Three-dimensional porous mycelium membrane and preparation method of three-dimensional porous mycelium membrane

Abstract

The invention provides a three-dimensional porous mycelium membrane and a preparation method of the three-dimensional porous mycelium membrane, and belongs to the field of membrane materials. The preparation method comprises the following steps: culturing ganoderma lucidum hyphae by taking a Sabourald glucose agar culture medium as a nutrient source and a birch plate as a carrier, so that the ganoderma lucidum hyphae grow on the birch plate to form an initial hypha membrane with a three-dimensional porous grid structure; performing alkaline treatment on the initial hypha membrane to convert chitin in the initial hypha membrane into chitosan to obtain an intermediate membrane; soaking the intermediate membrane in a mixed solution composed of a PEI solution and a TA solution to react for a first specified duration, and adjusting the pH value of the mixed solution to 2-4 after the reaction is finished; and adjusting the pH value of the mixed solution to 6-7, and continuously soaking the intermediate membrane in the mixed solution for a second specified duration to obtain the three-dimensional porous mycelium membrane. The preparation method provided by the invention is simple in preparation process and low in cost, and the hydrophilic and oleophobic three-dimensional porous mycelium membrane with excellent performance can be prepared.

Description

Technical Field

[0001] The present application relates to the technical field of membrane materials, and particularly relates to a three-dimensional porous mycelium membrane and a preparation method thereof. Background Art

[0002] In the field of water treatment technology, the membrane separation process plays a crucial role, and it plays a key role in purifying water quality and separating different substances.

[0003] Currently, technologies such as electrospinning, freeze-drying, and 3D printing are commonly used means for preparing porous membranes. The electrospinning technology can precisely control the porous structure of the membrane material through one-step or coaxial methods, etc., and is widely used in the synthesis of membranes for water treatment; the freeze-drying technology can be used to prepare hydrophilic pulp cellulose-based membranes, etc., and has its unique advantages in the preparation of membrane materials; the 3D printing technology uses materials such as nano-graphene oxide to manufacture membranes with specific properties, and has also made certain progress in the field of membrane material preparation.

[0004] However, these commonly used technologies usually require the use of organic solvents, which not only increases the preparation cost, but also may cause secondary pollution problems such as environmental pollution. Secondly, these technologies often rely on complex instrument equipment and have strict requirements for operating conditions, further increasing the difficulty and cost of preparation. Therefore, it is of great significance to develop a simple and low-cost preparation method for such porous membranes and apply them to the field of oil-water separation. Summary of the Invention

[0005] In view of this, the present application provides a three-dimensional porous mycelium membrane and a preparation method thereof, which can provide a hydrophilic and oleophobic three-dimensional porous mycelium membrane with a simple preparation process, low cost, and excellent performance.

[0006] Specifically, the present application is realized through the following technical solutions:

[0007] The first aspect of the present application provides a preparation method for a three-dimensional porous mycelium membrane, and the method includes:

[0008] Using Sabouraud dextrose agar medium as a nutrient source and a birch board as a carrier to culture Ganoderma lucidum mycelium, so that the Ganoderma lucidum mycelium grows into an initial mycelium membrane with a three-dimensional porous grid structure on the birch board;

[0009] Performing alkaline treatment on the initial mycelium membrane to convert chitin in the initial mycelium membrane into chitosan, obtaining an intermediate membrane;

[0010] Soaking the intermediate membrane in a mixed solution composed of a PEI solution and a TA solution for a first specified period of time, and after the reaction ends, adjusting the pH value of the mixed solution to 2-4;

[0011] Adjust the pH value of the mixed solution to 6 - 7, and continue to immerse the intermediate membrane in the mixed solution for a second specified duration to obtain the three-dimensional porous mycelial membrane.

[0012] The second aspect of the present application provides a three-dimensional porous mycelial membrane, which is prepared based on the preparation method of the three-dimensional porous mycelial membrane.

[0013] The third aspect of the present application provides an application of the three-dimensional porous mycelial membrane, which is applied to the fields of water purification, water-in-oil emulsion separation, and oil-water mixture separation.

