CN116036891A - Hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane and preparation method thereof - Google Patents
Hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane and preparation method thereof Download PDFInfo
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- CN116036891A CN116036891A CN202310044334.8A CN202310044334A CN116036891A CN 116036891 A CN116036891 A CN 116036891A CN 202310044334 A CN202310044334 A CN 202310044334A CN 116036891 A CN116036891 A CN 116036891A
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- 239000012510 hollow fiber Substances 0.000 title claims abstract description 89
- 239000012528 membrane Substances 0.000 title claims abstract description 83
- 229920002981 polyvinylidene fluoride Polymers 0.000 title claims abstract description 61
- 239000002033 PVDF binder Substances 0.000 title claims abstract description 60
- 238000000108 ultra-filtration Methods 0.000 title claims abstract description 50
- 238000002360 preparation method Methods 0.000 title claims abstract description 12
- 238000005266 casting Methods 0.000 claims abstract description 35
- 239000002904 solvent Substances 0.000 claims abstract description 23
- 229920000728 polyester Polymers 0.000 claims abstract description 22
- 238000005191 phase separation Methods 0.000 claims abstract description 19
- 239000011148 porous material Substances 0.000 claims abstract description 13
- 238000001914 filtration Methods 0.000 claims abstract description 12
- 230000004907 flux Effects 0.000 claims abstract description 11
- 239000003607 modifier Substances 0.000 claims abstract description 8
- 239000004094 surface-active agent Substances 0.000 claims abstract description 8
- 239000008399 tap water Substances 0.000 claims abstract description 6
- 235000020679 tap water Nutrition 0.000 claims abstract description 6
- 239000000243 solution Substances 0.000 claims description 56
- 230000001112 coagulating effect Effects 0.000 claims description 32
- 239000007788 liquid Substances 0.000 claims description 29
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 19
- 238000000034 method Methods 0.000 claims description 17
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 16
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims description 15
- 238000004140 cleaning Methods 0.000 claims description 13
- 229940068918 polyethylene glycol 400 Drugs 0.000 claims description 12
- 238000003756 stirring Methods 0.000 claims description 12
- 239000000835 fiber Substances 0.000 claims description 11
- 229920000036 polyvinylpyrrolidone Polymers 0.000 claims description 10
- 239000001267 polyvinylpyrrolidone Substances 0.000 claims description 10
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims description 10
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 9
- 229910052757 nitrogen Inorganic materials 0.000 claims description 8
- 238000004804 winding Methods 0.000 claims description 8
- 230000009471 action Effects 0.000 claims description 7
- 238000001816 cooling Methods 0.000 claims description 7
- 238000004090 dissolution Methods 0.000 claims description 7
- 230000007246 mechanism Effects 0.000 claims description 7
- 229920001223 polyethylene glycol Polymers 0.000 claims description 7
- 239000002202 Polyethylene glycol Substances 0.000 claims description 6
- 235000010482 polyoxyethylene sorbitan monooleate Nutrition 0.000 claims description 5
- 229920000053 polysorbate 80 Polymers 0.000 claims description 5
- 238000007711 solidification Methods 0.000 claims description 5
- 230000008023 solidification Effects 0.000 claims description 5
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 4
- 229920001214 Polysorbate 60 Polymers 0.000 claims description 4
- 238000009954 braiding Methods 0.000 claims description 4
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 3
- 229920001213 Polysorbate 20 Polymers 0.000 claims description 3
- 238000009945 crocheting Methods 0.000 claims description 3
- 239000011259 mixed solution Substances 0.000 claims description 3
- 239000000256 polyoxyethylene sorbitan monolaurate Substances 0.000 claims description 3
- 235000010486 polyoxyethylene sorbitan monolaurate Nutrition 0.000 claims description 3
- LZZYPRNAOMGNLH-UHFFFAOYSA-M Cetrimonium bromide Chemical compound [Br-].CCCCCCCCCCCCCCCC[N+](C)(C)C LZZYPRNAOMGNLH-UHFFFAOYSA-M 0.000 claims description 2
- 229920003171 Poly (ethylene oxide) Polymers 0.000 claims description 2
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 2
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 claims description 2
- FBCHMEOPUKIZJN-UHFFFAOYSA-N dodecyl 2-aminopropanoate;sodium Chemical compound [Na].CCCCCCCCCCCCOC(=O)C(C)N FBCHMEOPUKIZJN-UHFFFAOYSA-N 0.000 claims description 2
- GVGUFUZHNYFZLC-UHFFFAOYSA-N dodecyl benzenesulfonate;sodium Chemical compound [Na].CCCCCCCCCCCCOS(=O)(=O)C1=CC=CC=C1 GVGUFUZHNYFZLC-UHFFFAOYSA-N 0.000 claims description 2
- 229920000609 methyl cellulose Polymers 0.000 claims description 2
- 239000001923 methylcellulose Substances 0.000 claims description 2
- -1 polyoxyethylene Polymers 0.000 claims description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 2
- 229940080264 sodium dodecylbenzenesulfonate Drugs 0.000 claims description 2
