysulfone). The total polymer concentration was 1 8 wt% in all cases. Films were cast on a commercial nonwoven polyester support layer and immersed in 1 8 ⁇ laboratory deionized water at room temperature to induce precipitation. Polysulfone was chosen as the base membrane and blend polymer because it is a well studied ultrafiltration membrane material. Permeability and rejection tests were conducted in a dead- end flow cell (HP4750 Stirred Cell, Sterlitech Corp.) using 4 cm diameter membrane samples taken from membranes cast on different days and prepared from different casting solutions.
  • a dead- end flow cell HP4750 Stirred Cell, Sterlitech Corp.
  • ⁇ is the membrane porosity
  • d p is the membrane pore diameter
  • // is the liqu id dynamic viscosity
  • / is the effective membrane thickness.
  • ⁇ is skin layer porosity
  • / is skin layer thickness (i.e., apparent pore length including tortuosity)
  • Ap is the pressure drop across the skin layer.
  • Membrane samples were prepared for SEM (Nova 600 NanoLab DualBeam"- SEM FIB, FEI Company) analysis by soaking in pH 1 H2SO4 solutions for 1 h and drying overnight in a desiccator. Membranes containing polyaniline were made electrically conductive by this doping step, so surface coating (by gold, palladium, platinum, etc.) prior to imaging was unnecessary. Pure polysulfone membranes were sputter-coated with gold to prevent charging. Membrane cross-sections were prepared by freeze fracturing using liquid nitrogen. Membrane surface milling was achieved by a focused ion beam (FI B) operated using a gallium source at a current of 10 nA, accelerating voltage of 30 kV, and a magnification of 5000X.
  • FI B focused ion beam
  • Membrane pore size and surface porosity were determined by image analyses of scanning electron micrographs using NIH ImageJ software. High magnification grey-scale surface images were converted to black and white images ( Figure 1 6) fol lowing a previously described procedure. Surface porosity was calculated by dividing the sum of the black pixels (Attack) by the total pixels in an image. Average pore diameter (d p , aV g) was calculated by the following equation:
  • n is the number of continuous dark areas (pores) counted by the software. Maximum pore diameter (d p max ) was estimated similarly, but using the largest individual black spot observed.
  • Membrane surface roughness was measured using atomic force microscopy (AFM) (Synergy ESPM 3-D, Novascan). Air dried membranes were scanned in tapping mode in 500 nm X 500 nm sections. Water contact angles were measured using a goniometer (DSA 10, russ). The captive bubble technique was employed here rather than the sessile drop technique due to the porous and hydrophilic nature of pure polyaniline fi lms. Ten drops were measured for each membrane with the highest and lowest values being d iscarded.
  • Membranes of varying polyaniline and polysulfone content were formed using the immersion precipitation technique. Images of each membrane are shown in Figure 1 7. Water permeability and nanoparticle and protein rejection were measured for polyani line- polysulfone composite membranes. Pure polyaniline membranes are an order of magnitude more permeable than pure polysulfone and composite membranes, i.e., there is a sharp decrease in permeability when polysulfone is introduced.
  • Membranes have comparable rejection for 48 nm silica particles. Membranes containing large fractions of polyaniline showed little or no BSA rejection, whi le the pure polysulfone membrane showed greater than 45% BSA rejection. Error bars in membrane performance data reflect batch-to-batch variability.
  • Captive bubble contact angles were measured using deionized water on all composite membranes. Contact angle values and surface energies for each membrane composition are given in Table 2. As expected, the pure polysulfone membrane is the most hydrophobic, and membrane hydrophilicity general ly increases with increasing polyaniline content. When surface roughness is considered, the free energy of cohesion for the 1 : 1 PANi:PSf membrane approaches that of the hydrophobic pure polysulfone membrane.
