A modifier, a modified permeable membrane, and a preparation method and application thereof

Abstract

The present invention provides a preparation method of a modifier, comprising the steps of: S1, dispersing mineral materials in a polar small molecule solvent to obtain a mixed solution; the mineral materials include one or more of kaolinite and montmorillonite; the mass-volume ratio of the mineral materials to the polar small molecule solvent is 60-150 mg: 30 mL; the polar small molecule solvent includes one or more of water, glycerol and ethanol; S2, performing ultrasonic liquid-phase exfoliation treatment on the mixed solution to obtain a reaction solution; S3, performing solid-liquid separation on the reaction solution, and taking the upper-layer liquid as the modifier. The present invention uses kaolinite and montmorillonite as raw materials to obtain a modifier that can be used to improve the performance of a permeation membrane, and can ensure the desalination effect of the modified permeation membrane on brine.

Description

Technical Field

[0001] The present invention relates to the field of seawater desalination, and particularly to a modifier, a modified permeable membrane, and a preparation method and application thereof. Background Art

[0002] With the continuous increase of the world's population and the sustainable development of the global economy, the shortage of fresh water resources has become one of the key links restricting the social development of various countries, and it is a topic that must be faced and solved in the new era. Turning to the ocean for fresh water has become a strategic decision to solve the shortage of water resources. To achieve this goal, various countries have developed seawater desalination technologies. With the increasing maturity of seawater desalination technologies, they will show greater price advantages than cross-basin and long-distance water diversion.

[0003] Seawater desalination can increase the total amount of fresh water resources, and has the advantages of not flooding land, not resettling people, not competing for water, and not being affected by climate, which is conducive to the harmonious development of humans and nature. The utilization of seawater is an effective way to solve the problem of lack of fresh water resources in coastal areas of our country, and has great strategic significance for ensuring the water supply safety and water ecological balance of our country. However, at present, seawater desalination technologies are limited by membrane materials and have not been widely applied.

[0004] In view of this, it is necessary to provide a modifier, a modified permeable membrane, and a preparation method and application thereof to solve or at least alleviate the technical defect that seawater desalination technologies are limited by membrane materials. Summary of the Invention

[0005] The main object of the present invention is to provide a modifier, a modified permeable membrane, and a preparation method and application thereof, aiming to solve the technical problem that seawater desalination technologies are limited by membrane materials.

[0006] To achieve the above object, the present invention provides a preparation method of a modifier, comprising the steps of:

[0007] S1, mixing ore materials into a polar small molecule solvent to obtain a mixed solution;

[0008] The ore materials include one or more of kaolinite and montmorillonite;

[0009] The polar small molecule solvent includes one or more of water, glycerol, and ethanol;

[0010] The mass-volume ratio of the ore materials to the polar small molecule solvent is 60 - 150 mg: 30 mL;

[0011] S2, performing ultrasonic liquid-phase exfoliation treatment on the mixed solution to obtain a reaction solution;

[0012] S3, performing solid-liquid separation on the reaction solution, and taking the upper-layer liquid as the modifier.

[0013] Further, the ore material is the kaolinite.

[0014] Further, the ore material is the kaolinite and the montmorillonite, and the mass ratio of the kaolinite to the montmorillonite is 5 - 3:5 - 7.

[0015] Further, the ultrasonic liquid-phase exfoliation treatment includes: exfoliating the mixed solution at an ultrasonic power of 300 - 500 W for 12 - 24 h.

[0016] The present invention also provides a modifier, which is prepared by using the preparation method of the modifier described in any one of the above.

[0017] The present invention also provides a preparation method of a modified permeable membrane, including: passing the modifier described in any one of the above through a microporous filtration membrane, so that the active components in the modifier are loaded on the microporous filtration membrane to obtain the modified permeable membrane.

[0018] Further, during the loading process, the volume of the modifier: the cross-sectional area of the microporous filtration membrane is 1 - 2 mL:1 cm 2 .