- DQWPFSLDHJDLRL-UHFFFAOYSA-N triethyl phosphate Chemical compound CCOP(=O)(OCC)OCC DQWPFSLDHJDLRL-UHFFFAOYSA-N 0.000 claims description 2
- WVLBCYQITXONBZ-UHFFFAOYSA-N trimethyl phosphate Chemical compound COP(=O)(OC)OC WVLBCYQITXONBZ-UHFFFAOYSA-N 0.000 claims description 2
- 239000002994 raw material Substances 0.000 claims 1
- 238000011282 treatment Methods 0.000 abstract description 9
- 238000004519 manufacturing process Methods 0.000 abstract description 5
- 239000012466 permeate Substances 0.000 abstract description 4
- 239000010865 sewage Substances 0.000 abstract description 4
- 239000000463 material Substances 0.000 abstract description 3
- 239000000126 substance Substances 0.000 abstract description 3
- 238000010612 desalination reaction Methods 0.000 abstract description 2
- 235000020188 drinking water Nutrition 0.000 abstract description 2
- 239000003651 drinking water Substances 0.000 abstract description 2
- 239000003814 drug Substances 0.000 abstract description 2
- 238000000746 purification Methods 0.000 abstract description 2
- 239000012779 reinforcing material Substances 0.000 abstract description 2
- 239000013535 sea water Substances 0.000 abstract description 2
- 238000009826 distribution Methods 0.000 abstract 1
- 238000009987 spinning Methods 0.000 abstract 1
- 239000011248 coating agent Substances 0.000 description 7
- 238000000576 coating method Methods 0.000 description 7
- 230000008569 process Effects 0.000 description 6
- 229920006316 polyvinylpyrrolidine Polymers 0.000 description 5
- 238000005303 weighing Methods 0.000 description 5
- 239000007864 aqueous solution Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- 239000005708 Sodium hypochlorite Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 2
- 101100112111 Caenorhabditis elegans cand-1 gene Proteins 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 238000007385 chemical modification Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000005345 coagulation Methods 0.000 description 1
- 230000015271 coagulation Effects 0.000 description 1
- 238000003851 corona treatment Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000009730 filament winding Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 238000009998 heat setting Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- RAYLUPYCGGKXQO-UHFFFAOYSA-N n,n-dimethylacetamide;hydrate Chemical compound O.CN(C)C(C)=O RAYLUPYCGGKXQO-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229940113116 polyethylene glycol 1000 Drugs 0.000 description 1
- 229940113115 polyethylene glycol 200 Drugs 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000002145 thermally induced phase separation Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/30—Polyalkenyl halides
- B01D71/32—Polyalkenyl halides containing fluorine atoms
- B01D71/34—Polyvinylidene fluoride
-
- 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
- B01D61/145—Ultrafiltration
-
- 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
- B01D67/0009—Organic membrane manufacture by phase separation, sol-gel transition, evaporation or solvent quenching
- B01D67/0016—Coagulation
-
- 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
-
- 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
- C02F1/444—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by ultrafiltration or microfiltration
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/24—Mechanical properties, e.g. strength
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/124—Water desalination
- Y02A20/131—Reverse-osmosis
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Water Supply & Treatment (AREA)
- Dispersion Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Organic Chemistry (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention relates to the field of porous membrane manufacturing, in particular to a hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane and a preparation method thereof. The hollow fiber ultrafiltration membrane adopts a polyester hollow woven tube as an inner reinforcing material, polyvinylidene fluoride is used as a membrane material, a hydrophilic modifier, a surfactant, a solvent and the like are added to prepare a membrane casting solution, the membrane casting solution is coated on a membrane forming layer on the outer surface of the hollow woven tube, the membrane casting solution partially permeates the woven layer of the hollow woven tube, and the polyvinylidene fluoride hollow fiber ultrafiltration membrane is prepared by adopting a non-solvent induced phase separation spinning process. The prepared hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane has high tensile strength, polyvinylidene fluoride enters into the woven layer of the hollow woven tube, has high bonding strength with the hollow woven tube, high rupture pressure, small pore diameter, uniform pore diameter distribution, high pore porosity and high flux of the coated membrane layer, has good hydrophilicity and pollution resistance, and can be applied to filtration treatment of drinking water, filtration and purification treatment of municipal tap water and sewage in industries such as chemical industry, food, medicine and the like, various industrial sewage treatments, pretreatment of sea water desalination and the like.
