A light-oxygen dual transfer membrane, a preparation method and application thereof

Abstract

This invention provides a light-oxygen dual-transfer membrane, its preparation method, and its application. The preparation method of the light-oxygen dual-transfer membrane includes the following steps: (1) PVDF, organic solvent, and pore-forming agent are added sequentially to a container, stirred at 60℃-80℃ for 5-7 hours, and degassed under negative pressure to obtain PVDF casting solution; (2) PDMS and curing agent are added sequentially to a container, stirred evenly at 20-25℃, and allowed to stand to degassed to obtain PDMS casting solution; (3) PVDF casting solution is coated onto a glass plate, then placed in a cleaning tank to rinse off the organic solvent and pore-forming agent, and dried to obtain an initial membrane; (4) PDMS casting solution is coated onto the reverse side of the initial membrane, placed at room temperature for 2-4 hours, and dried to obtain the light-oxygen dual-transfer membrane. The method of this invention is simple and convenient, and the obtained membrane has a simple structure and possesses both light transmittance and air permeability.

Description

Technical Field

[0001] This invention belongs to the field of water treatment membrane preparation. Specifically, this invention relates to a light-oxygen dual-transfer membrane, its preparation method, and its application. Background Technology

[0002] The use of algae-microbe symbiotic systems for wastewater treatment has attracted widespread attention. Within this system, under light conditions, microalgae utilize dissolved organic carbon produced in the system or present in the wastewater, along with nitrogen and phosphorus elements, to perform photosynthesis, synthesizing growth substances necessary for their proliferation and simultaneously producing oxygen. At the same time, aerobic bacteria utilize the oxygen and electron-donating organic carbon produced by the algae for aerobic respiration, generating inorganic nutrients required by the algae. In this cyclical process, bacteria and microalgae, while completing their own growth, adsorb and remove pollutants from the wastewater. However, in algae-microbe symbiotic systems, the disturbance caused by aeration can disrupt the interaction between bacteria and algae, leading to limited photosynthesis; conversely, lack of aeration can reduce stability. Membrane-aerated biofilm reactors (MABRs) are a wastewater treatment technology that has been extensively studied in recent years. One of the key features of MABRs is their oxygen transfer mechanism; oxygen in MABRs is at the micron level, without the generation of visible bubbles. Applying MABRs to algae-microbe symbiotic systems, using membranes for bubble-free aeration, also prevents algae from experiencing growth limitations due to excessive dissolved oxygen.

[0003] Within this algae-bacterial system, algae require light to perform photosynthesis. Currently, most membranes used for bubble-free aeration are not light-transmitting, making it difficult for light to penetrate into the algae-bacterial sludge mixture, which limits algae growth. To improve the application efficiency of membranes in algae-bacterial symbiotic systems, the light transmission performance of membranes still needs to be improved and optimized. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a light-oxygen dual-transfer membrane, its preparation method, and its application. The method of this invention is simple and convenient, and the resulting membrane has a simple structure while possessing both light transmittance and gas permeability.

[0005] The present invention adopts the following technical solution:

[0006] This invention provides a method for preparing a light-oxygen dual-transfer membrane, comprising the following steps:

[0007] (1) Add PVDF, organic solvent and pore-forming agent into a container in sequence, stir at 60℃-80℃ for 5-7 hours, degas under negative pressure to obtain PVDF casting solution;

[0008] (2) Add PDMS and curing agent into the container in sequence, stir evenly at 20-25℃, let stand to remove bubbles, and obtain PDMS casting solution;

[0009] (3) The PVDF casting solution is scraped onto a glass plate, then rinsed in a cleaning tank and dried to obtain the initial film;

[0010] (4) Apply PDMS casting solution to the reverse side of the initial membrane, let it stand at room temperature for 2-4 hours, and then dry it to obtain a light-oxygen dual-transfer membrane.