[0019] The present invention also provides a modified permeable membrane, which is prepared by using the preparation method of the modified permeable membrane described in any one of the above.

[0020] The present invention also provides an application of the modifier described in any one of the above and / or the modified permeable membrane described in any one of the above in desalinated water.

[0021] Further, the desalination of the brine is carried out by the forward osmosis method.

[0022] Compared with the prior art, the present invention has at least the following advantages:

[0023] The present invention uses kaolinite and montmorillonite as raw materials to obtain a modifier that can be used to improve the performance of the permeable membrane; the present invention selects kaolinite, or combines kaolinite and montmorillonite in a specific ratio, which can further ensure the treatment effect of the modified permeable membrane on brine (seawater); in particular, the modified permeable membrane prepared by using kaolinite and montmorillonite in a mixing ratio of 5 - 3:5 - 7 has a rejection rate of sodium chloride exceeding that of the modified permeable membranes prepared from single kaolinite and montmorillonite.

[0024] In addition, the polar small molecule solvent in the present invention is selected from one of water, glycerol, and ethanol, which can make the morphology of the obtained kaolinite / montmorillonite nanosheets more regular without affecting the structural properties of the kaolinite / montmorillonite nanosheets; the kaolinite / montmorillonite required by the present invention can all be obtained from coal gangue and coal slime, with wide sources and low prices. Therefore, the present invention can also be used as a way to treat solid waste. Brief Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0026] Figure 1 SEM images of kaolinite and montmorillonite after grinding in the present invention; among them, (a) is the SEM image of kaolinite, and (b) is the SEM image of montmorillonite;

[0027] Figure 2 TEM images of the active ingredients in the modifiers of Example 1 and Example 7 of the present invention; among them, (a) is the TEM image of the active ingredient in the modifier of Example 1, and (b) is the TEM image of the active ingredient in the modifier of Example 7;

[0028] Figure 3 AFM images of the active ingredients in the modifiers of Example 1 and Example 7 of the present invention; among them, (a) is the AFM image of the active ingredient in the modifier of Example 1, and (b) is the AFM image of the active ingredient in the modifier of Example 7;

[0029] Figure 4 SEM images of the microporous filtration membranes used in each example and comparative example of the present invention, and SEM images of the modified permeation membranes in Example 1 and Example 7;

[0030] Among them, (a) is the SEM image of the front (water permeable surface) of the microporous filtration membrane; (b) is the SEM image of the side (end face) of the microporous filtration membrane; (c) is the SEM image of the front (water permeable surface) of the modified permeation membrane in Example 1; (d) is the SEM image of the side (end face) of the modified permeation membrane in Example 1; (e) is the SEM image of the front (water permeable surface) of the modified permeation membrane in Example 7; (f) is the SEM image of the side (end face) of the modified permeation membrane in Example 7.

[0031] The realization, functional characteristics and advantages of the objectives of the present invention will be further described in conjunction with the embodiments with reference to the drawings. Detailed Embodiments

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0033] Moreover, the technical solutions between various embodiments of the present invention can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions appears to be contradictory or unable to be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0034] It should be understood that membrane-based seawater desalination has become the mainstream seawater desalination technology in China, and its production scale has gradually expanded from the initial daily production of hundreds of tons to thousands of tons, tens of thousands of tons, and hundreds of thousands of tons, greatly alleviating the problem of water resource shortage in some areas of China; however, the costs of reverse osmosis and electrodialysis seawater desalination are still relatively high.

[0035] Forward osmosis is a new type of membrane separation technology driven by concentration developed in recent years. It is a membrane separation process that spontaneously realizes water transfer by relying on the osmotic pressure difference on both sides of a selectively permeable osmotic membrane. Since this process is a spontaneous process and does not require the input of additional energy, the forward osmosis membrane technology has much lower energy consumption than the reverse osmosis membrane technology and has great development prospects in the field of seawater desalination.