[0014] The three-dimensional porous mycelial membrane and the preparation method of the three-dimensional porous mycelial membrane provided by the present application use Sabouraud dextrose agar medium and birch wood board as the nutrient source and carrier for the growth of Ganoderma lucidum mycelium. These materials are widely sourced and inexpensive. Sabouraud dextrose agar medium is a common microbial medium, and birch wood board is also easily obtainable, reducing the production cost. At the same time, they are natural materials, which are more environmentally friendly than the organic solvents and complex instruments used in the preparation of traditional porous membranes, reducing environmental pollution and potential harm to the human body. And the entire preparation process mainly includes three steps: mycelium culture, alkaline treatment, and roughness modification (roughness modification means immersing the intermediate membrane in a mixed solution composed of a PEI solution and a TA solution for a first specified duration, adjusting the pH value of the mixed solution to 2 - 4 after the reaction, adjusting the pH value of the mixed solution to 6 - 7, and continuing to immerse the intermediate membrane in the mixed solution for a second specified duration). It does not require complex equipment and processes, and the operation is relatively simple. In the mycelium culture stage, using the natural growth characteristics of Ganoderma lucidum mycelium, it self-assembles into a three-dimensional porous structure under suitable conditions; the alkaline treatment and roughness modification treatment steps also have mild conditions and are easy to control, and no harmful chemical substances are introduced, which conforms to the concept of green chemistry and is conducive to large-scale production. In addition, the prepared three-dimensional porous mycelial membrane has a balance of hydrophilicity and underwater oleophobicity, which enables it to perform excellently in the field of oil-water separation; the underwater oil contact angle, membrane flux, and separation efficiency of the three-dimensional porous mycelial membrane remain stable under various different environmental conditions and after multiple cycles, so that the membrane can continuously and stably work in complex actual application scenarios, has a long service life, and reduces the cost and trouble of frequently replacing membrane materials; the membrane has a high removal rate of heavy metal ions in the emulsion, providing a new way to solve the problem of wastewater treatment contaminated by heavy metals. Description of the Drawings

[0015] Figure 1 It is a flowchart of the first embodiment of the preparation method of the three-dimensional porous mycelial membrane provided by the present application; Figure 2Schematic diagram of the results of scanning electron microscope tests on the surfaces and cross-sections of OR-MM, NaOH-MM, and MM@N-PT shown in this application; Figure 3 ATR-FTIR spectra of OR-MM, NaOH-MM, and MM@N-PT; Figure 4 X-ray photoelectron spectra of OR-MM, NaOH-MM, and MM@N-PT; Figure 5 High-resolution C1S, O1S, and N1S spectra of OR-MM; Figure 6 High-resolution C1S, O1S, and N1S spectra of NaOH-MM; Figure 7 High-resolution C1S, O1S, and N1S spectra of MM@N-PT; Figure 8 Separation effect diagrams of water-in-oil emulsions obtained by MM@N-PT with different growth times; Figure 9 Separation effect diagrams of water-in-oil emulsions after MM@N-PT is immersed in NaCl solution (3.5 wt%) for 0–48 h; Figure 10 Underwater oil contact angles of MM@N-PT membrane after being immersed in NaCl solution (3.5 wt%) for 0–48 h; Figure 11 Separation effect diagrams of water-in-oil emulsions after MM@N-PT is immersed in solutions with different pH values for 4 h; Figure 12 Schematic diagram of the cyclic separation of pure water by MM@N-PT; Figure 13 Schematic diagram of the cyclic separation of methyl silicone oil-water mixture by MM@N-PT; Figure 14 Process diagram of MM@N-PT membrane for separating oil-water mixture; Figure 15 Membrane flux and separation efficiency diagrams of MM@N-PT for separating different types of oil-water mixtures; Figure 16 Process diagram of MM@N-PT for separating methylene blue solution; Figure 17 Absorbance spectra of MM@N-PT before and after separating methylene blue solution; Figure 18 Experimental process and microscopic images of the separation of water-in-oil emulsion; Figure 19 Pore size distribution diagram of MM@N-PT; Figure 20It is the diagram of the cyclic separation result of NaOH-MM for the oil-in-water emulsion; Figure 21 It is the diagram of the cyclic separation result of MM@N-PT for the oil-in-water emulsion; Figure 22 It is the diagram of the membrane flux and separation efficiency of MM@N-PT for separating different types of oil-in-water emulsions; Figure 23 It is the particle size distribution diagram of the oil droplets in the oil-in-water emulsion before and after separation; Figure 24 It is the removal efficiency diagram of the NaOH-MM membrane and the MM@N-PT membrane shown in this application for Pb 2+ . Detailed implementation manners

[0016] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation manners described in the following exemplary embodiments do not represent all the implementation manners consistent with this application.