[0011] The main raw materials selected for this invention are PVDF and PDMS. PDMS liquid is clear and transparent, and the smooth film formed after curing also has ultra-high optical transparency. PDMS is used as a filler material to fill the pores of the PVDF hydrophobic membrane, thereby removing the pores in the membrane material. After curing, a dense composite membrane with an outer PDMS membrane and a PVDF membrane as the support layer is formed, eliminating the refraction of light by the pores of the PVDF membrane and preparing a light-oxygen dual-transmission membrane with optical transparency.

[0012] It should be noted that the polydimethylsiloxane (PDMS) used in this application is typically used in conjunction with a compatible curing agent, and methods described in existing literature can be referenced. For ease of operation, it can also be purchased commercially available, such as the Xinwei two-component kit, which includes PDMS and a curing agent in a 10:1 mixing ratio, and the Dow Corning SYLGARD DC184 two-component kit, which includes PDMS and a curing agent in a 10:1 mixing ratio, also available commercially.

[0013] Preferably, the organic solvent is DMAC (N,N-dimethylacetamide).

[0014] In some embodiments, the porogen is one or more of polyvinylpyrrolidone, lithium chloride, and zinc chloride; more preferably, the porogen is lithium chloride.

[0015] In some embodiments, when the porogen is polyvinylpyrrolidone, the mass percentages of PVDF, organic solvent, and porogen in step (1) are: PVDF 12%-14%, porogen polyvinylpyrrolidone 3%-12%, and the remainder is organic solvent.

[0016] In some embodiments, when the porogen is lithium chloride, the mass percentages of PVDF, organic solvent and porogen in step (1) are: PVDF 12%-14%, lithium chloride 0.4%-5% and the remainder is organic solvent.

[0017] Preferably, the PVDF content is 12%-14%, the pore-forming agent lithium chloride content is 0.4%-1%, and the remainder is an organic solvent.

[0018] In some embodiments, when the porogen is zinc chloride, the mass percentages of PVDF, organic solvent and porogen in step (1) are: PVDF 12%-14%, zinc chloride 0.5%-1%, and the remainder is organic solvent.

[0019] In some embodiments, in step (3), the coating thickness is 300 μm.

[0020] In some embodiments, in step (3), rinsing is performed by soaking in deionized water at a temperature of 20-25°C until a film is formed.

[0021] In some embodiments, in step (3), the drying temperature is 30-40°C and the time is 30-60 minutes. In some embodiments, the drying can be carried out in a forced-air drying oven.

[0022] In some embodiments, in step (4), the amount of coating applied is 17-25 mg / cm³. 2 .

[0023] In some embodiments, in step (4), the drying temperature is 60-65°C and the time is 4-6 hours; in some embodiments, the drying can be carried out in a blower drying oven.

[0024] This invention also provides a light-oxygen dual-transfer membrane prepared by the above method, wherein the light-oxygen dual-transfer membrane is processed into a flat plate and has a thickness of 400-500 μm.

[0025] This invention also provides applications of the aforementioned light-oxygen dual-transfer membrane in scenarios requiring both light irradiation and gas transport. As an example, it can be used in algae-bacterial symbiotic systems.

[0026] The advantages and effects of this invention are:

[0027] (1) The method for preparing the light-oxygen dual-transfer membrane of the present invention is simple and can be prepared on a large scale. The special feature of the light-oxygen dual-transfer membrane is that the membrane is thin and transparent while being permeable to air, and the preparation method is universal and has wide application value in scenarios that require light irradiation and gas transport.

[0028] (2) The light-oxygen dual-transfer membrane of the present invention can effectively irradiate the inside of the bacterial-algae mixture, so that the bacteria and algae inside the reactor can also grow well, and also improve the utilization rate of light. Attached Figure Description

[0029] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0030] Figure 1This is a schematic diagram of the structure of the light-oxygen dual-transfer membrane in an embodiment of the present invention.

[0031] A—PVDF support layer, B—PDMS outer layer.

[0032] Figure 2 Electron micrograph of the light-oxygen dual-transfer membrane prepared in Example 5; in the figure:

[0033] (a) is the surface of the membrane; (b) is the cross-section of the light-oxygen dual-transmission membrane; (c) is the distribution of Si elements in the cross-section of the light-oxygen dual-transmission membrane.

