KR20110076333A - Method for manufacturing microfiltration membrane and high flux microfiltration membrane manufactured therefrom - Google Patents
Method for manufacturing microfiltration membrane and high flux microfiltration membrane manufactured therefrom Download PDFInfo
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- KR20110076333A KR20110076333A KR1020090133015A KR20090133015A KR20110076333A KR 20110076333 A KR20110076333 A KR 20110076333A KR 1020090133015 A KR1020090133015 A KR 1020090133015A KR 20090133015 A KR20090133015 A KR 20090133015A KR 20110076333 A KR20110076333 A KR 20110076333A
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- 239000012528 membrane Substances 0.000 title claims abstract description 91
- 238000001471 micro-filtration Methods 0.000 title claims abstract description 33
- 238000000034 method Methods 0.000 title claims abstract description 17
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 15
- 230000004907 flux Effects 0.000 title abstract 2
- 229920000642 polymer Polymers 0.000 claims abstract description 68
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 27
- 239000002033 PVDF binder Substances 0.000 claims abstract description 19
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims abstract description 19
- 229910017053 inorganic salt Inorganic materials 0.000 claims abstract description 13
- 238000001035 drying Methods 0.000 claims abstract description 7
- 239000012510 hollow fiber Substances 0.000 claims abstract description 7
- 239000004745 nonwoven fabric Substances 0.000 claims abstract description 7
- 239000003960 organic solvent Substances 0.000 claims abstract description 6
- 239000012153 distilled water Substances 0.000 claims abstract description 5
- 239000011148 porous material Substances 0.000 claims description 60
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical group [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 33
- 239000011780 sodium chloride Substances 0.000 claims description 16
- 230000035699 permeability Effects 0.000 claims description 10
- 239000013557 residual solvent Substances 0.000 claims description 8
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 6
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims description 5
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 4
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 4
- 238000007872 degassing Methods 0.000 claims description 4
- 238000007598 dipping method Methods 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 3
- 229920001223 polyethylene glycol Polymers 0.000 claims description 3
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 claims description 2
- WHNWPMSKXPGLAX-UHFFFAOYSA-N N-Vinyl-2-pyrrolidone Chemical compound C=CN1CCCC1=O WHNWPMSKXPGLAX-UHFFFAOYSA-N 0.000 claims description 2
- 238000005266 casting Methods 0.000 claims description 2
- SBZXBUIDTXKZTM-UHFFFAOYSA-N diglyme Chemical compound COCCOCCOC SBZXBUIDTXKZTM-UHFFFAOYSA-N 0.000 claims description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 2
- 239000002904 solvent Substances 0.000 abstract description 26
- 230000000149 penetrating effect Effects 0.000 abstract 1
- 238000009826 distribution Methods 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 13
- 238000001914 filtration Methods 0.000 description 10
- 238000005191 phase separation Methods 0.000 description 10
- 230000007423 decrease Effects 0.000 description 8
- 230000000694 effects Effects 0.000 description 5
- 238000007654 immersion Methods 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 229920000036 polyvinylpyrrolidone Polymers 0.000 description 4
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 description 4
- 239000001267 polyvinylpyrrolidone Substances 0.000 description 4
- 238000005259 measurement Methods 0.000 description 3
- 239000000654 additive Substances 0.000 description 2
- 239000012298 atmosphere Substances 0.000 description 2
- 238000005345 coagulation Methods 0.000 description 2
- 230000015271 coagulation Effects 0.000 description 2
- 239000002667 nucleating agent Substances 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 238000000108 ultra-filtration Methods 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 239000002202 Polyethylene glycol Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000001112 coagulating effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000000635 electron micrograph Methods 0.000 description 1
- 238000000445 field-emission scanning electron microscopy Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910003002 lithium salt Inorganic materials 0.000 description 1
- 159000000002 lithium salts Chemical class 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000012982 microporous membrane Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 229920000620 organic polymer Polymers 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000011343 solid material Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 229910021642 ultra pure water Inorganic materials 0.000 description 1
- 239000012498 ultrapure water Substances 0.000 description 1
Classifications
-
- 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
- B01D67/0006—Organic membrane manufacture by chemical reactions
-
- 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
- B01D61/147—Microfiltration
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D63/00—Apparatus in general for separation processes using semi-permeable membranes
- B01D63/02—Hollow fibre modules
-
- 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
- B01D67/0011—Casting solutions therefor
-
- 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
- B01D67/0013—Casting processes
-
- 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
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0081—After-treatment of organic or inorganic membranes
- B01D67/0095—Drying
-
- 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
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/10—Supported membranes; Membrane supports
- B01D69/107—Organic support material
- B01D69/1071—Woven, non-woven or net mesh
-
- 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
-
- 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
- B01D2323/00—Details relating to membrane preparation
- B01D2323/12—Specific ratios of components used
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/15—Use of additives
- B01D2323/218—Additive materials
- B01D2323/2181—Inorganic additives
- B01D2323/21817—Salts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/219—Specific solvent system
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/02—Details relating to pores or porosity of the membranes
- B01D2325/022—Asymmetric membranes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/02—Details relating to pores or porosity of the membranes
- B01D2325/026—Sponge structure
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/02—Details relating to pores or porosity of the membranes
- B01D2325/0283—Pore size
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/20—Specific permeability or cut-off range
Abstract
Description
본 발명의 구현예들은 수처리를 위한 정밀여과막의 제조방법에 관한 것이다. Embodiments of the present invention are directed to a method for producing a microfiltration membrane for water treatment.