Description
Technical Field
The invention relates to the field of porous membrane manufacturing, in particular to a hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane and a preparation method of a non-solvent induced phase separation method thereof.
Background
Polyvinylidene fluoride (PVDF) is a crystalline polymer with high strength, good toughness and good flexibility; the polyvinylidene fluoride product has excellent weather aging resistance and long service life; has excellent chemical stability, particularly has excellent oxidation resistance and is widely applied to the manufacture of water treatment separation membranes.
The hollow fiber membrane is broken under the influence of various factors in the use process, so that the hollow fiber membrane is required to have higher strength, and the strength of the homogeneous hollow fiber membrane prepared by a non-solvent induced phase separation method is lower; the hollow fiber membrane prepared by the thermally induced phase separation method has higher strength, but the hollow fiber membrane also needs to be subjected to processes such as stretching, heat setting, extraction and the like, and a layer of filtering membrane layer is coated on the surface of the membrane by a non-solvent induced phase separation method generally, so that the process is complex and the cost is high; at present, a polyester fiber hollow braided tube is generally adopted as a lining reinforcing material, and a non-solvent induced phase separation method process is adopted to coat a casting solution on the surface of the hollow braided tube to prepare the hollow fiber membrane. The strength of the hollow braided tube is high, the strength of the hollow fiber membrane is greatly enhanced, the preparation process is simpler, but as the membrane layer is coated on the surface of the hollow braided tube, the polyester fiber and the polyvinylidene fluoride are two different materials, and the membrane has the risk of falling off from the hollow braided tube after the use time of the membrane. In order to increase the bonding strength of the film layer and the hollow woven tube, methods such as heating, corona treatment, chemical modification treatment, multiple coating and the like of the hollow woven tube are mainly adopted at present, and the methods increase production procedures and production cost and have limited effects.
The adhesion between the woven tube and the polyvinylidene fluoride membrane layer in the hollow woven tube reinforced polyvinylidene fluoride hollow fiber membrane in the prior art is insufficient, and the adhesion strength between the woven tube and the polyvinylidene fluoride membrane layer needs to be further enhanced.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane. The hollow fiber ultrafiltration membrane has the advantages of high tensile strength, high bonding degree of a membrane layer and a hollow woven tube, high rupture pressure, small pore diameter, high porosity, high flux, good hydrophilicity and pollution resistance.
Hollow braided tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane is formed by braiding polyester fibers in a crocheting mode.
The hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane comprises the following components in percentage by weight:
polyvinylidene fluoride: 75-95%
Hydrophilic modifier: 5 to 20 percent
And (2) a surfactant: 0-10%.
The hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane comprises the following components in percentage by weight:
polyvinylidene fluoride: 17-25%
Hydrophilic modifier: 7 to 25 percent
And (2) a surfactant: 0 to 5 percent
Solvent: 50-70%.
Preferably, the hollow braided tube has an inner diameter of 0.6 to 1.5mm and an outer diameter of 1.1 to 2.5mm, more preferably 0.7 to 1.2mm and an outer diameter of 1.2 to 2.0mm.
Preferably, the thickness of the film layer is 0.05 to 0.25mm, more preferably 0.07 to 0.15mm.