[0034] Figure 3 The figures show the appearance of the light-oxygen dual-transfer membranes from Examples 1 to 5 and the corresponding transmittance of the samples. In the figures:

[0035] (a) Appearance and transparency of the light-oxygen dual-transfer membrane; (b) Light transmittance of the corresponding sample; (c) Light transmittance data of the corresponding sample; (d) Illuminance data of the corresponding sample. (e) Test method of (b).

[0036] Figure 4 The figures show the appearance of the light-oxygen dual-transfer membranes and the transmittance of the corresponding samples from Comparative Examples 1 to 6.

[0037] (a) shows the appearance and transparency of the light-oxygen dual-transfer membrane; (b) shows the transmittance data of the corresponding sample. Detailed Implementation

[0038] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0039] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0040] Unless otherwise specified, the materials, reagents, and apparatus used in the following examples can be obtained commercially or prepared according to methods published in the literature.

[0041] In this document, when values ​​are described as ranges, it should be understood that such disclosure includes disclosure of all possible subranges within that range, as well as the specific numerical values ​​falling within that range, regardless of whether the specific numerical value or specific subrange is explicitly specified.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the meanings commonly understood by one of ordinary skill in the art to which this invention pertains.

[0043] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0044] In this article, the term “approximately” refers to + / - 10% of the listed values.

[0045] This invention provides a method for preparing a light-oxygen dual-transfer membrane, comprising the following steps:

[0046] (1) Add PVDF, organic solvent and pore-forming agent into a container in sequence, stir at 60℃-80℃ for 5-7 hours, degas under negative pressure to obtain PVDF casting solution;

[0047] (2) Add PDMS and curing agent into the container in sequence, stir evenly at 20-25℃, let stand to remove bubbles, and obtain PDMS casting solution;

[0048] (3) The PVDF casting solution is scraped onto a glass plate, then rinsed in a cleaning tank and dried to obtain the initial film;

[0049] (4) Apply PDMS casting solution to the reverse side of the initial membrane, let it stand at room temperature for 2-4 hours, and then dry it to obtain a light-oxygen dual-transfer membrane.

[0050] It should be noted that the polydimethylsiloxane (PDMS) used in this application is typically used in conjunction with a compatible curing agent, and methods described in existing literature can be referenced. For ease of operation, it can also be purchased commercially available, such as the Xinwei two-component kit, which includes PDMS and a curing agent in a 10:1 mixing ratio, and the Dow Corning SYLGARD DC184 two-component kit, which includes PDMS and a curing agent in a 10:1 mixing ratio, also available commercially.

[0051] In the method of this embodiment of the invention, non-limiting examples include:

[0052] In step (1), the temperature can be 60℃, 65℃, 70℃, 75℃, 80℃, etc., and the stirring time can be 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, etc.

[0053] In step (2), the temperature can be 20℃, 22℃, 23℃, 24℃, 25℃, etc.

[0054] In step (4), the room temperature placement time can be 2 hours, 2.2 hours, 3 hours, 3.5 hours, 4 hours, etc.

[0055] Preferably, the organic solvent is DMAC (N,N-dimethylacetamide).

[0056] In some embodiments, the porogen is one or more of polyvinylpyrrolidone, lithium chloride, and zinc chloride; non-limiting examples include: the porogen is a combination of polyvinylpyrrolidone, lithium chloride, zinc chloride, a combination of polyvinylpyrrolidone and lithium chloride, a combination of polyvinylpyrrolidone and zinc chloride, a combination of lithium chloride and zinc chloride, or a combination of polyvinylpyrrolidone, lithium chloride, and zinc chloride; more preferably, the porogen is lithium chloride.

[0057] In some embodiments, when the porogen is polyvinylpyrrolidone, the mass percentages of PVDF, organic solvent, and porogen in step (1) are: PVDF 12%-14%, polyvinylpyrrolidone 3%-12%, and the remainder being organic solvent. Non-limiting examples include: PVDF can be 12%, 12.5%, 13%, 13.5%, 14%, etc., and polyvinylpyrrolidone porogen can be 3%, 5%, 6%, 8%, 12%, etc., with the remainder being organic solvent.

