CN114392651A - Composite ultrafiltration membrane and preparation method thereof - Google Patents

Composite ultrafiltration membrane and preparation method thereof Download PDF

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Publication number
CN114392651A
CN114392651A CN202111657790.7A CN202111657790A CN114392651A CN 114392651 A CN114392651 A CN 114392651A CN 202111657790 A CN202111657790 A CN 202111657790A CN 114392651 A CN114392651 A CN 114392651A
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membrane
ultrafiltration membrane
polyvinylidene fluoride
filaments
deionized water
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CN202111657790.7A
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Chinese (zh)
Inventor
廖香红
徐梅
曾凡付
许白羽
钱铖
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Deland Water Technology Co ltd
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Deland Water Technology Co ltd
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    • 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
    • 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
    • B01D61/18—Apparatus therefor
    • 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
    • B01D61/20—Accessories; Auxiliary operations
    • 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
    • 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
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12—Composite membranes; Ultra-thin membranes
    • 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
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/24—Mechanical properties, e.g. strength

Abstract

The invention provides a composite ultrafiltration membrane, which comprises a membrane component and a supporting pipe, wherein the membrane component comprises a plurality of membrane filaments, and raw material liquid of the membrane filaments is uniformly coated on the outer surface of the supporting pipe. According to the membrane assembly, the supporting tubes are inserted in the membrane assembly, so that most pressure can be borne by the membrane filaments, the pressure borne by the membrane filaments is reduced, the service life of the membrane filaments is prolonged, and the strength performance of the membrane assembly can be improved.