수처리용 분리막은 물속에 존재하는 미세 고형물을 분리하는데 사용하는 막으로, 고형 물질의 제거성능 및 여과수의 투과성능이 높을수록 좋다. 그러나 제거성능과 투과성능은 서로 반대급부에 있는 관계로, 두 성능을 동시에 만족시키기가 쉽지 않다. 이러한 요구를 충족시키기 위해, 제거성능에 영향을 미치는 분리막 표면의 기공크기는 작게 하고, 투과성능에 영향을 미치는 단면의 기공크기는 분리막 표면으로부터 점진적으로 커져 단면방향으로 여과저항을 줄이는 비대칭막이 제안되었다. 막의 재료가 되는 고분자를 적절한 용매에 녹여 고분자 용액을 제조하고 이를 비용매에 침지하여 상분리를 유도하여 평판형 또는 중공사형 비대칭막을 제조할 수 있다. 이러한 비용매에 의한 상분리법에 의해 비대칭막을 제조할 경우 고분자 용액의 열역학적 또는 동역학적 특성과 용매 또는 비용매의 종류, 비용매의 온도, 제막시의 온도 및 습도 등 다양한 인자에 의해 분리막 표면 또는 단면의 미세 기공 구조가 영향을 받는다. 따라서, 이와 같은 다양한 인자들을 조절하여 기공크기가 수십 나노미터인 한외여과막 또는 기공크기가 수백 나노미터인 정밀여과막을 제조한다. The separation membrane for water treatment is a membrane used to separate fine solids present in water, and the higher the removal performance of the solid material and the higher the permeation performance of the filtered water. However, since the removal performance and permeation performance are in opposite parts, it is not easy to satisfy both performances at the same time. In order to meet these demands, an asymmetric membrane has been proposed to reduce the pore size of the membrane surface affecting the removal performance and the pore size of the cross section affecting the permeation performance to gradually increase from the membrane surface to reduce the filtration resistance in the cross-sectional direction. . A polymer solution may be prepared by dissolving a polymer, which is a material of a membrane, in an appropriate solvent, and immersing it in a non-solvent to induce phase separation to prepare a flat or hollow fiber asymmetric membrane. When the asymmetric membrane is prepared by such a non-solvent phase separation method, the membrane surface or cross section is determined by various factors such as thermodynamic or kinetic properties of the polymer solution, the type of solvent or non-solvent, the temperature of the non-solvent, and the temperature and humidity at the time of film formation. The fine pore structure of is affected. Therefore, by controlling such various factors, an ultrafiltration membrane having a pore size of several tens of nanometers or a microfiltration membrane having a pore size of several hundred nanometers is prepared.
일반적으로 고분자 용액이 열역학적으로 안정된 상태에서 비용매에 침지되어 상분리가 급격히 일어날수록 분리막 표면의 기공크기는 작아지고 단면의 비대칭성은 증가한다. 반면, 비용매 침지전 대기 중에서 비용매 증기 유입시간이 주어지는 지연된 상분리의 경우 표면의 기공크기가 증가하고 비대칭성이 감소한다. In general, as the polymer solution is immersed in the non-solvent in a thermodynamically stable state, as the phase separation rapidly occurs, the pore size of the membrane surface decreases and the asymmetry of the cross section increases. On the other hand, in the case of delayed phase separation in which the nonsolvent vapor inlet time is given in the non-solvent immersion atmosphere, the pore size of the surface increases and the asymmetry decreases.
정밀여과막을 제조하는 경우 분리막 표면 기공의 성장을 위해 비용매 침지전 대기 중에서 비용매 증기 도입에 의한 미세 상분리 시간을 충분히 갖는 한편, 고분자 용액에 비용매를 도입하여 고분자 용액의 열역학적 불안정성을 증가시키거나, 폴리비닐피롤리돈, 폴리에틸렌글리콜 등 친수성 유기 고분자 또는 리튬염 등 무기염을 기핵제로 첨가하여 기공형성을 촉진하는 등 다양한 제조방법이 알려져 있다. In case of manufacturing the microfiltration membrane, the microporous membrane has sufficient time to separate the phase of the nonsolvent by introducing the nonsolvent vapor in the atmosphere before the non-solvent immersion for the growth of the surface pores of the membrane, while introducing the nonsolvent into the polymer solution to increase the thermodynamic instability of the polymer solution Hydrophilic organic polymers such as polyvinylpyrrolidone, polyethylene glycol or inorganic salts such as lithium salts are added as nucleating agents to promote pore formation.