[0058] In some embodiments, when the porogen is lithium chloride, the mass percentages of PVDF, organic solvent, and porogen in step (1) are: PVDF 12%-14%, lithium chloride 0.4%-5%, and the remainder organic solvent. Non-limiting examples include: PVDF can be 12%, 12.5%, 13%, 13.5%, 14%, etc., and lithium chloride 0.4%, 1%, 2%, 3%, 4%, 5%, etc., with the remainder organic solvent.

[0059] In some embodiments, when the porogen is zinc chloride, the mass percentages of PVDF, organic solvent, and porogen in step (1) are: PVDF 12%-14%, zinc chloride 0.5%-1%, and the remainder organic solvent. Non-limiting examples include: PVDF can be 12%, 12.5%, 13%, 13.5%, 14%, etc., and zinc chloride 0.5%, 0.6%, 0.8%, 0.9%, 1%, etc., with the remainder organic solvent.

[0060] In some embodiments, in step (3), the coating thickness is 300 μm.

[0061] In some embodiments, in step (3), rinsing involves soaking in deionized water at a temperature of 20-25°C until a film forms. Non-limiting examples include temperatures of 20°C, 22°C, 23°C, 24°C, 25°C, etc.

[0062] In some embodiments, in step (3), the drying temperature is 30-40°C and the drying time is 30-60 min. In some embodiments, the drying can be carried out in a forced-air drying oven. Non-limiting examples include: the drying temperature can be 30°C, 32°C, 35°C, 38°C, 40°C, etc., and the drying time can be 30 min, 35 min, 45 min, 50 min, 60 min, etc.

[0063] In some embodiments, in step (4), the amount of coating applied is 17-25 mg / cm³. 2 Non-limiting examples include: coating amounts of up to 17 mg / cm³. 2 18.5 mg / cm 2 20mg / cm 2 22mg / cm 2 25mg / cm 2 etc.

[0064] In some embodiments, in step (4), the drying temperature is 60-65°C and the drying time is 4-6 hours; in some embodiments, the drying can be carried out in a forced-air drying oven. Non-limiting examples include: the drying temperature can be 60°C, 61°C, 62°C, 64°C, 65°C, etc., and the drying time can be 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, etc.

[0065] This invention also provides a light-oxygen dual-transfer membrane prepared by the above method, wherein the light-oxygen dual-transfer membrane is processed into a flat plate and has a thickness of 400-500 μm. Non-limiting examples include membrane thicknesses of 400 μm, 420 μm, 450 μm, 480 μm, 500 μm, etc.

[0066] This invention also provides applications of the aforementioned light-oxygen dual-transfer membrane in scenarios requiring both light irradiation and gas transport. As an example, it can be used in algae-bacterial symbiotic systems.

[0067] In the embodiments and comparative examples of this invention, the product source is:

[0068] PVDF, purchased from Solvay, France, model: Solef6010.

[0069] PDMS and curing agent: Dow Corning SYLGARD DC184 two-component kit, which includes PDMS and curing agent in a 10:1 mixing ratio, is a commercially available product.

[0070] In this invention:

[0071] Scanning electron microscope (SEM)

[0072] Scanning electron microscopy (SEM) is mainly used to characterize the morphology of light-oxygen dual-transmission films, as well as their morphology and compactness. The SEM used in this paper is a Regulus 8100 from Hitachi, Japan. Before sample testing, to preserve the true structure of the sample, the film sample was quenched in liquid nitrogen during cross-sectional sample preparation. The sample was then sputter-coated with gold to enhance its conductivity.

[0073] Energy-dispersive X-ray spectroscopy (EDX)

[0074] Energy-dispersive X-ray spectroscopy (EDS) is mainly used to analyze the relative abundance and distribution of elements in light-oxygen dual-transfer membranes. The EDS used in this paper is an Ultim Max 65 from Oxford, UK, which is attached to a scanning electron microscope. Before testing, the sample needs to be sputter-coated with gold and then fixed to the sample tray using conductive adhesive. The operating voltage is 20 kV.