Preferably, the molecular weight of the polyvinylidene fluoride is 40-100 ten thousand, more preferably 60-100 ten thousand, and two polyvinylidene fluorides with different molecular weights can be selected for blending.
Preferably, the hydrophilic modifier is selected from one or more of polyethylene glycol, polyvinylpyrrolidone, polyvinyl alcohol, polyoxyethylene and methylcellulose, more preferably from one or two of polyethylene glycol and polyvinylpyrrolidone, the molecular weight of polyethylene glycol is 200-20000, more preferably the molecular weight is 400-10000, the K value of polyvinylpyrrolidone is 15-90, more preferably the K value is 30-80, and one polyvinylpyrrolidone or a combination of two different K values can be added according to the requirements of film preparation. Polyethylene glycol and polyvinylpyrrolidone have hydrophilic modification effect and also have pore-forming agent effect, in the phase separation and cleaning processes, polyethylene glycol is easy to separate from the membrane, polyvinylpyrrolidone part is easy to separate from the membrane, the lower the K value is, and the polyvinylpyrrolidone can be further cleaned by sodium hypochlorite after the membrane is formed. The viscosity of the casting solution can be adjusted by selecting polyethylene glycols with different molecular weights and polyvinylpyrrolidone with different K values.
Preferably, the surfactant is selected from one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium dodecyl aminopropionate, cetyltrimethylammonium bromide, tween 20, tween 60 and tween 80, more preferably one or more of tween 20, tween 60 and tween 80.
Preferably, the solvent is selected from one or more of dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, trimethyl phosphate and triethyl phosphate, more preferably one or more of dimethylformamide, dimethylacetamide and N-methylpyrrolidone.
The invention further aims at providing a preparation method of the hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane, which is prepared by a non-solvent induced phase separation method and comprises the following preparation steps:
step (1): firstly, polyvinylidene fluoride, a hydrophilic modifier, a surfactant and a solvent are put into a dissolution kettle according to a certain proportion, and are stirred for more than 20 hours at 50-90 ℃ to be fully and uniformly dissolved;
step (2): then stopping stirring, filtering, vacuumizing and defoaming, and cooling to obtain a casting solution at 40-80 ℃;
step (3): then, the casting solution is conveyed to a sleeve-type spinneret with the temperature of 40-80 ℃ through a metering pump under the action of nitrogen pressure, a hollow braided tube enters an inner hole of the spinneret at the speed of 10-40 m/min through a wire feeding mechanism, the casting solution is coated on the outer surface of the hollow braided tube, and the hollow braided tube is extruded into a hollow fiber shape;
step (4): finally, the hollow fiber is solidified and formed in the coagulating liquid at 40-80 ℃ after passing through the air distance of 10-300 mm, and phase separation occurs at the same time, the hollow fiber continuously moves in the coagulating liquid for 7m after passing through the godet wheel at the bottom of the coagulating liquid after vertically moving downwards in the coagulating liquid for 3m, enters the cleaning liquid at 40-80 ℃, and is wound at the speed of 10-40 m/min through the winding wheel after moving 15m in the cleaning liquid, so that the hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane is obtained.
Preferably, the coagulating liquid is a mixed solution of water, solvent and polyethylene glycol 400, wherein the concentration of the solvent is 5-70%, more preferably the concentration of the solvent is 10-50%; the concentration of polyethylene glycol 400 is 0 to 30%, and more preferably the concentration of polyethylene glycol 400 is 2 to 20%. The water is tap water filtered by the ultrafiltration membrane, the solvent is dimethylacetamide, the coagulation speed is slowed down along with the increase of the concentration of the solvent and the polyethylene glycol 400 in the coagulating liquid, the phase separation time is prolonged, a spongy structure is formed behind a surface compact layer, the formation of finger-shaped holes is restrained, and the membrane has higher porosity. The cleaning fluid is tap water filtered by an ultrafiltration membrane.