일반적으로 고분자의 열역학적 불안정성이 증대될수록 비용매 도입에 따른 고분자 용액의 상분리의 속도 제어가 어려워 표면 기공크기의 분포가 커지고, 단면의 기공구조가 분리막 표면의 기공크기 범위에서 크게 벗어나지 않는 대칭구조가 되는 경향이 있어 단면방향으로의 여과저항이 커져 투과성능에 좋지 않은 문제 점이 있다. In general, the higher the thermodynamic instability of the polymer, the more difficult it is to control the phase separation of the polymer solution due to the introduction of the non-solvent, so that the surface pore size distribution becomes larger, and the pore structure of the cross section becomes a symmetrical structure that does not deviate significantly from the pore size range of the membrane surface. There is a tendency to increase the filtration resistance in the cross-sectional direction, there is a problem that is not good for permeation performance.
한편, 고분자 용액의 유동성이 클수록 고분자 용액 내의 고분자 사슬들의 물리적인 엉킴이 약해 고분자 용액이 비용매와 접촉시 비용매가 고분자 용액 내로 들어가고 고분자 용액 내의 용매가 비용매상으로 빠져나오는 용매/비용매 치환이 빠른 속도로 일어나 분리막 표면의 기공크기는 작아지며, 단면 방향으로의 빠른 확산으로 인해 거대 기공이 생성되어 막의 기계적 강도를 약화시키는 문제점이 있다. 이를 개선하기 위해 고분자 용액 내에 고분자의 농도를 증가시켜 유동성을 감소시키기도 하지만, 고분자 농도 증가에 따라 분리막의 기공크기와 기공도가 낮아져 투과성능이 급격히 저하되는 문제점이 있다. On the other hand, the greater the fluidity of the polymer solution, the weaker the physical entanglement of the polymer chains in the polymer solution, and thus, the faster the solvent / non-solvent substitution in which the non-solvent enters the polymer solution and the solvent in the polymer solution escapes into the non-solvent phase. The pore size of the surface of the separation membrane is small due to the speed, the large pore is generated due to the rapid diffusion in the cross-sectional direction to weaken the mechanical strength of the membrane. In order to improve this, the fluidity may be decreased by increasing the concentration of the polymer in the polymer solution, but as the polymer concentration increases, the pore size and the porosity of the separator are lowered.
본 발명의 구현예들은 무기염을 사용하여 고분자 용액의 열역학적 불안정성을 증가시키는 한편 고분자 농도의 증가 없이 고분자 용액의 유동성을 감소시킴으로써, 분리막 표면의 기공분포가 좁고 투수성능이 우수하며 분리막 단면에 거대기공이 없는 비대칭 정밀여과막의 제조방법을 제공한다. Embodiments of the present invention by using an inorganic salt to increase the thermodynamic instability of the polymer solution while reducing the fluidity of the polymer solution without increasing the polymer concentration, the pore distribution on the surface of the membrane is narrow, the water permeability is excellent and the macropores on the membrane cross-section It provides a method for producing asymmetric microfiltration membrane.
본 발명의 구현예들은 상기 제조방법에 의해 제조된 고투수성 정밀여과막을 제공한다. Embodiments of the present invention provide a high permeability microfiltration membrane prepared by the above production method.
본 발명의 하나의 양상은One aspect of the present invention
폴리비닐리덴플루오라이드(PVDF) 및 무기염을 유기용매와 혼합하여 고분자 용액을 제조하는 단계; 상기 고분자 용액을 탈포한 후 부직포에 캐스팅하여 중공사 형태의 막을 제조하는 단계; 상기 막을 증류수에 침지하여 응고시키는 단계; 상기 막 내의 잔류용매를 제거한 후 건조시키는 단계를 포함하는 정밀여과막의 제조방법에 관한 것이다. Preparing a polymer solution by mixing polyvinylidene fluoride (PVDF) and an inorganic salt with an organic solvent; Degassing the polymer solution and casting the nonwoven fabric to form a hollow fiber membrane; Solidifying the membrane by dipping in distilled water; It relates to a method for producing a microfiltration membrane comprising the step of removing the residual solvent in the membrane and then drying.
본 발명의 다른 양상은 Another aspect of the invention
폴리비닐리덴플루오라이드(PVDF) 및 무기염을 유기용매와 혼합하여 고분자 용액을 제조하는 단계; 상기 고분자 용액을 탈포한 후 노즐에 통과시켜 중공사 형태의 막을 제조하는 단계; 제조된 막을 증류수에 침지하여 응고시키는 단계; 상기 막 내의 잔류용매를 제거한 후 건조시키는 단계를 포함하는 정밀여과막의 제조방법에 관한 것이다.Preparing a polymer solution by mixing polyvinylidene fluoride (PVDF) and an inorganic salt with an organic solvent; Degassing the polymer solution and passing it through a nozzle to prepare a membrane in the form of a hollow fiber; Solidifying the prepared membrane by dipping in distilled water; It relates to a method for producing a microfiltration membrane comprising the step of removing the residual solvent in the membrane and then drying.