  • the 1 : 1 PANi:PSf membrane has a sponge-like substructure with few macrovoids. Scanning electron micrographs were taken while simultaneously exposing composite membrane surfaces to a focused ion beam (FIB). The FIB removes surface material by bombarding the surface with gallium ions. Time step images in Figure 1 show varied membrane surface resistance to the FIB due to some combination of membrane chemical composition and skin layer thickness.
  • FIB focused ion beam
  • Membrane pore size was calculated using silica nanoparticle and BSA rejection data and eqn (12). Approximate pore diameters for each membrane are shown in Table 3. Tabl 3 Membrane pore-stnicture analyses
  • Partial silica nanoparticle rejection (/3 ⁇ 4 ⁇ 2 ) by the pure polyaniline membrane translates into an average pore diameter of 60 nm, classifying this membrane as a "loose" ultrafiltration membrane.
  • Complete nanoparticle rejection gives an incomplete picture of membrane pore diameter; pore diameter is less than the particle diameter.
  • Partial BSA rejection indicates that the pure polysulfone membrane is a much tighter ultrafiltration membrane with an average pore diameter of 14 nm.
  • Membrane average pore diameter, maximum pore diameter, and surface porosity were approximated by analyzing surface SEM images of composite membranes (Table 3). Average membrane pore diameters ranging from 5-1 1 nm were found for composite polyaniline-polysulfone membranes. Pore diameter was found to decrease with increasing polysulfone content. Maximum observed pore diameters were typically 3-5 times greater than average pore diameters for each membrane, which may have affected solute rejection and permeability. Surface porosity ranged from 2-5%, and did not follow a noticeable trend with relative polymer content. Effective pore length was calculated using eqn ( 1 ) and was found to generally increase with increasing polysulfone content.
  • the 1 : 1 composite membrane is an exception as it appears to have a mixture of sponge-like and finger-like morphology.
  • the pure polyaniline membrane had the shortest erosion time (thinnest skin layer) of the composite membranes. The majority of the skin layer was removed after only 5 min.
  • the pure polysulfone and 3 : 1 PANi:PSf membrane showed marked erosion near the 10 min mark indicating that their skin layers are thinner than those of the 1 : 1 and 1 :3 PANi:PSf membranes. These results mirror the results of the skin layer SEM images.
  • the 1 : 1 PANi:PSf membrane shows slight pitting after 10 min, which may be the exposed sponge-like sublayer.
  • the 1 :3 PANi: PSf membrane shows very slight pitting only after 15 min of FIB irradiation.
  • An obvious limitation to this analysis lies in the assumption that each polymer has similar physical/thermal resistance to the FI B, whereby skin layer th ickness is proportional to erosion time.
  • Such properties can be improved by changing the organic solvent that the trimesoyl chloride is dissolved in the subsequent thin-film formation step.
  • an isoparaffin hydrocarbon solvent lsopar-G, Exxon Mobil Chemical, Houston, TX
  • the resulting thin-film composite membrane outperformed the CTA membrane in terms of water permeability and selectivity when tested under the same conditions (PRO- mode, 32 g/L NaCl draw solution, deionized water feed solution, and constant temperature 20°C) ( Figure 21 ).
  • the difference in performance could be attributed to several factors, including the difference in MPD solubility and diffusivity and the boiling points of the two organic solvents.
  • the lower solubility of M PD in hexane allowed for less MPD to partition from the support into the reaction zone (presumably on the hexane side of the aqueous hexane interface) during interfacial polymerization.
  • the higher diffusivity of MPD in hexane gives rise to faster film formation, generally producing a thinner (more permeable) coating film with a high cross-linking density.
  • the lower boiling point of hexane compared to isopar enabled a lower curing temperature, which prevented the pores of the PAN i-blended support membrane from contracting by annealing such as may happen when curing at higher temperature which is required for membranes formed using high boiling point solvents like isopar.

