CN110917894A - Preparation method of polyvinylidene fluoride hollow fiber porous membrane - Google Patents
Preparation method of polyvinylidene fluoride hollow fiber porous membrane Download PDFInfo
- Publication number
- CN110917894A CN110917894A CN201911230562.4A CN201911230562A CN110917894A CN 110917894 A CN110917894 A CN 110917894A CN 201911230562 A CN201911230562 A CN 201911230562A CN 110917894 A CN110917894 A CN 110917894A
- Authority
- CN
- China
- Prior art keywords
- hollow fiber
- polyvinylidene fluoride
- porous membrane
- fiber porous
- forming agent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
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
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0002—Organic membrane manufacture
-
- 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
Abstract
The invention provides a preparation method of a polyvinylidene fluoride hollow fiber porous membrane, which comprises the following steps: 1) the following components are prepared according to the weight ratio: 25-65% of polyvinylidene fluoride resin, 10-60% of organic pore-forming agent, 10-50% of modified MOF material and 0-5% of additive; 2) mixing the modified MOF material with an ethanol solution of an organic pore-forming agent according to the weight ratio, adding polyvinylidene fluoride resin and an additive, and uniformly mixing; drying to remove ethanol to obtain mixed powder for casting film; 3) melting and extruding the mixed powder, cooling the mixed powder in a coagulating bath, and then stretching and heat setting the mixed powder; 4) and extracting to remove the organic pore-forming agent to prepare the polyvinylidene fluoride hollow fiber porous membrane. The method is simple and effective, the three wastes are less generated in the membrane preparation process, and the prepared PVDF hollow fiber porous membrane has excellent performance and uniform pore size distribution.
Description
Technical Field
The invention relates to a preparation method, in particular to a preparation method of a polyvinylidene fluoride hollow fiber porous membrane, and belongs to the technical field of membranes.
Background
At this stage, with the advancement of technology, the industrial application of microfiltration and ultrafiltration membranes has become one of the new chemical unit operations. The microfiltration membrane and the ultrafiltration membrane can be used for separating, concentrating and purifying biological products, medical products and food industry, and can also be used as terminal treatment devices in blood treatment, wastewater treatment and ultrapure water preparation.
Among microfiltration and ultrafiltration membrane materials, polyvinylidene fluoride (PVDF) is a membrane material with excellent performance, can be cleaned by a common oxidizing agent due to hydrophobicity, heat resistance, chemical stability, radiation resistance and good physical and mechanical properties, is widely applied to preparation of separation membranes in recent years, and is widely applied to the fields of electrophoretic painting, printing and dyeing, electroplating and other industrial wastewater and municipal sewage treatment, recovery of protein, starch and the like from food industrial wastewater, pretreatment for removing bacteria and ultrapure water preparation in water, clarification and concentration of traditional Chinese medicine preparations, membrane bioreactors and the like.
Regarding the preparation method of polyvinylidene fluoride hollow fiber membrane, firstly, it is mainly prepared by solution phase inversion method (NIPS method), and Chinese patents CN1128176A and CN1203119A describe the preparation method of wet and dry wet spinning technology in detail: mixing the film-forming polymer, excellent organic solvent and pore-forming agent according to a certain proportion, uniformly dissolving and defoaming, then feeding the mixture into a coagulating bath formed from non-solvent through a spinning nozzle, and extracting the excellent solvent and pore-forming agent in the polymer solution into the coagulating bath phase. However, in such a solution phase transfer method, it is difficult to cause uniform phase separation in the direction of the film thickness, resulting in the formation of a film having a dense skin layer and an asymmetric structure in which a support layer is composed of finger-like pores and sponge-like pores, and thus having isotropy and no orientation, resulting in poor mechanical strength. Further, since the film forming conditions for providing the film structure and the film performance have many factors, the film forming operation process is difficult to control, and the reproducibility is poor. In order to overcome these disadvantages, researchers have tried a thermally induced separation method (TIPS method) in which a phase separation phenomenon is caused by heat through experiments of different film forming processes, and a film is formed by using that polyvinylidene fluoride has good crystallinity, and forms crystals while phase separating in a phase separation process. Through the continuous improvement and solution of the problems in the process by researchers, an improved process for preparing polyvinylidene fluoride hollow fiber membrane by using a thermally induced phase separation method is developed in Chinese patent CN1265048A and Japanese patent JPH 03215535A. The method is that the polyvinylidene fluoride resin is mixed with organic pore-forming agent and hydrophobic silicon dioxide of inorganic micro powder, and the organic pore-forming agent and the hydrophobic silicon dioxide are extracted after the melting forming is carried out at the temperature of 250 ℃. Because a strong alkaline aqueous solution is needed when the hydrophobic silica is extracted, the polyvinylidene fluoride resin forming the membrane is easy to deteriorate, the service life of the membrane in engineering application is influenced, a large amount of inorganic waste water is generated in the membrane preparation process, other means are needed for treatment in the later period, the membrane is not economical and environment-friendly, and the added silica is easy to agglomerate, so that a large cavity defect is easy to form in the extracted membrane, the pore size distribution of the membrane is widened, and the interception effect on pollutants is reduced.