[0017] The terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The singular forms "a", "said", and "the" used in this application are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0018] It should be understood that although the terms first, second, third, etc. may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of this application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "when" or "while" or "in response to determining".

[0019] The following specific examples are given to introduce the technical solutions of this application in detail.

[0020] Example 1

[0021] Figure 1 It is the flowchart of Example 1 of the preparation method of the three-dimensional porous mycelium membrane provided by this application. Please refer to Figure 1 , the method provided in this embodiment may include:

[0022] S101. Use Sabouraud dextrose agar medium as the nutrient source and birch wood board as the carrier to culture Ganoderma lucidum mycelium, so that the Ganoderma lucidum mycelium grows into an initial mycelial membrane on the birch wood board.

[0023] Among them, the pore structure of the birch wood board provides a growth channel for the generation of the Ganoderma lucidum mycelium, and the Ganoderma lucidum mycelium grows along the surface and pores of the birch wood board based on its branching growth and expansion ability; the Ganoderma lucidum mycelium grows and twines on its own on the birch wood board and self-assembles to form an initial mycelial membrane with a three-dimensional porous grid structure.

[0024] It should be noted that Ganoderma lucidum mycelium has a high ability of branching growth and expansion. In the initial stage of growth, the mycelium starts from the inoculation point and rapidly extends to the surrounding surface and pores of the birch wood board. Its branching structure continuously differentiates and expands, and can quickly occupy the available growth space. This branching growth mode enables the mycelium to form a large-area coverage in a short time, increasing the contact area with the nutrient source and the environment. Based on its own growth characteristics, Ganoderma lucidum mycelium grows and twines on its own on the birch wood board and self-assembles. During the growth process, the mycelium will secrete some viscous substances, such as polysaccharides, etc., which help the mycelium to adhere and fix to each other. As the mycelium continues to grow and twine, an initial mycelial membrane with a three-dimensional porous grid structure is gradually formed. This self-assembly process is a natural and orderly biological process, without the need for additional complex process intervention, reflecting the unique advantages of the preparation of biological materials.

[0025] The growth and twining mode of Ganoderma lucidum mycelium determines the three-dimensional porous grid structure of the initial mycelial membrane. The growth of the mycelium on the birch wood board is not evenly spread, but presents a three-dimensional and intertwined state. The gaps between the mycelia form pores of different sizes, and these pores are interconnected to form a three-dimensional porous network. For example, during the growth process, the mycelium will continuously branch and fuse to form a net-like structure, and the size and shape of the pores therein are affected by factors such as the growth rate, branching angle and density of the mycelium. This three-dimensional porous grid structure in subsequent membrane applications, such as for water purification or oil-water separation, the porous structure can provide a large specific surface area, which is conducive to the adsorption and filtration of substances. At the same time, the connectivity of the pores ensures that liquids or gases can be smoothly transported within the membrane, improving the flux and separation efficiency of the membrane.

[0026] It should be noted that before preparing the three-dimensional porous mycelial membrane, first prepare the experimental materials. Specifically, the experimental materials include: D(+) glucose, monohydrate (C6H 12 O6·H2O, AR), potassium dihydrogen phosphate (KH2PO4, AR), magnesium sulfate (MgSO4, AR), sodium hydroxide (NaOH, AR), anhydrous sodium sulfate (Na2SO4, AR), cetyltrimethylammonium bromide (CTAB, AR), methylene blue (MB) purchased from Sinopharm Chemical Reagent Co., Ltd. Cyclohexane (C6H12 ), tetrachloroethylene (C2C l4 ) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Yeast powder was purchased from Beijing Hongrun Baoshun Technology Co., Ltd. Sabouraud dextrose agar medium (SDA) was purchased from Haibo Biotechnology Co., Ltd. Sudan Red III, polyethyleneimine (PEI, M.W. 1800, 99%), and tannic acid (TA, AR) were purchased from Shanghai Macklin Biochemical Co., Ltd. Corn flour, methyl silicone oil, lubricating oil, sunflower seed oil, and vacuum pump oil were obtained from a local supermarket. Birch wood boards and Ganoderma lucidum mycelium mother strains were used, and all chemical products were not further processed.

