WO2022040790A1 - Membrane nanostructurée supermouillable à double fonction - Google Patents

Membrane nanostructurée supermouillable à double fonction Download PDF

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Publication number
WO2022040790A1
WO2022040790A1 PCT/CA2021/051171 CA2021051171W WO2022040790A1 WO 2022040790 A1 WO2022040790 A1 WO 2022040790A1 CA 2021051171 W CA2021051171 W CA 2021051171W WO 2022040790 A1 WO2022040790 A1 WO 2022040790A1
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water
membrane
oil
separation
pva
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PCT/CA2021/051171
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English (en)
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Malcolm XING
Yuqing Liu
Shiyi Chen
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University Of Manitoba
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    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/70—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres
    • D04H1/72—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged
    • D04H1/728—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged by electro-spinning
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • B01D67/0004—Organic membrane manufacture by agglomeration of particles
    • B01D67/00042—Organic membrane manufacture by agglomeration of particles by deposition of fibres, nanofibres or nanofibrils
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0079—Manufacture of membranes comprising organic and inorganic components
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12—Composite membranes; Ultra-thin membranes
    • B01D69/125—In situ manufacturing by polymerisation, polycondensation, cross-linking or chemical reaction
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/14—Dynamic membranes
    • B01D69/141—Heterogeneous membranes, e.g. containing dispersed material; Mixed matrix membranes
    • B01D69/148—Organic/inorganic mixed matrix membranes
    • 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
    • B01D71/02—Inorganic material
    • B01D71/021—Carbon
    • 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
    • B01D71/38—Polyalkenylalcohols; Polyalkenylesters; Polyalkenylethers; Polyalkenylaldehydes; Polyalkenylketones; Polyalkenylacetals; Polyalkenylketals
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/447—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by membrane distillation
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/04—Carbon
    • C08K3/042—Graphene or derivatives, e.g. graphene oxides
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/04—Oxygen-containing compounds
    • C08K5/07—Aldehydes; Ketones
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/30—Cross-linking
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/39—Electrospinning
    • 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
    • B01D61/14—Ultrafiltration; Microfiltration
    • 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
    • B01D61/36—Pervaporation; Membrane distillation; Liquid permeation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/30—Organic compounds
    • C02F2101/32—Hydrocarbons, e.g. oil
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/08—Seawater, e.g. for desalination
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2305/00—Use of specific compounds during water treatment
    • C02F2305/08—Nanoparticles or nanotubes
    • 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
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00—Technologies for wastewater treatment
    • Y02W10/30—Wastewater or sewage treatment systems using renewable energies
    • Y02W10/37—Wastewater or sewage treatment systems using renewable energies using solar energy

Definitions

  • Chemical grafting is another surface modification technique that tailors the surface energy of the membrane by grafting functional groups with special affinity towards water or oil (15,23,24).
  • membranes fabricated by this method may suffer from lack of stability under harsh environments containing acid, alkaline or mineral compounds. Once the grafted outer layer is damaged, the substrate material is prone to severe oil fouling.
  • Biomimetic mineralization is another method to enhance the hydrophilicity property of the membrane, involving construction of an oil-repellent barrier on the surface.
  • the surface chemistry and architecture are modified to achieve special wettability (25, 26).
  • decorating minerals also reduces the pore size of the membrane, resulting in resistance during emulsion separation and consequently lower flux.
  • the mechanical strength of the membranes must also be improved as the materials used to endow oil repellence are far from robust, i.e. hydrogels (27-29), aerogels (12,30,31 ).
  • materials utilizing rigid substrate such as stainless steel (32,33) lack flexibility and deformability. Therefore, robust, anti-fouling and scalable materials are needed to treat highly emulsified oily industrial wastewater.
  • a method of preparing a water purification membrane comprising: electrospinning a quantity of polymers into nanofibers, said polymers selected from the group consisting of: polyvinyl alcohol (PVA); poly(N-isopropylacrylamide) (PNIPAM); poly(vinylidene fluoride) (PVDF); poly(methacrylic acid) (PMAA); and poly(acrylic acid) (PAA), forming a membrane from the nanofibers by crosslinking the nanofibers; depositing nanoparticles on the membrane by oxidation of pyrrole monomers; and washing the membrane.
  • PVA polyvinyl alcohol
  • PNIPAM poly(N-isopropylacrylamide)
  • PVDF poly(vinylidene fluoride)
  • PMAA poly(methacrylic acid)
  • PAA poly(acrylic acid)
  • a water purification and/or desalination membrane prepared according to the method described above.
  • a method of purifying contaminated water comprising: flowing the contaminated water through a membrane as described above, said membrane allowing water to flow therethrough, thereby purifying the water.
  • a method of desalinating water comprising: flowing salt water through a membrane as described above while exposed to light of at least one solar wavelength, said membrane allowing water to flow therethrough and converting the water to steam and condensing the steam, thereby recovering desalinated water.