Disclosure of Invention
The invention aims to provide a preparation method of a polyvinylidene fluoride hollow fiber porous membrane, which is simple and effective, generates less three wastes in the membrane preparation process, and the prepared polyvinylidene fluoride hollow fiber porous membrane has excellent product performance and uniform pore size distribution.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the preparation method of the polyvinylidene fluoride hollow fiber porous membrane is characterized by comprising the following steps:
1) the following components are prepared according to the weight ratio:
25-65%, preferably 30-60%,
10-60%, preferably 22-50% of organic pore-forming agent,
10-50%, preferably 15-40% of the modified MOF material,
0 to 5%, preferably 0 to 3%,
2) mixing the modified MOF material with an ethanol solution of an organic pore-forming agent according to the weight ratio, adding polyvinylidene fluoride resin and an additive, and uniformly mixing; drying to remove ethanol to obtain mixed powder for casting film;
3) melting and extruding the mixed powder, cooling the mixed powder in a coagulating bath, and then stretching and heat setting the mixed powder;
4) and extracting to remove the organic pore-forming agent to prepare the polyvinylidene fluoride hollow fiber porous membrane.
Further, the modified MOF material is graft-modified to the MOF material by an amphiphilic copolymer; preferably, the amphiphilic copolymer is one or more of styrene-maleic anhydride copolymer, ethylene-vinyl alcohol copolymer, polystyrene-b-polyisopropylacrylamide (PS-b-PNIPAAm), polystyrene-b-polymethylmethacrylate (PS-b-PMMA), poly-2- (dimethylamino) ethyl methacrylate-b-polyacrylic acid (PDMAEMA-b-PAA), polymethylmethacrylate-b-poly-2- (dimethylamino) ethyl methacrylate (PMMA-b-PDMAEMA), polystyrene-b-polyacrylic acid (PS-b-PAA).
Further, the grafting rate of the amphiphilic copolymer in the MOF material is 15-40%.
Further, the amphiphilic copolymer and the MOF material are subjected to RAFT polymerization reaction to prepare the modified MOF material.
Further, the MOF material is an MOF material containing nitrogen heterocyclic organic ligand, carboxyl group-containing organic ligand, mixed ligand of nitrogen heterocyclic and carboxylic acid or mixed ligand of two carboxylic acids, preferably one or more of ZIF series, MIL series and MOF series, more preferably ZIF-11, ZIF-8, MIL-100(Cr), MOF-199 and MOF-5.
Further, the polyvinylidene fluoride resin is polyvinylidene fluoride homopolymer or copolymer with the weight-average molecular weight of 20-70 ten thousand; when the proportion of the polyvinylidene fluoride resin is too large, the viscosity of the membrane-forming liquid is too high, the membrane-forming is difficult, the requirement on equipment is high, and when the proportion is too small, the requirement on feeding is high, and the mechanical strength of the obtained porous membrane is weak. Therefore, the addition amount of the polyvinylidene fluoride resin is preferably 25 to 65%, more preferably 30 to 60%.
The organic pore-forming agent is one or more of phthalic acid esters, benzoic acid esters, sebacic acid esters, adipic acid esters, phosphoric acid esters, benzophenone, acetyl tributyl citrate, soybean oil, diphenylmethane, trioctyl trimellitate, ethylene bis stearamide and gamma-butyrolactone;
further, the phthalate pore-forming agent is preferably one or more of dibutyl phthalate, dioctyl phthalate, diethyl phthalate, dimethyl isophthalate and dioctyl terephthalate; the benzoate pore former is preferably one or more of diethylene glycol dibenzoate (DEDB), dipropylene glycol dibenzoate (DPGDB), triethylene glycol dibenzoate (TEDB); the sebacic acid ester pore-forming agent is one or two of dioctyl sebacate (DOS) and didecyl sebacate (DIDS); the adipate pore-forming agent is one or more of dioctyl adipate, diisobutyl adipate and diisononyl adipate; the phosphate pore-forming agent is one or more of tributyl phosphate, tricresyl phosphate and triphenyl phosphate.
The additive is one or more of lubricant, antioxidant, heat stabilizer, ultraviolet absorbent and anti-aging agent;
the extractant of the organic pore-forming agent is one or more of N-hexane, cyclohexane, gasoline, ethanol, N-dimethylformamide, N-dimethylacetamide, dichloromethane, trichloromethane and isopropanol.
Further, in the ethanol solution of the organic pore-forming agent, the mass ratio of the organic pore-forming agent to ethanol is 1-5: 1.
Further, the drying temperature in the step 2) is 40-60 ℃; the melting temperature of the step 3) is 120-280 ℃.