[0075] The following are specific embodiments and comparative examples of the present invention. It should be further noted that the schemes in the comparative examples are not prior art, but are only set up for comparison with the schemes in the embodiments, and are not intended to limit the present invention.

[0076] Example 1

[0077] A method for preparing a light-oxygen dual-transfer membrane includes the following steps:

[0078] 12wt% PVDF, 85wt% DMAC and 3wt% polyvinylpyrrolidone were added sequentially to a mixing tank and stirred for 7 hours at 70℃. The mixture was then degassed under negative pressure to obtain the PVDF casting solution.

[0079] 10g PDMS and 1g curing agent were added to a mixing tank and stirred until homogeneous at 25℃. After standing to remove bubbles, PDMS casting solution was obtained.

[0080] PVDF casting solution was coated onto a glass plate to a thickness of 300 μm. The plate was then immersed in a deionized water bath at 20°C until film formation (approximately 1-2 minutes), followed by rinsing to remove organic solvents and pore-forming agents. The film was then dried in a forced-air drying oven at 35°C for 1 hour to obtain the initial membrane.

[0081] The PDMS casting solution was applied to the reverse side of the initial membrane at a concentration of 24.2 mg / cm². 2 After being placed at room temperature for 4 hours, the film was placed in a forced-air drying oven and dried at 60°C for 4 hours to obtain a light-oxygen dual-transmission membrane with a thickness of approximately 450 μm.

[0082] Example 2

[0083] A method for preparing a light-oxygen dual-transfer membrane includes the following steps:

[0084] 12wt% PVDF, 87.6wt% DMAC and 0.4wt% lithium chloride were added sequentially to a stirred tank and stirred for 7 hours at 60℃. The mixture was then degassed under negative pressure to obtain the PVDF casting solution.

[0085] 10g of PDMS and 1g of curing agent were added to a mixing tank and stirred until homogeneous at 25℃. The mixture was then allowed to stand to remove bubbles, thus obtaining the PDMS casting solution.

[0086] The PVDF casting solution was coated onto a glass plate to a thickness of 300 μm. It was then immersed in a deionized water bath at 20°C until film formation, followed by rinsing to remove organic solvents and pore-forming agents. Finally, it was dried in a forced-air drying oven at 35°C for 1 hour.

[0087] The initial membrane was obtained;

[0088] The PDMS casting solution was applied to the reverse side of the initial membrane at a concentration of 17.1 mg / cm². 2 After being placed at room temperature for 2 hours, the film was placed in a forced-air drying oven and dried at 60°C for 6 hours to obtain a light-oxygen dual-transmission membrane with a thickness of approximately 450 μm.

[0089] Example 3

[0090] A method for preparing a light-oxygen dual-transfer membrane includes the following steps:

[0091] 12wt% PVDF, 87wt% DMAC and 1wt% zinc chloride were added to a mixing tank in sequence and stirred at 60℃ for 7 hours. The mixture was then degassed under negative pressure to obtain the PVDF casting solution.

[0092] 10g of PDMS and 1g of curing agent were added to a mixing tank and stirred until homogeneous at 25℃. The mixture was then allowed to stand to remove bubbles, thus obtaining the PDMS casting solution.

[0093] PVDF casting solution was coated onto a glass plate to a thickness of 300 μm. The plate was then immersed in a deionized water bath at 20°C until film formation, followed by rinsing to remove organic solvents and pore-forming agents. The film was then dried in a forced-air drying oven at 35°C for 1 hour to obtain the initial film.

[0094] The PDMS casting solution was applied to the reverse side of the initial membrane at a concentration of 17.8 mg / cm². 2 After being placed at room temperature for 2 hours, the film was placed in a forced-air drying oven and dried at 60°C for 6 hours to obtain a light-oxygen dual-transmission membrane with a thickness of approximately 450 μm.

[0095] Example 4

[0096] The difference from Example 2 is that the ratio of PVDF, DMAC, and lithium chloride is 14 wt%, 85 wt% DMAC, and 1 wt% lithium chloride. Everything else is the same as in Example 2.