Compared with the prior art, the invention has the following advantages:
(1) The polyester fiber in the braided tube is braided too tightly, the casting solution cannot permeate the braided layer, the polyester fiber is braided too loosely, and the casting solution can further enter the hollow inner hole after seeping into the braided layer to block the hollow inner hole. The hollow braided tube is formed by braiding polyester fibers in a crocheting mode, the compactness among the polyester fibers is moderate, the braided tube has higher strength, and meanwhile, the flexibility is good. The viscosity of the casting solution is adjusted by adjusting the formula and the temperature of the casting solution, so that the casting solution permeates into the braiding layer of the braided tube and does not enter the inner hole of the braided tube, and the hollow inner hole of the braided tube is not blocked. The casting solution permeates the woven layer to wrap the polyester fiber, so that the film layer and the woven tube are firmly combined together, the bonding strength of polyvinylidene fluoride and the woven tube is greatly enhanced, and the risk of falling of the film layer is reduced.
(2) According to the preparation method of the hollow braided tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane, the hollow fiber continuously moves in the coagulating liquid through the godet wheel at the bottom of the coagulating liquid after entering the coagulating liquid and vertically downwards moving for 3 meters, the hollow fiber has long phase separation time before contacting the godet wheel, the casting solution coated on the surface of the hollow braided tube is basically coagulated, the hollow fiber is not extruded and deformed when passing through the godet wheel, and the shape is kept stable. The residence time of the hollow fiber in the coagulating liquid can reach 1 minute, and the phase separation time is long; the coagulating liquid is added with solvent and polyethylene glycol 400, the concentration of the solvent is up to 70%, the coagulating speed is greatly slowed down, the phase separation time is prolonged, the formation of finger-shaped holes in the membrane is inhibited, and more spongy structures are formed in the membrane. Compared with the finger-shaped hole structure, the spongy structure is favorable for improving the stability of membrane separation and the strength of the membrane, the contact area between the spongy membrane layer structure and the surface of the hollow woven tube polyester fiber is larger, and the bonding strength is larger.
The hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane prepared by the invention has high tensile strength, high bonding strength of polyvinylidene fluoride and the hollow woven tube, high rupture pressure, 0.6-1.5 mm inner diameter, 1.2-3.0 mm outer diameter, 80-400N tensile rupture strength, 0.4-0.6 MPa rupture pressure, 0.01-0.1 mu m average pore diameter and 300-2000L/m pure water flux 2 ·h(0.1MPa、25℃)。
The hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane prepared by the invention can be applied to filtration treatment of drinking water, municipal tap water and sewage treatment, filtration and purification treatment in industries such as chemical industry, food, medicine and the like, industrial sewage treatment, pretreatment of sea water desalination and the like.
Detailed Description
The present invention is further illustrated by the following specific examples, which are only a part of the present invention, but not all the present invention, and are not to be construed as limiting the present invention, and any modifications, alternatives, improvements, etc. within the scope of the present invention should be included.
The present invention will be described in detail with reference to the following examples.
Example 1: weighing 17.8% of polyvinylidene fluoride with the molecular weight of 80 ten thousand, 12% of polyethylene glycol 1000, 6% of polyvinylpyrrolidone K45, 1.2% of Tween 80 and 63% of dimethylacetamide according to weight percentage, putting into a dissolution kettle, stirring for 20 hours at the temperature of 90 ℃, stopping stirring, filtering, vacuumizing and defoaming, cooling to obtain a casting solution at 60 ℃, conveying the casting solution to a sleeve-type spinneret at 60 ℃ under the action of nitrogen pressure through a metering pump, feeding a polyester hollow braided tube with the inner diameter of 0.65mm and the outer diameter of 1.2mm into an inner hole of the spinneret at the speed of 20m/m & lt/m & gt through a wire feeding mechanism, coating the casting solution on the outer surface of the polyester hollow braided tube, extruding into hollow fiber, then feeding the hollow fiber into a mixed solution of 50 ℃ and 30% of dimethylacetamide and 10% of polyethylene glycol 400 at the air distance of 50 ℃, solidifying and forming, simultaneously carrying out phase separation, carrying out vertical downward running for 3m & lt/m & gt in the solidifying solution, continuing to run for 7m & lt/m & gt in the solidifying solution through a guide wheel at the bottom of the solidifying solution under the pressure of nitrogen, feeding the washing solution into the washing solution, carrying out ultra-filtration for 5m & lt/m & gt, and winding up the hollow fiber after running into the washing solution at the speed of 20m & lt/m & gt, and the hollow fiber through the ultra-filtration membrane, and the hollow fiber winding up through the hollow fiber. The prepared hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane has the inner diameter of 0.65mm, the outer diameter of 1.35mm, the average pore diameter of 0.09 mu M and the pure water flux of 1800L/M 2 H (0.1 MPa, 25 ℃ C.) and the tensile breaking strength was 100N and the breaking pressure was 0.45MPa.