Description

Composite ultrafiltration membrane and preparation method thereof
Technical Field
The invention belongs to the technical field of water treatment devices, and particularly relates to a composite ultrafiltration membrane and a preparation method thereof.
Background
With the rapid development of industrialization and urbanization processes in China, the sewage discharge amount is continuously increased at a high speed, the problems of water environment deterioration and water resource shortage are increasingly highlighted, the improvement of the life quality of people is greatly influenced, and the development of national economy is restricted. In the future, with the deepened development of the social economy of China and the enhancement of the environmental consciousness of the people, the demand for water quantity is kept high and increased, and stricter requirements are put forward on the improvement and the improvement of water quality. Therefore, the strengthening of water pollution control and the effective treatment of sewage are important strategic targets for protecting the environment in the future in China for a long time.
The membrane separation technology is a green water treatment technology, can protect the environment from being polluted, and can recycle useful resources in water. The effluent after membrane separation can be used for circulating cooling water, papermaking water and the like with low requirements on water quality, the utilization rate of the water is improved, and meanwhile, the cost is reduced by recycling resources, and sustainable development is realized.
In recent years, as the market demands for separation technology have been increasing, membrane separation technology has been developed, which is a selective separation technology capable of screening molecular particles at a molecular level in a process in which a mixture passes through a semipermeable membrane, and is a method of manufacturing a membrane having selective permeability using a special material and method and separating the mixture by an external force. The technology comprises a plurality of assembly modes such as a hollow fiber membrane, a rolling membrane, a flat membrane and the like, wherein the advantages of the hollow fiber membrane are most outstanding, and the advantages of large packing density per unit volume, high separation efficiency, small occupied area of equipment, simple structure, simple and convenient operation and the like are included.
At present, ultrafiltration membrane technology has been widely applied and developed in the field of water treatment, but in the actual operation process, the traditional ultrafiltration membrane has weak anti-pollution capability, various organic matters and other pollutants are easily deposited on the surface of the membrane, the ultrafiltration membrane needs to be frequently cleaned, and due to the fact that the strength of the traditional ultrafiltration membrane is not high, membrane threads of the ultrafiltration membrane are abraded in the cleaning process, so that the membrane threads are broken, the membrane performance is quickly attenuated, the service lives of the membrane and a system are reduced, and the operation and operation cost of the system is increased. In summary, the problem of ultrafiltration membrane loss is an obstacle to limiting the further spread of ultrafiltration technology, with the limitations of the quality of water used and other conditions.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
The invention aims to provide a composite ultrafiltration membrane, which improves the mechanical property and pure water flux of the ultrafiltration membrane by adding a supporting tube in the ultrafiltration membrane.
The second purpose of the invention is to provide a preparation method of the composite ultrafiltration membrane, and the ultrafiltration membrane prepared by the method can improve the mechanical property and pure water flux of the ultrafiltration membrane.
In order to achieve the technical purpose, the invention provides the following technical scheme:
the invention provides a composite ultrafiltration membrane, which comprises a membrane component and a supporting pipe, wherein the membrane component comprises a plurality of membrane filaments, and raw material liquid of the membrane filaments is uniformly coated on the periphery of the supporting pipe.
In the prior art, raw water is often pretreated by a mechanical filter such as a multi-media filter and a disc filter before an ultrafiltration system. If the pretreatment process breaks down, the membrane filaments are blocked, the pressure of the membrane filaments is increased, and once the pressure exceeds the pressure bearing capacity range of the membrane filaments, the membrane filaments are broken, so that the serious consequences of unqualified effluent, reduced effluent and the like are caused.
According to the membrane assembly, the supporting tubes are inserted in the membrane assembly, so that the membrane filaments can bear most of pressure, the pressure borne by the membrane filaments is reduced, the service life of the membrane filaments is prolonged, and the strength performance of the membrane assembly can be improved.
Preferably, the membrane filaments comprise 15-25% of PVDF polyvinylidene fluoride, 50-70% of DMAC and deionized water.
In addition, the invention also provides a preparation method of the composite ultrafiltration membrane, which comprises the following steps:
(A) drying a PVDF (polyvinylidene fluoride) polyvinylidene fluoride raw material at high temperature, and dissolving and mixing the dried PVDF polyvinylidene fluoride, DMAC (dimethylacetamide) and deionized water;
(B) uniformly mixing, standing and defoaming to prepare an ultrafiltration membrane stock solution;
(C) uniformly coating the ultrafiltration membrane stock solution obtained in the step (B) on the surface of a support tube in a spraying mode;
(D) and cooling and solidifying to obtain the composite ultrafiltration membrane.
Preferably, the standing time is 16 to 20 hours.
Preferably, the cooling solidification is carried out by soaking in deionized water.
Preferably, the high-temperature drying mode is oven drying.
Preferably, the PVDF polyvinylidene fluoride accounts for 15-25% by weight, the DMAC accounts for 50-70% by weight, and the rest deionized water is used.
Compared with the prior art, the invention has the beneficial effects that:
(1) according to the membrane assembly, the supporting tubes are inserted in the membrane assembly, so that the membrane replacement filaments can bear most of pressure, the pressure borne by the membrane filaments is reduced, and the service life of the membrane filaments is prolonged.
(2) The preparation method of the composite ultrafiltration membrane provided by the invention is simple and low in cost.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
fig. 1 is a flow chart of a preparation process of the composite ultrafiltration membrane provided by the embodiment of the invention.
Detailed Description
The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and the detailed description, but those skilled in the art will understand that the following described embodiments are some, not all, of the embodiments of the present invention, and are only used for illustrating the present invention, and should not be construed as limiting the scope of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In order to more clearly illustrate the technical solution of the present invention, the following description is made in the form of specific embodiments.
Example 1
Referring to fig. 1, which is a flowchart of a method for preparing a composite ultrafiltration membrane according to this embodiment, a PVDF polyvinylidene fluoride raw material is first dried at a high temperature, and then the dried PVDF polyvinylidene fluoride, DMAC, and deionized water are dissolved and mixed; then mixing uniformly and standing for 18 hours for defoaming to prepare ultrafiltration membrane stock solution; then the ultrafiltration membrane stock solution is uniformly coated on the outer surface of the supporting tube in a spraying mode; and finally, placing the ultrafiltration composite membrane in deionized water for cooling and curing to obtain the composite ultrafiltration membrane.
Finally, the composite ultrafiltration membrane is made into a small membrane component, the small membrane component is connected to a testing device in a quick insertion mode, the testing device is operated for a certain time under the external pressure of 0.1MPa, the transmittance of pure water and trapped fluid is obtained, and the obtained data are stable and reliable. And (5) after the test is finished, calculating the obtained data to obtain a corresponding result. The calculation method in this embodiment is as follows:
calculation of membrane area: a is n pi DL,
in the formula: a- - - -membrane area, m2；
n is the number of the hollow fiber membranes;
d- - -diameter of the hollow fiber membrane (inner diameter of the inner pressure membrane and outer diameter of the outer pressure membrane), m;
l- - -the effective length of the hollow fiber membrane, m.
Calculation of water flux:
Figure BDA0003448745990000051
in the formula: f- -water flux, L/(m)2.h)；
Q- - -pure water permeability, L;
a- - - -membrane area, m2；
t- -the time taken to collect the water breakthrough, h.
The rejection was calculated as follows:
Figure BDA0003448745990000052
in the formula: ru- - -Retention,%;
c1- -concentration of polyethylene oxide in the stock solution, mg/L;
c2- -concentration of polyethylene oxide in the permeate, mg/L.
Example 2
The other operating steps are identical to those of example 1, except that: the membrane raw material liquid is composed of 20% of PVDF polyvinylidene fluoride, 50% of DMAC and 30% of deionized water.
Example 3
The other operating steps are identical to those of example 1, except that: the membrane feed liquid consists of 25% of PVDF polyvinylidene fluoride, 55% of DMAC and 20% of deionized water.
Example 4
The other operating steps are identical to those of example 1, except that: the membrane raw material liquid is composed of 30% of PVDF polyvinylidene fluoride, 60% of DMAC and 10% of deionized water.
Comparative example 1
The other operating steps are identical to those of example 1, except that: there is no internal support tube.
Comparative example 2
The other operating steps are identical to those of example 2, except that: there is no internal support tube.
Comparative example 3
The other operating steps are identical to those of example 3, except that: there is no internal support tube.
Comparative example 4
The other operating steps are identical to those of example 4, except that: there is no internal support tube.
The following data were obtained from examples 1 to 4 and comparative examples 1 to 4 described above:
water flux (L/m)2·h) Retention (%) Strength (Mpa)
Example 1 952.3 74.7 132.65
Example 2 1268.4 78.7 134.85
Example 3 1435.46 82.4 135.25
Example 4 1556.78 86.1 137.55
Comparative example 1 312.5 71.3 2.75
Comparative example 2 410.68 75.6 2.55
Comparative example 3 420.25 81.5 2.85
Comparative example 4 375.68 86.4 2.65
From the above data, the following conclusions can be drawn:
(1) through comparison of examples 1-4, the water flux, rejection rate and membrane filament strength of the composite ultrafiltration membrane can be affected when the components of PVDF, DMAC and deionized water in the membrane filament are different, and experiments show that example 4 is the optimal effect when the membrane filament is composed of 30% of PVDF, 60% of DMAC and 10% of deionized water.
(2) Through comparison of four pairs of data, namely example 1 and comparative example 1, example 2 and comparative example 2, example 3 and comparative example 3, and example 4 and comparative example 4, it can be found that even if the components of PVDF polyvinylidene fluoride, DMAC and deionized water in the membrane filaments are the same, the water bucket amount and the membrane filament strength are greatly improved after the support tube is added into the ultrafiltration membrane.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (7)

