CN110585934A - Composite filter membrane of nano-pore surface layer/micron-pore supporting layer and preparation method and application thereof - Google Patents
Composite filter membrane of nano-pore surface layer/micron-pore supporting layer and preparation method and application thereof Download PDFInfo
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- CN110585934A CN110585934A CN201910708937.7A CN201910708937A CN110585934A CN 110585934 A CN110585934 A CN 110585934A CN 201910708937 A CN201910708937 A CN 201910708937A CN 110585934 A CN110585934 A CN 110585934A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0079—Manufacture of membranes comprising organic and inorganic components
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- 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
- B01D71/08—Polysaccharides
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Abstract
The invention belongs to the technical field of filter membrane materials, and discloses a composite filter membrane of a nano-pore surface layer/a micron-pore supporting layer, a preparation method and application thereof, wherein the composite filter membrane is prepared by adding a cellulose raw material into an alkaline mixed solution at the temperature of-5 to-15 ℃ to form a cellulose suspension, and then stirring and dissolving the cellulose suspension at room temperature to obtain a cellulose solution; under the condition of high-speed homogeneous dispersion, cellulose solution is dripped into alkaline aqueous solution to obtain nano cellulose dispersion, and the nano cellulose dispersion is prepared by diluting with water and filtering. The preparation process is simple and quick, the obtained composite filter membrane of the nano-pore surface layer/the micron-pore supporting layer forms a secondary structure of the nano-pore surface layer/the micron-pore supporting layer, the composite filter membrane has excellent performance and controllable filtering performance, can give consideration to both separation efficiency and separation flux, and realizes separation based on the self gravity of emulsion liquid.
Description
Technical Field
The invention belongs to the technical field of filter membrane materials, and particularly relates to a composite filter membrane of a nano-pore surface layer/a micron-pore supporting layer, and a preparation method and application thereof.
Background
The oily wastewater produced in industrial production and daily life has great harm to the natural environment and ecological balance, seriously pollutes water resources and excites the practical contradiction of water resource shortage in China. In addition, frequent crude oil leakage events have immeasurable impact on the ecological environment of the ocean and near shore. Therefore, an efficient oil-water separation technology is important and urgent, and is a hot point of attention in the industry and the scientific community. The oil-water mixture can be separated by traditional methods such as gravity, centrifugation and the like, but the methods have low efficiency when used for separating oil-water emulsion, and even can not achieve the purpose of separation. Compared with demulsification methods such as an external electric field or a chemical agent, the membrane separation technology is simple in process, can simultaneously complete demulsification and separation processes, and is the main method for separating oil-water emulsion at present. However, the application of the membrane separation technology in the oil-water separation industry field is restricted by the problems of low separation flux, easy pollution or blockage of the pore channels on the surface of the membrane, high cost and the like.
When an oil-water emulsion is separated, the problem of low separation flux exists in the ultrafiltration membrane, while the problem of low separation efficiency exists in the microfiltration membrane. Therefore, the construction of the multi-layer structure membrane with the surface micro-nano-pores and the supporting layer micro-pores is an effective way for solving the contradiction between the separation efficiency and the separation flux in the oil-water emulsion separation. CN107583472A discloses a preparation method of a nano-cellulose/filter paper composite filter membrane material, which mainly realizes the purposes of high flux and high retention rate by carrying out hierarchical composite or embedded composite on nano-cellulose and base material filter paper. However, the method for obtaining the nanocellulose is the combination of TEMPO oxidation and mechanical treatment, and the preparation process of the nanocellulose is complex, high in energy consumption and high in preparation cost, so that the method is not beneficial to popularization and practical application.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, and the primary aim of the invention is to provide a composite filter membrane of a nano-pore surface layer/a micron-pore support layer. The composite filter membrane has excellent performance and controllable filtering performance. When the method is used for separating oil-water emulsion, high separation efficiency and high flux can be obtained.
The invention also aims to provide a preparation method of the composite filter membrane of the nano-pore surface layer/the micron-pore support layer. The method has simple and rapid preparation process.
The invention also aims to provide the application of the composite filter membrane of the nano-pore surface layer/the micron-pore support layer.
The above purpose of the invention is realized by the following technical scheme:
a composite filter membrane of a nano-pore surface layer/a micron-pore supporting layer is characterized in that a cellulose raw material is added into an alkaline mixed solution at the temperature of-5 to-15 ℃ to form a cellulose suspension, and then the cellulose suspension is stirred and dissolved at room temperature to obtain a cellulose solution; under the condition of high-speed homogeneous dispersion, cellulose solution is dripped into alkaline aqueous solution to obtain nano cellulose dispersion, and the nano cellulose dispersion is prepared by diluting with water and filtering.