Example 2: weighing 19% of polyvinylidene fluoride with molecular weight of 80 ten thousand, 10% of polyethylene glycol 400, 8% of polyvinylpyrrolidone K30, 1.5% of tween 80 and 61.5% of dimethylacetamide according to weight percentage, putting into a dissolution kettle, stirring for 20 hours at 90 ℃, stopping stirring, filtering, vacuumizing and defoaming, cooling to obtain casting solution at 60 ℃, conveying the casting solution to a sleeve-type spinneret at 60 ℃ under the action of nitrogen pressure through a metering pump, feeding a hollow woven polyester tube with inner diameter of 0.7mm and outer diameter of 1.3mm into an inner hole of the spinneret at a speed of 20 m/min through a wire feeding mechanism, and coating the casting solution on the hollow polyester tubeThe outer surface of the braided tube is extruded into a hollow fiber shape, then the hollow fiber is solidified and formed in a coagulating liquid of 40% dimethylacetamide aqueous solution at 50 ℃ through an air distance of 80mm, and phase separation occurs at the same time, after the hollow fiber vertically walks downwards in the coagulating liquid for 3 meters, the hollow fiber continuously walks 7 meters in the coagulating liquid after passing through a godet wheel at the bottom of the coagulating liquid, and enters an ultrafiltration water cleaning liquid at 50 ℃, and the hollow fiber is wound at a speed of 20 m/min through a winding wheel after walking for 15 meters in the cleaning liquid, so that the hollow braided tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane is obtained. The prepared hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane has the inner diameter of 0.70mm, the outer diameter of 1.46mm, the average pore diameter of 0.06 mu M and the pure water flux of 1500L/M 2 H (0.1 MPa, 25 ℃ C.) with a tensile breaking strength of 120N and a breaking pressure of 0.51MPa.
Comparative example 2: referring to the formulation and process of example 2, the concentration of dimethylacetamide in the coagulating liquid was changed to 10%, the other was unchanged, and the prepared hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane had an inner diameter of 0.70mm, an outer diameter of 1.46mm, an average pore diameter of 0.06 μm and a pure water flux of 1300L/M 2 H (0.1 MPa, 25 ℃ C.) and the tensile breaking strength was 117N and the breaking pressure was 0.49MPa.
Example 3: weighing 20% of polyvinylidene fluoride with the molecular weight of 65 ten thousand, 10% of polyethylene glycol 400, 10% of polyvinylpyrrolidone K30, 1.5% of Tween 60 and 58.5% of dimethylacetamide according to weight percentage, putting into a dissolution kettle, stirring for 20 hours at the temperature of 90 ℃, stopping stirring, filtering, vacuumizing and defoaming, cooling to obtain a casting solution at 60 ℃, conveying the casting solution to a sleeve-type spinneret at 60 ℃ under the action of nitrogen pressure through a metering pump, conveying a polyester hollow braided tube with the inner diameter of 1.0mm and the outer diameter of 1.8mm into an inner hole of the spinneret through a wire feeding mechanism at the speed of 20m/mi, coating the casting solution on the outer surface of the polyester hollow braided tube, extruding into hollow fiber, then conveying the hollow fiber into a coagulating solution of 50% of dimethylacetamide water solution at the temperature of 50 ℃ through an air distance of 120mm, simultaneously carrying out phase separation, conveying the hollow fiber into the coagulating solution at the temperature of 5m after the coagulating solution vertically and downwardly for 3m, conveying the hollow fiber into the coagulating solution at the temperature of 50 ℃ for 7m after the hollow fiber is conveyed through a wire guide wheel at the bottom of the coagulating solutionIn the filtered water cleaning solution, the hollow fiber is rolled up at a speed of 30 m/min through a filament winding wheel after walking for 15m in the cleaning solution, and the hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane is obtained. The prepared hollow braided tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane has the inner diameter of 1.0mm, the outer diameter of 2.02mm, the average pore diameter of 0.05 mu M and the pure water flux of 1200L/M 2 H (0.1 MPa, 25 ℃ C.) and the tensile breaking strength was 170N and the breaking pressure was 0.53MPa.