본 발명의 다른 양상은, 상기 제조방법에 의하여 제조된 내투수성이 우수한 정밀여과막에 관한 것이다. Another aspect of the present invention relates to a fine filtration membrane having excellent water permeability produced by the above production method.
본 발명의 구현예들에 의해 제조된 정밀여과막은 분리막 표면의 기공도가 높고, 기공분포가 좁으며, 단면 비대칭 구조가 스펀지 구조를 가져 투수 성능이 뛰어나고, 장기간의 운전에도 운전 안정성이 우수할 뿐만 아니라 막의 교체수명을 늘릴 수 있어 안정된 수질을 확보할 수 있다. 또한, 무기염으로 염화나트륨을 사용하여 환경에의 악영향을 해소하고 낮은 제조원가로 고품질의 분리막 제조가 가능하다.The microfiltration membrane manufactured by the embodiments of the present invention has a high porosity on the surface of the separator, a narrow pore distribution, a cross-sectional asymmetric structure having a sponge structure, and excellent permeability performance, and excellent operation stability even for long-term operation. In addition, the replacement life of the membrane can be extended to ensure stable water quality. In addition, the use of sodium chloride as an inorganic salt eliminates adverse effects on the environment and enables the production of high quality separators at low manufacturing costs.
이하, 본 발명의 구현예들에 의한 정밀여과막의 제조방법을 구성하는 각 단계에 대하여 상세하게 설명한다. Hereinafter, each step constituting the manufacturing method of the microfiltration membrane according to the embodiments of the present invention will be described in detail.
(1) 고분자 용액 제조 단계 (1) step of preparing a polymer solution
본 발명의 일 구현예에 의한 고분자 용액은 고분자 및 무기염을 용매에 녹여 제조할 수 있다. 고분자로는 폴리비닐리덴플루오라이드(PVDF)를 사용할 수 있으며, 사용량은 고분자 용액 내에서 폴리비닐리덴플루오라이드가 5 ~ 10 중량%의 농도가 되도록 사용한다. 일반적으로 비용매에 의한 상분리법으로 제조되는 폴리비닐리덴플루오라이드 분리막 제조시 고분자의 함량은 고분자 용액 중 10~25중량% 이나, 본 발명의 구현예에 의한 고분자 용액은 무기염의 첨가에 의해 고분자 용액의 유동성이 급격히 감소하는 특성을 이용하여 고분자 농도의 증가 없이 유동성이 적은 고분자 용액을 사용할 수 있기 때문에 일반적인 비용매 상분리법에 비해 적은 고분자 함량으로도 제막이 가능하다. The polymer solution according to one embodiment of the present invention may be prepared by dissolving a polymer and an inorganic salt in a solvent. As the polymer, polyvinylidene fluoride (PVDF) may be used, and the amount of polyvinylidene fluoride is used so that the concentration of polyvinylidene fluoride is 5 to 10% by weight in the polymer solution. In general, the content of the polymer when preparing the polyvinylidene fluoride membrane prepared by the non-solvent phase separation method is 10 to 25% by weight in the polymer solution, the polymer solution according to an embodiment of the present invention is a polymer solution by the addition of an inorganic salt Due to the rapid decrease in the fluidity, the polymer solution with less fluidity can be used without increasing the polymer concentration, so that the film can be formed with a lower polymer content than the general non-solvent phase separation method.
고분자의 함량이 5 중량% 미만이면 고분자 용액의 유동성이 커져 단면에 거대기공이 존재하며 분리막의 물성이 약해지는 문제가 있고, 10 중량%를 초과하면 기공율이 낮아져 투수성능이 저하된다. If the content of the polymer is less than 5% by weight, the fluidity of the polymer solution is increased, there is a problem that the large pore is present in the cross-section, the physical properties of the membrane is weakened, if the content exceeds 10% by weight, the porosity is lowered and the permeability is lowered.
사용가능한 용매로는 디메틸포름아마이드(dimetylformamide), N-메틸-2-피롤리돈(N-methyl-2-pyrrolidone), 디메틸아세트아마이드(dimethylacetamide), 디메틸술폭사이드(dimethylsulfoxide) 등이 있으나, 반드시 이에 제한되는 것은 아니다. Solvents that can be used include dimethylformamide, N-methyl-2-pyrrolidone, dimethylacetamide, and dimethylsulfoxide. It is not limited.
