Carbon-based honeycomb porous membrane as well as preparation method and application thereof

Abstract

The invention provides a carbon-based honeycomb-shaped porous membrane and a preparation method and application thereof, the honeycomb-shaped porous membrane is a hexagonal porous membrane, the wall thickness between two adjacent holes in the top surface of the porous membrane is 0.4-0.5 mm, and the aperture of the honeycomb-shaped porous membrane is gradually reduced from the top end to the bottom end of the porous membrane. The porous membrane has the beneficial effects that the porous membrane has the hexagonal honeycomb-shaped pore structure, and the wall thickness between every two adjacent pores is relatively small, so that the porous membrane has the maximum unit light receiving area. The pore diameter of the porous membrane is gradually reduced from 1.3 mm to 1.5 mm to about 0.2 mm from the top end to the bottom end of the porous membrane. The preparation method of the porous membrane is simple, material components are easy to control, and the obtained porous membrane can absorb the full spectrum of sunlight, can effectively convert solar energy into heat energy, is good in stability and weather resistance and high in photo-thermal conversion efficiency, and has good application prospects in the fields of seawater desalination, sewage concentration, greenhouse sunlight shed heat collection and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of solar energy utilization, and specifically relates to a carbon-based honeycomb porous membrane and a preparation method and application thereof. Background Art

[0002] The earth's freshwater resources are limited and extremely unevenly distributed. my country is a country that is seriously short of fresh water for living. The earth's surface is rich in seawater resources, so solar desalination is a very important channel for obtaining freshwater resources.

[0003] Solar energy is the real and ultimate source of all energy on earth. It is a renewable and clean energy source that can be obtained sustainably. Solar energy can be obtained through various processes such as photovoltaics, photocatalysis and thermal conversion. For the utilization of solar energy, its thermal conversion rate is a technical prerequisite for utilization. Collecting solar energy and converting it into thermal energy plays an important role in many applications such as power generation, residential heating, seawater desalination and sewage treatment. In this regard, although a lot of progress and many methods have been made, there is still a problem of how to achieve higher thermal conversion efficiency with a simpler structure. Carbon materials represented by carbon black have natural black properties and have aroused great interest in the application of solar thermal conversion. They have good absorption rate in the entire solar spectrum range and are an excellent light absorption material with stable performance. They can still maintain excellent light absorption performance under long-term exposure to sunlight. At the same time, carbon black carbon materials have the advantage of low price, so they can be widely used in light-heat conversion. At present, in the application of solar heat collection, flat blackboards are used as heat-absorbing materials, with an absorption rate of about 15% of light energy, high light reflectivity and low heat absorption effect. Therefore, it is an extremely difficult challenge to develop carbon-based photothermal conversion carbon-based composite materials that are efficient, low-cost and can be applied on a large scale. Summary of the invention

[0004] In view of the above technical problems, the present invention provides a carbon-based honeycomb porous membrane with a maximum unit light receiving area and a light energy absorption rate of up to 90%, as well as a preparation method and application thereof.

[0005] The first aspect of the present invention provides a carbon-based honeycomb porous membrane, which is a hexagonal porous membrane, and the wall thickness between two adjacent holes on the top surface of the porous membrane is 0.4-0.5mm, and the pore size of the honeycomb porous membrane gradually decreases from the top to the bottom of the porous membrane.

[0006] Since the wall thickness between two adjacent holes in the porous membrane is 0.4-0.5mm, the porous membrane has the largest unit light receiving area. This is because the surface of carbon-based silicone rubber only absorbs about 15% of the light energy absorption rate. Only the light energy entering the hexagonal holes can be absorbed by the pigment carbon black and converted into heat energy. Therefore, the minimum wall thickness between two adjacent holes can provide the largest light receiving area and heat collection effect.

[0007] Since the pore size of the porous membrane gradually decreases from the top to the bottom of the porous membrane, and the depth is about (5±0.5) mm, after the light enters the hexagonal hole, it is reflected downward on the surface of the gradually decreasing conical hole, and is absorbed by the carbon black pigment and converted into heat energy. Because the reflection of light on the surface of the conical hole is the reflection from the depth of the conical hole, all the light entering the hole is absorbed by the carbon black pigment, and no light is reflected outward, and the hexagonal hole becomes a black body.

[0008] The carbon-based honeycomb porous membrane is, as a preferred embodiment, a regular hexagonal porous membrane, and the thickness of the honeycomb porous membrane is 4.5-5.5 mm;

[0009] Preferably, the pore size of the honeycomb porous membrane gradually decreases from 1.3 mm-1.5 mm to 0.2 mm, and the depth is (5±0.5) mm.

[0010] The second aspect of the present invention provides a mold for preparing the porous membrane described in the first aspect of the present invention, comprising a plurality of hexagonal pyramids and a fixing member, wherein the end faces of the hexagonal pyramids with large cross-sections are closely connected and located on the same horizontal plane, and the fixing member is used to seal the periphery surrounded by the plurality of hexagonal pyramids to form a porous mold;

[0011] Preferably, the fixing member is a piece of software.

[0012] A third aspect of the present invention provides a method for preparing a carbon-based honeycomb porous membrane, comprising the following steps:

[0013] (1) Take a number of hexagonal bars, grind one end of each bar into a hexagonal cone, and closely arrange the other ends of each bar for fixing, and ensure that the ends with smaller cross sections of the hexagonal bars are on the same horizontal plane;

[0014] (2) using a fixing member to seal the periphery formed by the hexagonal pyramids at the ends of the plurality of hexagonal rods to form a porous membrane mold;

[0015] (3) pouring a carbon-based silicone rubber composite material into a porous membrane mold, curing it, and removing the fixings and hexagonal rods to obtain the carbon-based honeycomb porous membrane.

[0016] When fixing the hexagonal rods, ensure that two adjacent hexagonal rods are in close contact (not the hexagonal cone ends), so that the gap formed by the hexagonal cone ends of two adjacent hexagonal rods is relatively small (the wall thickness between two adjacent holes forming the porous membrane is relatively thin), and a casting space can be formed between the hexagonal cone ends of several hexagonal rods and the fixing parts.

[0017] The above-mentioned method for preparing a carbon-based honeycomb porous membrane is a preferred embodiment. In step (1), the diameter of the hexagonal rod is 1.3mm-1.5mm, and the diameter of the hexagonal pyramid at the end of the hexagonal rod gradually decreases from 1.3mm-1.5mm to 0.2mm, with a depth of (5±0.5)mm.

[0018] Preferably, the length of the hexagonal pyramid at the end of the hexagonal rod is 4.5-5.5 mm.

[0019] The above-mentioned method for preparing a carbon-based honeycomb porous membrane is, as a preferred embodiment, in step (2), the bottom end of the fixing member and the bottom end of the hexagonal pyramid at the end of the hexagonal rod are located on the same horizontal plane; the top end of the fixing member is higher than the top end of the hexagonal pyramid at the end of the hexagonal rod;

[0020] Preferably, the fixing member is a sheet of soft material, such as PVC soft material or soft iron.

[0021] The sheet-packed soft material is sealed around the periphery of the hexagonal platform at the end of the hexagonal rod, so that a casting cavity is formed between the sheet-packed soft material and the hexagonal platform at the end of the hexagonal rod.

[0022] As a preferred solution, the fixing piece can also be made of a vessel. The shape of the cross section of the vessel matches the outer shape of the hexagonal pyramid at the end of the hexagonal rod, and a through hole is provided at the bottom of the vessel for the hexagonal pyramid at the end of the hexagonal rod to pass through.

[0023] As a preferred embodiment of the method for preparing the above-mentioned carbon-based honeycomb porous membrane, the plane where the top end of the fixing member is located is 0.5-1.5 mm higher than the plane where the hexagonal pyramid at the end of the hexagonal rod is located.

[0024] The above-mentioned method for preparing a carbon-based honeycomb porous membrane is a preferred embodiment. In step (3), the carbon-based silicone rubber composite material includes a reaction product of transparent silicone rubber and carbon black, preferably pigment carbon black; preferably, the pigment carbon black is pigment carbon black MCF-2.

[0025] Preferably, the mass ratio of transparent silicone rubber to carbon black is 2-4:1.

[0026] The transparent silicone rubber used in this application is transparent silicone rubber RVT-2, which was purchased from Chengdu Guibao Technology Co., Ltd.

[0027] As a preferred embodiment of the method for preparing the carbon-based honeycomb porous membrane, the curing condition is curing at 20-30° C. for 24 hours.

[0028] The fourth aspect of the present invention provides the use of the porous mold described in the first aspect of the present invention and the porous membrane obtained by the preparation method described in the third aspect of the present invention in seawater desalination, sewage concentration, and greenhouse solar shed heat collection.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: the porous membrane of the present invention has a hexagonal honeycomb pore structure, and the wall thickness between two adjacent pores is relatively thin, so that the porous membrane has the largest unit light receiving area. The pore size of the porous membrane of the present invention gradually decreases from the top to the bottom of the porous membrane, so that the hexagonal holes become a black body, which is convenient for absorbing light and converting it into heat energy.

[0030] The preparation method of the porous membrane of the present invention is simple and the material components are easy to control. The obtained porous membrane can absorb the full spectrum of sunlight, can effectively convert solar energy into thermal energy, has good stability and weather resistance, and has high photothermal conversion efficiency. It has good application prospects in the fields of seawater desalination, sewage concentration, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is an outline diagram of the carbon-based honeycomb porous membrane described in Example 1 of the present invention ( Figure 1 Figure f is Figure 1 (partial enlarged view of Figure c in the middle);

[0032] Figure 2 is a full spectrum absorption diagram of the carbon-based honeycomb porous membrane described in Example 1 of the present invention;

[0033] Figure 3 This is a full spectrum absorption comparison diagram of the carbon-based honeycomb porous membrane and the flat membrane material described in Example 1 of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments and drawings. The specific embodiments described herein are only used to explain the present invention and are not intended to constitute any limitation to the present invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concepts of the present disclosure. Such structures and technologies are also described in many publications.

[0035] Unless otherwise specified, the methods described in this application are all conventional methods, and the reagents used, unless otherwise specified, can be obtained from commercial sources.

[0036] The transparent silicone rubber used in the embodiment of the present invention is transparent silicone rubber RVT-2, which was purchased from Chengdu Guibao Technology Co., Ltd.

[0037] Example 1

[0038] A carbon-based honeycomb porous membrane is prepared from the following raw materials in parts by weight: 75 parts of transparent silicone rubber and 25 parts of pigment carbon black;

[0039] The specific preparation steps of the carbon-based honeycomb porous membrane are as follows:

[0040] (1) Weigh 39.99 g of commercially available transparent silicone rubber, add 13.33 g of carbon black pigment into liquid silicone rubber, mix and stir evenly to obtain a black silicone rubber paste;

[0041] (2) Inject black paste silicone rubber into the disc-shaped groove formed by the hexagonal pyramids at the end of the hexagonal metal rod fixed by the fixing piece within 1 hour, and fill the volume of the groove with the black paste, and cure at 25°C for 24 hours;

[0042] The specific preparation method of the disc-shaped groove described in this embodiment is:

[0043] a. Take several hexagonal metal rods with a diameter of 1.3 mm, grind one end of each rod into a hexagonal pyramid, and gradually reduce the diameter of the hexagonal pyramid from 1.3 mm to 0.2 mm, and closely arrange and fix the other end of each rod, and ensure that the ends of the hexagonal pyramids of the several hexagonal rods are located on the same horizontal plane; as a preferred embodiment, the length of the hexagonal pyramid is 5 mm;

[0044] b. Use soft iron to seal the periphery surrounded by the hexagonal pyramids at the ends of the hexagonal rods, and ensure that the bottom end of the fixing piece and the bottom end of the hexagonal pyramid at the end of the hexagonal rod are located on the same horizontal plane, and the top end of the fixing piece is 1 mm higher than the top end of the hexagonal pyramid at the end of the hexagonal rod to form a porous membrane mold (disc-shaped groove);

[0045] A black silicone rubber paste is poured into the mold. After curing, the fixings are removed and the hexagonal rods are pulled out from the silicone rubber plate to obtain a carbon-based honeycomb porous membrane. The wall thickness between two adjacent holes on the top surface of the obtained carbon-based honeycomb porous membrane is 0.4 mm, and the pore size of the honeycomb porous membrane gradually decreases from 1.3 mm to 0.2 mm.

[0046] Comparative Example 1

[0047] The carbon-based honeycomb porous membrane described in Comparative Example 1 is different from the porous membrane described in Example 1 in that: the carbon-based honeycomb porous membrane described in Comparative Example 1 is a hexagonal porous membrane, and the wall thickness between two adjacent holes on the top surface of the porous membrane is 0.8-1 mm.

[0048] Comparative Example 2

[0049] The carbon-based honeycomb porous membrane described in Comparative Example 2 is different from the porous membrane described in Example 1 in that: the carbon-based honeycomb porous membrane described in Comparative Example 2 is a hexagonal porous membrane, and the wall thickness between two adjacent holes on the top surface of the porous membrane is 0.2-0.3 mm.

[0050] Comparative Example 3

[0051] The difference between the carbon-based honeycomb porous membrane described in Comparative Example 3 and the porous membrane described in Example 1 is that the amount of pigment carbon black used in the carbon-based honeycomb porous membrane described in Comparative Example 3 is 33 g.

[0052] Comparative Example 4

[0053] The carbon-based honeycomb porous membrane described in Comparative Example 4 is different from the porous membrane described in Example 1 in that the carbon-based honeycomb porous membrane described in Comparative Example 4 uses natural rubber instead of transparent silicone rubber.

[0054] 1. The appearance diagram and partial enlarged diagram of the carbon-based honeycomb porous membrane described in Example 1 of the present invention are as follows: Figure 1 As shown:

[0055] from Figure 1 It can be seen that the carbon-based honeycomb porous membrane described in Example 1 of the present invention has regular hexagonal structure holes with thin pore walls. This structure has a large light receiving area, high mechanical strength structure, black body-like holes, and extremely low reflectivity.