Example 4: weighing 22% of polyvinylidene fluoride with the molecular weight of 65 ten thousand, 10% of polyethylene glycol 200, 8% of polyvinylpyrrolidone K30 and 60% of dimethylacetamide according to weight percentage, putting the materials into a dissolution kettle, stirring for 20h at the temperature of 90 ℃, stopping stirring, filtering, vacuumizing and defoaming, cooling to obtain a casting solution at 60 ℃, conveying the casting solution to a sleeve-type spinneret at 60 ℃ through a metering pump under the action of nitrogen pressure, feeding a polyester hollow braided tube with the inner diameter of 0.7mm and the outer diameter of 1.3mm into an inner hole of the spinneret through a wire feeding mechanism at the speed of 30m/m & lt/m & gt, coating the casting solution on the outer surface of the polyester hollow braided tube, extruding the coating solution into hollow fiber, then performing solidification molding in a solidification solution of mixed aqueous solution of 30% of dimethylacetamide and 20% of polyethylene glycol 400 at the temperature of 100mm, simultaneously performing phase separation, continuously performing 7m distance in the solidification solution after the hollow fiber vertically walks down in the solidification solution for 3m distance, entering a winding water at 60 ℃, and winding the hollow fiber after the hollow fiber walks in the ultra-filtration solution for enhancing the hollow fiber by the speed of 30m & lt/m & gt by the ultra-filtration liquid after the hollow fiber walks in the ultrasonic fiber for 15m & lt/m & gt. The prepared hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane has the inner diameter of 0.7mm, the outer diameter of 1.46mm, the average pore diameter of 0.03 mu M and the pure water flux of 980L/M 2 H (0.1 MPa, 25 ℃ C.) and a tensile breaking strength of 125N and a breaking pressure of 0.56MPa.
Example 5: weighing 20% of polyvinylidene fluoride with molecular weight of 80 ten thousand, 8% of polyethylene glycol 400, 12% of polyvinylpyrrolidone K30, 3% of polyvinylpyrrolidone K90 and 57% of dimethylacetamide according to weight percentage, putting into a dissolution kettle, stirring for 20 hours at 90 ℃, stopping stirring, filtering, vacuumizing and defoamingAnd cooling to obtain a casting solution at 60 ℃, conveying the casting solution to a sleeve-type spinneret at 60 ℃ through a metering pump under the action of nitrogen pressure, enabling a polyester hollow braided tube with the inner diameter of 0.7mm and the outer diameter of 1.25mm to enter an inner hole of the spinneret through a wire feeding mechanism at the speed of 20 m/min, coating the casting solution on the outer surface of the polyester hollow braided tube, extruding the hollow fiber, enabling the casting solution to pass through an air distance of 100mm, enabling the casting solution to enter a coagulating solution of 30% dimethylacetamide aqueous solution at 50 ℃ for coagulating and forming, enabling phase separation to occur, enabling the hollow fiber to travel a distance of 3m vertically downwards in the coagulating solution, enabling the hollow fiber to travel a distance of 7m in the coagulating solution after passing through a wire guiding wheel at the bottom of the coagulating solution, enabling the hollow fiber to enter an ultrafiltration water cleaning solution at 50 ℃, and enabling the hollow fiber to travel a distance of 15m in the cleaning solution and then to be rolled up at the speed of 20 m/min through a wire winding wheel, thus obtaining the hollow fiber ultrafiltration membrane of hollow fiber reinforced polyvinylidene fluoride of the hollow fiber of the hollow braided tube. The prepared hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane has the inner diameter of 0.7mm, the outer diameter of 1.4mm, the average pore diameter of 0.04 mu M and the pure water flux of 1150L/M 2 H (0.1 MPa, 25 ℃ C.) and the tensile breaking strength was 122N and the breaking pressure was 0.53MPa.
Comparative example 5: the hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane prepared in example 5 was immersed in a sodium hypochlorite aqueous solution at 40℃and 1% concentration for 5 hours, then washed with ultrafiltration water, and the membrane was tested again for performance with an average pore diameter of 0.04 μm and a pure water flux of 1350L/M 2 H (0.1 MPa, 25 ℃ C.) and a tensile breaking strength of 120N and a breaking pressure of 0.51MPa.