본 발명의 일 구현예에서, 무기염으로는 염화나트륨이 사용될 수 있다. 염화나트륨 첨가에 의해 고분자 용액은 열역학적 불안정성이 증가되어 상분리가 촉진되며, 상분리시 기핵제 역할을 한다. 한편, 염화나트륨은 용매와 산-염기 복합물(complex)을 형성하는데, 나트륨이온과 폴리비닐리덴플루오라이드의 전자 주게 그룹과의 작용으로 인해 고분자 용액의 유동성을 감소시켜 기공형성시 빠른 비용매/용매 치환에 따른 거대기공의 형성을 억제한다. In one embodiment of the invention, sodium chloride may be used as the inorganic salt. The addition of sodium chloride increases the thermodynamic instability of the polymer solution, thereby promoting phase separation and acting as a nucleating agent during phase separation. On the other hand, sodium chloride forms a solvent and an acid-base complex, which decreases the fluidity of the polymer solution due to the action of the electron donor group of sodium ions and polyvinylidene fluoride, resulting in rapid nonsolvent / solvent substitution during pore formation. It suppresses the formation of macropores.
본 발명의 일 구현예에서, 염화나트륨은 5~25 중량%를 첨가하는 것이 바람직하다. 염화나트륨의 농도가 5 중량% 미만일 경우 고분자 용액의 유동성 감소효과가 미미하고, 25 중량% 이상인 경우 고분자 유동성 감소에 의해 분리막의 전체적인 기공성장이 억제되어 투수성능이 오히려 저하될 뿐만 아니라 높은 점도로 인해 제막에도 어려움이 있다. In one embodiment of the present invention, sodium chloride is preferably added 5 to 25% by weight. When the concentration of sodium chloride is less than 5% by weight, the effect of reducing the fluidity of the polymer solution is insignificant. When the concentration of the sodium chloride is more than 25% by weight, the overall pore growth of the membrane is inhibited by the decrease of the fluidity of the membrane, and the permeability is not lowered. There is a difficulty.
또한, 본 발명의 일구현예에서, 제조되는 분리막의 기공 크기를 조절하기 위하여 별도의 첨가제가 추가로 사용될 수 있다. 이를 기공 조절제라 하는데, 이는 당 분야에서 널리 공지된 방법으로, 목적하는 기공크기에 적합하도록 공지의 기공 조절제를 선택하여 적당량 첨가하여 사용한다. 기공 크기를 키우기 위한 기공 조절제로는 여러 분자량의 폴리(에틸렌글리콜), 폴리(비닐피롤리돈), 폴리(비닐알코올)이 선택적으로 사용될 수 있으며, 기공크기를 줄이기 위한 기공 조절제로는 1,4-다이옥산, 디에틸렌글리콜디메틸에테르 등이 선택적으로 사용될 수 있다. In addition, in one embodiment of the present invention, a separate additive may be additionally used to control the pore size of the separator prepared. This is referred to as a pore regulator, which is well known in the art, and selects a known pore modifier to suit the desired pore size and adds an appropriate amount. As pore regulators to increase pore size, poly (ethylene glycol), poly (vinylpyrrolidone), and poly (vinyl alcohol) of various molecular weights can be optionally used. Pore regulators to reduce pore size are 1,4 -Dioxane, diethylene glycol dimethyl ether, or the like can be optionally used.
고분자 용액을 구성하는 용매 혹은 첨가제들이 고분자와 강하게 상호작용하면 고분자와 응고조 용액과의 '디믹싱(demixing) 지연효과'로 인하여 스폰지구조 (sponge-like structure)를 형성하고, 고분자와의 상호작용이 약해지면 ‘디믹싱 효과’가 급속히 진행되어 핑거구조(finger-like structure)를 형성한다. 스폰지 구조는 기계적인 강도 측면에서 핑거구조에 비하여 유리하지만, 수투과도 측면에 있어서는 불리하다. 그 이유는 스폰지 구조는 수리학적 저항성이 핑거구조에 비하 여 강하게 걸리기 때문이다. When the solvent or additives constituting the polymer solution strongly interact with the polymer, a sponge-like structure is formed due to the 'demixing delay effect' between the polymer and the coagulation bath solution, and the polymer interacts with the polymer. When this weakens, the 'demixing effect' proceeds rapidly to form a finger-like structure. The sponge structure is advantageous over the finger structure in terms of mechanical strength, but disadvantageous in terms of water permeability. This is because the sponge structure has a strong hydraulic resistance compared to the finger structure.
(2) 응고 단계(2) solidification stage
탈포 과정을 거친 용액을 부직포 위에 캐스팅하거나 부직포를 사용하지 않고 노즐을 사용하여 중공사 형태로 막을 제조한 후 비용매 또는 비용매와 용매의 혼합액으로 이루어진 응고액에 침지하여 막을 응고시킨다. 본 발명의 일 구현예에서 비용매로는 물, 알코올 등이 사용될 수 있으나 반드시 이에 제한되는 것은 아니다. The membrane subjected to the defoaming process is cast on the nonwoven fabric or the membrane is manufactured in the form of hollow fiber using a nozzle without using the nonwoven fabric, and then the membrane is solidified by immersion in a coagulating solution composed of a nonsolvent or a mixture of a nonsolvent and a solvent. In one embodiment of the present invention, water, alcohol, etc. may be used as the non-solvent, but is not necessarily limited thereto.