[0056] 2. The carbon-based honeycomb porous membrane described in Example 1 of the present invention is tested by a UV-visible-near infrared spectrophotometer. The spectrophotometer is manufactured by Shimadzu Corporation of Japan and the model is UV3600. The full spectrum absorption diagram of the carbon-based honeycomb porous membrane described in Example 1 is as follows: Figure 2 As shown:

[0057] from Figure 2 It can be seen that the porous membrane described in Example 1 of the present invention has a membrane thickness of 5 mm and has the best absorption rate, and the absorption rate in some bands has reached 90%. The other four samples are Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4. The absorption rates of the four samples to light are relatively low, with an average absorption rate of about 45%, indicating that the porous membrane in Example 1 described in the present application has a higher spectral absorption effect.

[0058] 3. Comparison of the full spectrum absorption of the carbon-based honeycomb porous membrane described in Example 1 of the present invention and the existing planar material membrane. The results are as follows: Figure 3 As shown:

[0059] from Figure 3It can be seen from the figure that the light absorption rate of the honeycomb porous film of the present invention is increased by multiples. The flat film 40MCF-200 is a mixture of 13.33g of pigment carbon black and 39.99g of transparent silicone rubber, which is coated on an aluminum film. The coating thickness is about 120 microns, and the light absorption rate is about 15%. The absorption rate of the honeycomb porous film is increased to a maximum of 90%. This is because the porous honeycomb shape increases the light absorption area and prolongs the refraction path of the light wave. That is, the honeycomb porous film of the present invention has a better light absorption effect.

[0060] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A carbon-based honeycomb porous membrane, characterized in that: The honeycomb porous membrane is a hexagonal porous membrane, the wall thickness between two adjacent holes on the top surface of the porous membrane is 0.4-0.5 mm, and the pore size of the honeycomb porous membrane gradually decreases from the top to the bottom of the porous membrane.

2. The porous membrane according to claim 1, characterized in that The honeycomb porous membrane is a regular hexagonal porous membrane, and the thickness of the honeycomb porous membrane is 4.5-5.5 mm; Preferably, the pore size of the honeycomb porous membrane gradually decreases from 1.3-1.5 mm to 0.2 mm.

3. A mold for preparing the porous membrane according to any one of claims 1 to 2, characterized in that: It comprises a plurality of hexagonal pyramids and fixing parts, wherein the end faces of the hexagonal pyramids with large cross sections are closely connected and located on the same horizontal plane, and the fixing parts are used to seal the periphery surrounded by the plurality of hexagonal pyramids to form a porous mold; Preferably, the fixing member is a piece of software.

4. A method for preparing a carbon-based honeycomb porous membrane, characterized in that: The following steps are involved: (1) Take a number of hexagonal bars, grind one end of each bar into a hexagonal cone, and closely arrange the other ends of each bar for fixing, and ensure that the ends with smaller cross sections of the hexagonal bars are on the same horizontal plane; (2) using a fixing member to seal the periphery formed by the hexagonal pyramids at the ends of the plurality of hexagonal rods to form a porous membrane mold; (3) pouring a carbon-based silicone rubber composite material into a porous membrane mold, curing it, and removing the fixings and hexagonal rods to obtain the carbon-based honeycomb porous membrane.

5. The preparation method according to claim 4, characterized in that: In step (1), the diameter of the hexagonal rod is 1.3 mm-1.5 mm, and the diameter of the hexagonal pyramid at the end of the hexagonal rod gradually decreases from 1.3 mm-1.5 mm to 0.2 mm; Preferably, the length of the hexagonal pyramid at the end of the hexagonal rod is 4.5-5.5 mm.

6. The preparation method according to claim 4, characterized in that: In step (2), the bottom end of the fixing member and the bottom end of the hexagonal pyramid at the end of the hexagonal rod are located on the same horizontal plane; the top end of the fixing member is higher than the top end of the hexagonal pyramid at the end of the hexagonal rod; Preferably, the fixing member is a sheet of soft material.

7. The preparation method according to claim 6, characterized in that: The plane where the top of the fixing piece is located is 0.5-1.5 mm higher than the plane where the top of the hexagonal pyramid at the end of the hexagonal rod is located.

8. The preparation method according to claim 4, characterized in that: In step (3), the carbon-based silicone rubber composite material comprises a reaction product of transparent silicone rubber and carbon black, preferably pigment carbon black; Preferably, the mass ratio of transparent silicone rubber to carbon black is 2-4:

1.

9. The preparation method according to claim 4, characterized in that: The curing condition is curing at 20-30° C. for 24 hours.

10. Use of the porous membrane according to any one of claims 1 to 2 or the porous membrane obtained by the preparation method according to any one of claims 4 to 9 in seawater desalination, sewage concentration, and greenhouse solar shed heat collection.

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