[0027] Specifically, when implemented, using Sabouraud dextrose agar medium as the nutrient source and birch wood boards as the carrier to culture Ganoderma lucidum mycelium, and enabling the Ganoderma lucidum mycelium to grow into an initial mycelial membrane on the birch wood boards, including: preparing mycelial suspension spores; performing high-temperature and high-pressure sterilization treatment on birch wood boards of specified size, and placing the treated birch wood boards in a petri dish containing sterilized Sabouraud dextrose agar medium; inoculating the mycelial suspension spores onto the edge of the birch wood boards under sterile conditions to obtain a petri dish inoculated with spores; statically culturing the petri dish at 28°C for a specified number of days, and after the end of the culture, tearing off the Ganoderma lucidum mycelial membrane generated on the birch wood boards with tweezers; rinsing the Ganoderma lucidum mycelial membrane with deionized water to obtain the initial mycelial membrane.

[0028] It should be noted that Sabouraud dextrose agar medium (SDA), as the nutrient source, is rich in various nutrients required for the growth of Ganoderma lucidum mycelium, such as carbon sources, nitrogen sources, minerals, and vitamins. It can provide sufficient energy and material basis for the growth of mycelium, ensuring the normal metabolism and proliferation of mycelium. The birch wood board, as the carrier, has unique advantages. On the one hand, the natural pore structure on the surface of the birch wood board provides growth space and physical support for the mycelium. These pores allow the mycelium to penetrate into them and grow along the pore walls, which helps the mycelium form a stable attachment and growth structure. On the other hand, the material properties of the birch wood board have a certain compatibility with the growth of the mycelium and will not inhibit or have an adverse effect on the growth of the mycelium.

[0029] It should be noted that preparing mycelial suspension spores includes: preparing a liquid medium using corn flour, deionized water, glucose, yeast powder, potassium dihydrogen phosphate, and magnesium sulfate; dispensing the liquid medium into conical flasks and performing high-temperature and high-pressure sterilization treatment on the conical flasks; inoculating mycelial slices into the conical flasks in a laminar flow hood; statically culturing the conical flasks inoculated with mycelium for two days, and after the end of the static culture, placing the conical flasks in a constant temperature incubator and continuously culturing for a specified number of days in a culture environment at a first specified temperature and a specified rotation speed to obtain the mycelial suspension spores. Preferably, the first specified temperature here can be 28°C, the specified rotation speed can be 150 rmp, and the specified number of days can be 3 days.

[0030] Specifically, 5 g of corn flour was added to 100 ml of deionized water and heated with continuous stirring. The filtrate was taken out, and then 15 g of glucose, 2.5 g of yeast powder, 1 g of potassium dihydrogen phosphate, and 0.5 g of magnesium sulfate were added, and the volume was made up to 500 ml with deionized water to prepare a liquid medium. Then the liquid medium was stirred thoroughly, and after standing and clarification, the supernatant was taken and dispensed into conical flasks. Then, it was subjected to high-temperature and high-pressure sterilization for 30 min (which can effectively kill the possible contaminants therein and ensure the purity of subsequent culture). On a super-clean workbench, the mother culture tube fungus was cut into mycelium slices of about 0.6×0.6×0.3 cm 3 in size and placed in a conical flask with liquid, and cultured statically for two days to enable the mycelium to initially adapt to the environment and start growing. Then it was placed in a constant-temperature incubator and cultured for 3 days at 28°C and 150 rpm. By controlling the temperature and rotation speed, suitable temperature, humidity, and oxygen conditions were provided for the growth of the mycelium, promoting the rapid growth and reproduction of the mycelium, and finally forming mycelium suspension spores.

[0031] The birch wood board was cut into 4×5×0.3 cm 3 in size, and then subjected to high-temperature and high-pressure sterilization for 30 min to completely kill the microorganisms that may be carried on the surface and inside of the birch wood board and prevent them from contaminating the Ganoderma lucidum mycelium culture. The treated birch wood board was placed in a petri dish containing sterilized SDA medium, so that the birch wood board could fully absorb the nutrients in the medium, and at the same time provide a stable support and nutrient supply interface for the growth of the mycelium. Then, under sterile conditions, the mycelium suspension spores were inoculated on the edge of the birch wood board (adding a small amount of liquid culture medium can promote the faster growth of the mycelium). After that, the above-mentioned petri dish inoculated with spores was statically cultured at 28°C for about 6 days. Finally, the Ganoderma lucidum mycelium membrane growing on the birch wood board was gently torn off with forceps and rinsed once with deionized water to obtain the initial mycelium membrane. The obtained sample was named OR-MM.