  • a method of purifying and desalinating contaminated salt water comprising: flowing the contaminated water through a membrane as described above while exposed to light of at least one solar wavelength, said membrane allowing water to flow therethrough, thereby purifying the water; said membrane converting the water to steam and condensing the steam, thereby recovering desalinated water.
  • FIG. 1 (a) Schematic Illustration of the preparation process of the NPM membrane and the dual functions of the membrane, (b) the on-site set-up illustration for seawater desalination.
  • Figure 2 Surface morphological changes of the electrospun PVA membrane (a-c) before and (d-f) after coated with PPy nanoparticles, (g) Tensile stress versus strain curves of the crosslinked PVA membranes coated with PPy nanoparticles in situ polymerized for different periods of time, (h) Underwater chloroform contact angle and water contact angle of PVA without PPy coating(NPMI ) or treated with PPy for 5 hours (NPM2), 1 day (NPM3), 2 days (NPM4) and 3 days (NPM5). (i) FT-IR spectrum of as-electrospun NPM1 (red), PPy particles (blue) and NPM5 (black).
  • Figure 4 Snap shots of (a) water droplets and (b) chloroform droplets spreading on superhydrophilic and underwater superoleophobic NPM5 surfaces, (c) The underwater sliding angle of dichloromethane of NPM 5. d) Droplets of dyed organic solvents on the top of NPM underwater, (e) Underwater Oil Contact Angles and (f) Underwater sliding Angles of the NPM against different oily droplets.
  • FIG. 5 Oil/sea water emulsion separation installation, petroleum ether was selected as the non-soluble organic solvent sample and was tinted with pink pigment, (b) Oil-in-water emulsion was prepared with 10% petroleum ether in distilled water sonicated for 30 min. (d) The filtrated solution. (c,e) Optical microscopy of emulsions before (c) and after (e) separation, (f) The separation flux in response to increasing NPM thicknesses, (g) Particle size distribution of the petroleum ether-in- water microscale mixture.
  • Figure 7 Distribution of oil drops with different diameter ranges with and without emulsifier stabilization, a) DLS results of surfactant-free hexane-in-water emulsion and b) SDS stabilized hexane-in-water emulsion, c) DLS results of surfactant-free petroleum ether-in-water emulsion and d) SDS stabilized petroleum ether-in-water emulsion. Images of the surfactant stabilized 10% oil-in-water emulsions on e) day 1 and f) day 15.
  • BSA bovine serum albumin mixed SDS stabilized mechanical pump oil-in-water emulsion separation.
  • Figure 9 (a) Schematic set up for solar-vapor desalination unit used in the experiment, (b) the solar vapor radiation installation setup and the NPM floating on water in a beaker, (c) Mass change over 60 min with and without the NPM5 under 0.5 and 1 solar flux, (d) The comparison of evaporation rates of NPM1 , NPM2, NPM3, NPM4, NPM5 and pure water on Copt from 0.1 to 1 (with dark evaporation subtracted), (e) Solar vapor efficiencies of NPM1 , NPM2, NPM3, NPM4, NPM5 for different values of Copt, (f) The summary of energy efficiencies and evaporation rates of NPM with various degree of PPy coating.
  • Figure 10 (a) UV-vis NIR spectra comparison of NPM samples with 200 pm thickness, (b) Swelling ratios of NPM1 , NPM3 and NPM5 under a 15 min interval, (c) IR images indicating the thermal dispersion of the NPM5 and water placed above the water surface with 1 kW m -2 solar flux irradiance at different time points.
  • FIG. 11 The salinity test result using NPM5 with salinity result before and after desalination.
  • the blue and red lines refer to the World Health Organization (WHO) and Health Canada (HC) salinity standards for drinkable water,
  • WHO World Health Organization
  • HC Health Canada
  • Calculated concentrations of four major ions in an artificial seawater sample before and after desalination
  • the blue bar indicates the evaporation rates range between 2.72 and 2.91 kg m -2 h -1 .
  • Graphene oxide as one of the most important derivatives of graphene, is valued for its non-toxicity, excellent dispersity and has long been used as reinforcement elements to strengthen the material.
  • 0.2% graphene oxide was mixed into the PVA electrospinning solution as a reinforcement to strengthen the material.
  • the NPM exhibits the integrated properties of mechanical robustness, superhydrophilic/underwater superoleophobic wettability and broadband solar absorption.
  • the crosslinked electrospun PVA nanofibrous mat acts as a porous skeleton with fine flexibility and internal gaps, leading to a high permeate flux during oil/water separation.
  • the PPy nanoparticles are deposited on the surface of the PVA nanofibers in a close-packed fashion, giving the membrane a rough surface with superhydrophilicity and underwater superoleophobicity (158°C) and an extremely low oil-adhesion property.
  • the ultra-porous structure with superwettability provides the membrane with the separation ability of surfactant-stabilized immiscible mixtures, with high separation efficiency (oil residue in filtrate after one-time separation lower than 0.01 wt %) and high flux.
  • PVA is less prone to oil fouling due to its intrinsic hydrophilicity.