Further, the drawing process in the step 3) is to draw the hollow fiber membrane filaments obtained by melt extrusion by 1.5-4 times in the length direction and then wind the hollow fiber membrane filaments.
Further, the heat setting process in the step 3) comprises the step of carrying out heat treatment on the wound hollow fiber membrane filaments at the temperature of 80-160 ℃ for 1-5 hours.
The MOF (Metal Organic Framework) material is also called coordination polymer, and is a novel Organic-inorganic hybrid porous material with regular pore channels or cavities formed by connecting Metal ions or Metal clusters as nodes and Organic ligands through coordination bonds. In order to reduce the influence of the film-making process on the film performance, reduce the generation of three wastes and improve the pollution resistance of the film, the invention fully utilizes the special 3D pore structure and the nanometer characteristics of the MOF material, introduces the modified MOF material grafted with the amphiphilic copolymer into the PVDF hollow fiber film prepared by the thermally induced phase separation method, and prepares the PVDF hollow fiber porous film through subsequent continuous treatment, a plurality of MOF material crystals can be mutually connected to form a three-dimensional network structure of the film after the film is formed, so that the porosity of the film is larger, and the flux is higher. Meanwhile, due to the special pore structure of the MOF material, the MOF material does not need to be extracted and removed after film formation, so that the extraction process and the inorganic wastewater caused by the extraction process are saved, the cavity defect and quality deterioration caused by the extraction of the inorganic material can be effectively avoided, and the MOF material has the technical advantages of uniform pore diameter, high mechanical strength, good interception effect and the like. Therefore, the invention not only greatly reduces the three wastes generated in the membrane preparation process, but also improves the separation performance of the membrane, and the preparation method is economic and environment-friendly and has important practical significance and economic benefit.
Drawings
FIG. 1 is a scanning electron microscope picture of the outer surface of the hollow fiber membrane prepared in example 1;
FIG. 2 is a scanning electron micrograph of a cross section of a hollow fiber membrane prepared in example 1;
FIG. 3 is a scanning electron microscope picture of the outer surface of the hollow fiber membrane prepared in comparative example 1;
FIG. 4 is a scanning electron microscope picture of a cross section of the hollow fiber membrane prepared in comparative example 1;
fig. 5 is a pore size distribution diagram of the hollow fiber membrane prepared in example 3.
Detailed Description
The present invention is further illustrated by the following specific examples, which are intended to be illustrative of the invention and are not to be construed as limiting the scope of the invention.
The raw material sources in the examples and the comparative examples are as follows:
styrene-maleic anhydride polymer (Nanjing silver New chemical, SMA 1000);
ethylene-vinyl alcohol polymer (japanese kohli, F104B);
PS-b-PNIPAAm (Siam Rexi Biotech Co., Ltd.);
PS-b-PMMA (Sienna Rexi Biotech Co., Ltd.);
PDMAEMA-b-PAA (SiAnruix Biotech, Inc.);
PMMA-b-PDMAEMA (Sienna Rexi Biotech Co., Ltd.);
PS-b-PAA (Sian Ruixi Biotech, Inc.);
all MOF materials (shanghai quantitty chemical science and technology limited);
polyvinylidene fluoride (belgian Solvay,
6010)
other raw materials and reagents can be obtained by ordinary commercial routes unless otherwise specified.
The separation performance of the prepared PVDF hollow fiber porous membrane is evaluated and mainly characterized by two characteristic parameters, namely the average pore diameter and the pure water flux of the membrane.
(1) Average pore diameter of membrane: the measurement is carried out by using a POROLUX1000 aperture analyzer, and the test principle calculation formula is as follows:
D＝4δcosθ/P
in the formula: d, the diameter of a membrane pore, mu m;
delta-surface tension of the liquid, N/m;
θ -the contact angle, degree, between the liquid and the pore wall;
p-gas pressure, Pa;
(2) pure water flux (LMH) is defined as: under a certain operating pressure condition, the volume of water penetrating through the effective membrane area in unit time is calculated by the following formula:
J＝Q/At
wherein: j-flux, L/m2·h@0.1mPa；
Q is the permeability of pure water, L;
a-filtration area of the membrane, m2；
t-time for collecting permeate, h;
[ example 1 ]
(1) Preparation of modified MOF material:
a. weighing 4g of ZIF-11 solid powder, filling the powder into 100mL of toluene, uniformly stirring, adding 5mmol of ethylenediamine, and refluxing for 12 hours; cooling and filtering after the reaction is finished to obtain ZIF-NH2Repeatedly washing the nano particles by using absolute ethyl alcohol, drying in vacuum, and grinding for later use;
b. mixing 8g ZIF-NH2Dispersing nano particles and 500mL of dichloromethane by ultrasonic for 1h, cooling to room temperature, adding 4gRAFT reaction reagent 4-cyano-4- [ (dodecyl sulfanyl thiocarbonyl) sulfanyl]Valeric acid (CDP), ice-bath is carried out for 30min, 10g of Dicyclohexylcarbodiimide (DCC) and 2g of 4-Dimethylaminopyridine (DMAP) are added, reaction is carried out for 48h at room temperature, the CDP is fixed on the surface of ZIF nanoparticles to form ZIF-CDP, products are centrifugally separated, and the products are fully washed by ethanol and pure water and then are freeze-dried for standby application;
c. adding 50g of N, N-Dimethylacetamide (DMAC) dispersion of ZIF-CDP nanoparticles into a flask (200mL), ultrasonically dispersing for 30min, introducing nitrogen for 30min, adding 2g of an initiator 2,2' -azobis (isobutyronitrile) (AIBN), 30g (accounting for 60% of the nanoparticles) of a styrene-maleic anhydride polymer and 1g of CDP, introducing nitrogen for 1h, transferring the container into a 70 ℃ oil bath to start RAFT reaction, and carrying out nitrogen protection and magnetic stirring in the whole process. After reacting for 1 hour, carrying out ice bath extraction and cooling to terminate the reaction, repeatedly diluting the reactant with DMAC, centrifuging, washing away unreacted substances to obtain a ZIF nano particle material with the surface grafted with a styrene-maleic anhydride polymer, and calculating by adopting a weighing method, wherein the grafting rate of the styrene-maleic anhydride polymer in ZIF-11 is 23%.
