CN117619160A - Method for producing hollow fiber composite membrane and hollow fiber composite membrane - Google Patents
Method for producing hollow fiber composite membrane and hollow fiber composite membrane Download PDFInfo
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- CN117619160A CN117619160A CN202211038648.9A CN202211038648A CN117619160A CN 117619160 A CN117619160 A CN 117619160A CN 202211038648 A CN202211038648 A CN 202211038648A CN 117619160 A CN117619160 A CN 117619160A
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- 239000012528 membrane Substances 0.000 title claims abstract description 150
- 239000012510 hollow fiber Substances 0.000 title claims abstract description 110
- 239000002131 composite material Substances 0.000 title claims abstract description 109
- 238000004519 manufacturing process Methods 0.000 title claims description 3
- 239000004698 Polyethylene Substances 0.000 claims abstract description 97
- -1 polyethylene Polymers 0.000 claims abstract description 97
- 229920000573 polyethylene Polymers 0.000 claims abstract description 97
- 239000000654 additive Substances 0.000 claims abstract description 64
- 238000005266 casting Methods 0.000 claims abstract description 62
- 230000000996 additive effect Effects 0.000 claims abstract description 56
- 238000009987 spinning Methods 0.000 claims abstract description 48
- 238000000034 method Methods 0.000 claims abstract description 47
- 230000002787 reinforcement Effects 0.000 claims abstract description 40
- 238000000926 separation method Methods 0.000 claims abstract description 36
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 28
- 239000003085 diluting agent Substances 0.000 claims abstract description 26
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 42
- 239000000835 fiber Substances 0.000 claims description 35
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 25
- 238000000605 extraction Methods 0.000 claims description 24
- 239000000203 mixture Substances 0.000 claims description 22
- 239000000377 silicon dioxide Substances 0.000 claims description 21
- 239000002202 Polyethylene glycol Substances 0.000 claims description 20
- 229920001903 high density polyethylene Polymers 0.000 claims description 20
- 239000004700 high-density polyethylene Substances 0.000 claims description 20
- 238000002156 mixing Methods 0.000 claims description 20
- 229920001223 polyethylene glycol Polymers 0.000 claims description 20
- 239000011148 porous material Substances 0.000 claims description 19
- 239000000084 colloidal system Substances 0.000 claims description 17
- 239000007788 liquid Substances 0.000 claims description 17
- 229920002037 poly(vinyl butyral) polymer Polymers 0.000 claims description 15
- NNBZCPXTIHJBJL-UHFFFAOYSA-N decalin Chemical compound C1CCCC2CCCCC21 NNBZCPXTIHJBJL-UHFFFAOYSA-N 0.000 claims description 14
- 239000003921 oil Substances 0.000 claims description 14
- 235000019198 oils Nutrition 0.000 claims description 14
- 229920000642 polymer Polymers 0.000 claims description 14
- 229920000728 polyester Polymers 0.000 claims description 12
- 239000004699 Ultra-high molecular weight polyethylene Substances 0.000 claims description 11
- 229920000785 ultra high molecular weight polyethylene Polymers 0.000 claims description 11
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 10
- 238000005345 coagulation Methods 0.000 claims description 10
- 230000015271 coagulation Effects 0.000 claims description 10
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 claims description 9
- 238000009826 distribution Methods 0.000 claims description 9
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 8
- 238000001035 drying Methods 0.000 claims description 8
- 238000005406 washing Methods 0.000 claims description 8
- 239000005038 ethylene vinyl acetate Substances 0.000 claims description 7
- 239000000155 melt Substances 0.000 claims description 7
- 229920001200 poly(ethylene-vinyl acetate) Polymers 0.000 claims description 7
- PXXNTAGJWPJAGM-UHFFFAOYSA-N vertaline Natural products C1C2C=3C=C(OC)C(OC)=CC=3OC(C=C3)=CC=C3CCC(=O)OC1CC1N2CCCC1 PXXNTAGJWPJAGM-UHFFFAOYSA-N 0.000 claims description 7
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 6
- 239000003960 organic solvent Substances 0.000 claims description 6
- 238000000746 purification Methods 0.000 claims description 6
- CXWXQJXEFPUFDZ-UHFFFAOYSA-N tetralin Chemical compound C1=CC=C2CCCCC2=C1 CXWXQJXEFPUFDZ-UHFFFAOYSA-N 0.000 claims description 6
- 238000000498 ball milling Methods 0.000 claims description 5
- 239000004408 titanium dioxide Substances 0.000 claims description 5
- 239000004743 Polypropylene Substances 0.000 claims description 4
- USIUVYZYUHIAEV-UHFFFAOYSA-N diphenyl ether Chemical compound C=1C=CC=CC=1OC1=CC=CC=C1 USIUVYZYUHIAEV-UHFFFAOYSA-N 0.000 claims description 4
- 229920001155 polypropylene Polymers 0.000 claims description 4
- 239000011780 sodium chloride Substances 0.000 claims description 4
- 229920000219 Ethylene vinyl alcohol Polymers 0.000 claims description 3
- 239000004952 Polyamide Substances 0.000 claims description 3
- 229920001400 block copolymer Polymers 0.000 claims description 3
- 239000001110 calcium chloride Substances 0.000 claims description 3
- 229910001628 calcium chloride Inorganic materials 0.000 claims description 3
- 229920006242 ethylene acrylic acid copolymer Polymers 0.000 claims description 3
- 229920002647 polyamide Polymers 0.000 claims description 3
- 239000011787 zinc oxide Substances 0.000 claims description 3
- 229920003171 Poly (ethylene oxide) Polymers 0.000 claims description 2
- 125000004122 cyclic group Chemical group 0.000 claims description 2
- LYCAIKOWRPUZTN-UHFFFAOYSA-N ethylene glycol Substances OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 2
- 239000003350 kerosene Substances 0.000 claims description 2
- 229940057995 liquid paraffin Drugs 0.000 claims description 2
- XNGIFLGASWRNHJ-UHFFFAOYSA-L phthalate(2-) Chemical compound [O-]C(=O)C1=CC=CC=C1C([O-])=O XNGIFLGASWRNHJ-UHFFFAOYSA-L 0.000 claims description 2
- 235000012424 soybean oil Nutrition 0.000 claims description 2
- 239000003549 soybean oil Substances 0.000 claims description 2
- 239000000463 material Substances 0.000 abstract description 6
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 12
- 238000002360 preparation method Methods 0.000 description 10
- 239000002994 raw material Substances 0.000 description 10
- 235000012239 silicon dioxide Nutrition 0.000 description 10
- 238000005516 engineering process Methods 0.000 description 9
- 238000004804 winding Methods 0.000 description 9
- 238000002145 thermally induced phase separation Methods 0.000 description 8
- 230000001112 coagulating effect Effects 0.000 description 7
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 5
- 239000003361 porogen Substances 0.000 description 5
- 239000002904 solvent Substances 0.000 description 5
- 230000004907 flux Effects 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 229920001747 Cellulose diacetate Polymers 0.000 description 3
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 3
- 238000001000 micrograph Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 238000005191 phase separation Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 239000012982 microporous membrane Substances 0.000 description 2