  • the PPy coated on the surface of PVA further creates a hierarchical structure and superhydrophilic chemistry that act as an oil-repellent barrier, thereby enhancing the anti-fouling performance.
  • the NPM exhibited a 98% flux recovery ratio after continuous cyclic surfactant-stabilized oil-in-water emulsion separation.
  • solar steam generation was realized by placing an NPM on the seawater-air interface with solar irradiation. Owing to the high area-to-volume ratio of nanofibers and the high energy conversion efficiency of PPy, the densely packed PPy nanoparticles on the PVA fibers can quickly harvest the solar light and convert it into thermal energy.
  • the hydrophilic nature of PVA helps efficiently transport water due to capillary effects, sustaining a continuous water supply for steam generation.
  • the efficient solar energy absorption was verified by an over 99% light absorption of the material within a broadband wavelength (250 to 1100 nm).
  • a water evaporation rate of 2.87 kg m -2 h -1 was realized with one sun irradiation.
  • a solar steam generator was installed and utilized to collect purified water under natural sunlight and a freshwater collection capability of solar water purification yield of 14.3 I rrr 2 daily.
  • the oil-water separation and desalination performance of the NPM is compared with other related materials; the dual-functional NPM not only achieved a remarkably separation efficiency (>99.99%) but also demonstrated an excellent desalination performance (with the evaporation rate of 2.87 kg m -2 h -1 ).
  • the dualfunctional superwetting membrane represents a new approach to more effective purification of clean, safe drinkable water from any source, whether from the ocean or contaminated industrial supplies.
  • a method of preparing a water purification membrane comprising: electrospinning a quantity of polymers into nanofibers, said polymers selected from the group consisting of: polyvinyl alcohol (PVA); poly(N-isopropylacrylamide) (PNIPAM); poly(vinylidene fluoride) (PVDF); poly(methacrylic acid) (PMAA); and poly(acrylic acid) (PAA), forming a membrane from the nanofibers by crosslinking the nanofibers; depositing nanoparticles on the membrane by oxidation of pyrrole monomers; and washing the membrane.
  • PVA polyvinyl alcohol
  • PNIPAM poly(N-isopropylacrylamide)
  • PVDF poly(vinylidene fluoride)
  • PMAA poly(methacrylic acid)
  • PAA poly(acrylic acid)
  • the oxidation of pyrrole monomers is carried out slowly, for example, by carrying the reaction out at a low temperature. It is of note that suitable low temperatures will be readily apparent to one of skill in the art. In one exemplary example, the low temperature may be about 4C.
  • the oxidation of pyrrole monomers takes place in the presence of Fe ions.
  • the Fe ions are Fe (III) ions, for example, from FeCl 3 or Fe(NO 3 ) 3 .
  • the membrane may have a thickness of at least 0.2 mm.
  • the crosslinking agent may be glutaraldehyde.
  • the nanofibers prior to crosslinking, may be precrosslinked by exposure to a vaporous crosslinking agent, such as, for example, but by no means limited to glutaraldehyde.
  • a vaporous crosslinking agent such as, for example, but by no means limited to glutaraldehyde.
  • a method of purifying contaminated water comprising: flowing the contaminated water through a membrane prepared as described above, said membrane allowing water to flow therethrough, thereby purifying the water.
  • the contaminated water may be for example wastewater, salt water, contaminated water from an industrial process or contaminated water from an industrial accident.
  • a method of desalinating water comprising: flowing salt water through a membrane as described herein while exposed to light of at least one solar wavelength, said membrane allowing water to flow therethrough and converting the water to steam and condensing the steam, thereby recovering desalinated water.
  • the light of at least one solar wavelength may be for example sunlight or any suitable wavelength capable of sufficient absorption by the membrane so as to sufficiently heat the membrane, as discussed herein.
  • a method of purifying and desalinating contaminated salt water comprising: flowing the contaminated water through a membrane of claim 13 while exposed to light of at least one solar wavelength, said membrane allowing water to flow therethrough, thereby purifying the water; said membrane converting the water to steam and condensing the steam, thereby recovering desalinated water.
  • purification of water in all its grammatical forms, does not require absolute purity but only that the purity of the sample of water have been improved by the removal of a quantity of a contaminant. It is further noted that methods for determining the purity of water are well-known in the art and may be used for determining the purity of a sample of water both prior to and after exposure to the membrane of the invention.
  • ahigh oil contact angle is an important property because an oil contact angle higher than 150 degrees indicates oleophobicity of a material, which is why the membrane can repel oil droplets.
  • low sliding angles are a crucial property indicative of low oil adhesion, which provides the membrane with anti-fouling properties, meaning that the membrane is suitable for repeated use and long-term separation.
  • the membrane of the invention can absorb a large range of wavelengths from sunlight, which provides the membrane with high sunlight utilization efficiency. Furthermore, the membranes have low calculated equivalent enthalpy, which indicates that the membranes have high solar steam efficiency, as discussed herein.