Landscapes

  • Engineering & Computer Science (AREA)
  • Water Supply & Treatment (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

Une membrane d'osmose directe semi-perméable présente des perméabilité et stabilité exceptionnelles et est agencée pour des applications comprenant des dispositifs de dessalement à faible énergie par osmose directe, de production d'énergie osmotique, d'administration de médicament, de déshydratation d'aliments et de boissons et d'échantillonnage d'eau osmotique. La membrane peut comprendre une couche de support polymère et un film polymérisé sur la couche de support. La couche de support polymère peut comprendre un mélange d'au moins deux polymères, comprenant un polysulfone et/ou une polyaniline. Le film peut comprendre un polyamide, un polyéther, une polyéther-urée, un polyester ou un polyimide, ou leurs copolymères ou mélanges.
PCT/US2012/035188 2011-04-26 2012-04-26 Membrane d'osmose directe dotée d'un support à base de polymères mélangés Ceased WO2012149141A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201161479393P 2011-04-26 2011-04-26
US61/479,393 2011-04-26

Publications (1)

Publication Number Publication Date
WO2012149141A1 true WO2012149141A1 (fr) 2012-11-01

Family

ID=47072748

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2012/035188 Ceased WO2012149141A1 (fr) 2011-04-26 2012-04-26 Membrane d'osmose directe dotée d'un support à base de polymères mélangés

Country Status (1)

Country Link
WO (1) WO2012149141A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014186552A1 (fr) * 2013-05-15 2014-11-20 The Regents Of The University Of California Membranes en polyaniline formées par inversion de phase destinées à des applications d'osmose directe
WO2014204403A3 (fr) * 2013-06-19 2016-07-14 National University Of Singapore Fibres creuses composites à couche mince permettant de générer un pouvoir osmotique
CN106430426A (zh) * 2016-10-26 2017-02-22 上海应用技术大学 一种电镀镍废液及镀镍洗涤废水处理的方法
CN109289541A (zh) * 2018-11-07 2019-02-01 温州莲华环保科技有限公司 一种有机正渗透膜的制备方法
US10265662B2 (en) 2012-10-12 2019-04-23 The Regents Of The University Of California Polyaniline membranes, uses, and methods thereto
US10532328B2 (en) 2014-04-08 2020-01-14 The Regents Of The University Of California Polyaniline-based chlorine resistant hydrophilic filtration membranes

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030162939A1 (en) * 1996-05-31 2003-08-28 Hsing-Lin Wang Permeable polyaniline articles for gas separation
US20100224555A1 (en) * 2007-09-21 2010-09-09 Hoek Eric M V Nanocomposite membranes and methods of making and using same
US20110017666A1 (en) * 2004-12-06 2011-01-27 Cath Tzahi Y Systems and methods for purification of liquids

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030162939A1 (en) * 1996-05-31 2003-08-28 Hsing-Lin Wang Permeable polyaniline articles for gas separation
US20110017666A1 (en) * 2004-12-06 2011-01-27 Cath Tzahi Y Systems and methods for purification of liquids
US20100224555A1 (en) * 2007-09-21 2010-09-09 Hoek Eric M V Nanocomposite membranes and methods of making and using same