(3) 잔류용매의 제거 및 건조 단계(3) Removal and drying step of residual solvent
응고 단계를 거쳐 제조된 막 내에 잔류하는 용매를 제거하기 위하여 50 ~ 90 ℃정도의 물로 10 ~ 30 시간 처리된다. 이 후 막을 건조시켜 정밀여과막을 얻을 수 있다. In order to remove the solvent remaining in the membrane prepared through the coagulation step, it is treated with water of about 50 ~ 90 ℃ 10 to 30 hours. Thereafter, the membrane may be dried to obtain a microfiltration membrane.
이하, 구체적인 실시예를 가지고 본 발명의 구성 및 효과를 보다 상세히 설명하지만, 이들 실시예는 단지 본 발명을 보다 명확하게 이해시키기 위한 것일 뿐, 본 발명의 범위를 한정하고자 하는 것은 아니다. Hereinafter, the configuration and effects of the present invention will be described in more detail with specific examples, but these examples are only intended to more clearly understand the present invention and are not intended to limit the scope of the present invention.
실시예Example 1 : One : 정밀여과막Precision filtration membrane 제조 Produce
폴리비닐리덴플루오라이드 7 중량%, 폴리비닐피롤리돈 5 중량%, 염화나트륨 5 중량%를 디메틸아세트아마이드와 혼합하고 80℃ 에서 24시간 교반하여 고분자 용 액을 제조하였다. 제조된 고분자 용액을 탈포 냉각하여 부직포 위에 300μm의 두께로 도포하고 40 ℃의 물에 침지하여 응고시켰다. 제조된 정밀여과막을 24 시간 60 ℃의 물에 침지하여 잔류 용매를 제거한 후 건조시켰다. 7% by weight of polyvinylidene fluoride, 5% by weight of polyvinylpyrrolidone, and 5% by weight of sodium chloride were mixed with dimethylacetamide and stirred at 80 ° C. for 24 hours to prepare a polymer solution. The prepared polymer solution was defoamed and cooled to apply a thickness of 300 μm on the nonwoven fabric, and solidified by immersion in water at 40 ° C. The prepared microfiltration membrane was immersed in water at 60 ° C. for 24 hours to remove residual solvents and then dried.
실시예Example 2 : 2 : 정밀여과막Precision filtration membrane 제조 Produce
염화나트륨을 15 중량% 사용한 것을 제외하고 실시예 1과 동일한 방법으로 정밀여과막을 제조하였다. A microfiltration membrane was prepared in the same manner as in Example 1 except that 15 wt% of sodium chloride was used.
실시예Example 3 : 3: 정밀여과막Precision filtration membrane 제조 Produce
염화나트륨을 25 중량% 사용한 것을 제외하고 실시예 1과 동일한 방법으로 정밀여과막을 제조하였다. A microfiltration membrane was prepared in the same manner as in Example 1, except that 25% by weight of sodium chloride was used.
비교예Comparative example 1: One: 정밀여과막Precision filtration membrane 제조 Produce
폴리비닐리덴플루오라이드 7 중량%, 폴리비닐피롤리돈 5 중량%, 디메틸아세트아마이드 88 중량%를 혼합하고 80℃ 에서 24시간 교반하여 고분자 용액을 제조하였다. 제조된 고분자 용액을 탈포 냉각하여 부직포 위에 300μm의 두께로 도포하고 40 ℃의 물에 침지하여 응고시켰다. 제조된 정밀여과막을 24 시간 60 ℃의 물에 침지하여 잔류 용매를 제거한 후 건조시켰다. 7% by weight of polyvinylidene fluoride, 5% by weight of polyvinylpyrrolidone, and 88% by weight of dimethylacetamide were mixed and stirred at 80 ° C for 24 hours to prepare a polymer solution. The prepared polymer solution was defoamed and cooled to apply a thickness of 300 μm on the nonwoven fabric, and solidified by immersion in water at 40 ° C. The prepared microfiltration membrane was immersed in water at 60 ° C. for 24 hours to remove residual solvents and then dried.
비교예Comparative example 2: 2: 정밀여과막Precision filtration membrane 제조 Produce
폴리비닐리덴플루오라이드 15 중량%, 폴리비닐피롤리돈 5 중량%, 디메틸아 세트아마이드 80 중량%를 혼합하여 80℃ 에서 24시간 교반하여 고분자 용액을 제조한 것을 제외하고 비교예 1과 동일한 방법으로 정밀여과막을 제조하였다. In the same manner as in Comparative Example 1 except that 15% by weight of polyvinylidene fluoride, 5% by weight of polyvinylpyrrolidone and 80% by weight of dimethylacetamide were mixed and stirred at 80 ° C for 24 hours to prepare a polymer solution. A microfiltration membrane was prepared.
실시예 1 내지 3 및 비교예 1 내지 2에서 제조된 정밀여과막의 표면 기공분포 및 단면 구조 측정을 다음과 같은 방법으로 실시하고, 그 결과를 하기 표 1에 나타내었다. Surface pore distribution and cross-sectional structure measurement of the microfiltration membranes prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were carried out by the following method, and the results are shown in Table 1 below.