  • GO content makes the membrane stronger but also more brittle. Accordingly, as discussed herein, suitable amounts of graphene oxide are added to the membrane depending on the intended use of the membrane. For example, If the membrane is in a fixed position, then flexibility of the membrane is not required. In these cases, GO content can go beyond 2%. As will be appreciated by one of skill in the art, a membrane with GO has the same functionality as a membrane without GO, but the addition of GO strengthens the membrane.
  • the reaction time is long enough so that all incorporated pyrrole monomer polymerize.
  • the percentage of the PPy in the membrane is exclusively dependent on the pyrrole monomer added in the reaction.
  • PPy has a similar effect on the membrane as GO, specifically, that more PPy means higher brittleness.
  • a moderate amount of PPy (10%) was used and found to maintain flexibility and strength of the membrane.
  • different percentages may be added, depending on the intended end use and the desired characteristics of the membrane.
  • PPy is black, which is ideal for light absorption.
  • shorter reaction times resulted in lower incorporation levels which in turn produced a membrane that is lighter in color (deep green) compared to a membrane with higher PPv incorporation.
  • Membranes with relatively lower incorporation have lower light absorption abilities, which, as discussed herein, is important at least for desalination.
  • the electrospun PVA membrane was first precrosslinked with glutaraldehyde vapor rather than solution, because the as- electrospun PVA nanofibers are dissolvable in glutaraldehyde water solution. After 24 hours of vapor treatment, the pre-crosslinked PVA membrane was processed with liquid phase crosslinking in glutaraldehyde acetone solution to further crosslink the PVA nanofibers. Until now, the PVA membrane was fully crosslinked and capable of keeping the integrity under water (referred as NPM1 ). Afterward, the membrane was dipped in a mixture of Fe 3+ and pyrrole monomer solution.
  • the scale of the PPy nanoparticle layer on the surface was controlled to be much smaller than the PVA nanofibers to construct a hierarchical nanostructure.
  • this reaction is temperature sensitive. Specifically, higher temperatures will overly accelerate the reaction and will cause the polymerized pyrrole agglomerate deposit as clusters on the membrane. If the reaction is carried out at a temperature below room temperature, for example, about 4C, the nanoparticles are approximately evenly deposited on the membrane which in turn gives rise to a nano-hierarchical structure.
  • PPy nanoparticles significantly roughen the surface and provide the membrane with superhydrophilicity/superolephobicity, which plays a critical role in the separation of surfactant-stabilized immiscible oil/water mixture as well as fouling-resistant properties, as discussed herein.
  • the entangled PVA fibers form a porous interconnected 3D network with irregular interstice.
  • the mechanical properties of the membrane were modified by adding GO during electrospinning based on GO’S high Young’s modulus and strong mechanical properties.
  • the ratio of GO and PVA was investigated to understand its effect on the mechanical properties of the membrane.
  • the mechanical properties of the NPM can be adjusted by varying the ratio of reinforcement (GO) and matrix (PVA). As predicted, by changing the ratio of GO to PVA from 0 to 0.3% led to a decrease of elongation from 60.07% to 17.14% and an increase of modulus from 10.42 MPa to 114.36 MPa.
  • the tensile strength of the nanofibers With a decrease of the GO/PVA ratio, the tensile strength of the nanofibers initially increased. At the 0.3% ratio of GO/PVA, the nanofiber membranes exhibited the ultimate tensile strength of 6.08 MPa and the strain at break of 17.14%. However, the high ratio of GO/PVA results in brittleness in mechanical property, which is undesirable in the separation. Given that PPy will further strengthen the material, 0.2% GO/PVA was chosen as an optimal amount which possesses high strength but also a reasonable flexibility. As discussed herein, the strength and flexibility characteristics can be varied according to the intended end use.
  • Figure 2g shows typical stress-strain curve of the NPM with different extent of PPy coating.
  • the mechanical property of NPM is tunable by changing the proportion of rigid constituent (PPy) and flexible constituent (PVA).
  • NPM1 The crosslinked PVA membranes (NPM1 ) are immersed in pyrrole monomer solution for 5 hours (NPM2), 1 day (NPM3), 2 days (NPM4) and 3 days (NPM5), respectively.
  • NPM2 pyrrole monomer solution
  • NPM3 1 day
  • NPM4 2 days
  • NPM5 3 days
  • the NPM5 shows the highest strength at break of 9.69 MPa and a Young's modulus of 159.37 MPa with an elongation of 8.75%, comparing to the NPM1 with lower modulus (10.42 MPa) and higher flexibility (fracture strain at 33.75%).
  • NPM1 exhibits a water contact angle of 13° and an underwater oil contact angle of 123°.
  • the water contact angle reduces to 0° and the underwater oil contact angle increases to 132°.
  • more PPy nanoparticles are synthesized and deposited onto the surface of the PVA nanofibers, leading to higher hydrophilicity and oleophobicity with an underwater oil contact angle of 148° after 1 day.
  • the water contact angle stays at 0° while the underwater oil contact angle increases to approximately 152°.