[0097] Example 5

[0098] The difference from Example 4 is that the PDMS casting solution was applied to the reverse side of the initial film and left at room temperature for 3 hours. Everything else is the same as in Example 4.

[0099] Comparative Example 1

[0100] A method for preparing a light-oxygen dual-transfer membrane includes the following steps:

[0101] 12wt% PVDF, 87.6wt% DMAC and 0.4wt% lithium chloride were added sequentially to a stirred tank and stirred for 7 hours at 60℃. The mixture was then degassed under negative pressure to obtain the PVDF casting solution.

[0102] 10g of PDMS and 1g of curing agent were added to a mixing tank and stirred until homogeneous at 25℃. The mixture was then allowed to stand to remove bubbles, thus obtaining the PDMS casting solution.

[0103] PVDF casting solution was coated onto a glass plate to a thickness of 300 μm. The plate was then immersed in a deionized water bath at 20°C until film formation, followed by rinsing to remove organic solvents and pore-forming agents. The film was then dried in a forced-air drying oven at 35°C for 1 hour to obtain the initial film.

[0104] Apply PDMS casting solution to the front side of the initial membrane at a concentration of 17 mg / cm². 2 After being placed at room temperature for 2 hours, the film was placed in a forced-air drying oven and dried at 60°C for 6 hours to obtain a light-oxygen dual-transmission membrane with a thickness of approximately 450 μm.

[0105] Comparative Example 2

[0106] The difference from Example 2 is that the PDMS casting solution was applied to the reverse side of the initial film and left at room temperature for 2 minutes. Everything else is the same as in Example 2.

[0107] Comparative Example 3

[0108] The difference from Example 2 is that the PDMS casting solution was applied to the reverse side of the initial film and left at room temperature for 10 minutes. Everything else is the same as in Example 2.

[0109] Comparative Example 4

[0110] The difference from Example 2 is that the PDMS casting solution was applied to the reverse side of the initial film and left at room temperature for 30 minutes. Everything else is the same as in Example 2.

[0111] Comparative Example 5

[0112] The difference from Example 2 is that the PDMS casting solution was applied to the reverse side of the initial film and left at room temperature for 60 minutes. Everything else is the same as in Example 2.

[0113] Comparative Example 6

[0114] A method for preparing a light-oxygen dual-transfer membrane includes the following steps:

[0115] 15wt% PVDF, 83.5wt% DMAC and 1.5wt% lithium chloride were added sequentially to a stirred tank and stirred at 60℃ for 4 hours. The mixture was then degassed under negative pressure and allowed to stand at room temperature to obtain PVDF casting solution 1.

[0116] Add 1.5g of PDMS to 4.5g of PVDF casting solution 1 and stir in a mixing tank. After stirring at 25℃ for 4 hours, add 0.15g of curing agent and stir at 25℃ for 0.5 hours. Degas under negative pressure to obtain casting solution 2.

[0117] The casting solution 2 was coated onto a glass plate to a thickness of 300 μm. After being placed on the glass plate for 40 seconds, the plate was immersed in a cleaning bath of deionized water at 20°C until film formation. The organic solvent was then rinsed off to obtain a light-oxygen dual-transmission membrane, which was then dried before use.

[0118] The above-mentioned light-oxygen dual-transfer membrane products were tested, and the test results are shown in Table 1.

[0119] ① Oxygen transfer rate test method: Follow the "Test Method for Oxygenation Performance of Chemical Deoxygenation Aerators in Clear Water"

[0120] The oxygen mass transfer coefficient (K) of the aeration membrane is calculated using the method (DB37 / T 2667-2015). La ), oxygen transfer rate (OTR).

[0121] Oxygen total transfer coefficient K LaT Calculation formula:

[0122] ln(C S,T -C)=lnC-K LaT ×t...............................(1)

[0123] In the formula:

[0124] K LaT —Total oxygen transfer coefficient of the aerator in a clear water experiment at test water temperature, h -1 ;

[0125] C S,T —Oxygen saturation, mg / L;

[0126] C—Dissolved oxygen concentration in water at time t during aeration, mg / L;

[0127] t — any moment during the aeration test, h.