(2) Preparing a PVDF hollow fiber porous membrane:
respectively preparing 22% of the modified ZIF-11 crystal, 27% of dioctyl phthalate, 11% of dibutyl phthalate and 40% of polyvinylidene fluoride according to the mass ratio, uniformly mixing the ZIF-11 crystal, the dioctyl phthalate and the dibutyl phthalate with ethanol in a high-speed mixer (the mass ratio of the total weight of the dioctyl phthalate and the dibutyl phthalate to the ethanol is 2: 1 at 30 ℃) to uniformly disperse the materials in an organic phase, then adding polyvinylidene fluoride, and drying for 5 hours at 50 ℃ after mixing to remove the ethanol.
The mixed materials are passed through a double screw extruder (the diameter of a screw is 20mm, the length-diameter ratio is 40: 1), the barrel temperature is controlled to be 250 ℃ for mixing and melting, then the materials pass through a circular spinning nozzle with the outer diameter of 2mm and the inner diameter of 1mm, a nozzle mold with the temperature of a nozzle controlled to be 240 ℃ is controlled, air is injected into the inner diameter of the spinning nozzle through the air flow of 50mL/min, the extruded hollow fiber membrane yarn is introduced into a pure water solidification cooling bath with the temperature controlled to be 30 ℃, the hollow fiber membrane yarn is drawn from the solidification bath at the speed of 20m/min through a drawing wheel, the membrane yarn is drawn to the drawing wheel at the drawing ratio of 2 times of the speed of 40m/min, and the membrane yarn is wound. Winding the film filaments on a certain number of filament winding wheels, putting the film filaments into a heat setting oven with the temperature of 120 ℃ for heat setting for 5 hours, taking the film filaments off the filament winding wheels, and immersing the film filaments into a 95% ethanol solution with the temperature controlled at 65 ℃ for extraction for 6 hours to extract the dioctyl phthalate and the dibutyl phthalate in the film filaments.
The outer surface and the cross section of the hollow fiber porous membrane prepared in this example were photographed by a scanning electron microscope, and are shown in fig. 1 and fig. 2, respectively.
[ example 2 ]
(1) Preparation of modified MOF material:
the modified MOF material is prepared by the method in example 1, except that the MOF material is ZIF-8, the amphiphilic copolymer is an ethylene-vinyl alcohol copolymer, and the addition amount of the copolymer in step (1) c is 40% of the mass of the ZIF-CDP nanoparticles. The graft ratio of the copolymer in ZIF-8 is 15% calculated by adopting a weighing method.
(2) Preparing a PVDF hollow fiber porous membrane:
the PVDF hollow fiber porous membrane prepared by the method in the embodiment 1 is different in that the materials and the corresponding mass ratio are as follows: 10% of the modified ZIF-8 crystal, 22% of trioctyl trimellitate, 5% of benzophenone, 60% of polyvinylidene fluoride and 3% of antioxidant 1010. The mass ratio of the organic pore-forming agent (trioctyl trimellitate and benzophenone) to the ethanol is 1: 1.
[ example 3 ]
(1) Preparation of modified MOF material:
the modified MOF material was prepared by the method of example 1, except that MIL-100(Cr) was selected as the MOF material, the amphiphilic copolymer was an ethylene-vinyl alcohol polymer, and the amount of copolymer added in step (1). The graft ratio of the copolymer in ZIF-8 is 33% calculated by adopting a weighing method.