[0036] In order to obtain a membrane material with excellent forward osmosis performance, the present invention first provides a preparation method of a modifier. The modifier is a modifier for membranes, and the preparation method of the modifier includes the steps:

[0037] S1, mixing mineral materials into a polar small molecule solvent to obtain a mixed solution.

[0038] The mineral materials include or are one or more of kaolinite and montmorillonite, and both kaolinite and montmorillonite can be obtained from coal gangue or coal slime.

[0039] Exemplarily, the mineral materials can be only the kaolinite; the mineral materials can also be the kaolinite and the montmorillonite. In this mixture, the mass ratio of the kaolinite to the montmorillonite can be 5 - 3:5 - 7.

[0040] The mass-volume ratio of the mineral materials to the polar small molecule solvent is 60 - 150 mg:30 mL.

[0041] The polar small molecule solvent includes or is one or more of water, glycerol, and ethanol.

[0042] S2. Perform ultrasonic liquid-phase exfoliation treatment on the mixed solution to obtain a reaction solution.

[0043] The ultrasonic liquid-phase exfoliation treatment includes or is: exfoliating the mixed solution for 12 - 24 h at an ultrasonic power of 300 - 500 W; the ultrasonic liquid-phase exfoliation treatment can be carried out in an ultrasonic cleaner.

[0044] S3. Perform solid-liquid separation on the reaction solution, and take the upper-layer liquid (supernatant) as the modifier. The method of solid-liquid separation can be to let it stand for 10 - 40 minutes or centrifuge for 3 minutes at 3000 - 5000 rpm with a centrifuge.

[0045] It should be understood that in the present invention, relying on the traditional ultrasonic liquid-phase exfoliation treatment, the bubbles and cavities generated by ultrasound in the solution, the high-energy impact generated by the rupture of the two causes the interlayer dissociation of the three-dimensional layered crystal, and then monolayer or few-layer nanosheet materials can be produced.

[0046] The present invention also provides a modifier, which is prepared by using the preparation method of the modifier described in any of the above embodiments.

[0047] Based on the modifier, the present invention also provides a preparation method of a modified permeable membrane, including: passing the modifier described in any of the above embodiments through a microporous filtration membrane, so that the active components in the modifier are loaded on the microporous filtration membrane to obtain the modified permeable membrane; the active component is a substance that can be loaded on the microporous filtration membrane after ultrasonic exfoliation.

[0048] The loading means combining the active components in the modifier with the microporous filtration membrane.

[0049] The loading method includes or is vacuum loading, specifically: placing the microporous filtration membrane at the bottom of the modifier, and then using a vacuum pump to evacuate from the lower part of the microporous filtration membrane (under airtight conditions), so that the modifier passes through the microporous filtration membrane from top to bottom, and the active components in the modifier are combined in the microporous filtration membrane.

[0050] The microporous filtration membrane involved in the present invention is a mixed cellulose (MCE) membrane (Mixed Cellulose Ester (MCE) Membrane), which is sourced from Tianjin Jinteng Experimental Equipment Co., Ltd.; those skilled in the art should know that the mixed cellulose (MCE) membrane is a commonly used water-based membrane, which is composed of a mixture of cellulose nitrate ester and cellulose acetate ester.

[0051] When performing the loading, the volume of the modifier: the cross-sectional area of the microporous filtration membrane can be 1 - 2 mL:1 cm2 It should be noted that the cross-sectional area of the microfiltration membrane is the water-permeable area of the microfiltration membrane. Exemplarily, the cross-section of the microfiltration membrane can be a circular surface, and the diameter of the circular surface can be 50 mm; the pore size of the microfiltration membrane can be 0.2 um.

[0052] The present invention also provides a modified permeation membrane, which is prepared by using the preparation method of the modified permeation membrane described in any of the above embodiments.

[0053] Based on the efficacy of the modifier and the performance of the modified permeation membrane, the present invention also provides an application of the modifier and / or the modified permeation membrane described in any of the above embodiments in desalinated water, and the brine can be seawater.

[0054] In the specific application process, the reverse osmosis method or the forward osmosis method can be adopted.

[0055] Considering the energy consumption of the reverse osmosis method and the low rejection rate of substances such as sodium chloride by the reverse osmosis method. And in view of the excellent forward osmosis performance of the seawater desalination membrane provided by the invention, therefore, it is preferred to use the modified permeation membrane in the present invention for the forward osmosis method, that is, to desalinate the brine by the forward osmosis method.

[0056] Exemplarily, the forward osmosis method can be: contacting the feed liquid (brine) with one side of the modified permeation membrane, and during the contact process, contacting the other side of the modified permeation membrane with the driving liquid; the osmotic pressure of the feed liquid (brine) is lower than the osmotic pressure of the driving liquid, so that the water in the feed liquid flows into the driving liquid, realizing the separation of water and substances such as sodium chloride in the feed liquid, and providing a basis for the desalination of the feed liquid (brine).

[0057] For example, inject the feed liquid at one end of a U-shaped tube, inject the driving liquid at the other end, and separate the feed liquid and the driving liquid with the modified permeation membrane, and the modified permeation membrane is located in the middle of the U-shaped tube.

[0058] For the convenience of further understanding of the invention, the following is an example:

[0059] In the following examples and comparative examples, the kaolinite and montmorillonite used are of the same batch, and the microfiltration membranes used are also of the same batch.

[0060] Example 1

[0061] 1. Add 60 mg of kaolinite and 0 mg of montmorillonite to 30 mL of water to obtain a mixed solution; among them, the kaolinite is ground with a grinder before use and sieved through a 60-mesh sieve.

[0062] After subjecting the mixture to ultrasonic liquid-phase exfoliation for 16 h under the condition of an ultrasonic power of 400 W, solid-liquid separation was carried out by standing for 20 minutes, and the supernatant was taken as the membrane modifier.

[0063] 2. By vacuum filtration, the membrane modifier was passed through the microporous filtration membrane, so that the active components in the membrane modifier were loaded in the microporous filtration membrane to obtain a modified osmotic membrane.

[0064] Among them, the microporous filtration membrane is a mixed cellulose (MCE) membrane (Mixed Cellulose Ester (MCE) Membrane), with a pore size of 0.2 um, a diameter of 50 mm, circular, and is sourced from Tianjin Jinteng Experimental Equipment Co., Ltd.

[0065] 3. The modified osmotic membrane was subjected to a forward osmosis experiment in a U-shaped tube for 4 h, and its water flux and rejection rate of sodium chloride were measured; among them, one side of the modified osmotic membrane was a 50 mL 3.5 wt% sodium chloride solution, and the other side was 50 mL of deionized water.

[0066] 4. Take the same batch of modified osmotic membranes, and let 100 mL of deionized water pass through the modified osmotic membrane from top to bottom under the condition of vacuum filtration, and measure the suction filtration flux of the modified osmotic membrane for water.

[0067] The test results of this example are shown in the following table:

[0068]

[0069] Example 2

[0070] Compared with Example 1, in this example, the addition amount of kaolinite was adjusted to 54 mg, and the addition amount of montmorillonite was adjusted to 6 mg, and other conditions remained unchanged.

[0071] The test results of this example are shown in the following table:

[0072]

[0073] Example 3

[0074] Compared with Example 1, in this example, the addition amount of kaolinite was adjusted to 42 mg, and the addition amount of montmorillonite was adjusted to 18 mg, and other conditions remained unchanged.

[0075] The test results of this example are shown in the following table:

[0076]

[0077] Example 4

[0078] In this example, compared with Example 1, the addition amount of kaolinite was adjusted to 30 mg, and the addition amount of montmorillonite was adjusted to 30 mg, while other conditions remained unchanged.

[0079] The test results of this example are shown in the following table:

[0080]

[0081] Example 5

[0082] In this example, compared with Example 1, the addition amount of kaolinite was adjusted to 18 mg, and the addition amount of montmorillonite was adjusted to 42 mg, while other conditions remained unchanged.