[0128] Calculate the standard oxygen total transfer factor k La(20) formula:

[0129] k La(20) =K La(T) / 1.024 (T-20) ...............................(2)

[0130] In the formula K La(T) —Total oxygen transfer coefficient at water temperature T, h -1 ;

[0131] K La(20) —Total oxygen transfer coefficient at a water temperature of 20℃, h -1 ;

[0132] T—Design temperature, °C;

[0133] The dissolved oxygen saturation C in the water experiment measured at T℃ S,T Convert to C S,20 The oxygen saturation value can be calculated using the standard oxygen saturation value and the actual atmospheric pressure P, as shown in the following formula:

[0134]

[0135] In the formula: C S,20 —Dissolved oxygen saturation concentration in water at 20℃, mg / L;

[0136] C S,T —Oxygen saturation, mg / L;

[0137] C S,S,20 —Standard dissolved oxygen saturation concentration at 20℃, mg / L, see Appendix B;

[0138] C S,S,T —Standard oxygen saturation, mg / L, see Appendix B;

[0139] 0.1013 — Standard atmospheric pressure, MPa;

[0140] P — Actual atmospheric pressure during the test, MPa.

[0141] Formula for calculating the standard oxygen transfer rate (SOTR):

[0142]

[0143] In the formula:

[0144] SOTR—Standard oxygen transfer rate, kg / h;

[0145] k La20 —The total oxygen transfer coefficient (h) of the aerator in the clear water experiment under standard test conditions. -1 ;

[0146] C S,20 —Dissolved oxygen saturation concentration in water at 20℃, mg / L;

[0147] V — The volume of water in the test tank, in meters. 3 .

[0148] ② Test methods for light transmittance and haze

[0149] "Determination of light transmittance and haze of transparent plastics" (GB / T2410-2008)

[0150] Standard Test Methods for Haze and Transmittance of Transparent Plastics (D1003-13)

[0151] The optical properties of the membranes—transmittance and haze—were characterized using a UV-Vis spectrophotometer. The spectrophotometer's light source wavelength range was set to 400-800 nm, and membrane samples of uniform thickness were used to eliminate the influence of sample thickness on transmittance and haze data. Membrane samples were cut to the same size, fixed on a special test film sample holder, and placed in a UV-Vis spectrophotometer equipped with an integrating sphere for testing. Transmittance and haze were calculated using the following formulas.

[0152]

[0153]

[0154] In the formula: T1 is the incident light flux; T2 is the total transmitted light flux through the sample; T3 is the instrument scattered light flux; T4 is the scattered light flux of the instrument and the sample.

[0155] Table 1

[0156] Example 1 <![CDATA[10.10g / m 2 ·h]]> 85％ Example 2 <![CDATA[6.85g / m 2 ·h]]> 81％ Example 3 <![CDATA[3.21g / m 2 ·h]]> 85％ Example 4 <![CDATA[4.08g / m 2 ·h]]> 97％ Example 5 <![CDATA[4.17g / m 2 ·h]]> 91％ Comparative Example 1 <![CDATA[3.13g / m 2 ·h]]> 15％ Comparative Example 2 - 18％ Comparative Example 3 - 27％ Comparative Example 4 - 39％ Comparative Example 5 - 57％ Comparative Example 6 - 16％

[0157] As can be seen from the oxygen transfer rate and transmittance data of Examples 1-5 and Comparative Examples 1-6 in Table 1, the preparation method provided by the present invention is simple and the light-oxygen dual-transfer membrane prepared has high oxygen permeability and high transmittance.

[0158] Figure 2 Electron micrograph of the light-oxygen dual-transfer membrane prepared in Example 5; from Figure 2 As can be seen in (a), a stable and dense structure is formed on the film surface, and it is relatively flat. Figure 2(b) shows the cross-section of the light-oxygen dual-transmission membrane. As can be seen from the figure, PDMS is uniformly coated on the PVDF membrane, forming a dense layer (PDMS layer) with a thickness of about 150 μm. Figure 2 In the middle (c), the distribution of Si element in the cross section of the light-oxygen dual-transmission membrane is shown. It can be seen from the figure that Si element has been uniformly penetrated into the PVDF membrane.