(2) Preparing a PVDF hollow fiber porous membrane:
the PVDF hollow fiber porous membrane prepared by the method in the embodiment 1 is different in that the materials and the corresponding mass ratio are as follows: 40% of the modified MIL-100(Cr) crystal, 34.5% of acetyl tributyl citrate, 25% of polyvinylidene fluoride and 0.5% of heat stabilizer. The mass ratio of the organic pore-forming agent (acetyl tributyl citrate) to the ethanol is 5: 1.
the pore size and pore size distribution of the hollow fiber porous membrane prepared in this example were measured by a german prometrol Porolux1000 pore size analyzer, and the results are shown in fig. 5.
[ example 4 ]
(1) Preparation of modified MOF material:
the method for preparing the modified MOF material in the embodiment 1 is adopted, and the difference is that the MOF material is MOF-199, the amphiphilic copolymer is PS-b-PNIPAAm, and the adding amount of the copolymer in the step (1) c is 90% of the mass of ZIF-CDP nanoparticles. The graft ratio of the copolymer in ZIF-8 is 40% calculated by adopting a weighing method.
(2) Preparing a PVDF hollow fiber porous membrane:
the PVDF hollow fiber porous membrane prepared by the method in the embodiment 1 is different in that the materials and the corresponding mass ratio are as follows: 15% of the modified MOF-199 crystal, 15% of ethylene bis stearamide, 5% of gamma-butyrolactone and 65% of polyvinylidene fluoride. The mass ratio of the organic pore-forming agent (ethylene bis stearamide and gamma-butyrolactone) to ethanol is 3: 1.
[ example 5 ]
(1) Preparation of modified MOF material:
the method for preparing the modified MOF material in the embodiment 1 is adopted, and the difference is that the MOF material is MOF-5, the amphiphilic copolymer is PMMA-b-PDMAEMA, and the adding amount of the copolymer in the step (1) c is 75% of the mass of ZIF-CDP nanoparticles. The graft ratio of the copolymer in ZIF-8 is 28% calculated by adopting a weighing method.
(2) Preparing a PVDF hollow fiber porous membrane:
the PVDF hollow fiber porous membrane prepared by the method in the embodiment 1 is different in that the materials and the corresponding mass ratio are as follows: 50% of the modified MOF-5 crystal, 14% of tributyl phosphate, 6% of soybean oil and 30% of polyvinylidene fluoride. The mass ratio of the organic pore-forming agent (tributyl phosphate and soybean oil) to the ethanol is 4: 1.
[ example 6 ]
(1) Preparation of modified MOF material:
the modified MOF material was prepared by the method of example 1, except that ZIF-90 was selected as the MOF material, the amphiphilic copolymer was PDMAEMA-b-PAA, and the amount of copolymer added in step (1). c was 70% of the mass of ZIF-CDP nanoparticles. The graft ratio of the copolymer in ZIF-8 is 25% calculated by adopting a weighing method.
(2) Preparing a PVDF hollow fiber porous membrane:
the PVDF hollow fiber porous membrane prepared by the method in the embodiment 1 is different in that the materials and the corresponding mass ratio are as follows: 30% of the modified ZIF-90 crystal, 10% of diethylene glycol dibenzoate (DEDB), 55% of polyvinylidene fluoride and 5% of an ultraviolet absorbent. The mass ratio of the organic pore-forming agent (diethylene glycol dibenzoate) to the ethanol is 2.5: 1.
[ example 7 ]
(1) Preparation of modified MOF material:
the modified MOF material was prepared by the method of example 1, except that MIL-125(Ti) was selected as the MOF material, the amphiphilic copolymer was PS-b-PAA, and the amount of copolymer added in step (1) c was 50% of the mass of ZIF-CDP nanoparticles. The graft ratio of the copolymer in ZIF-8 is 18 percent by calculation of a weighing method.
(2) Preparing a PVDF hollow fiber porous membrane:
the PVDF hollow fiber porous membrane prepared by the method in the embodiment 1 is different in that the materials and the corresponding mass ratio are as follows: 12% of the modified MIL-125(Ti) crystal, 37% of dioctyl sebacate, 13% of dioctyl adipate and 38% of polyvinylidene fluoride. The mass ratio of the organic pore-forming agent (dioctyl sebacate and dioctyl adipate) to the ethanol is 1.5: 1.
[ example 8 ]
(1) Preparation of modified MOF material:
the modified MOF material is prepared by the method in the embodiment 1, and the difference is that the MOF material is ZIF-7, the amphiphilic copolymer is PS-b-PMMA, and the addition amount of the copolymer in the step (1) c is 65% of the mass of ZIF-CDP nanoparticles. The graft ratio of the copolymer in ZIF-8 is 26% calculated by adopting a weighing method.
(2) Preparing a PVDF hollow fiber porous membrane:
the PVDF hollow fiber porous membrane prepared by the method in the embodiment 1 is different in that the materials and the corresponding mass ratio are as follows: 11% of the modified ZIF-7 crystal, 32% of acetyl tributyl citrate, 28% of dibutyl phthalate and 29% of polyvinylidene fluoride. The mass ratio of the organic pore-forming agent (acetyl tributyl citrate and dibutyl phthalate) to the ethanol is 1: 1.
comparative example 1
The PVDF hollow fiber porous membrane prepared by the method in the embodiment 1 is different in that the materials and the corresponding mass ratio are as follows: 30% dioctyl phthalate, 15% dibutyl phthalate, 55% polyvinylidene fluoride, without adding modified MOF material.