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10265662B2 (en) 2012-10-12 2019-04-23 The Regents Of The University Of California Polyaniline membranes, uses, and methods thereto
US10780404B2 (en) 2012-10-12 2020-09-22 The Regents Of The University Of California Polyaniline membranes, uses, and methods thereto
WO2014186552A1 (fr) * 2013-05-15 2014-11-20 The Regents Of The University Of California Membranes en polyaniline formées par inversion de phase destinées à des applications d'osmose directe
KR20160008621A (ko) * 2013-05-15 2016-01-22 더 리젠츠 오브 더 유니버시티 오브 캘리포니아 정삼투식 적용을 위한 상 반전에 의해 형성된 폴리아닐린 막
CN105451866A (zh) * 2013-05-15 2016-03-30 加州大学评议会 用于正向渗透应用的通过相反转形成的聚苯胺膜
US10456755B2 (en) 2013-05-15 2019-10-29 The Regents Of The University Of California Polyaniline membranes formed by phase inversion for forward osmosis applications
KR102375661B1 (ko) 2013-05-15 2022-03-16 더 리젠츠 오브 더 유니버시티 오브 캘리포니아 정삼투식 적용을 위한 상 반전에 의해 형성된 폴리아닐린 막
WO2014204403A3 (fr) * 2013-06-19 2016-07-14 National University Of Singapore Fibres creuses composites à couche mince permettant de générer un pouvoir osmotique
US10987846B2 (en) 2013-06-19 2021-04-27 National University Of Singapore Thin film composite hollow fiber membranes for osmotic power generation
US10532328B2 (en) 2014-04-08 2020-01-14 The Regents Of The University Of California Polyaniline-based chlorine resistant hydrophilic filtration membranes
CN106430426A (zh) * 2016-10-26 2017-02-22 上海应用技术大学 一种电镀镍废液及镀镍洗涤废水处理的方法
CN109289541A (zh) * 2018-11-07 2019-02-01 温州莲华环保科技有限公司 一种有机正渗透膜的制备方法

Similar Documents

Publication Publication Date Title
Wang et al. Developing thin‐film‐composite forward osmosis membranes on the PES/SPSf substrate through interfacial polymerization
Chong et al. From micro to nano: Polyamide thin film on microfiltration ceramic tubular membranes for nanofiltration
Choi et al. Thin-film composite membranes comprising ultrathin hydrophilic polydopamine interlayer with graphene oxide for forward osmosis
Jahanshahi et al. Developing thin film composite poly (piperazine-amide) and poly (vinyl-alcohol) nanofiltration membranes
CN102665882B (zh) 用于海水脱盐的正渗透膜及其制备方法
Sun et al. Novel thin-film composite nanofiltration hollow fiber membranes with double repulsion for effective removal of emerging organic matters from water
Shahmirzadi et al. Tailoring PES nanofiltration membranes through systematic investigations of prominent design, fabrication and operational parameters
Zhu et al. Mixed matrix membranes containing MIL-53 (Al) for potential application in organic solvent nanofiltration
Hermans et al. Study of synthesis parameters and active layer morphology of interfacially polymerized polyamide–polysulfone membranes
Chou et al. Characteristics and potential applications of a novel forward osmosis hollow fiber membrane
Zhou et al. Thin-film composite membranes formed by interfacial polymerization with natural material sericin and trimesoyl chloride for nanofiltration
Razzaghi et al. Morphological and separation performance study of PVDF/CA blend membranes
US9156006B2 (en) High flux thin-film composite forward osmosis and pressure-retarded osmosis membranes
Li et al. Layer-by-layer aided β-cyclodextrin nanofilm for precise organic solvent nanofiltration
Ding et al. Effects of polysulfone (PSf) support layer on the performance of thin-film composite (TFC) membranes
EP2902095B1 (fr) Membrane semi-perméable composite
JP6052172B2 (ja) 複合半透膜の製造方法
Guan et al. Interfacial polymerization of thin film selective membrane layers: Effect of polyketone substrates
WO2012149141A1 (fr) Membrane d'osmose directe dotée d'un support à base de polymères mélangés
Arjmandi et al. Physical modification of polymeric support layer for thin film composite forward osmosis membranes by metal–organic framework‐based porous matrix membrane strategy
Li et al. High rejection seawater reverse osmosis TFC membranes with a polyamide-polysulfonamide interpenetrated functional layer
Iranizadeh et al. Preparation and characterization of thin-film composite reverse osmosis membrane on a novel aminosilane-modified polyvinyl chloride support
WO2018091273A1 (fr) Nouveaux procédés de traitement d'eau
Lee et al. Interfacial polymerization on hydrophobic PVDF UF membranes surface: Membrane wetting through pressurization
Hou et al. Construction of a gradient cross-linked nanofiltration membrane with quaternized surface for efficient heavy metal removal

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 12776048

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 12776048

Country of ref document: EP

Kind code of ref document: A1