[0083] The test results of this example are shown in the following table:

[0084]

[0085] Example 6

[0086] In this example, compared with Example 1, the addition amount of kaolinite was adjusted to 6 mg, and the addition amount of montmorillonite was adjusted to 54 mg, while other conditions remained unchanged.

[0087] The test results of this example are shown in the following table:

[0088]

[0089] Example 7

[0090] In this example, compared with Example 1, the addition amount of kaolinite was adjusted to 0 mg, and the addition amount of montmorillonite was adjusted to 60 mg, while other conditions remained unchanged.

[0091] The test results of this example are shown in the following table:

[0092]

[0093] Comparative Example 1

[0094] In this comparative example, compared with Example 1, the modified permeable membrane was not prepared (Steps 1 and 2 were deleted), and the modified permeable membrane in Steps 3 and 4 was replaced with a microfiltration membrane (the same as in Example 1), while other conditions remained unchanged.

[0095] The test results of this comparative example are shown in the following table:

[0096]

[0097] Analysis Example 1

[0098] It can be obtained that Figure 1 before sonication, both kaolinite and montmorillonite are large lamellar masses.

[0099] It can be obtained that Figure 2 after sonication, kaolinite and montmorillonite become nano single-layer or few-layer nanosheets (active ingredients), which indicates that sonication can exfoliate kaolinite and montmorillonite into nano single-layers.

[0100] It can be obtained that Figure 3 the thickness of the nanosheets of kaolinite and montmorillonite (active ingredients) after sonication is only about 1 - 2 nm, which also better demonstrates that sonication exfoliates kaolinite and montmorillonite into nano single-layers.

[0101] It can be obtained that Figure 4 by vacuum filtration, both kaolinite and montmorillonite form a dense film on the microporous filter membrane, indicating that the combined membrane of kaolinite, montmorillonite and the microporous filter membrane is prepared in this invention.

[0102] It can be obtained from the data in Examples 1 - 7 that

[0103] among the modified osmotic membranes prepared with different mixing ratios of kaolinite and montmorillonite, the modified osmotic membranes with the kaolinite:montmorillonite ratio of 5:5 and 3:7 have the highest rejection rate for sodium chloride solution.

[0104] In the above technical solutions of the present invention, the above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made under the technical concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A preparation method of a modifier, characterized in that, it includes the steps: S1, mixing mineral materials into a polar small molecule solvent to obtain a mixed solution; the mineral materials are kaolinite and montmorillonite, and the mass ratio of the kaolinite to the montmorillonite is 5 - 3:5 - 7; the polar small molecule solvent includes one or more of water, glycerol and ethanol; the mass - volume ratio of the mineral materials to the polar small molecule solvent is 60 - 150 mg:30 mL; S2, performing ultrasonic liquid - phase exfoliation treatment on the mixed solution to obtain a reaction solution; S3, performing solid - liquid separation on the reaction solution, and taking the upper - layer liquid as the modifier.

2. The preparation method of the modifier according to claim 1, characterized in that, the ultrasonic liquid - phase exfoliation treatment includes: exfoliating the mixed solution for 12 - 24 h under an ultrasonic power of 300 - 500 W.

3. A modifier, characterized in that, it is prepared by using the preparation method of the modifier according to claim 1 or 2.

4. A preparation method of a modified osmotic membrane, characterized in that, it includes: passing the modifier according to claim 3 through a microporous filtration membrane, so that the active components in the modifier are loaded on the microporous filtration membrane to obtain the modified osmotic membrane.

5. The preparation method of the modified osmotic membrane according to claim 4, characterized in that, During the process of the load, the volume of the modifier: the cross-sectional area of the microporous filtration membrane is 1-2 mL: 1 cm 2 .

6. A modified osmotic membrane, characterized in that, it is prepared by using the preparation method of the modified osmotic membrane according to claim 4 or 5.

7. An application of the modified osmotic membrane according to claim 6 in desalinating brine.

8. The application according to claim 7, characterized in that, the brine is desalinated by the method of forward osmosis.

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