The outer surface and the cross section of the hollow fiber porous membrane prepared in the comparative example were photographed by a scanning electron microscope, and are shown in fig. 3 and 4, respectively.
Comparative example 2
The PVDF hollow fiber porous membrane prepared by the method in the embodiment 1 is different in that the materials and the corresponding mass ratio are as follows: 20% of dioctyl phthalate, 15% of dibutyl phthalate, 40% of polyvinylidene fluoride and 25% of nano silicon dioxide. And a post-treatment process of extracting for 4 hours at 65 ℃ by adopting 5% sodium hydroxide is added, so that the silicon dioxide in the membrane filaments is extracted. After the extraction process is finished, a large amount of strong-alkaline inorganic waste liquid containing sodium silicate is generated, and the treatment difficulty and cost of subsequent waste liquid can be increased.
The PVDF hollow fiber porous membranes prepared in the above examples and comparative examples were subjected to performance tests, and the test data are shown in table 1:
TABLE 1PVDF hollow fiber porous Membrane Performance test results
As can be seen from the performance test results of the hollow fiber porous membranes of examples 1 to 8 and comparative examples 1 to 2, the PVDF hollow fiber porous membrane prepared by the preparation method has the outer diameter of 0.9 to 1.25mm, the wall thickness of 0.2 to 0.3mm, the porosity of 72 to 88 percent, the membrane aperture of 0.02 to 0.82 mu m, and the pure water flux of 830 to 8830L/m2H @0.1mPa,25 ℃, the tensile breaking strength of 8.49-14.47 MPa, and the tensile breaking elongation of 75-187%.
In addition, as can be seen from comparison of fig. 1 and 3, the hollow fiber membrane prepared in example 1 of the present invention has a higher surface aperture ratio, which results in a greater pure water flux; comparing fig. 2 and 4, it can be seen that the sponge structure of the cross section of the hollow fiber membrane prepared in example 1 of the present invention is denser, has no void defect, and can better ensure the retention performance, mechanical strength and long-term service life of the membrane in the later use process of the membrane. The pore size distribution chart in fig. 3 shows that the membrane filaments obtained by the method of the invention in example 3 have uniform pore size and narrower pore size distribution, the single-point pore size ratio exceeds 95%, and the repeatability among different membrane filaments is good.
Therefore, the PVDF hollow fiber porous membrane obtained by the modified MOF material and other processes is easier to control the pore diameter, more uniform in pore diameter distribution, higher in flux and higher in strength, and only the organic pore-forming agent in the PVDF hollow fiber porous membrane needs to be extracted in the post-treatment stage, so that the instability of chemical properties caused by the color change (yellow brown) of the membrane filaments in the comparative example 2 is avoided, and the damage to the membrane and a large amount of three wastes generated by the subsequent extraction treatment are reduced.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and additions can be made without departing from the method of the present invention, and these modifications and additions should also be regarded as the protection scope of the present invention.
Claims (10)
1. The preparation method of the polyvinylidene fluoride hollow fiber porous membrane is characterized by comprising the following steps:
1) the following components are prepared according to the weight ratio:
25-65%, preferably 30-60%,
10-60%, preferably 22-50% of organic pore-forming agent,
10-50%, preferably 15-40% of the modified MOF material,
0 to 5%, preferably 0 to 3%,
2) mixing the modified MOF material with an ethanol solution of an organic pore-forming agent according to the weight ratio, adding polyvinylidene fluoride resin and an additive, and uniformly mixing; drying to remove ethanol to obtain mixed powder for casting film;
3) melting and extruding the mixed powder, cooling the mixed powder in a coagulating bath, and then stretching and heat setting the mixed powder;
4) and extracting to remove the organic pore-forming agent to prepare the polyvinylidene fluoride hollow fiber porous membrane.
2. The method for preparing a polyvinylidene fluoride hollow fiber porous membrane according to claim 1, wherein the modified MOF material is graft-modified with an amphiphilic copolymer; preferably, the amphiphilic copolymer is one or more of styrene-maleic anhydride copolymer, ethylene-vinyl alcohol copolymer, PS-b-PNIPAAm, PS-b-PMMA, PDMAEMA-b-PAA, PMMA-b-PDMAEMA and PS-b-PAA.
3. The preparation method of the polyvinylidene fluoride hollow fiber porous membrane according to claim 2, wherein the grafting ratio of the amphiphilic copolymer in the MOF material is 15-40%.
4. The preparation method of the polyvinylidene fluoride hollow fiber porous membrane according to claim 3, wherein the modified MOF material is prepared by RAFT polymerization of the amphiphilic copolymer and the MOF material.