- 238000000614 phase inversion technique Methods 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 239000004753 textile Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 239000004695 Polyether sulfone Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000005273 aeration Methods 0.000 description 1
- 238000007605 air drying Methods 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000000748 compression moulding Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 239000007822 coupling agent Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 229910021389 graphene Inorganic materials 0.000 description 1
- 230000002209 hydrophobic effect Effects 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 230000009965 odorless effect Effects 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 229920002492 poly(sulfone) Polymers 0.000 description 1
- 229920006393 polyether sulfone Polymers 0.000 description 1
- 229920006254 polymer film Polymers 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 229920006126 semicrystalline polymer Polymers 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 239000008096 xylene Substances 0.000 description 1
Classifications
-
- 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
- B01D69/08—Hollow fibre membranes
-
- 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
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention relates to the technical field of membrane separation materials, in particular to a method for preparing a hollow fiber composite membrane and the hollow fiber composite membrane. The method comprises the following steps: (1) Providing a casting solution containing polyethylene, a hydrophilic additive, a pore-forming agent and a diluent; (2) And the casting solution is combined on the outer surface of the tubular reinforcement body by adopting a concentric circle composite spinning mode. The method can effectively improve the hydrophilicity of the polyethylene hollow fiber composite membrane and improve the mechanical property of the polyethylene hollow fiber composite membrane, so that the obtained hollow fiber composite membrane can meet the requirements of application scenes such as a membrane bioreactor system and the like.
Description
Technical Field
The invention relates to the technical field of membrane separation materials, in particular to a method for preparing a hollow fiber composite membrane and the hollow fiber composite membrane.
Background
The membrane separation technology is a novel separation technology formed by intersecting and fusing multiple subjects such as materials, textile, chemical industry, environment and the like, has the characteristics of high efficiency, environmental protection, energy conservation and the like, and plays an important role in solving the water resource crisis, environmental and energy problems and the like. The hollow fiber microporous membranes are mostly prepared by adopting a solution phase inversion method, such as polysulfone, polyethersulfone, polyvinylidene fluoride and the like, but the membranes often have the defects of poor mechanical property, acid and alkali resistance, poor chemical reagent resistance and the like, and are limited in application in a plurality of fields, such as sewage treatment of a Membrane Bioreactor (MBR) system, filtration of liquid with strong acidity or alkalinity, purification or purification of an organic solvent and the like.
Polyethylene (PE) is nontoxic and odorless white powder or particles, has milky appearance, good chemical stability, thermal stability and water resistance, good mechanical property, easily obtained raw materials and low cost, and is one of the most widely used polymer film materials at present. However, PE is a semi-crystalline polymer, and is insoluble in any organic solvent at normal temperature, so that the conventional solution phase inversion method cannot be used to prepare PE hollow fiber membranes. PE belongs to thermoplastic polymers and can form homogeneous solutions with certain solvents at high temperatures. PE hollow fiber membranes can be generally prepared by a melt spinning-stretching process (MS-S) and a Thermally Induced Phase Separation (TIPS) process. Although the MS-S method does not need to add any organic solvent in the spinning membrane preparation process, and has no pollution to the environment, the prepared hollow fiber membrane has capillary holes with larger pore diameters, wider pore diameter distribution, larger difficulty in pore diameter regulation and control, poor hydrophilicity, lower tensile strength and the like, so the application is limited to a certain extent. The PE hollow fiber membrane prepared by the TIPS method has narrower pore size distribution, but the tensile strength of the membrane is still lower, such as the membrane is subjected to compression of high-pressure water flow for a long time in an MBR system, aeration impact disturbance and frequent cleaning, which can cause larger damage to membrane wires, and the problems of membrane wire breakage or fracture and the like are easy to occur, so that the reliability and the service life of the membrane operation are seriously affected.
CN103143272a discloses a preparation method of polyethylene microporous membrane, melt mixing composition containing ultra-high molecular weight polyethylene and diluent at a certain temperature, making into film by compression molding, removing diluent, washing, drying and shaping to obtain polyethylene microporous membrane, pore size distribution of the membrane is uniform, porosity is high, but the obtained membrane is a flat membrane, strength of the membrane is low, and hydrophilicity is poor. CN110523298A discloses a preparation method of reinforced polyethylene hollow fiber membrane, which comprises the steps of mixing a film forming polymer system composed of polyethylene, graphene oxide, a coupling agent, a hydrophilic agent, a diluent, a pore-forming agent and the like at high speed to prepare a film forming material, cutting the film forming material into narrow strips of 7-50 mm through a dividing and cutting machine, sending the narrow strips into winding equipment, winding the narrow strips on an organic fiber woven tube to prepare a hollow fiber tube, separating the diluent and the pore-forming agent from the hollow fiber tube through gas phase or liquid phase separation, and sintering the hollow fiber tube at low temperature to obtain the reinforced polyethylene hollow fiber membrane. CN102068918A discloses a hydrophilic polyethylene hollow fiber membrane and a preparation method thereof, comprising: preparing a hydrophobic primary polyethylene hollow fiber membrane in advance, immersing the primary hollow fiber membrane in a cellulose diacetate solution with the concentration of 2-5%, fully immersing the cellulose diacetate solution into pores of membrane filaments, and removing a solvent of the cellulose diacetate solution to prepare the hydrophilic polyethylene hollow fiber membrane. Although the method can improve the hydrophilicity of the polyethylene hollow fiber membrane, the strength of the membrane filaments is lower and the solvent resistance of the surface of the membrane filaments is poor.
Disclosure of Invention
The invention aims to solve the problems that an MBR system in the prior art has high strength requirement on a polyethylene hollow fiber membrane, the polyethylene hollow fiber membrane is difficult to carry out hydrophilic modification and the like, and provides a method for preparing a hollow fiber composite membrane and the hollow fiber composite membrane. The method provided by the invention is simple and feasible, has low cost, and the prepared hollow fiber membrane has high strength and good hydrophilicity, and solves the problem that the polyethylene hollow fiber membrane is difficult to hydrophilically modify by a melt spinning-stretching method.
In order to achieve the above object, an aspect of the present invention provides a method of preparing a hollow fiber composite membrane, the method comprising:
(1) Providing a casting solution containing polyethylene, a hydrophilic additive, a pore-forming agent and a diluent;
(2) And the casting solution is combined on the outer surface of the tubular reinforcement body by adopting a concentric circle composite spinning mode.
The second aspect of the invention provides a hollow fiber composite membrane, which is prepared by adopting the method as described above;
alternatively, the hollow fiber composite membrane comprises a reinforcement and a surface separation layer, wherein the surface separation layer contains polyethylene and a hydrophilic additive and has a spongy pore structure, and the surface separation layer is partially embedded into the reinforcement to form a composite interface.
In a third aspect, the present invention provides a hollow fiber composite membrane prepared according to the method as described above or the use of a hollow fiber composite membrane as described above in purification and purification of a membrane bioreactor and/or an organic solvent.
Through the technical scheme, the invention has the following beneficial effects:
(1) The polyethylene hollow fiber composite membrane obtained by the method provided by the invention is composed of the surface separation layer inner reinforcement body partially embedded into the reinforcement body, so that the strength of the polyethylene hollow fiber membrane is effectively improved, the mechanical property of membrane wires is improved, and meanwhile, the hydrophilicity of the hollow fiber composite membrane is improved due to the adoption of a proper hydrophilic additive in the surface separation layer. The hollow fiber composite membrane completely meets the requirements of Membrane Bioreactor (MBR) systems and the like on the mechanical properties of membrane filaments, has good hydrophilicity, and expands the application range of polyethylene hollow fiber membranes;
(2) According to the method provided by the invention, core liquid is not required to be used in the cavity of the fiber woven tube in the spinning process, the thickness of the external separation layer is controllable, the preparation process is simple and easy to operate, and the quality stability can be ensured;
(3) In the method provided by the invention, the problem that the polyethylene hollow fiber membrane is difficult to hydrophilize and modify by adopting a mode of blending the hydrophilic additive and the polyethylene is solved, the anti-pollution performance of the membrane yarn is improved, and the service life of the membrane yarn is prolonged. The invention has simple hydrophilization process, low cost and easy scale application.
Drawings
FIG. 1 is a cross-sectional overall view of a polyethylene hollow fiber composite membrane A1 obtained in example 1 of the present invention;
FIG. 2 is a partially enlarged cross-sectional electron microscopic view of the polyethylene hollow fiber composite membrane A1 obtained in example 1 of the present invention;
FIG. 3 is an electron microscopic view of the outer surface of the polyethylene hollow fiber composite membrane A1 obtained in example 1 of the present invention.
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
The inventor of the invention skillfully discovers that the hollow fiber membrane prepared by adopting the casting solution has good hydrophilicity by blending polyethylene and hydrophilic additives, adopting a ball milling mode and the like to fully mix the polyethylene and the hydrophilic additives, and then mixing the obtained mixture with a diluent to prepare the casting solution, and on the other hand, the casting solution can be suitable for forming the composite hollow fiber membrane by adopting a composite spinning mode with higher treatment temperature and reinforcing the composite hollow fiber membrane by adopting a specific hydrophilic additive, thereby simplifying the preparation process of the polyethylene composite hollow fiber membrane, and improving the mechanical property of the polyethylene composite hollow fiber membrane, so that the composite hollow fiber membrane has wider application space. In addition, by adopting the casting solution and matching with specific preparation modes and conditions, the composite hollow fiber membrane with smaller pore size distribution range, better solvent resistance on the surface of the membrane wire and more compact membrane combination formed by the reinforcement and the casting solution can be obtained.
Based on the above findings, the present invention provides, in one aspect, a method of producing a hollow fiber composite membrane, the method comprising:
(1) Providing a casting solution containing polyethylene, a hydrophilic additive, a pore-forming agent and a diluent;
(2) And the casting solution is combined on the outer surface of the tubular reinforcement body by adopting a concentric circle composite spinning mode.
In the invention, in order to enable the subsequent spinning to be smooth and enable the surface separation layer and the reinforcement body in the obtained hollow fiber composite membrane to be combined more tightly, separation layer falling is avoided, and the casting membrane liquid provided in the step (1) needs to meet the requirements of uniform dispersion of each component and no sedimentation or layering phenomenon.
According to a preferred embodiment of the present invention, wherein in step (1), the polyethylene is selected from high density polyethylene and/or ultra high molecular weight polyethylene.
Preferably, the high density polyethylene has a melt index of 0.5-5g/10min.
Preferably, the ultra-high molecular weight polyethylene has a weight average molecular weight of 200 to 350 ten thousand.
According to a preferred embodiment of the present invention, wherein in step (1), the hydrophilic additive comprises a polymer additive and/or an inorganic additive. The polymer additive is preferably at least one selected from the group consisting of ethylene-vinyl acetate copolymer, ethylene-ethylene glycol block copolymer, polyvinyl butyral, ethylene-vinyl alcohol copolymer and ethylene-acrylic acid copolymer. The inorganic additive is preferably at least one selected from the group consisting of hydrophilic silica, hydrophilic titanium dioxide and hydrophilic zinc oxide.
Preferably, the weight average molecular weight of the polymer additive is from 10 to 50 tens of thousands.
The inventor of the present invention also found in the study that when the polymer additive and the inorganic additive (according to a certain proportion) are mixed for use, the dispersion degree of the hydrophilic additive in the casting solution can be improved, so that the casting solution is more uniform, and the hydrophilicity of the obtained polyethylene hollow fiber composite membrane is further improved.
Preferably, the hydrophilic additive is a mixture of a polymer additive and an inorganic additive, and the weight ratio of the polymer additive to the inorganic additive is 5:1-5:5.
According to a preferred embodiment of the present invention, wherein in step (1), the porogen is selected from at least one of polyethylene glycol, polyethylene oxide, calcium chloride and sodium chloride.
According to a preferred embodiment of the present invention, wherein in step (1), the diluent is selected from at least one of white oil (typically a mixture of normal isoparaffins of C16-C31), kerosene, decalin, tetralin, diphenyl ether, phthalate, soybean oil and liquid paraffin (typically a mixture of normal paraffins of C10-C18 with a melting point below 40 ℃).
According to a preferred embodiment of the present invention, in the step (1), the polyethylene content in the casting solution is 6 to 18wt%, the hydrophilic additive content is 6 to 12wt%, the diluent content is 40 to 83wt%, and the porogen content is 5 to 30wt%.
Preferably, in the casting solution, the weight ratio of polyethylene, hydrophilic additive, diluent and pore-forming agent is 1:0.6-1:6-8:1-2.
In the present invention, the casting solution used in the step (1) may be a commercially available or custom product (finished product) having the above characteristics, or may be a self-made product having the above characteristics.
In order to make the hydrophilic modification effect better, according to a preferred embodiment of the present invention, the preparation method of the casting solution in the step (1) includes: and (3) carrying out first mixing on polyethylene, a hydrophilic additive and a pore-forming agent, and carrying out second mixing on the obtained first mixed product and a diluent to obtain a casting solution.
The inventor of the present invention also found that when polyethylene and a hydrophilic additive are sufficiently mixed, the hollow fiber membrane prepared by using the casting solution has better hydrophilic performance. And the pore-forming agent and the polyethylene are fully and uniformly mixed, so that the pore size distribution range of the prepared hollow fiber membrane can be effectively controlled, the pore size distribution range is narrower, and the performance of the hollow fiber membrane is improved.
In the present invention, the purpose of the first mixing is mainly to thoroughly mix the polyethylene, the hydrophilic additive and the porogen. In order to enable a more uniform mixing of the polyethylene with the hydrophilic additive and the porogen, it is preferred that the first mixing is performed by means of ball milling. For example, the polyethylene, hydrophilic additive and porogen may be mixed and then ball milled to form a more uniform mixture (first mixed product).
More preferably, the conditions of the first mixing include: the rotating speed of the ball mill is 100-500rpm, and the ball milling time is 1-6h.
In the present invention, the purpose of the second mixing is mainly to disperse the first mixed product in the diluent, thereby forming a uniform casting solution. In order to enable the first mixed product to be sufficiently dispersed in the diluent, preferably, the second mixing is performed by means of a colloid pump.
More preferably, the conditions of the second mixing include: the rotation speed of the colloid pump is 1000-6000rpm, and the dispersing time is 10-60min.
According to a preferred embodiment of the invention, wherein in step (2), the reinforcement is selected from the group consisting of a fiber woven tube.
Preferably, the fiber woven tube is selected from a fiber woven tube made of at least one of polyester fiber (polyester), polyamide fiber (nylon), polypropylene fiber (polypropylene) and polyethylene fiber (polyethylene) in a crochet or woven form.
Preferably, the outer diameter of the fiber braided tube is 1.4-2mm, the wall thickness is 0.2-0.5mm, and the density is 20-40 meshes. The density of the fiber woven tube refers to the size of the woven structure pores.
The inventors of the present invention have also found in the study that the reinforcement in the obtained composite hollow fiber membrane can be more tightly bonded to the hydrophilically modified polyethylene composite membrane (separation layer) on the surface thereof by using specific spinning conditions. Meanwhile, the thickness of the separation layer and the depth of the embedded reinforcement can be effectively controlled, so that the quality stability of the hollow fiber composite membrane can be ensured.
According to a preferred embodiment of the present invention, in the step (2), the conditions of the concentric circle composite spinning include: the spinning temperature is 150-230 ℃, the spinning speed is 6-25m/min, and the contact distance between the casting solution and the reinforcement body (i.e. the height of the cavity of the spinneret) is 0-8cm. In the invention, the spinning speed is the winding speed when the film yarn is wound after being solidified by the coagulating bath.
Preferably, step (2) further comprises the operation of sequentially placing the casting solution in an air bath and a coagulation bath after it is bonded to the exterior surface of the reinforcement body.
More preferably, the conditions of the air bath include: the height is 5-25cm, and the temperature is 20-30 ℃. The depth of the surface separation layer embedded in the reinforcement can be regulated and controlled by controlling the height of the air bath, and the bonding strength of the surface separation layer and the reinforcement can be improved by adopting the preferable height of the air bath.
More preferably, the conditions of the coagulation bath include: the temperature is 10-70deg.C, preferably 25-50deg.C, and the coagulation bath path is 2-5m. The coagulation bath temperature can influence the curing speed of the casting solution, thereby influencing the membrane wire strength and the membrane flux. Preferably, the coagulation bath is carried out with water. By adopting the coagulation bath under the above conditions, the strength and flux of the membrane filaments can be improved.
According to a preferred embodiment of the present invention, wherein the process further comprises subjecting the product of step (2) to extraction, water washing and drying sequentially. In the invention, the extraction, water washing and drying can be carried out by adopting conventional operation modes and conditions.
Preferably, the extraction mode is selected from dynamic extraction, preferably the extraction conditions include: after the extraction barrel rotates forwards for 20-40min, rotates reversely for 20-40min, the rotation speed is 10-50rpm, and the extraction time is 12-24h. In the invention, the dynamic extraction can be performed by using an extraction barrel with controllable rotation speed and direction. The adhesion of membrane wires can be avoided by adopting a dynamic extraction mode.
Preferably, the conditions of the water washing include: the temperature is 25-50 ℃ and the duration is 24-48h.
Preferably, the drying mode can be air drying at room temperature, or low-temperature drying at a temperature which has no influence on the performance of the hollow fiber composite membrane can be adopted.
The second aspect of the invention provides a hollow fiber composite membrane, which is prepared by adopting the method;
alternatively, the hollow fiber composite membrane comprises a reinforcement and a surface separation layer, wherein the surface separation layer contains polyethylene and a hydrophilic additive and has a spongy pore structure, and the surface separation layer is partially embedded into the reinforcement to form a composite interface.
The characteristics of the reinforcement in the hollow fiber composite membrane and the polyethylene and hydrophilic additive contained in the surface separation layer provided by the invention are as described above, and are not described in detail herein.