  • a surfactant-free oil/water mixture was prepared by sonicating a 10% petroleum ether-in-water mixture for 10 minutes in a water bath.
  • NPM5 with a diameter of 8 mm and a thickness of 200 pm was fixed in between a funnel and an Erlenmeyer flask.
  • the oil-in-water emulsion was transferred into the funnel, which was in direct contact with NPM5.
  • the oil-water emulsion was demulsified once in contact with the membrane as water permeated through NPM5 and oil remained above.
  • the filtered water was examined (Figure 5d) to study the separation efficiency by counting the oil droplets residue after separation.
  • Membrane permeability was comprehensively investigated.
  • the fluxes of sundry solvent-in-water emulsions were measured as shown in Figure 6a.
  • the separation fluxes are all above 2638 L m -2 h -1 for surfactant free emulsion and 1271 L m -2 h -1 for surfactant- stabilized emulsion.
  • the flux of hexane-in-water emulsion is the highest (12689 L m -2 while the flux of surfactant-stabilized hexane-in-water emulsion is 3962 L m -2 h -1 .
  • the average droplet size of surfactant free hexane-in-water emulsion is 2327 nm while the average droplet size of surfactant stabilized hexane-in-water emulsion is 510.4 nm, which is a 78% reduction in hexane droplet size in the presence of surfactant.
  • the average droplet size of surfactant free petroleum ether-in-water emulsion is 1873 nm while the average droplet size of surfactant stabilized petroleum ether-in-water emulsion is 713.4 nm, which is a 62% reduction in petroleum ether droplet size in the presence of surfactant.
  • the moderately larger change of hexane micelle size after inducing surfactant is consistent with the bigger difference of fluxes of separating surfactant-free and surfactant-stabilized emulsions.
  • the larger droplet size of hexane is consistent with the result of slightly higher flux during the separation compared to petroleum ether.
  • the membrane exhibited high separation efficiency (>99.99%) in oil-in-water emulsions after 20 separations, indicating the stability of the membrane ( Figure 6b). Furthermore, the 0.01 % sodium dodecyl sulfate (SDS) stabilized emulsions are left unshaken for a prolonged period of time. As can be seen from Figure 7e-f, no stratification was observed after 15 days, exhibiting excellent separation efficiency of stabilized emulsions of the membrane. As can be observed from the above separation results, the NPM shows prominent performance in oil or organic solvents/water separation for surfactant-free or surfactant-stabilized oil-in- water emulsion. The membrane can quickly absorb water as soon as it is in contact with the emulsion mixture. Afterwards, the superhydrophilic and underwater superoleophobic properties allow water to instantly permeate through the membrane while the oil phase remains above.
  • the NPM is capable of resisting acidic/alkaline conditions in severe pH environments.
  • Figure 6c shows water contact angles of NPM in artificial sea water with varying pH.
  • the oil-in-water acidic or alkaline emulsion was prepared by mixing 10% of organic solvent and artificial seawater with the addition of HCI or NaOH solution to adjust the pH.
  • the filtration device was the same as described above, with the membrane fixed in between the rims of flask and the funnel. After the equipment was set up, the emulsion was poured into the funnel under 0.2 bar pressure. In this case, hexane-in-water emulsion was selected as an example.
  • the cloudy emulsion transformed into transparent, clear water in the flask, indicating potent separation.
  • the as-prepared NPM can separate stabilized micro and nanoscale oil-in-water emulsions effectively under acid, basic and briny conditions.
  • the as-described membrane can retain the superhydrophilicity/underwater superoleophobicity property under harsh environments.
  • the membrane shows extremely high efficiency (>99.6%) under a wide range of pH value, indicating its stability under complex separation environments. The above results indicate that the NPM has the capability of resisting acidic/basic environment under a series of pH conditions.
  • the droplet was deformed into an ellipsoid while during the lifting process, the droplet shape returned to a sphere and no further deformation was observed when the droplet was detached from the membrane surface. Similar phenomenon was observed when highly viscous mechanical pump oil was utilized in the test. The results demonstrate the extremely low adhesion between the oil droplet and the NPM, which is beneficial for relieving oil-fouling during separation.
  • the NPM5 also possesses easy-cleaning properties.
  • the NPM1 and NPM5 were immersed in mechanical pump oil, followed by shaking in DI water. As can be seen from Figure 8a, oil droplets were easily shed from the NPM5 after shaking in water and the oil droplets can be observed from surface of the water.
  • a cyclic filtration test was carried out on the NPM with several foulants including surfactant (SDS), Bovine Serum Albumin (BSA) and humic acid (HA).
  • SDS surfactant
  • BSA Bovine Serum Albumin
  • HA humic acid
  • FRR flux recovery ratio
  • Mechanical pump oil was utilized in this test in view of its similar composition to crude oil (petroleum distillates) and high viscosity.
  • surfactant free mechanical pump oil-in-water emulsion was tested and the relative flux result is shown in Figure 8b.
  • the FRR of NPM5 maintained beyond 98% after 420 min of repeated separation and washing processes, compared to the FRR of 87% of NPM1 .