5. The preparation method of the polyvinylidene fluoride hollow fiber porous membrane according to any one of claims 2 to 4, wherein the MOF material is an MOF material of a nitrogen-containing heterocyclic organic ligand, a carboxyl-containing organic ligand, a mixed ligand of a nitrogen-containing heterocyclic ring and a carboxylic acid or a mixed ligand of two carboxylic acids, preferably one or more of ZIF series, MIL series and MOF series, and more preferably ZIF-11, ZIF-8, MIL-100(Cr), MOF-199 and MOF-5.
6. The method for preparing a polyvinylidene fluoride hollow fiber porous membrane according to any one of claims 1 to 5, wherein the polyvinylidene fluoride resin is a polyvinylidene fluoride homopolymer or copolymer having a weight average molecular weight of 20 to 70 ten thousand;
the organic pore-forming agent is one or more of phthalic acid esters, benzoic acid esters, sebacic acid esters, adipic acid esters, phosphoric acid esters, benzophenone, acetyl tributyl citrate, soybean oil, diphenylmethane, trioctyl trimellitate, ethylene bis stearamide and gamma-butyrolactone;
the additive is one or more of lubricant, antioxidant, heat stabilizer, ultraviolet absorbent and anti-aging agent;
the extractant of the organic pore-forming agent is one or more of N-hexane, cyclohexane, gasoline, ethanol, N-dimethylformamide, N-dimethylacetamide, dichloromethane, trichloromethane and isopropanol.
7. The method for producing a polyvinylidene fluoride hollow fiber porous membrane according to any one of claims 1 to 6, wherein a mass ratio of the organic pore-forming agent to ethanol in the ethanol solution of the organic pore-forming agent is 1 to 5: 1.
8. The method for preparing a polyvinylidene fluoride hollow fiber porous membrane according to any one of claims 1 to 7, wherein the drying temperature of the step 2) is 40 to 60 ℃; the melting temperature of the step 3) is 120-280 ℃.
9. The method for preparing a polyvinylidene fluoride hollow fiber porous membrane according to any one of claims 1 to 8, wherein the drawing process in the step 3) is to draw the hollow fiber membrane filaments obtained by melt extrusion by 1.5 to 4 times in the length direction and then to wind the hollow fiber membrane filaments.
10. The method for preparing a polyvinylidene fluoride hollow fiber porous membrane according to any one of claims 1 to 9, wherein the heat setting in the step 3) is performed by heat-treating the wound hollow fiber membrane filaments at 80 to 160 ℃ for 1 to 5 hours.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911230562.4A CN110917894B (en) | 2019-12-05 | 2019-12-05 | Preparation method of polyvinylidene fluoride hollow fiber porous membrane |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911230562.4A CN110917894B (en) | 2019-12-05 | 2019-12-05 | Preparation method of polyvinylidene fluoride hollow fiber porous membrane |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110917894A true CN110917894A (en) | 2020-03-27 |
| CN110917894B CN110917894B (en) | 2022-02-15 |
Family
ID=69856837
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911230562.4A Active CN110917894B (en) | 2019-12-05 | 2019-12-05 | Preparation method of polyvinylidene fluoride hollow fiber porous membrane |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110917894B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111847751A (en) * | 2020-08-29 | 2020-10-30 | 江苏美能膜材料科技有限公司 | Zero-emission recovery process for waste liquid generated by preparing polyvinylidene fluoride porous membrane |
| CN112973459A (en) * | 2021-03-09 | 2021-06-18 | 万华化学集团股份有限公司 | Fluoropolymer hollow fiber porous membrane and preparation method thereof |
| CN113019145A (en) * | 2021-04-03 | 2021-06-25 | 浙江海洋大学 | Preparation method of super-wetting oil-water separation membrane |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03215535A (en) * | 1989-01-12 | 1991-09-20 | Asahi Chem Ind Co Ltd | Porous polyvinylidene fluoride film and production thereof |
| CN1265048A (en) * | 1996-12-10 | 2000-08-30 | 旭化成工业株式会社 | Porous polyvinylidene fluoride resin film and process for producing same |
| CN1281301C (en) * | 2004-09-30 | 2006-10-25 | 浙江大学 | Method for preparing for polyvinylidene fluoride hollow fiber microporous film by melt spinning-pull stretching method |
| KR20130047226A (en) * | 2011-10-31 | 2013-05-08 | 웅진케미칼 주식회사 | Pvdf membrane for water treatment improving membrane properties and manufacturing method thereof |
| CN107866155A (en) * | 2016-09-26 | 2018-04-03 | 天津工业大学 | A kind of method that polymer matrix MOFs hollow fiber ultrafiltration membranes are prepared using thermally induced phase separation |
| CN109529634A (en) * | 2018-10-30 | 2019-03-29 | 南京理工大学 | The preparation method of metal organic framework ZIF-67-PVDF hollow-fibre membrane |