Preferably, the weight ratio of polyethylene and hydrophilic additive in the surface separation layer is 1-0.5:1.
preferably, the surface separation layer has a thickness of 0.5 to 1 times the thickness of the reinforcement.
Preferably, the surface separation layer is embedded in the reinforcement to a depth of 20-50% of the reinforcement thickness.
In the present invention, when the reinforcement is a fiber-woven tube, the reinforcement thickness means the wall thickness of the fiber-woven tube. The thickness of the surface separation layer refers to the sum of the thickness of the formed membrane layer and the depth of embedding it into the reinforcement when the casting solution is combined outside the reinforcement (surface separation layer thickness=hollow fiber composite membrane wall thickness-reinforcement thickness+depth of embedding the surface separation layer into the reinforcement).
According to a preferred embodiment of the present invention, wherein the polyethylene hollow fiber composite membrane has a breaking strength of 140 to 170MPa, a water contact angle of 75 ° to 100 °, an average pore diameter of 0.1 to 0.4 μm, and a pore size distribution of 0.05 to 0.6 μm.
The mechanical property and the hydrophilicity of the hollow fiber composite membrane provided by the invention are improved well, so that the hollow fiber composite membrane can meet the requirements of application scenes such as a membrane bioreactor and the like. Especially, the hollow fiber membrane has higher strength, can resist the compression of high-pressure water flow, has better solvent resistance on the surface of the membrane wire, has better hydrophilicity, effectively improves the pollution resistance and prolongs the service life of the membrane wire. Based on this, a third aspect of the present invention provides the use of a hollow fiber composite membrane as described above in a membrane bioreactor and/or in purification of organic solvents.
The present invention will be described in detail by examples. It should be understood that the following examples are illustrative only and are not intended to limit the invention.
In the following examples, high-density ethylene was used having a melt index of 0.8.+ -. 0.1g/10min and an ultra-high molecular weight polyethylene having a weight average molecular weight of 300.+ -. 5 ten thousand. White oil was purchased from Tianjin textile auxiliary Co., ltd, grade 32#. Unless specifically stated, the reagents used were all commercially available from regular chemical suppliers in analytically pure purity.
In the following examples, the raw materials were ball milled (i.e., first mixed) using a planetary ball mill. The dynamic extraction is carried out by adopting an extraction barrel, the extraction barrel is set to carry out the cyclic extraction according to the mode that the rotation speed is 30rpm, the forward rotation is 30min, and then the reverse rotation is 30min, and the extraction time is 24h.
Example 1
(1) The casting film liquid raw material is weighed according to the mass fraction composition of 10 weight percent of high-density polyethylene, 4 weight percent of polyvinyl butyral, 1 weight percent of hydrophilic silicon dioxide (the particle size is about 12 nm), 5 weight percent of polyethylene glycol, 5 weight percent of calcium chloride and 75 weight percent of white oil. The high-density polyethylene, the hydrophilic additive (polyvinyl butyral and hydrophilic silicon dioxide) and the pore-forming agent (polyethylene glycol) are fully ball-milled and mixed by adopting a ball mill (the rotating speed of the ball mill is 100rpm for 6 hours), and then the obtained mixture and the diluent (white oil) are stirred and mixed uniformly by adopting a colloid pump (the rotating speed of the colloid pump is 1000rpm for 60 minutes), so as to obtain the casting solution.
(2) The casting film liquid is processed by a double screw extruder to form uniform spinning solution at 180 ℃, based on a thermally induced phase separation method, the concentric circle composite spinning technology is adopted, the spinning solution is contacted with a polyester fiber woven tube with an outer diameter of 1.4mm, a wall thickness of 0.2mm and a density of 30 meshes through a spinneret (the height of a spinneret cavity is 0 cm), and is coated on the outer layer of the woven tube, and is wound at a winding speed of 6m/min after being solidified and molded in a water coagulating bath (path is 3 m) at 10 ℃ through an air bath of 5cm, and is sequentially extracted by extracting agent dichloromethane, washed and dried (at 25 ℃ for 120 min) to obtain the polyethylene hollow fiber composite film A1. The cross section and the outer surface of the polyethylene hollow fiber composite membrane A1 are observed by adopting an electron microscope, and the results are shown in figures 1-3. Wherein, fig. 1 is a cross-sectional overall electron microscope image, fig. 2 is a cross-sectional partial enlarged electron microscope image, and fig. 3 is an outer surface electron microscope image.
Example 2
(1) The casting film liquid raw material is weighed according to the mass fraction composition of 10wt% of high-density polyethylene, 8wt% of ethylene-vinyl acetate copolymer, 2wt% of hydrophilic titanium dioxide (P25), 5wt% of polyethylene glycol, 15wt% of sodium chloride and 60wt% of white oil. The high-density polyethylene, the hydrophilic additive (ethylene-vinyl acetate copolymer and hydrophilic titanium dioxide) and the pore-forming agent (polyethylene glycol) are fully ball-milled and mixed by adopting a ball mill (the conditions comprise that the rotating speed of the ball mill is 500rpm and the time length is 1 h), and then the obtained mixture and the diluent (white oil) are stirred and mixed uniformly by adopting a colloid pump (the rotating speed of the colloid pump is 6000rpm and the time length is 10 min), so as to obtain the casting solution.
(2) The casting film liquid is processed by a double screw extruder to form uniform spinning solution at 180 ℃, based on a thermal phase separation method, a concentric circle composite spinning technology is adopted, the spinning solution is contacted with a polyethylene fiber woven tube with an outer diameter of 2mm, a wall thickness of 0.5mm and a density of 30 meshes through a spinneret (the height of a spinneret cavity is 8 cm), and is coated on the outer layer of the woven tube, and is wound at a winding speed of 20m/min after being solidified and formed in a water coagulating bath (path is 3 m) at 70 ℃ through an air bath of 25cm, and is sequentially extracted by extracting agent dimethylbenzene, washed and dried (at 25 ℃ for 120 min) to obtain the polyethylene hollow fiber composite film A2. The cross section and the outer surface of the polyethylene hollow fiber composite membrane A2 were observed by using an electron microscope, and the result was similar to that of the composite membrane A1.