실험예Experimental Example 1: 막의 표면 기공분포 측정 1: Measurement of Surface Pore Distribution of Membrane
실시예 1 ~ 3 및 비교예 1 ~ 2에 의해 제조된 막의 표면 기공분포를 기공분석기(PMI사, Capillary Flow Porometer)를 사용하여 측정하였다. Surface pore distribution of the membranes prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were measured using a pore analyzer (Capillary Flow Porometer, PMI).
분리막을 소정의 액체로 적신 후 가해진 압력에 따라 투과되는 유체의 양을 측정하고 이로부터 기공크기의 분포를 계산하였다. 구해진 기공분포로부터 평균 기공크기를 정량화하고, 최대기공크기와 평균기공크기의 비로써 기공분포의 범위를 정량화하였다. After the membrane was wetted with a predetermined liquid, the amount of fluid permeated according to the applied pressure was measured, and the pore size distribution was calculated therefrom. The average pore size was quantified from the obtained pore distribution, and the range of pore distribution was quantified by the ratio of the maximum pore size and the average pore size.
실험예Experimental Example 2: 막의 단면 구조 측정 2: Measurement of the cross-sectional structure of the membrane
실시예 1 ~ 3 및 비교예 1 ~ 2에 의해 제조된 막의 단면 기공구조를 전자현미경(FE-SEM, JEOL사 JSM-6700F)을 사용하여 측정하였다. 전자현미경 사진을 판독하여 분리막 단면의 구조를 확인하고, 단면에 20 μm 이상의 거대기공 유무를 확인하였다. The cross-sectional pore structures of the membranes prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were measured using an electron microscope (FE-SEM, JESM JSM-6700F). Electron micrographs were read to confirm the structure of the membrane section, and the presence or absence of macropores of 20 μm or more in the section was confirmed.
[표 1] TABLE 1
실시예 1~3 및 비교예 1~2의 평균기공 크기는 0.11 내지 0.21 μm로 전형적인 정밀여과막 수준의 기공크기를 나타내었다. 그러나 분리막 표면에 존재하는 최대기공크기와 평균기공크기의 비로 측정된 기공분포도는 실시예 1~3의 경우 2 이하로 좁은 분포를 나타낸 반면 염화나트륨을 첨가하지 않은 비교예 1~ 2는 분포 범위가 넓음을 알 수 있다. 특히, 고분자 점도가 낮은 비교예 1의 경우 최대 기공크기가 평균기공 크기에 비하여 5배 이상 넓은 분포를 보였으며, 이는 낮은 고분자 농도로 인한 고분자 용액의 유동성 증가로 인해 기공의 성장속도가 빨라졌기 때문인 것으로 생각된다. The average pore size of Examples 1 to 3 and Comparative Examples 1 to 2 ranged from 0.11 to 0.21 μm, representing the pore size at typical microfiltration membrane levels. However, the pore distribution measured by the ratio of the maximum pore size and the average pore size present on the surface of the separator showed a narrow distribution of 2 or less in Examples 1 to 3, while Comparative Examples 1 and 2 without addition of sodium chloride had a wide distribution range. It can be seen. In particular, in Comparative Example 1 having a low polymer viscosity, the maximum pore size was distributed more than 5 times larger than the average pore size, because the growth rate of pores was increased due to the increased fluidity of the polymer solution due to the low polymer concentration It is thought to be.
반면 실시예 1은 비교예 1과 같은 고분자 농도로 조제되었으나 염화나트륨의 첨가에 의해 고분자 용액의 유동성이 감소됨으로써, 기공의 성장속도를 억제하여 좁은 기공분포를 보인 것으로 생각된다. 단면의 구조는 거대기공이 존재하지 않는 스펀지 구조가 형성되었으며, 이는 염화나트륨 첨가에 의한 고분자 용액의 유동성 감소에 기인하는 것으로 생각된다. On the other hand, Example 1 was prepared at the same polymer concentration as in Comparative Example 1, but the fluidity of the polymer solution was reduced by the addition of sodium chloride, and thus, it was thought that the pore growth rate was suppressed to show a narrow pore distribution. The structure of the cross section was formed with a sponge structure without the presence of macropores, which is thought to be due to the decrease in fluidity of the polymer solution by the addition of sodium chloride.
실험예Experimental Example 3: 막의 순수투과속도 및 용질배제율 측정 3: Determination of pure permeation rate and solute rejection of membrane
실시예 1 ~ 3 및 비교예 1 ~ 2에 의해 제조된 막의 순수투과속도와 용질배제율을 측정하기 위하여 초순수를 원수로 하여 48시간 여과하여 여과성능을 측정하였다. 상기 막을 원수와의 접촉면적이 28.7 ㎠ 인 가압형셀 (AMICON사 Stirred Cell Filtration System 8200)에 장착하여 20℃, 0.5 기압 하에서 통수하였다. In order to measure the pure permeation rate and solute rejection rate of the membranes prepared in Examples 1 to 3 and Comparative Examples 1 to 2, ultrapure water was filtered for 48 hours, and the filtration performance was measured. The membrane was mounted in a pressurized cell (AMICON's Stirred Cell Filtration System 8200) having a contact area of raw water of 28.7 cm 2 and passed through at 20 ° C and 0.5 atm.
초여과된 물의 부피를 측정하여 다음과 같은 식으로 순수투과속도를 계산하였다. The pure permeation rate was calculated by measuring the volume of the ultrafiltration water as follows.
[수학식 1][Equation 1]
계산된 정밀여과막의 순수투과속도를 하기 표 2에 나타내었다. The pure permeation rate of the calculated microfiltration membrane is shown in Table 2 below.
[표 2]TABLE 2
상기 표 2를 참조하면, 실시예 1~3의 투수성능이 비교예 1, 2에 비해 높 음을 알 수 있다. 이는 무기염 첨가에 의해 고분자 용액의 불안정성이 증가하여, 분리막 표면에서의 상분리가 촉진되어 표면의 기공도가 높아지는 것에 기인한 것으로 생각된다. 특히, 무기염의 첨가 없이 기공분포 및 단면 거대기공의 축소를 위해 고분자 농도를 높인 비교예 2의 경우 분리막 표면층을 중심으로 밀집된 기공구조가 형성되어 투수성능이 대폭 저하되었음을 알 수 있다. Referring to Table 2, it can be seen that the water permeability of Examples 1 to 3 is higher than Comparative Examples 1 and 2. This is thought to be due to the increase of the instability of the polymer solution due to the addition of the inorganic salt, to promote phase separation on the surface of the separator and to increase the porosity of the surface. In particular, in Comparative Example 2 in which the polymer concentration was increased in order to reduce the pore distribution and cross-sectional macropores without addition of an inorganic salt, a dense pore structure was formed around the surface layer of the separator and thus the water permeability was significantly reduced.
한편, 실시예 1에 비하여 염화나트륨의 첨가량이 많은 실시예 2의 투수성능이 큰 폭으로 증가하였다. 이는 염화나트륨 증가에 따른 표면 기공수의 증가에 기인한 것으로 생각된다. 그러나 실시예 3의 경우 투수성능이 오히려 감소되었는데, 이는 고분자 용액의 유동성이 지나치게 감소함으로써 단면에서의 기공성장이 제한되어 비대칭성이 감소했기 때문인 것으로 생각된다. On the other hand, compared with Example 1, the water permeation performance of Example 2 with much addition amount of sodium chloride increased significantly. This is thought to be due to the increase in surface pore number with increasing sodium chloride. However, in the case of Example 3, the water permeation performance was rather reduced, which is considered to be due to a decrease in asymmetry because pore growth in the cross section was limited due to excessive decrease in fluidity of the polymer solution.
이상에서 본 발명의 바람직한 구현예를 들어 본 발명에 대해서 상세하게 설명하였으나, 본 발명의 정신 및 범위를 벗어나지 않는 범위 내에서 본 발명이 다양하게 변경 또는 변형될 수 있음은 당업자에게 자명하므로, 이러한 모든 변경 및 변형예들도 본 발명의 보호범위에 포함되는 것으로 해석되어야 한다. Although the present invention has been described in detail with reference to preferred embodiments of the present invention, it will be apparent to those skilled in the art that the present invention may be variously changed or modified without departing from the spirit and scope of the present invention. Modifications and variations are also to be construed as being included in the scope of protection of the present invention.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| KR101485119B1 (en) * | 2014-02-12 | 2015-01-22 | 광주과학기술원 | Improved preparation method of polyethersulfone nanofiber membrane using electrospinning |
| WO2017007267A1 (en) * | 2015-07-08 | 2017-01-12 | 광주과학기술원 | Method for preparing functional nanofiber filter, and functional nanofiber filter prepared thereby |
| CN110772999A (en) * | 2019-10-28 | 2020-02-11 | 德蓝水技术股份有限公司 | Preparation method of special membrane for preparing health water |
| KR20210136321A (en) * | 2020-05-07 | 2021-11-17 | 한국전력공사 | Manufacturing method of β-phase polyvinylidene fluoride thin film |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| KR101485119B1 (en) * | 2014-02-12 | 2015-01-22 | 광주과학기술원 | Improved preparation method of polyethersulfone nanofiber membrane using electrospinning |
| WO2017007267A1 (en) * | 2015-07-08 | 2017-01-12 | 광주과학기술원 | Method for preparing functional nanofiber filter, and functional nanofiber filter prepared thereby |
| CN110772999A (en) * | 2019-10-28 | 2020-02-11 | 德蓝水技术股份有限公司 | Preparation method of special membrane for preparing health water |
| KR20210136321A (en) * | 2020-05-07 | 2021-11-17 | 한국전력공사 | Manufacturing method of β-phase polyvinylidene fluoride thin film |
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