-
2019
- 2019-12-05 CN CN201911230562.4A patent/CN110917894B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03215535A (en) * | 1989-01-12 | 1991-09-20 | Asahi Chem Ind Co Ltd | Porous polyvinylidene fluoride film and production thereof |
| CN1265048A (en) * | 1996-12-10 | 2000-08-30 | 旭化成工业株式会社 | Porous polyvinylidene fluoride resin film and process for producing same |
| CN1281301C (en) * | 2004-09-30 | 2006-10-25 | 浙江大学 | Method for preparing for polyvinylidene fluoride hollow fiber microporous film by melt spinning-pull stretching method |
| KR20130047226A (en) * | 2011-10-31 | 2013-05-08 | 웅진케미칼 주식회사 | Pvdf membrane for water treatment improving membrane properties and manufacturing method thereof |
| CN107866155A (en) * | 2016-09-26 | 2018-04-03 | 天津工业大学 | A kind of method that polymer matrix MOFs hollow fiber ultrafiltration membranes are prepared using thermally induced phase separation |
| CN109529634A (en) * | 2018-10-30 | 2019-03-29 | 南京理工大学 | The preparation method of metal organic framework ZIF-67-PVDF hollow-fibre membrane |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111847751A (en) * | 2020-08-29 | 2020-10-30 | 江苏美能膜材料科技有限公司 | Zero-emission recovery process for waste liquid generated by preparing polyvinylidene fluoride porous membrane |
| CN112973459A (en) * | 2021-03-09 | 2021-06-18 | 万华化学集团股份有限公司 | Fluoropolymer hollow fiber porous membrane and preparation method thereof |
| CN112973459B (en) * | 2021-03-09 | 2022-08-05 | 万华化学集团股份有限公司 | Fluoropolymer hollow fiber porous membrane and preparation method thereof |
| CN113019145A (en) * | 2021-04-03 | 2021-06-25 | 浙江海洋大学 | Preparation method of super-wetting oil-water separation membrane |
| CN113019145B (en) * | 2021-04-03 | 2022-03-22 | 浙江海洋大学 | Preparation method of super-wetting oil-water separation membrane |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110917894B (en) | 2022-02-15 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110917894B (en) | Preparation method of polyvinylidene fluoride hollow fiber porous membrane | |
| CN100584437C (en) | Hydrophilic polyvinylidene fluoride hollow fiber microporous membrane and preparation method thereof | |
| US8967391B2 (en) | Method for preparing composite multilayer porous hollow membrane and device and product thereof | |
| CN102245284B (en) | Hydrophobic ozone-stable membrane made of polyvinylidene fluoride | |
| CN104548950B (en) | Inorganic nano-particle enhanced polypropylene hollow fiber microporous membrane and preparation method thereof | |
| EP2052771B1 (en) | Porous membrane of vinylidene fluoride resin and process for producing the same | |
| CN102210979B (en) | Positively charged polyvinyl chloride hollow fiber nanofiltration membrane and preparation method thereof | |
| US9095819B2 (en) | Composition for preparation of hollow fiber porous membrane and preparation method using the same | |
| KR101539608B1 (en) | Polyvinylidene fluoride Hollow Fiber Membranes and Preparation Thereof | |
| US20150136691A1 (en) | Method for preparing double layered porous hollow membrane and device and product thereof | |
| CN101015773A (en) | Porous polyvinylidene blending porous membrane and process for producing same | |
| CN110201558B (en) | Large-flux reinforced PVDF unlined ultrafiltration membrane and preparation method thereof | |
| WO2016115908A1 (en) | Polyvinylidene fluoride hollow fibre membrane of in-situ pore-forming agent and preparation method therefor | |
| EP3147024A1 (en) | Hollow-fibre polymer membrane | |
| CN103394293A (en) | Preparation method for hydrophilia polyvinylidene fluoride hollow fiber membrane | |
| CN101439269A (en) | Method for preparing thermoplastic polyurethane elastic hollow fiber membrane | |
| JP2003210954A (en) | Method of manufacturing hollow fiber membrane and hollow fiber membrane | |
| CN108499361B (en) | Preparation method of nano-porous polymer film with adjustable pore size | |
| CN103861477A (en) | Polyvinylidene fluoride/palladium nanoparticle hybrid hollow fiber membrane and preparation method thereof | |
| JP4564758B2 (en) | Method for producing vinylidene fluoride resin porous membrane | |
| JPS5916503A (en) | Porous hollow yarn membrane of polyvinylidene fluoride resin and its production | |
| CN114588792B (en) | Polyvinyl butyral blending reinforced polyvinylidene chloride ultrafiltration membrane and preparation method thereof | |
| RU2440181C2 (en) | Porous membrane from vinylidene fluoride resin and method of its production | |
| Shahgaldi et al. | Investigation of the effect of electrospun polyethersulfone nanofibers in membrane | |
| CN106560231B (en) | A kind of method that fumed silica prepares PVC microfiltration membranes as pore-foaming agent |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |