A salt difference power generation heterogeneous membrane and its preparation method and application

Abstract

The present invention provides a salt difference power generation heterogeneous membrane and its preparation method and application. The heterogeneous membrane includes an ion selective hydrogel and a PET nanochannel membrane. The ion selective hydrogel is adhered to one side of the outer surface of the PET nanochannel membrane, and the thickness ratio of the two is (100-500): (10-12). By covering the PET nanochannel membrane with the ion selective hydrogel, the negative impact of concentration polarization on salt difference power generation is eliminated. The two sides of the heterogeneous membrane have different pore sizes, charge densities, and wettabilities, breaking the symmetry of the cylindrical PET porous membrane. The asymmetric structure can not only improve the ion selectivity of the PET nanochannel and accelerate the passage of counterions through the pores, but also prevent the counterions from gathering near the channel outlet to form ion polarization, reducing the negative impact on power generation, and can fully utilize the salt difference energy. Under the condition of 50 times the concentration difference, it can maintain a high power generation power of 1.92W / m 2 .

Description

Technical Field

[0001] The present invention belongs to the field of ion channel film technology and applications, and specifically relates to a salt difference power generation heterogeneous membrane and a preparation method and application thereof. Background Art

[0002] With the development of the times, people's demand for renewable and sustainable energy continues to increase. Typical renewable energy sources include photovoltaic power generation, wind power generation, hydropower generation, geothermal power generation, wave power generation, tidal energy and biomass energy. However, these energy sources still have defects, such as dependence on weather and environment, and unstable power supply. Salinity gradient power generation is semi-permanent and does not emit pollutants during operation. It is a promising renewable and sustainable (blue) energy source. If fully utilized, it is expected to solve the energy crisis facing human society. To date, different technologies have been developed to capture the energy of salinity gradient, including pressure-retarded osmosis (PRO) and reverse electrodialysis (RED). Among these technologies, RED focuses on utilizing the potential difference in salinity gradient between seawater and river water to generate electricity. Traditional commercial ion exchange membranes face the problem of not being able to balance ion selectivity and transfer rate.

[0003] In recent years, solid-state nanopores have attracted much attention. A research team has prepared a single-layer MoS2 with ultra-small pore size and ultra-high charge density for salt-difference power generation, which has improved the power generation capacity (JDFeng, et al. Nature 2016, 536, 197-200). However, considering the atomic thickness of a single nanopore membrane, their preparation is very difficult, and the research can only stay on the theoretical model, rather than on practical application. More importantly, the ultra-high power generation capacity of a single nanopore membrane cannot be simply linearly extrapolated to a porous membrane. Although increasing the pore density of a given surface area of the membrane can lead to a greater ion flux, the increase in ion flux will also lead to a decrease in the salt concentration near the membrane surface in contact with the concentrated solution, and an increase in the salt concentration around the film surface in contact with the dilute solution. This phenomenon is called concentration polarization. Concentration polarization reduces the concentration gradient near the membrane surface, reduces the driving force of diffusion transport, reduces the actual membrane potential, and has a huge negative impact on the power generation of the porous membrane. When the pore density reaches 104cm-2, the apparent selectivity of the membrane (the ratio of the actual membrane potential to the ideal membrane potential) begins to decline rapidly. When the pore density exceeds 106cm-2, concentration polarization begins to seriously affect the solution concentration near the membrane surface, and the apparent selectivity eventually approaches 0 (L.Wang, et al.ACS Nano 2021, 15, 4093-4107).

[0004] Therefore, improving ion selectivity while reducing the negative impact of concentration polarization is the key to improving power generation. The power generation of ordinary commercial membranes is mostly concentrated in the range of 0.3 to 1.1 W / m 2When one wants to further increase the pore density of the nanoporous membrane to increase the power generation efficiency, concentration polarization will reduce the apparent selectivity, and the power generation efficiency will decrease instead of increase. Summary of the Invention

[0005] The purpose of the present invention is to address the above-mentioned deficiencies in the prior art and to provide a salt difference power generation heterogeneous membrane and a preparation method and application thereof.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The first object of the present invention is to provide a salt difference power generation heterogeneous membrane, comprising an ion selective hydrogel and a PET nanochannel membrane, wherein the ion selective hydrogel is adhered to one side of the outer surface of the PET nanochannel membrane, and the thickness ratio of the ion selective hydrogel to the thickness of the PET nanochannel membrane is (100-500):(10-12).

[0008] Furthermore, the PET nanochannel membrane has a pore size of 20 to 300 nm and a pore density of 10 4 ~10 10 cm -2 , thickness is 10~12μm.

[0009] Furthermore, the thickness of the ion-selective hydrogel is 100 to 500 μm.

[0010] Furthermore, the ion-selective hydrogel is prepared by mixing monomers, a cross-linking agent and a photoinitiator.

[0011] Furthermore, the monomer includes at least one of acrylamide, 2-acrylamido-2-methylpropane sulfonic acid and (3-acrylamidopropyl)trimethylammonium chloride.

[0012] Furthermore, the cross-linking agent includes N,N′-methylenebisacrylamide or dimethylacrylamide.

[0013] Furthermore, the photoinitiator is 2-hydroxy-2-methylacetone.

[0014] A second object of the present invention is to provide a method for preparing the above-mentioned salt difference power generation heterogeneous membrane, comprising the following specific steps:

[0015] S1. Mixing monomers, crosslinking agents, and photoinitiators at certain concentrations to form a solution;

[0016] S2, dripping the solution obtained in step S1 into a mold and irradiating it under ultraviolet light to form an ion-selective hydrogel with a certain thickness;

[0017] S3. Adhere the hydrogel to the outer surface of the PET nanochannel membrane to obtain a heterogeneous membrane with an asymmetric structure.

[0018] Furthermore, in step S1, the concentration of the monomer is 1.5-3 mol / L, the concentration of the cross-linking agent is 0.02-0.06 mol / L, and the concentration of the photoinitiator is 0.002-0.014 mol / L.

[0019] Furthermore, in step S2, the wavelength of the ultraviolet light is 365±4 nm, and the irradiation time is 30-60 min.

[0020] The third object of the present invention is to provide the application of the above-mentioned salt difference power generation heterogeneous membrane in the preparation of small energy equipment.

[0021] Furthermore, a salinity difference power generation heterogeneous membrane is placed between a concentrated salt solution and a dilute salt solution, wherein the hydrogel of the salinity difference power generation heterogeneous membrane is located on one side of the dilute salt solution, and electrodes connected to a power supply are respectively inserted into the concentrated salt solution and the dilute salt solution. The salinity difference power generation heterogeneous membrane is negatively charged. When the anions and cations in the concentrated salt solution have a tendency to migrate toward the dilute salt solution driven by the salinity difference, the salinity difference power generation heterogeneous membrane with a negative charge allows the cations to pass through and blocks the migration of the anions, thereby generating a directional movement of charges, generating current, and realizing the conversion of salinity difference energy into electrical energy.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The salt difference power generation heterogeneous membrane provided by the present invention and its preparation method and application. A heterogeneous membrane is constructed by covering the PET nanochannel membrane with an ion-selective hydrogel to eliminate the negative impact of concentration polarization on salt difference power generation. The components on both sides of the heterogeneous membrane have different pore sizes, charge densities, and wettabilities, breaking the symmetry of the cylindrical PET porous membrane. The asymmetric structure of the heterogeneous membrane can not only improve the ion selectivity of the PET nanochannel and accelerate the passage of counterions through the pores, but also prevent the counterions from gathering near the channel outlet to form ion polarization, reduce the negative impact on power generation, and make full use of the salt difference energy. It can maintain a high power generation power (1.92W / m 2 ).

[0024] (2) The hydrogel in the heterogeneous membrane prepared by the present invention can be easily removed to restore the original properties of the nanoporous membrane. The membrane can be reused after being covered with hydrogel again, which is green and environmentally friendly.

[0025] (3) The salt difference power generation heterogeneous membrane provided by the present invention has a simple process, is easy to prepare, has low material prices, and has high economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1a This is a flow chart for preparing a heterogeneous membrane adhered with a cationic hydrogel according to Example 1 of the present invention;

[0027] Figure 1b This is a flow chart for preparing a heterogeneous membrane with anionic hydrogel adhered thereto according to Example 12 of the present invention;

[0028] Figure 1c Schematic diagram of the structure of a device for power generation using the heterogeneous membrane of the present invention;

[0029] Figure 2 This is an optical microscope image of the heterogeneous membrane of Example 1 of the present invention;

[0030] Figure 3 This is a SEM image of the heterogeneous membrane hydrogel prepared in Example 1 of the present invention. The hydrogel has wide 3D channels that can selectively transport counterions.

[0031] Figure 4 This is a comparison of the contact angles of the heterogeneous membrane before and after adhesion to the hydrogel in Example 1 of the present invention. The high hydrophilicity of the hydrogel is conducive to enhancing ion transport;

[0032] Figure 5 This is an IV curve of the heterogeneous membrane of Example 1 of the present invention in 0.1 M KCl solution. The hydrogel significantly enhances the ion selectivity of the cylindrical nanopores, and the curve exhibits an ion diode effect.

[0033] Figure 6 This is a graph of power density and current density of the heterogeneous membrane prepared in Example 1 of the present invention under a 50-fold concentration gradient;

[0034] Figure 7 This is a comparison of the power densities of the heterogeneous membranes prepared in Example 1 (cation selective gel) and Example 12 (anion selective gel) under a 50-fold concentration gradient of the present invention;

[0035] Figure 8 This is a comparison of the power density of heterogeneous membranes prepared in Example 1, Example 2, and Example 3 (different charged monomer concentrations) under a 50-fold concentration gradient;

[0036] Figure 9 This is a comparison of the power density of the heterogeneous membranes prepared in Example 1, Example 4, and Example 5 (different cross-linking agent concentrations) under a 50-fold concentration gradient;

[0037] Figure 10 This is a comparison chart of the power density of the heterogeneous membranes prepared in Example 1, Example 6, Example 7, Example 8, and Example 9 (with different hydrogel thicknesses) of the present invention under a 50-fold concentration gradient. DETAILED DESCRIPTION

[0038] To make the purpose, technical solutions and advantages of the present invention clearer, the specific embodiments of the present invention are described in further detail below in conjunction with specific examples and accompanying drawings. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this field or the product specifications are used. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be obtained commercially.

[0039] The PET nanochannel membrane in the present invention is a polyethylene terephthalate nanochannel membrane, which is also the PET cylindrical porous membrane in this embodiment, purchased from it4ip Nucleopore Membrane Company (Louvain-la-Neuve, Belgium).

[0040] In some embodiments of the present invention, a method for testing the power generation of the salt difference power generation heterogeneous membrane prepared by the present invention is provided, using Figure 1c The device shown in the figure sandwiches the salinity-differential power generation heterogeneous membrane in an electrolytic cell, with the hydrogel layer of the salinity-differential power generation heterogeneous membrane located on the low-concentration solution side. The test is conducted using a pair of Ag / AgCl electrodes. During salinity-differential power generation, a resistor box with adjustable resistance is connected to the circuit. For a given resistance value, the output power can be expressed as P = I 2 R calculation.

[0041] In the formula, I is the test current and R is the resistance of the resistance box.

[0042] 0.01 mol / L and 0.5 mol / L sodium chloride solutions were added to both sides of the electrolytic cell respectively, maintaining a 50-fold concentration gradient. The power generation under different external resistance values was tested, and the power generation density was calculated.

[0043] The ion-selective hydrogel provided by the present invention is prepared by mixing monomers, crosslinking agents and photoinitiators. The monomers may include at least one of acrylamide, 2-acrylamido-2-methylpropane sulfonic acid and (3-acrylamidopropyl)trimethylammonium chloride; the crosslinking agent may include N,N′-methylenebisacrylamide or dimethylacrylamide; and the photoinitiator may be 2-hydroxy-2-methylacetone.

[0044] In a specific implementation, the concentration of the above monomers is 1.5-3 mol / L, the concentration of the specific cross-linking agent is 0.02-0.06 mol / L, and the concentration of the photoinitiator is 0.002-0.014 mol / L. The above concentrations can all achieve the preparation of ion-selective hydrogels.

[0045] Example 1

[0046] The steps of the preparation method of the salt difference power generation heterogeneous membrane provided in this embodiment are as follows:

[0047] Step S1: Prepare 1 mL of a mixed solution containing 3.7 M acrylamide, 2.0 M 2-acrylamido-2-methylpropanesulfonic acid, 0.03375 M N,N′-methylenebisacrylamide, and 0.014 M 2-hydroxy-2-methylacetone at room temperature.

[0048] Step S2: Use a pipette to drop the mixed solution into a transparent mold with a depth of 200 μm, slowly cover it with a cover glass to ensure that no bubbles are generated, and clamp the cover glass with a clamp.

[0049] Step S3, irradiating with ultraviolet light with a wavelength of 365 nm for 40 minutes.

[0050] Step S4: Take out the formed hydrogel and adhere it to a 7 cm -2 , PET cylindrical porous membrane with a pore diameter of 30 nm.

[0051] Figure 1a Flowchart of the heterogeneous membrane prepared in this example and the chemical formula of the hydrogel components.

[0052] Figure 2 From the SEM image of the heterogeneous membrane prepared for this example, it can be seen that the hydrogel has a wide 3D transport network.

[0053] Figure 3 The power density and current density of the heterogeneous membrane prepared in this example under a 50-fold concentration gradient are shown, indicating that the heterogeneous membrane can reach 1.92 W / m under a 50-fold concentration gradient. 2 The ion-selective hydrogel can improve the selectivity of nanoporous membranes and reduce the negative impact of ion concentration polarization on power generation.

[0054] Example 2

[0055] The steps of the preparation method of the salt difference power generation heterogeneous membrane provided in this embodiment are as follows:

[0056] Step S1: Prepare 1 mL of a mixed solution containing 3.7 M acrylamide, 1.5 M 2-acrylamido-2-methylpropanesulfonic acid, 0.03375 M N,N′-methylenebisacrylamide, and 0.014 M 2-hydroxy-2-methylacetone at room temperature.

[0057] Step S2: Use a pipette to drop the mixed solution into a transparent mold with a depth of 200 μm, slowly cover it with a cover glass to ensure that no bubbles are generated, and clamp the cover glass with a clamp.

[0058] Step S3, irradiating with ultraviolet light with a wavelength of 365 nm for 40 minutes.

[0059] Step S4: Take out the formed hydrogel and adhere it to a 7 cm -2 , PET cylindrical porous membrane with a pore diameter of 30 nm.

[0060] Example 3

[0061] The steps of the preparation method of the salt difference power generation heterogeneous membrane provided in this embodiment are as follows:

[0062] Step S1: Prepare 1 mL of a mixed solution containing 3.7 M acrylamide, 2.5 M 2-acrylamido-2-methylpropanesulfonic acid, 0.03375 M N,N′-methylenebisacrylamide, and 0.014 M 2-hydroxy-2-methylacetone at room temperature.

[0063] Step S2: Use a pipette to drop the mixed solution into a transparent mold with a depth of 200 μm, slowly cover it with a cover glass to ensure that no bubbles are generated, and clamp the cover glass with a clamp.

[0064] Step S3, irradiating with ultraviolet light with a wavelength of 365 nm for 40 minutes.

[0065] Step S4: Take out the formed hydrogel and adhere it to a 7 cm -2 , PET cylindrical porous membrane with a pore diameter of 30 nm.

[0066] Example 4

[0067] The steps of the preparation method of the salt difference power generation heterogeneous membrane provided in this embodiment are as follows:

[0068] Step S1: Prepare 1 mL of a mixed solution containing 3.7 M acrylamide, 2 M 2-acrylamido-2-methylpropanesulfonic acid, 0.02250 M N,N′-methylenebisacrylamide, and 0.014 M 2-hydroxy-2-methylacetone at room temperature.

[0069] Step S2: Use a pipette to drop the mixed solution into a transparent mold with a depth of 200 μm, slowly cover it with a cover glass to ensure that no bubbles are generated, and clamp the cover glass with a clamp.

[0070] Step S3, irradiating with ultraviolet light with a wavelength of 365 nm for 40 minutes.

[0071] Step S4: Take out the formed hydrogel and adhere it to a 7 cm -2 , PET cylindrical porous membrane with a pore diameter of 30 nm.

[0072] Example 5

[0073] The steps of the preparation method of the salt difference power generation heterogeneous membrane provided in this embodiment are as follows:

[0074] Step S1: Prepare 1 mL of a mixed solution containing 3.7 M acrylamide, 2 M 2-acrylamido-2-methylpropanesulfonic acid, 0.045 M N,N′-methylenebisacrylamide, and 0.014 M 2-hydroxy-2-methylacetone at room temperature.

[0075] Step S2: Use a pipette to drop the mixed solution into a transparent mold with a depth of 200 μm, slowly cover it with a cover glass to ensure that no bubbles are generated, and clamp the cover glass with a clamp.

[0076] Step S3, irradiating with ultraviolet light with a wavelength of 365 nm for 40 minutes.

[0077] Step S4: Take out the formed hydrogel and adhere it to a 7 cm -2 , PET cylindrical porous membrane with a pore diameter of 30 nm.

[0078] Example 6

[0079] The steps of the preparation method of the salt difference power generation heterogeneous membrane provided in this embodiment are as follows:

[0080] Step S1: Prepare 1 mL of a mixed solution containing 3.7 M acrylamide, 2 M 2-acrylamido-2-methylpropanesulfonic acid, 0.03375 M N,N′-methylenebisacrylamide, and 0.014 M 2-hydroxy-2-methylacetone at room temperature.

[0081] Step S2: Use a pipette to drop the mixed solution into a transparent mold with a depth of 100 μm, slowly cover it with a cover glass to ensure that no bubbles are generated, and clamp the cover glass with a clamp.

[0082] Step S3, irradiating with ultraviolet light with a wavelength of 365 nm for 40 minutes.

[0083] Step S4: Take out the formed hydrogel and adhere it to a 7 cm -2 , PET cylindrical porous membrane with a pore diameter of 30 nm.

[0084] Example 7

[0085] The steps of the preparation method of the salt difference power generation heterogeneous membrane provided in this embodiment are as follows:

[0086] Step S1: Prepare 1 mL of a mixed solution containing 3.7 M acrylamide, 2 M 2-acrylamido-2-methylpropanesulfonic acid, 0.03375 M N,N′-methylenebisacrylamide, and 0.014 M 2-hydroxy-2-methylacetone at room temperature.

[0087] Step S2: Use a pipette to drop the mixed solution into a transparent mold with a depth of 300 μm, slowly cover it with a cover glass to ensure that no bubbles are generated, and clamp the cover glass with a clamp.

[0088] Step S3, irradiating with ultraviolet light with a wavelength of 365 nm for 40 minutes.

[0089] Step S4: Take out the formed hydrogel and adhere it to a 7 cm -2 , PET cylindrical porous membrane with a pore diameter of 30 nm.

[0090] Example 8

[0091] The steps of the preparation method of the salt difference power generation heterogeneous membrane provided in this embodiment are as follows:

[0092] Step S1: Prepare 1 mL of a mixed solution containing 3.7 M acrylamide, 2 M 2-acrylamido-2-methylpropanesulfonic acid, 0.03375 M N,N′-methylenebisacrylamide, and 0.014 M 2-hydroxy-2-methylacetone at room temperature.

[0093] Step S2: Use a pipette to drop the mixed solution into a transparent mold with a depth of 400 μm, slowly cover it with a cover glass to ensure that no bubbles are generated, and clamp the cover glass with a clamp.

[0094] Step S3, irradiating with ultraviolet light with a wavelength of 365 nm for 40 minutes.

[0095] Step S4: Take out the formed hydrogel and adhere it to a 7 cm -2 , PET cylindrical porous membrane with a pore diameter of 30 nm.