Example 3
(1) The casting film liquid raw materials are weighed according to the mass fraction composition of 10wt% of high-density polyethylene, 5wt% of ethylene-vinyl acetate copolymer, 2wt% of hydrophilic silicon dioxide (the particle size is about 12 nm), 6wt% of polyethylene glycol, 12wt% of sodium chloride and 65wt% of white oil. The ultra-high molecular weight polyethylene, hydrophilic additives (ethylene-vinyl acetate copolymer and hydrophilic silica) and pore-forming agent (polyethylene glycol) are fully ball-milled and mixed by adopting a ball mill (the rotating speed of the ball mill is 300rpm for 4 hours), and then the obtained mixture and the diluent (white oil) are stirred and mixed uniformly by adopting a colloid pump (the rotating speed of the colloid pump is 2000rpm for 30 minutes), so as to obtain the casting solution.
(2) The casting solution is processed by a double screw extruder to form uniform spinning solution at 200 ℃, based on a thermal phase separation method, a concentric circle composite spinning technology is adopted, a spinning solution spinneret is contacted with a polyester fiber woven tube with an outer diameter of 1.8mm, a wall thickness of 0.3mm and a density of 25 meshes (the height of a spinning head cavity is 5 cm), the polyester fiber woven tube is coated on the outer layer of the woven tube, and after solidification forming in a water solidification bath (path is 3 m) at 50 ℃ through an 8cm air bath, the spinning solution is coiled at a coiling speed of 15m/min, and is sequentially extracted by extracting agent xylene, washed and dried (25 ℃ for 120 min) to obtain the hydrophilic modified high-strength polyethylene hollow fiber composite membrane A3. The cross section and the outer surface of the polyethylene hollow fiber composite membrane A3 were observed by using an electron microscope, and the result was similar to that of the composite membrane A1.
Example 4
(1) The casting film liquid raw material is prepared from 4wt% of ultra-high molecular weight polyethylene, 5wt% of polyethylene-polyethylene glycol copolymer, 1wt% of hydrophilic silicon dioxide (the particle size is about 12 nm), 5wt% of polyethylene glycol, 5wt% of anhydrous calcium chloride and 80wt% of decalin. The ultra-high molecular weight polyethylene, hydrophilic additive (polyethylene-polyethylene glycol copolymer and hydrophilic silica) and pore-forming agent (anhydrous calcium chloride) are fully ball-milled and mixed by adopting a ball mill (the rotation speed of the ball mill is 80rpm for 8 hours), and then the obtained mixture and diluent (decalin) are stirred and mixed uniformly by adopting a colloid pump (the rotation speed of the colloid pump is 8000rpm for 5 minutes), so as to obtain the casting solution.
(2) The casting film liquid is processed by a double screw extruder to form uniform spinning solution at 200 ℃, based on a thermally induced phase separation method, a concentric circle composite spinning technology is adopted, the spinning solution is contacted with a crocheted polyester woven tube with an outer diameter of 1.8mm, a wall thickness of 0.3mm and a density of 25 meshes through a spinneret (the height of a cavity of the spinneret is 5 cm), and is coated on the outer layer of the woven tube, and is wound at a winding speed of 25m/min after being solidified and formed in a water coagulating bath (path is 3 m) at 50 ℃ through an 8cm air bath, and then the high-strength hydrophilic modified high-strength polyethylene hollow fiber composite film A4 is obtained through extraction by extracting agent dimethylbenzene, washing and drying (at 25 ℃ for 120 min). The cross section and the outer surface of the polyethylene hollow fiber composite membrane A4 were observed by using an electron microscope, and the result was similar to that of the composite membrane A1.
Example 5
(1) According to the mass fraction composition of 18wt% of high-density polyethylene, 5wt% of polyvinyl butyral, 2wt% (12 nm) of hydrophilic silicon dioxide, 5wt% of polyethylene glycol, 3wt% of anhydrous calcium chloride and 67wt% of white oil, the casting film liquid raw material is weighed. The high-density polyethylene, hydrophilic additives (polyvinyl butyral and hydrophilic silica) and pore-forming agents (polyethylene glycol and anhydrous calcium chloride) are fully ball-milled and mixed by adopting a ball mill (the rotating speed of the ball mill is 600rpm for 0.5 h), and then the obtained mixture and the diluent (decalin) are stirred and mixed uniformly by adopting a colloid pump (the rotating speed of the colloid pump is 500rpm for 90 min), so as to obtain the casting solution.
(2) The casting film liquid is processed by a double screw extruder to form uniform spinning solution at 180 ℃, based on a thermally induced phase separation method, the concentric circle composite spinning technology is adopted, the spinning solution is contacted with a polyester fiber woven tube with an outer diameter of 1.8mm, a wall thickness of 0.3mm and a density of 30 meshes (the height of a spinning head cavity is 5 cm) through a spinning nozzle, the polyester fiber woven tube is coated on the outer layer of the woven tube, and is wound at a winding speed of 20m/min after being solidified and molded in a water coagulating bath (path is 3 m) at 50 ℃ through an air bath of 25cm, and the polyethylene hollow fiber composite film A5 is obtained through extraction by extracting agent dichloromethane, water washing and drying (at 25 ℃ for 120 min). The cross section and the outer surface of the polyethylene hollow fiber composite membrane A5 were observed by using an electron microscope, and the result was similar to that of the composite membrane A1.
Example 6
(1) The casting film liquid raw material is weighed according to the mass fraction of 9wt% of high-density polyethylene, 5wt% of polyvinyl butyral, 2wt% (12 nm) of hydrophilic silicon dioxide, 10wt% of polyethylene glycol and 74wt% of white oil. The high-density polyethylene, the hydrophilic additive (polyvinyl butyral and hydrophilic silicon dioxide) and the pore-forming agent (polyethylene glycol) are fully ball-milled and mixed by adopting a ball mill (the rotating speed of the ball mill is 300rpm for 3 hours), and then the obtained mixture and the diluent (decalin) are stirred and mixed uniformly by adopting a colloid pump (the rotating speed of the colloid pump is 2000rpm for 60 minutes), so as to obtain the casting solution.
(2) The casting film liquid is processed by a double screw extruder to form uniform spinning solution at 180 ℃, based on a thermally induced phase separation method, the concentric circle composite spinning technology is adopted, the spinning solution is contacted with a polyester fiber woven tube with an outer diameter of 1.4mm, a wall thickness of 0.2mm and a density of 25 meshes (the height of a spinning head cavity is 5 cm) through a spinning nozzle, and is coated on the outer layer of the woven tube, and is wound at a winding speed of 20m/min after being solidified and molded in a water coagulating bath (path is 3 m) at 50 ℃ through an air bath of 10cm, and is sequentially extracted by extracting agent dichloromethane, washed and dried (25 ℃ for 120 min) to obtain the polyethylene hollow fiber composite film A6. The cross section and the outer surface of the polyethylene hollow fiber composite membrane A6 were observed by using an electron microscope, and the result was similar to that of the composite membrane A1.