  • the FRR of NPM 5 maintained at the level of 95% after cyclic test of both HA mixed emulsion and BSA mixed emulsion. In contrast, the FRR of NPM1 decreased to 71 % for HA mixed emulsion and 73% for BSA mixed emulsion, respectively.
  • the NPM5 shows outstanding anti-fouling property as well as longevity for heavy-duty emulsion separation.
  • the underwater superoleophobicity/superhydrophilicity of the NPM was studied.
  • the solid surface wetting behavior is generally calculated by the contact angle as follows: (1 ) in which y sg is the solid-vapor interfacial energy, y sl is the solid-liquid interfacial energy and ylg is the liquid-vapor interfacial energy.
  • Y oi i-g is the oil-gas interface tension
  • v water-g is the water/gas interface tension
  • v oii-water is interface tension of oil and water interface
  • Equation 2 the phenomenon of a hydrophilic surface in air becoming oleophobic can be explained. If we use dichloromethane as an example, the water surface tension , while the interfacial tension of gas The dichloromethane-water interfacial tension Y oii-water is 28.3 mN With the presence of air, the dichloromethane contact angle on NPM ⁇ measured is almost 0, while water contact angle ⁇ -was 57.5. As indicated in Equation -0.49, therefore, ⁇ 3 equals to 155°, indicating the NPM behaved as a superoleophobic surface in water.
  • FIG. 9a The experiment installation of a solar vapor generation is shown in Figure 9a.
  • the installation is composed of a water supply, a sunlight simulator and an NPM as the functional light converter.
  • the membrane is floating on the surface of a container filled with water, while the sun simulator is perpendicularly illuminating the whole system from above.
  • NPM5 samples with a diameter 10 mm and a thickness of 200 pm are utilized for solar steam generation.
  • Figure 9b shows the temperature change with respect to time under 1 sun irradiation.
  • ambient temperature of 22°C bulk water started with a temperature of 18.9°C and reached 27.3°C after 5 min of illumination.
  • NPM5 the temperature of water rapidly increased to 39.4°C after 5 min of irradiation, demonstrating a remarkable solar-to-heat conversion ability.
  • Figure 9c demonstrates the effect of PPy on mass change under 1 sunlight and 0.5 sun illumination with respect to time. Once the solar steam reaches an equilibrium state, the evaporation rates under various Copt were recorded in Figure 9d.
  • NPM5 shows such outstanding solar vapor efficiency
  • the optical properties of NPM1 and NPM5 were measured via a UV-vis Spectrometer Ultraspec 4300 pro from 250-1100 nm.
  • the elestrospun PVA membrane (NPM1 ) shows mediocre light absorption properties due to the intrinsically high reflectivity of PVA nanofibers.
  • the surface becomes less reflective (the sunlight cannot be reflected, thus it shows a dark black appearance in macro scale) because of the excellent light absorbability of the PPy.
  • the light absorption of the NPM5 can reach 99.9% within a broad wavelength range from 250 nm to 1100 nm.
  • the absorption of PVA membrane can only reach 65% at 250 nm and 90% absorption along most wavelengths.
  • the corresponding energy efficiency (q) for solar steam generation was calculated using the following formula: where m refers to the mass flux, hv refers the evaporation enthalpy of water stored in the membrane, Po refers to the solar radiation power of 1 sun (1 kW m -2 ), while Copt is the optical concentration of the sunlight simulator. It is observed that the evaporation enthalpy of bulk water is larger than that in the NPM.
  • water cluster theory can be used to understand this increase in evaporation enthalpy. Either as one molecule or as clusters with multiple molecules, water can be evaporated and escape the liquid-air interface.
  • Figure 10c is the IR images of heat distribution of the NPM floating at the airliquid interface while sunlight irradiation starts from 0 s to 300 s.
  • the surface temperature of the NPM rapidly increases to 41.6°C during the first 300 s of irradiation.
  • the thermal distribution of the membrane surface shows minor changes after 300 s, ultimately reaching the highest at 42.3 °C, compared to the water temperature underneath the membrane which shows insignificant increase due to the low thermal conductivity of the material.
  • FIG. 1 1 b illustrates the concentration of Na, Ca, Mg and K ions.
  • FIG. 1 c illustrates the evaporation efficiency of a NPM under 20 cycles. The test was held under 1 sun irradiance and the membrane was washed and dried after each use. The evaporation rates of the 20 cycles fit in a narrow range between 2.72 and 2.91 kg m -2 h -1 .
  • a prototype water purification system utilizing NPM5 was used for on-site purification testing.
  • an NPM5 with 10 cm diameter and 200 pm thickness was fabricated ( Figure 11 e).
  • a brine tank with a floating NPM5 at the surface was placed in a plastic chamber for steam condensation.
  • the purified water was recovered by a tube connecting condensation chamber and a water bottle.
  • the natural sunlight led to an average per day purified water yield of ⁇ 1.2 L m -2 h -1 .