[0096] Example 9

[0097] The steps of the preparation method of the salt difference power generation heterogeneous membrane provided in this embodiment are as follows:

[0098] Step S1: Prepare 1 mL of a mixed solution containing 3.7 M acrylamide, 2 M 2-acrylamido-2-methylpropanesulfonic acid, 0.03375 M N,N′-methylenebisacrylamide, and 0.014 M 2-hydroxy-2-methylacetone at room temperature.

[0099] Step S2: Use a pipette to drop the mixed solution into a transparent mold with a depth of 500 μm, slowly cover it with a cover glass to ensure that no bubbles are generated, and clamp the cover glass with a clamp.

[0100] Step S3, irradiating with ultraviolet light with a wavelength of 365 nm for 40 minutes.

[0101] Step S4: Take out the formed hydrogel and adhere it to a 7 cm -2 , PET cylindrical porous membrane with a pore diameter of 30 nm.

[0102] Example 10

[0103] The steps of the preparation method of the salt difference power generation heterogeneous membrane provided in this embodiment are as follows:

[0104] Step S1: Prepare 1 mL of a mixed solution containing 3.7 M acrylamide, 2.0 M 2-acrylamido-2-methylpropanesulfonic acid, 0.03375 M N,N′-methylenebisacrylamide, and 0.014 M 2-hydroxy-2-methylacetone at room temperature.

[0105] Step S2: Use a pipette to drop the mixed solution into a transparent mold with a depth of 200 μm, slowly cover it with a cover glass to ensure that no bubbles are generated, and clamp the cover glass with a clamp.

[0106] Step S3, irradiating with ultraviolet light with a wavelength of 365 nm for 40 minutes.

[0107] Step S4: Take out the formed hydrogel and adhere it to a 7 cm -2 , PET cylindrical porous membrane with a pore diameter of 300nm.

[0108] Example 11

[0109] The steps of the preparation method of the salt difference power generation heterogeneous membrane provided in this embodiment are as follows:

[0110] Step S1: Prepare 1 mL of a mixed solution containing 3.7 M acrylamide, 2.0 M 2-acrylamido-2-methylpropanesulfonic acid, 0.03375 M N,N′-methylenebisacrylamide, and 0.014 M 2-hydroxy-2-methylacetone at room temperature.

[0111] Step S2: Use a pipette to drop the mixed solution into a transparent mold with a depth of 200 μm, slowly cover it with a cover glass to ensure that no bubbles are generated, and clamp the cover glass with a clamp.

[0112] Step S3, irradiating with ultraviolet light with a wavelength of 365 nm for 40 minutes.

[0113] Step S4: Take out the formed hydrogel and adhere it to a 9 cm -2 , PET cylindrical porous membrane with a pore diameter of 30 nm.

[0114] Example 12

[0115] The steps of the preparation method of the salt difference power generation heterogeneous membrane provided in this embodiment are as follows:

[0116] Step S1: Prepare 1 mL of a mixed solution containing 2.75 M acrylamide, 2.0 M (3-acrylamidopropyl)trimethylammonium chloride, 0.03375 M N,N′-methylenebisacrylamide, and 0.014 M 2-hydroxy-2-methylacetone at room temperature.

[0117] Step S2: Use a pipette to drop the mixed solution into a transparent mold with a depth of 200 μm, slowly cover it with a cover glass to ensure that no bubbles are generated, and clamp the cover glass with a clamp.

[0118] Step S3, irradiating with ultraviolet light with a wavelength of 365 nm for 40 minutes.

[0119] Step S4: Take out the formed hydrogel and adhere it to a 9 cm -2 , PET cylindrical porous membrane with a pore diameter of 30 nm.

[0120] Figure 1b Flowchart of the heterogeneous membrane prepared in this example and the chemical formula of the hydrogel components.