Preferably, the alkali in the alkaline aqueous solution is more than one of sodium hydroxide, lithium hydroxide or potassium hydroxide; the nano-cellulose loaded on the nano-pore surface layer in the composite filter membrane of the nano-pore surface layer/the micron-pore supporting layer is 0.5-5 g/m2。
Preferably, the alkaline mixed solution is sodium hydroxide-urea, sodium hydroxide-thiourea, lithium hydroxide-urea or lithium hydroxide-urea thiourea.
More preferably, the concentration of sodium hydroxide or lithium hydroxide in the alkaline mixed solution is 5-10 wt%; the concentration of the urea or thiourea is 5-15 wt%.
Preferably, the concentration of the cellulose suspension is 1-8 wt%; the concentration of the alkaline aqueous solution is 0.5-7 wt%.
Preferably, the cellulose raw material is chemical pulp fiber, recycled waste paper fiber, microcrystalline cellulose or cotton.
The preparation method of the composite filter membrane of the nano-pore surface layer/the micron-pore supporting layer comprises the following specific steps:
s1, adding a cellulose raw material into an alkaline mixed solution at a temperature of between-5 and-15 ℃ to form a suspension, and stirring at room temperature until cellulose is completely dissolved to obtain a transparent cellulose solution;
s2, dripping a cellulose solution into an alkaline aqueous solution under the condition of high-speed homogeneous dispersion to obtain a nano-cellulose dispersion solution;
and S3, diluting the nano-cellulose dispersion liquid with water, and filtering to form the composite filter membrane of the nano-pore surface layer/the micron-pore supporting layer.
Preferably, the rotation speed of the high-speed homogeneous dispersion in the step S2 is 3000-25000 rpm; the dispersing time is 1-30 min.
Preferably, the volume ratio of the water to the nano-cellulose dispersion in the step S3 is (20-200): 1.
the composite filter membrane of the nano-pore surface layer/the micron-pore support layer is applied to oil-water emulsion separation.
Compared with the prior art, the invention has the following beneficial effects:
1. the composite filter membrane of the nano-pore surface layer/micron-pore supporting layer has a secondary structure of the nano-pore surface layer and the micron-pore supporting layer, has excellent performance and controllable filtering performance, can give consideration to both separation efficiency and separation flux, and realizes separation based on the self gravity of emulsion liquid.
2. Compared with other methods, the method for preparing the nano-cellulose by adopting the dissolving-regenerating process does not need complex equipment or chemical modification, and has the advantages of high speed, high efficiency and low cost.
3. The nano-cellulose prepared by the method has controllable size, and the surface nano-aperture of the composite filter membrane can be adjusted to adapt to the separation of emulsions with different particle sizes.
Drawings
Fig. 1 is a photograph of an aqueous solution of nanocellulose prepared in example 1.
FIG. 2 is a photograph of an oil-water emulsion separator used in the present invention.
Detailed Description
The following examples are presented to further illustrate the present invention and should not be construed as limiting the invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. Reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated.
Example 1
1. Dispersing 3g of microcrystalline cellulose in a mixed solution of 7 wt% of sodium hydroxide and 12 wt% of urea, cooling to-12 ℃, and mechanically stirring at room temperature for 300 r/min until the microcrystalline cellulose is completely dissolved to obtain a cellulose solution;
2. 1mL of cellulose solution is taken and added into 2 wt% of sodium hydroxide solution under the condition of 7000 r/min for homogeneous dispersion for 3 min, so as to obtain nano-cellulose solution.
3. Taking 2mL of nano-cellulose solution, diluting the nano-cellulose solution to 100mL by using distilled water, and uniformly stirring; then filtering with medium-speed quantitative filter paper until the nano-cellulose is uniformly deposited on the surface of the filter paper support layer to form a surface layer with nano-pores, and washing with distilled water to be neutral to obtain the composite filter membrane.
Preparing 5 wt% of toluene emulsion, pouring the toluene emulsion into a separation device shown in figure 2, and achieving the purpose of oil-water separation only based on the self gravity of the emulsion under the condition of no additional vacuum filtration device. The separation flux of the composite filter membrane is 95.5L/(m) through the measurement of oil-water emulsion separation2H) the separation efficiency was 99.88%.
Fig. 1 is a photograph of an aqueous solution of nanocellulose prepared in example 1. As shown in FIG. 1, the nano-cellulose solution has a significant Tyndall effect, which indicates that the size of the generated nano-cellulose is in the submicron level.
Example 2
The difference from the embodiment 1 is that the cellulose raw material in the step 1 is replaced by any one of chemical pulp fiber, recycled waste paper fiber, microcrystalline cellulose or cotton.
Example 3
The difference from example 1 is that the cellulose solution in step 1 is replaced by any one of sodium hydroxide/urea, sodium hydroxide/thiourea, lithium hydroxide/urea, lithium hydroxide/thiourea.