  • COMSOL Multiphysics a simulation software for multiphysics simulation
  • a steady-state heat transfer module was used because the actual experiment occurred under quasisteady conditions, with constant evaporation rate.
  • the oil/water separation efficiency is over 99.99% with the highest flux of 12740 L m -2 h -1 for surfactant free oil/water emulsions and 6503 L m -2 h -1 for surfactant-stabilized emulsions with sundry organic solvents emulsions. Due to the porous architecture of NPM5 and its high thermal insulation, the conductive heat loss to bulk water during sunlight illumination was reduced, thereby increasing the solar energy efficiency.
  • the PPy coated PVA membrane demonstrate the ability to absorb a wide range of wavelengths (250-1100 nm) of sunlight to thermal energy with an absorbance of over 99.9%. Thanks to the low thermal conductivity of PVA, the thermal energy was restrained in the NPM, achieving high energy localization.
  • the NPM solar steam system demonstrates a solar steam generation efficiency around 87.5% with an evaporation rate of 2.87 kg nr 2 h ⁇ 1 under 1 sun irradiation.
  • the proof-of-concept method toward oil/water separation and seawater desalination provides a solution for the real-life application of efficient, scalable oil/water separation, desalination and wastewater purification.
  • glutaraldehyde G, 25% aqueous solution, Alfa Aesar
  • pyrrole 98%+, Alfa Aesar
  • Iron(lll) nitrate anhydrous, 98%, Alfa Aesar
  • hydrochloric acid HCI, 37% reagent grade, Sigma Aldrich
  • GO Teanfeng Tech. Inc., China
  • BSA Sigma-Aldrich
  • humic acid Millipore Sigma.
  • Deionized water was obtained water from EASYpure II LF ultrapure water system.
  • PVA powder 10 g was dissolved in 90 g of water under vigorous stirring for 6 h to prepare 10% PVA solution. Different concentrations of GO were homogeneously mixed into the PVA solution with vortex mixer. The PVA-GO mixture was added in a 10 ml syringe fitted with 18G flat end stainless steel needle. Electrospinning of the PVA-GO mixture was set up with a 15-18 KV high voltage and the distance between the tip of the needle and the collector was 165 mm.
  • the PVA solution was pumped out by a syringe pump (PHD2000, Harvard Apparatus) at a flow rate of 5 mL/h to achieve a continuous nanofiber deposition and the NPM were formed onto a textiled nickel mesh (10 cm X 10 cm) as a collector.
  • PLD2000 Harvard Apparatus
  • the obtained PVA-GO membranes were instantaneously dissolved in water as PVA has a high swell ratio and fibers can fuse with each other.
  • the electrospun GO-PVA mat was pre-crosslined with glutaraldehyde vapor.
  • the pre-crosslink was carried out by exposure of the as-electrospun PVA-GO mat to with 600 pl GA(2.6M) and 200 pl HCI (37%) in a sealed container for 24 hours.
  • the GO-PVA membrane was immersed in 40 ml acetone solution with 500 pl GA for further crosslinking.
  • the originally separate nanofibers merged and entangled among each other and bonding was formed at the intersection points between the nanofibers.
  • the membranes were washed with distilled water 5 times, before drying under ambient atmosphere.
  • the membrane was referred to as NPM1 .
  • the crosslinked PVA-PPy-GO membrane was coated with PPy via in situ polymerization of pyrrole.
  • the crosslinked membrane was soaked in 10 ml solution of 8 wt% Fe(lll) nitrate for 20 min under 4°C. Afterwards, another solution containing 340 pl of pyrrole dissolved in 10 ml of deionized water was added under 4°C. After polymerization for 3 days, the PPy coated membrane was taken out of the solution, washed with deionized Milli-Q water and dried at ambient atmosphere.
  • FTIR Fourier-transform infrared
  • Underwater oil contact angle and water contact angle were tested on a goniometer (JY-PHA, Shengding, China).
  • a 5 pl chosen organic solvent or oil was dispensed on a NPM placed in a water-filled petri-dish.
  • a 15 pl chosen organic solvent or oil droplet was placed on the membrane and the sliding angle was the minimum tilt angle required for the droplet to move.
  • the anti-fouling capability of the NPM was evaluated by a self-cleaning experiment: a NPM was immersed in canola oil, followed by transferring the NPM to a container filled with DI water. The container was gently shacked to remove the oil from the NPM. Dynamic oil adhesion test was carried out to examine the capability of the NPM to repel oil with high viscosity, in which a 5 pl of highly viscous mechanical pump oil was pressed on the surface of NPM and subsequently detached from the membrane surface.
  • Surfactant-free oil/water emulsion was prepared by sonicating a 10% chosen organic solvent-in-water mixture for 10 minutes in water bath.
  • the surfactant- stabilized emulsion was prepared by mixing 0.01 % SDS into 500 ml of DI water, followed by adding 50 ml chosen organic solvent or oil into the solution.
  • a homogenized emulsion was obtained after sonicating the oil/surfactant/water mixture for 2 h in water bath.