1. The composite ultrafiltration membrane is characterized by comprising a membrane assembly and a supporting tube, wherein the membrane assembly comprises a plurality of membrane filaments, and raw material liquid of the membrane filaments is uniformly coated on the outer surface of the supporting tube.
2. The composite ultrafiltration membrane of claim 1, wherein the feed solution composition of the membrane filaments comprises 15-25% PVDF polyvinylidene fluoride, 50-70% DMAC, and deionized water.
3. A method of preparing a composite ultrafiltration membrane according to any one of claims 1 to 2, comprising the steps of:
(A) drying a PVDF (polyvinylidene fluoride) polyvinylidene fluoride raw material at high temperature, and dissolving and mixing the dried PVDF polyvinylidene fluoride, DMAC (dimethylacetamide) and deionized water;
(B) uniformly mixing, standing and defoaming to prepare an ultrafiltration membrane stock solution;
(C) uniformly coating the ultrafiltration membrane stock solution obtained in the step (B) on the surface of a support tube in a spraying mode;
(D) and cooling and solidifying to obtain the composite ultrafiltration membrane.
4. The method according to claim 3, wherein the standing time is 16 to 20 hours.
5. The method according to claim 3, wherein the cooling solidification is carried out by immersing in deionized water.
6. The preparation method according to claim 3, wherein the high-temperature drying mode is oven drying.
7. The method according to claim 3, wherein the PVDF polyvinylidene fluoride comprises 15-25 wt%, DMAC comprises 50-70 wt% and the rest is deionized water.
CN202111657790.7A 2021-12-31 2021-12-31 Composite ultrafiltration membrane and preparation method thereof Pending CN114392651A (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070039886A1 (en) * 2003-05-23 2007-02-22 Sulzer Chemtech Gmbh-Membrantechnik Membrane pipe module
CN103691327A (en) * 2013-12-31 2014-04-02 沁园集团股份有限公司 Preparation method of support tube reinforced polymer hollow fiber membrane with high peel strength
CN111921384A (en) * 2020-08-11 2020-11-13 浙江易膜新材料科技有限公司 Casting membrane liquid of PVDF hollow fiber ultrafiltration membrane, spinning mechanism and production method thereof
CN113634140A (en) * 2020-04-27 2021-11-12 三达膜科技（厦门）有限公司 Internal support polyvinylidene fluoride hollow dry film and preparation method thereof
CN113813799A (en) * 2021-09-13 2021-12-21 上海海若环境集团有限公司 Preparation method of PVDF ultrafiltration membrane with polyester lining

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070039886A1 (en) * 2003-05-23 2007-02-22 Sulzer Chemtech Gmbh-Membrantechnik Membrane pipe module
CN103691327A (en) * 2013-12-31 2014-04-02 沁园集团股份有限公司 Preparation method of support tube reinforced polymer hollow fiber membrane with high peel strength
CN113634140A (en) * 2020-04-27 2021-11-12 三达膜科技（厦门）有限公司 Internal support polyvinylidene fluoride hollow dry film and preparation method thereof
CN111921384A (en) * 2020-08-11 2020-11-13 浙江易膜新材料科技有限公司 Casting membrane liquid of PVDF hollow fiber ultrafiltration membrane, spinning mechanism and production method thereof
CN113813799A (en) * 2021-09-13 2021-12-21 上海海若环境集团有限公司 Preparation method of PVDF ultrafiltration membrane with polyester lining

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