Example 4
The difference from the example 1 is that the cellulose regeneration alkali liquor in the step 1 is replaced by any one of sodium hydroxide, potassium hydroxide, lithium hydroxide and ammonia water.
Example 5
In contrast to example 1, the cellulose regeneration lye used in step 1 was 1% sodium hydroxide. The separation flux of the composite filter membrane is determined to be 103.2L/(m)2H) the separation efficiency was 98.9%.
Example 6
The difference from example 1 is that 4% sodium hydroxide is used as cellulose regeneration lye in step 1. The separation flux of the composite filter membrane is determined to be 88.4L/(m)2H) the separation efficiency was 99.2%.
Example 7
Different from example 1, 1mL of nanocellulose solution was aspirated in step 2. The separation flux of the composite filter membrane is determined to be 112.4L/(m)2H) the separation efficiency was 98.1%.
Example 8
Different from example 1, 3mL of nanocellulose solution was aspirated in step 2. The separation flux of the composite filter membrane is determined to be 90.1L/(m)2H) the separation efficiency was 99.4%.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations and simplifications are intended to be included in the scope of the present invention.
Claims (10)
1. A composite filter membrane of a nano-pore surface layer/a micron-pore supporting layer is characterized in that a cellulose raw material is added into an alkaline mixed solution at the temperature of-5 to-15 ℃ to form a cellulose suspension, and then the cellulose suspension is stirred and dissolved at room temperature to obtain a cellulose solution; under the condition of high-speed homogeneous dispersion, cellulose solution is dripped into alkaline aqueous solution to obtain nano cellulose dispersion, and the nano cellulose dispersion is prepared by diluting with water and filtering.
2. According to the claimsObtaining the composite filter membrane of the nano-pore surface layer/the micron-pore support layer 1, wherein the alkali in the alkaline aqueous solution is more than one of sodium hydroxide, lithium hydroxide or potassium hydroxide; the nano-cellulose loaded on the nano-pore surface layer in the composite filter membrane of the nano-pore surface layer/the micron-pore supporting layer is 0.5-5 g/m2。
3. The composite filter membrane of the nanopore skin/microporous support layer of claim 1, wherein the alkaline mixed solution is sodium hydroxide-urea, sodium hydroxide-thiourea, lithium hydroxide-urea, or lithium hydroxide-urea thiourea.
4. The composite filter membrane of the nano-pore surface layer/micro-pore support layer according to claim 3, wherein the concentration of sodium hydroxide or lithium hydroxide in the alkaline mixed solution is 5-10 wt%; the concentration of the urea or thiourea is 5-15 wt%.
5. The composite filter membrane of the nano-pore surface layer/micro-pore support layer according to claim 1, wherein the concentration of the cellulose suspension is 1-8 wt%; the concentration of the alkaline aqueous solution is 0.5-7 wt%.
6. The composite filter membrane of the nano/micro pore support layer of claim 1, wherein the cellulose material is chemical pulp fiber, recycled waste paper fiber, microcrystalline cellulose or cotton.
7. The method for preparing the composite filter membrane of the nano-pore surface layer/the micro-pore support layer according to any one of claims 1 to 6, which comprises the following specific steps:
s1, adding a cellulose raw material into an alkaline mixed solution at a temperature of between-5 and-15 ℃ to form a suspension, and stirring at room temperature until cellulose is completely dissolved to obtain a transparent cellulose solution;
s2, dripping a cellulose solution into an alkaline aqueous solution under the condition of high-speed homogeneous dispersion to obtain a nano-cellulose dispersion solution;
and S3, diluting the nano-cellulose dispersion liquid with water, and filtering to form the composite filter membrane of the nano-pore surface layer/the micron-pore supporting layer.
8. The method for preparing a composite filter membrane with a nano-pore surface layer/a micro-pore support layer according to claim 7, wherein the rotation speed of the high-speed homogeneous dispersion in the step S2 is 3000-25000 rpm; the dispersing time is 1-30 min.
9. The method for preparing a composite filter membrane with a nano-pore surface layer/a micro-pore support layer according to claim 7, wherein the volume ratio of the water to the nano-cellulose dispersion in step S3 is (20-200): 1.
10. use of a nanoporous surface layer/microporous support layer composite filter membrane as defined in any one of claims 1 to 6 in oil water emulsion separation.
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| CN114162779A (en) * | 2021-10-21 | 2022-03-11 | 北京大学 | Micro-nano composite filter membrane and preparation method and application thereof |
| CN114377471A (en) * | 2022-01-07 | 2022-04-22 | 中钢集团南京新材料研究院有限公司 | Suction filtration separation method of metal nanoparticles |
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Application publication date: 20191220 |