[0121] Based on the above implementation case, the current density and power density of the nanoporous membrane were tested under a 50-fold concentration gradient (i.e., 0.01-0.5 mol / L sodium chloride solution) to evaluate its power generation performance. 7 cm -2 , studies have shown that when the pore density reaches 10 4 cm -2 When the pore density exceeds 10 6 cm -2 When the concentration polarization begins to seriously affect the solution concentration near the membrane surface, the apparent selectivity eventually approaches 0. 6 cm -2 In the case of 2The present invention not only eliminates the negative impact of concentration polarization on power generation, but also improves the ion selectivity of the nanoporous membrane through hydrogel, making its power generation performance far superior to most traditional commercial membranes. This provides new options and broader development prospects for concentration-differential power generation. Generator sets can be installed in seaports and river mouths to supply electricity to nearby office buildings or coastal cities, and can also supply energy to small devices such as pacemaker implants, smart wearable devices, and smart textiles.

[0122] Any matters not mentioned above shall be subject to the existing technology.

[0123] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art should understand that the above examples are for illustration only and are not intended to limit the scope of the present invention. Those skilled in the art of the present invention may make various modifications or additions to the described specific embodiments or replace them in similar ways, but they will not deviate from the direction of the present invention or exceed the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent replacements, improvements, etc. made to the above embodiments based on the technical essence of the present invention should be included in the scope of protection of the present invention.

Claims

1. A salt difference power generation heterogeneous membrane, characterized in that: The invention comprises an ion selective hydrogel and a PET nanochannel membrane, wherein the ion selective hydrogel is adhered to one side of the outer surface of the PET nanochannel membrane, and the thickness ratio of the ion selective hydrogel to the thickness of the PET nanochannel membrane is (100-500):(10-12).

2. The salt difference power generation heterogeneous membrane according to claim 1, characterized in that: The PET nanochannel membrane has a pore size of 20 to 300 nm and a pore density of 10 4 ~10 10 cm -2 , thickness is 10~12μm.

3. The salt difference power generation heterogeneous membrane according to claim 1, characterized in that The thickness of the ion-selective hydrogel is 100 to 500 μm.

4. The salt difference power generation heterogeneous membrane according to any one of claims 1 to 3, characterized in that: The ion-selective hydrogel is prepared by mixing monomers, a cross-linking agent and a photoinitiator. The monomers include at least one of acrylamide, 2-acrylamido-2-methylpropane sulfonic acid and (3-acrylamidopropyl)trimethylammonium chloride.

5. The salt difference power generation heterogeneous membrane according to claim 4, characterized in that: The crosslinking agent includes N,N'-methylenebisacrylamide or dimethylacrylamide; and the photoinitiator is 2-hydroxy-2-methylacetone.

6. A method for preparing a salt difference power generation heterogeneous membrane according to claim 5, characterized in that: The preparation method comprises the following specific steps: S1. Mixing monomers, crosslinking agents, and photoinitiators at certain concentrations to form a solution; S2, dripping the solution obtained in step S1 into a mold and irradiating it under ultraviolet light to form an ion-selective hydrogel with a certain thickness; S3. Adhere the hydrogel to the outer surface of the PET nanochannel membrane to obtain a heterogeneous membrane with an asymmetric structure.

7. The preparation method according to claim 6, wherein In step S1 , the concentration of the monomer is 1.5 to 3 mol / L, the concentration of the cross-linking agent is 0.02 to 0.06 mol / L, and the concentration of the photoinitiator is 0.002 to 0.014 mol / L.

8. The preparation method according to claim 6, wherein In step S2, the wavelength of the ultraviolet light is 365±4 nm, and the irradiation time is 30-60 min.

9. Use of the salt difference power generation heterogeneous membrane according to any one of claims 1 to 5 in the preparation of small energy equipment.

10. The use according to claim 9, characterized in that A salinity difference power generation heterogeneous membrane is placed between a concentrated salt solution and a dilute salt solution, wherein the hydrogel of the salinity difference power generation heterogeneous membrane is located on the dilute salt solution side, and electrodes connected to a power supply are respectively inserted into the concentrated salt solution and the dilute salt solution. The salinity difference power generation heterogeneous membrane is negatively charged. When the anions and cations in the concentrated salt solution have a tendency to migrate to the dilute salt solution driven by the salinity difference, the salinity difference power generation heterogeneous membrane with a negative charge allows the cations to pass through and blocks the migration of the anions, thereby generating a directional movement of charges, generating current, and realizing the conversion of salinity difference energy into electrical energy.

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