  • the organic solvent/oil droplet size was measured by a dynamic light scattering machine (Zetasizer, Nano-ZS, Malvern, UK) and optical microscopy (Micromaster, Fisher Scientific).
  • the oil content was measured by a total organic carbon (TOC) analyzer (7000RMS, Mettler Toledo, Canada).
  • the separation efficiency of the NPM was calculated by comparing the oil content before (Co) and after (C P ) filtration according to the following equation:
  • a sun tester (Suntest XLS+, ATLAS) was utilized to test out the solar vapor generation performance of NPM.
  • the solar irradiance was set as 1 kW m -2 .
  • the NPM5 sample was cut into a round shape with diameter of 8 cm -2 .
  • a NPM5 (-200 pm in thickness) was placed and floated on simulated seawater water (or DI water as control group) in a beaker.
  • the set-up was located in the beam spot with various solar irradiance.
  • a weight balance was utilized to measure the water evaporation performance. Prior to radiation of the experimental set-up, the evaporation rate without any light source was calculated with the beaker placed in dark environment for 1 h. The evaporation rate without any light source was deducted from the solar irradiated evaporation rate.

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Abstract

La présente invention concerne une membrane de purification d'eau nanostructurée hiérarchique fabriquée avec des nanofibres de l'alcool polyvinylique (PVA) et des nanoparticules de polypyrrole (PPy) pour obtenir une séparation d'émulsion efficace avec une faible propriété d'adhérence à l'huile ainsi qu'un dessalement de l'eau de mer à haut débit. La membrane présente les propriétés intégrées de robustesse mécanique, de mouillabilité super-hydrophile/sous-marine superoléophobe et d'absorption solaire à large bande.
PCT/CA2021/051171 2020-08-25 2021-08-24 Membrane nanostructurée supermouillable à double fonction WO2022040790A1 (fr)

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CN114515518A (zh) * 2022-03-07 2022-05-20 四川大学 一种皮胶原纤维基复合膜材料及其制备方法和应用
CN114832647A (zh) * 2022-05-25 2022-08-02 中国海洋大学 一种温敏型可切换乳液型油水分离膜的制备方法与应用
CN114950156A (zh) * 2022-07-15 2022-08-30 中国科学院苏州纳米技术与纳米仿生研究所 仿鱼鳃结构的纳米纤维复合薄膜、其制备方法及应用
CN115006996A (zh) * 2022-06-15 2022-09-06 南京林业大学 一种不对称润湿性的Janus木膜、制备方法及其应用
CN115092982A (zh) * 2022-07-05 2022-09-23 中山大学 截留-蒸发界面分离型光热蒸发装置及其制备方法和应用
CN115230270A (zh) * 2022-08-18 2022-10-25 江苏省农业科学院 一种双响应高效生物基复合水凝胶体系及制备方法和应用

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WO2006098872A2 (fr) * 2005-03-09 2006-09-21 The Regents Of The University Of California Membranes nanocomposites et procedes de fabrication et d'utilisation associes
KR20150097257A (ko) * 2014-02-18 2015-08-26 전북대학교산학협력단 수처리용 나노복합재 분리막 및 그 제조 방법

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Publication number Priority date Publication date Assignee Title
WO2006098872A2 (fr) * 2005-03-09 2006-09-21 The Regents Of The University Of California Membranes nanocomposites et procedes de fabrication et d'utilisation associes
KR20150097257A (ko) * 2014-02-18 2015-08-26 전북대학교산학협력단 수처리용 나노복합재 분리막 및 그 제조 방법

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114515518A (zh) * 2022-03-07 2022-05-20 四川大学 一种皮胶原纤维基复合膜材料及其制备方法和应用
CN114832647A (zh) * 2022-05-25 2022-08-02 中国海洋大学 一种温敏型可切换乳液型油水分离膜的制备方法与应用
CN114832647B (zh) * 2022-05-25 2023-08-11 中国海洋大学 一种温敏型可切换乳液型油水分离膜的制备方法与应用
CN115006996A (zh) * 2022-06-15 2022-09-06 南京林业大学 一种不对称润湿性的Janus木膜、制备方法及其应用
CN115092982A (zh) * 2022-07-05 2022-09-23 中山大学 截留-蒸发界面分离型光热蒸发装置及其制备方法和应用
CN115092982B (zh) * 2022-07-05 2023-09-22 中山大学 截留-蒸发界面分离型光热蒸发装置及其制备方法和应用
CN114950156A (zh) * 2022-07-15 2022-08-30 中国科学院苏州纳米技术与纳米仿生研究所 仿鱼鳃结构的纳米纤维复合薄膜、其制备方法及应用
CN114950156B (zh) * 2022-07-15 2024-01-26 中国科学院苏州纳米技术与纳米仿生研究所 仿鱼鳃结构的纳米纤维复合薄膜、其制备方法及应用
CN115230270A (zh) * 2022-08-18 2022-10-25 江苏省农业科学院 一种双响应高效生物基复合水凝胶体系及制备方法和应用

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