Claims (10)
1. A hollow braided tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane is characterized in that the hollow braided tube is formed by braiding polyester fibers in a crocheting mode.
2. The hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane of claim 1, wherein the membrane layer comprises the following components in percentage by weight:
polyvinylidene fluoride: 75-95%
Hydrophilic modifier: 5 to 20 percent
And (2) a surfactant: 0-10%.
3. The hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane according to claim 1 or 2, wherein the hollow fiber ultrafiltration membrane has an inner diameter of 0.6 to 1.5mm, an outer diameter of 1.2 to 3.0mm, a membrane layer thickness of 0.06 to 0.25mm, a tensile breaking strength of 80 to 400N, a breaking pressure of 0.4 to 0.6MPa, an average pore diameter of 0.01 to 0.1 μm, and a pure water flux of 300 to 2000L/m 2 ·h(0.1MPa、25℃)。
4. The hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane according to claim 1, wherein the inner diameter of the polyester hollow woven tube is 0.6 to 1.5mm, and the outer diameter thereof is 1.1 to 2.5mm.
5. The hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane according to claim 2, wherein the preparation raw materials of the membrane layer comprise the following components in percentage by weight:
6. the hollow-weave-tube-reinforced polyvinylidene fluoride hollow-fiber ultrafiltration membrane according to claim 2 or 5, wherein the molecular weight of the polyvinylidene fluoride is 40 to 100 ten thousand.
7. The hollow-woven tube reinforced polyvinylidene fluoride hollow-fiber ultrafiltration membrane according to claim 2 or 5, wherein: the hydrophilic modifier is one or more selected from polyethylene glycol, polyvinylpyrrolidone, polyvinyl alcohol, polyoxyethylene and methylcellulose; the surfactant is one or more selected from sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium dodecyl aminopropionate, cetyltrimethylammonium bromide, tween 20, tween 60 and Tween 80.
8. The hollow-woven tube reinforced polyvinylidene fluoride hollow-fiber ultrafiltration membrane according to claim 5, wherein: the solvent is one or more selected from dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, trimethyl phosphate and triethyl phosphate.
9. The preparation method of the hollow braided tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane is characterized in that the polyvinylidene fluoride hollow fiber membrane is prepared by a non-solvent induced phase separation method, and the preparation steps are as follows:
step (1): firstly, polyvinylidene fluoride, a hydrophilic modifier, a surfactant and a solvent are put into a dissolution kettle according to a certain proportion, and are stirred for more than 20 hours at 50-90 ℃ to be fully and uniformly dissolved;
step (2): then stopping stirring, filtering, vacuumizing and defoaming, and cooling to obtain a casting solution at 40-80 ℃;
step (3): then, the casting solution is conveyed to a sleeve-type spinneret with the temperature of 40-80 ℃ through a metering pump under the action of nitrogen pressure, a hollow braided tube enters an inner hole of the spinneret at the speed of 10-40 m/min through a wire feeding mechanism, the casting solution is coated on the outer surface of the hollow braided tube, and the hollow braided tube is extruded into a hollow fiber shape;
step (4): finally, the hollow fiber is subjected to solidification forming in a coagulating liquid at 40-80 ℃ after passing through an air distance of 10-300 mm, phase separation occurs at the same time, the hollow fiber continuously moves 7m in the coagulating liquid after passing through a godet wheel at the bottom of the coagulating liquid after vertically moving downwards in the coagulating liquid for 3m distance, then enters a cleaning liquid at 40-80 ℃, and the hollow fiber is wound at a speed of 10-40 m/min through a winding wheel after moving 15m distance in the cleaning liquid, so that the hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane is obtained.
10. The method for preparing the hollow woven tube reinforced polyvinylidene fluoride hollow fiber ultrafiltration membrane according to claim 9, wherein the coagulating liquid is a mixed solution of water, a solvent and polyethylene glycol 400, wherein the concentration of the solvent is 5-70%, the concentration of the polyethylene glycol 400 is 0-30%, the water is tap water filtered by the ultrafiltration membrane, the solvent is dimethylacetamide, and the cleaning liquid is tap water filtered by the ultrafiltration membrane.
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