Example 7
(1) According to the mass fraction composition of 9wt% of high-density polyethylene, 5wt% of polyvinyl butyral, 2wt% of hydrophilic silicon dioxide (12 nm), 5wt% of polyethylene glycol, 2wt% of anhydrous calcium chloride and 77wt% of white oil, the casting film liquid raw material is weighed. The high-density polyethylene, hydrophilic additives (polyvinyl butyral and hydrophilic silica) and pore-forming agents (polyethylene glycol and anhydrous calcium chloride) are fully ball-milled and mixed by adopting a ball mill (the rotation speed of the ball mill is 200rpm for 4 hours), and then the obtained mixture and the diluent (decalin) are stirred and mixed uniformly by adopting a colloid pump (1000 rpm for 30 minutes), so as to obtain the casting solution.
(2) The casting film liquid is processed by a double screw extruder to form uniform spinning solution at 180 ℃, based on a thermally induced phase separation method, the concentric circle composite spinning technology is adopted, the spinning solution is contacted with a polyester fiber woven tube with an outer diameter of 1.4mm, a wall thickness of 0.2mm and a density of 25 meshes (the height of a spinning head cavity is 5 cm) through a spinning nozzle, and is coated on the outer layer of the woven tube, and is wound at a winding speed of 20m/min after being solidified and molded in a water coagulating bath (path is 3 m) at 50 ℃ through an air bath of 10cm, and is sequentially extracted by extracting agent dichloromethane, washed and dried (25 ℃ for 120 min) to obtain the polyethylene hollow fiber composite film A7. The cross section and the outer surface of the polyethylene hollow fiber composite membrane A7 were observed by using an electron microscope, and the result was similar to that of the composite membrane A1.
Example 8
The method of example 1 was used, except that the mass fraction of the components in the casting solution was: 25% of high-density polyethylene, 2% of polyvinyl butyral, 2% of hydrophilic silicon dioxide (12 nm), 2% of polyethylene glycol and 69% of white oil. The other operations and conditions were the same as in example 1, to obtain a polyethylene hollow fiber composite membrane A8. The cross section and the outer surface of the polyethylene hollow fiber composite membrane A8 are observed by adopting an electron microscope, and the membrane is compact in surface and small in aperture.
Example 9
The method of example 1 was used, except that the mass fraction of the components in the casting solution was: 18% of high-density polyethylene, 2% of polyethylene-polyethylene glycol copolymer, 1% of hydrophilic silica (12 nm) and 79% of white oil. The other operations and conditions were the same as in example 1, to obtain a polyethylene hollow fiber composite membrane A9. The cross section and the outer surface of the polyethylene hollow fiber composite membrane A9 are observed by adopting an electron microscope, and the membrane is compact in surface and small in aperture.
Example 10
The method of example 1 was used, except that the casting solution contained no hydrophilic silica and the mass fraction of polyvinyl butyral was adjusted to 5wt%. The other operations and conditions were the same as in example 1, to obtain a polyethylene hollow fiber composite membrane a10. The cross section and the outer surface of the polyethylene hollow fiber composite membrane A10 are observed by adopting an electron microscope, and the membrane holes are easy to collapse and shrink seriously.
Example 11
The method of example 1 was used, except that the casting solution contained no polyvinyl butyral, and the mass fraction of the hydrophilic silica was adjusted to 5wt%. The other operations and conditions were the same as in example 1, to obtain a polyethylene hollow fiber composite membrane a11. The cross section and the outer surface of the polyethylene hollow fiber composite membrane A11 are observed by adopting an electron microscope, and the silicon dioxide is found to be easy to agglomerate and uneven in distribution.
Example 12
The method of example 1 was adopted, except that the whole casting solution raw material was directly mixed and stirred and mixed uniformly at a rotation speed of 100rpm for 60 minutes to obtain a casting solution. The other operations and conditions were the same as in example 1, to prepare a polyethylene hollow fiber composite membrane a12. In the spinning process, the layering phenomenon of the casting solution is obvious, the spinning cannot be smoothly performed, and the preparation of the polyethylene hollow fiber composite membrane A12 fails.
Example 13
The process of example 1 was used, except that the high-density polyethylene used in example 1 was replaced with a polyethylene having a melt index of 10g/10 min. The other operations and conditions were the same as in example 1, to obtain a polyethylene hollow fiber composite membrane a13. The detection shows that the separation layer of the prepared polyethylene hollow fiber composite membrane has poor bonding strength with the reinforcement body, is easy to fall off and cannot be used normally.
Comparative example 1
The method of example 1 was adopted, except that hydrophilic additives (polyvinyl butyral and hydrophilic silica) were not added in the preparation of the casting solution, and after the hollow fiber composite membrane was obtained in the step (2), the surface modification was performed with the hydrophilic additives, and specific operations include: the mixture was immersed in a 30wt% aqueous glycerol solution at room temperature for 48 hours. The other operations and conditions were the same as in example 1, to obtain a polyethylene hollow fiber composite membrane D1. The tests found that the instantaneous hydrophilicity of the membrane surface was higher, but the long-term stability was poorer.
Test example 1
The polyethylene hollow fiber composite membranes obtained in the above examples and comparative examples were each examined for surface separation layer thickness, composite interface thickness, average pore diameter, breaking strength, water contact angle, and pure water flux (test pressure 0.1 MPa) by using a scanning electron microscope, a pore diameter tester, a stretcher, a water contact angle tester, and a water flux tester. The results are detailed in Table 1.
TABLE 1
Note that: in table 1, surface separation layer thickness = hollow fiber composite membrane wall thickness-reinforcement thickness + depth of surface separation layer embedded reinforcement; the thickness of the composite interface is the depth of the surface separation layer embedded in the reinforcement.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.
Claims (11)
1. A method of making a hollow fiber composite membrane, the method comprising:
(1) Providing a casting solution containing polyethylene, a hydrophilic additive, a pore-forming agent and a diluent;
(2) And the casting solution is combined on the outer surface of the tubular reinforcement body by adopting a concentric circle composite spinning mode.