[0159] Figure 3 Figure 1 shows the appearance of the light-oxygen dual-transfer membranes in Examples 1 to 5 and the transmittance of the corresponding samples. Figure (a) shows the appearance and transparency of the light-oxygen dual-transfer membrane; (b) shows the transmittance of the corresponding sample; (c) shows the transmittance data of the corresponding sample; (d) shows the illuminance data of the corresponding sample. Figure (e) shows the test method in (b). Figure 3 As can be seen from the light transmittance of the membrane in the embodiment, PVP, lithium chloride, and zinc chloride are used as pore-forming agents in the embodiment, which can all enable the filler PDMS to penetrate well into the membrane pores. The light transmittance of the light-oxygen dual-transmission membrane can reach more than 80%. An LED lamp with an illuminance of 6500 Lux can still achieve an illuminance of more than 3500 Lux after passing through the membrane.

[0160] Figure 4 The appearance of the light-oxygen dual-transfer membranes in Comparative Examples 1 to 6 and the transmittance of the corresponding samples are shown, where (a) shows the appearance and transparency of the light-oxygen dual-transfer membranes; and (b) shows the transmittance data of the corresponding samples. Figure 4 It can be seen that a short settling time after coating has a significant impact on the film's transmittance. Coating the film on the front side, applying too little coating time, and blending methods all fail to improve the film's transmittance.

[0161] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0162] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a light-oxygen dual-transmission membrane, characterized in that, Includes the following steps: (1) Add PVDF, organic solvent and pore-forming agent into a container in sequence, stir at 60℃-80℃ for 5-7 hours, degas under negative pressure to obtain PVDF casting solution; (2) Add PDMS and curing agent into the container in sequence, stir evenly at 20-25℃, let stand to remove bubbles, and obtain PDMS casting solution; (3) The PVDF casting solution is scraped onto a glass plate, then rinsed in a cleaning tank and dried to obtain the initial film; (4) Apply PDMS casting solution to the reverse side of the initial membrane, let it stand at room temperature for 2-4 hours, and then dry it at 60-65℃ for 4-6 hours to obtain a light-oxygen dual-transmission membrane; The pore-forming agent is one of polyvinylpyrrolidone, lithium chloride, and zinc chloride; When the porogen is polyvinylpyrrolidone, the mass percentages of PVDF, organic solvent and porogen in step (1) are: PVDF 12%-14%, polyvinylpyrrolidone 3%-12% and the remainder is organic solvent; When the porogen is lithium chloride, the mass percentages of PVDF, organic solvent and porogen in step (1) are: PVDF 12%-14%, lithium chloride 0.4%-5% and the remainder is organic solvent; When the porogen is zinc chloride, the mass percentages of PVDF, organic solvent and porogen in step (1) are: PVDF 12%-14%, zinc chloride 0.5%-1%, and the remainder is organic solvent; In step (3), the coating thickness is 300 μm; In step (4), the amount of coating applied is 17-25 mg / cm². 2 ; The light-oxygen dual-transmission membranes all have a light transmittance of over 80%; an LED lamp with an illuminance of 6500 Lux achieves an illuminance of over 3500 Lux after passing through the membrane.

2. The method for preparing a light-oxygen dual-transmission membrane according to claim 1, characterized in that, The organic solvent is DMAC.

3. The method for preparing a light-oxygen dual-transfer membrane according to claim 1, characterized in that, The pore-forming agent is lithium chloride.

4. The method for preparing a light-oxygen dual-transmission membrane according to claim 1, characterized in that, In step (3), rinsing involves soaking in deionized water at a temperature of 20-25℃ until a film is formed; And / or, in step (3), the drying temperature is 30-40°C and the time is 30-60 min.

5. A light-oxygen dual-transfer membrane, characterized in that, The light-oxygen dual-transfer membrane is prepared by the preparation method according to any one of claims 1-4.

6. The application of the light-oxygen dual-transfer membrane according to claim 5 in scenarios requiring light irradiation and gas transport.

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