2. The process according to claim 1, wherein in step (1) the polyethylene is selected from high density polyethylene and/or ultra high molecular weight polyethylene, preferably the high density polyethylene has a melt index of 0.5-5g/10min, preferably the ultra high molecular weight polyethylene has a weight average molecular weight of 200-350 ten thousand;
and/or the hydrophilic additive comprises a polymer additive and/or an inorganic additive, the polymer additive is preferably at least one selected from ethylene-vinyl acetate copolymer, ethylene-ethylene glycol block copolymer, polyvinyl butyral, ethylene-vinyl alcohol copolymer and ethylene-acrylic acid copolymer, and the inorganic additive is preferably at least one selected from hydrophilic silica, hydrophilic titanium dioxide and hydrophilic zinc oxide;
and/or the pore-forming agent is selected from at least one of polyethylene glycol, polyethylene oxide, calcium chloride and sodium chloride;
and/or the diluent is selected from at least one of white oil, kerosene, decalin, tetralin, diphenyl ether, phthalate, soybean oil and liquid paraffin;
preferably, the weight average molecular weight of the polymer additive is from 10 to 50 tens of thousands;
preferably, the hydrophilic additive is a mixture of a polymer additive and an inorganic additive, and the weight ratio of the polymer additive to the inorganic additive is 5:1-5:5;
preferably, the polyethylene content in the casting film liquid is 6-18wt%, the hydrophilic additive content is 6-12wt%, the diluent content is 40-83wt%, and the pore-forming agent content is 5-30wt%;
more preferably, in the casting solution, the weight ratio of polyethylene, hydrophilic additive, diluent and pore-forming agent is 1:0.6-1:6-8:1-2.
3. The method according to claim 1, wherein the method for preparing the casting solution in step (1) comprises: firstly mixing polyethylene, a hydrophilic additive and a pore-forming agent, and secondly mixing the obtained first mixed product with a diluent to obtain a casting solution;
preferably, the first mixing is performed by ball milling;
preferably, the second mixing is performed by dispersing with a colloid pump;
more preferably, the conditions of the first mixing include: the rotating speed of the ball mill is 100-500rpm, and the ball milling time is 1-6h;
more preferably, the conditions of the second mixing include: the rotation speed of the colloid pump is 1000-6000rpm, and the dispersing time is 10-60min.
4. The method of claim 1, wherein in step (2), the reinforcement is selected from the group consisting of a fiber woven tube;
preferably, the fiber braided tube is selected from a fiber braided tube with a structure in a crocheted or braided form from at least one of polyester fiber, polyamide fiber, polypropylene fiber and polyethylene fiber;
preferably, the outer diameter of the fiber braided tube is 1.4-2mm, the wall thickness is 0.2-0.5mm, and the density is 20-40 meshes.
5. The method of claim 1, wherein in step (2), the conditions of concentric circle composite spinning include: the spinning temperature is 150-230 ℃, the spinning speed is 6-25m/min, and the contact distance between the casting solution and the reinforcement body at the spinning nozzle is 0-8cm;
preferably, the step (2) further comprises an operation of sequentially placing the casting solution in an air bath and a coagulation bath after it is bonded to the outer surface of the reinforcement body;
more preferably, the conditions of the air bath include: the height is 5-25cm, and the temperature is 20-30 ℃;
more preferably, the conditions of the coagulation bath include: the temperature is 10-70deg.C, the coagulation bath path is 2-5m, and water is preferably used as coagulation bath.
6. The process according to claim 1 or 5, wherein the process further comprises subjecting the product of step (2) to extraction, water washing and drying sequentially;
preferably, the extraction mode is dynamic extraction by using an extraction barrel, and preferably, the extraction conditions comprise: after the extraction barrel rotates forwards for 20-40min, rotates reversely for 20-40min, the rotation speed is 10-50rpm, and the cyclic extraction is carried out for 12-24h;
preferably, the conditions of the water washing include: the temperature is 25-50 ℃ and the duration is 24-48h.
7. A hollow fiber composite membrane, characterized in that the hollow fiber composite membrane is produced by the method of any one of claims 1 to 6;
alternatively, the hollow fiber composite membrane comprises a reinforcement and a surface separation layer, wherein the surface separation layer contains polyethylene and a hydrophilic additive and has a spongy pore structure, and the surface separation layer is partially embedded into the reinforcement to form a composite interface.
8. The hollow fiber composite membrane of claim 7, wherein the reinforcement is selected from a fiber woven tube;
preferably, the fiber braided tube is selected from a fiber braided tube with a structure in a crocheted or braided form from at least one of polyester fiber, polyamide fiber, polypropylene fiber and polyethylene fiber;
preferably, the outer diameter of the fiber braided tube is 1.4-2mm, the wall thickness is 0.2-0.5mm, and the density is 20-40 meshes.
9. The polyethylene hollow fiber composite membrane of claim 7 wherein the polyethylene is selected from high density polyethylene and/or ultra high molecular weight polyethylene, preferably the high density polyethylene has a melt index of 0.5-5g/10min, preferably the ultra high molecular weight polyethylene has a weight average molecular weight of 200-350 ten thousand;
and/or the hydrophilic additive comprises a polymer additive and/or an inorganic additive, wherein the polymer additive is preferably at least one selected from ethylene-vinyl acetate copolymer, polyethylene-polyethylene glycol block copolymer, polyvinyl butyral, ethylene-vinyl alcohol copolymer and ethylene-acrylic acid copolymer, and the inorganic additive is at least one selected from hydrophilic silica, hydrophilic titanium dioxide and hydrophilic zinc oxide;
preferably, the weight ratio of polyethylene to additives is 1-0.5:1, a step of;
preferably, the thickness of the surface separation layer is 0.5-1 times the thickness of the reinforcement;
preferably, the surface separation layer is embedded in the reinforcement to a depth of 20-50% of the reinforcement thickness.
10. The polyethylene hollow fiber composite membrane according to any one of claims 7 to 9, wherein the polyethylene hollow fiber composite membrane has a breaking strength of 140 to 170MPa, a water contact angle of 75 ° to 100 °, an average pore diameter of 0.1 to 0.4 μm, and a pore size distribution of 0.05 to 0.6 μm.
11. Use of a hollow fiber composite membrane according to any one of claims 7 to 10 in a membrane bioreactor and/or in purification of organic solvents.
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