[0032] S102. Alkaline treatment was performed on the initial mycelium membrane to convert chitin in the initial mycelium membrane into chitosan, obtaining an intermediate membrane.

[0033] It should be noted that alkaline treatment of the initial mycelium membrane to convert chitin in the initial mycelium membrane into chitosan to obtain an intermediate membrane includes: putting the initial mycelium membrane into a NaOH solution and treating it at a second specified temperature for a specified duration; after alkaline treatment, washing the surface of the treated initial mycelium membrane with deionized water to remove NaOH to obtain an intermediate membrane, where the intermediate membrane is named NaOH-MM. Preferably, the second specified temperature here is 40°C and the specified duration is 2 hours.

[0034] It should be noted that in the initial mycelial membrane (OR-MM), chitin is an important component. Chitin undergoes a chemical reaction under alkaline conditions. The acetyl group (–COCH3) in its molecular structure reacts with hydroxide ions (OH - ) in the NaOH solution. Specifically, in a 1M NaOH solution, OH - attacks the acetyl group in the chitin molecule, causing it to undergo a hydrolysis reaction. After removing the acetyl group, an amino group (-NH2) is generated, thereby partially converting chitin into chitosan. This transformation not only changes the chemical composition of the membrane but also has an important impact on the properties of the membrane. Chitosan has better hydrophilicity than chitin because more hydrophilic groups (such as amino and hydroxyl groups) are added to its molecular structure, significantly enhancing the hydrophilicity of the membrane and making it more conducive to subsequent applications in water purification and other aspects.

[0035] The concentration of 1M NaOH solution is obtained through experimental optimization. A lower concentration of NaOH solution may not effectively cause sufficient deacetylation of chitin, resulting in incomplete conversion and affecting the performance of the final membrane. While a too-high concentration of NaOH solution may cause excessive damage to the overall structure of the mycelial membrane, reducing the mechanical strength and integrity of the membrane.

[0036] At a treatment temperature of 40°C, the chemical reaction rate is moderate, which can not only ensure the smooth conversion of chitin to chitosan but also prevent other unnecessary side reactions or accelerate the degradation of the membrane due to excessive temperature. At the same time, the treatment time of 2 hours is determined based on a comprehensive consideration of conversion efficiency and production efficiency. If the time is too short, the conversion of chitin is insufficient; if the time is too long, it may increase production costs and potential risks to the membrane structure.

[0037] In addition, after alkaline treatment, it is an essential step to wash the surface of the treated initial mycelial membrane with deionized water to remove the NaOH. Residual NaOH may affect subsequent treatment steps and the performance of the membrane. For example, when subsequently mixed and treated with PEI solution and TA solution, the residual NaOH may change the pH value of the solution, thereby affecting the reaction between PEI and TA and their binding effect with the membrane surface. In addition, the residual NaOH may gradually seep out during the use of the membrane, causing pollution to the treated liquid environment or affecting the stability of the membrane. By thorough washing, a pure intermediate membrane (NaOH-MM) can be obtained, providing a good basis for subsequent modification treatment.

[0038] S103. Immerse the intermediate membrane in a mixed solution composed of a PEI solution and a TA solution and react for a first specified duration. After the reaction ends, adjust the pH value of the mixed solution to 2 - 4.

[0039] It should be noted that polyethyleneimine (PEI) is a polymer material containing a large number of amino functional groups, and tannic acid (TA) has a polyphenol structure. When the PEI solution is mixed with the TA solution, an electrostatic attraction occurs between the positive charges of PEI and the negative charges of TA, and there is also an interaction of hydrogen bonds, thus self-assembling to form PT nanoparticles. These nanoparticles can adhere to the surface of the intermediate membrane (NaOH-MM) treated with alkali, increasing the surface roughness of the membrane. The increased surface roughness can effectively increase the specific surface area of the membrane, thereby improving the filtration efficiency and separation performance of the membrane. For example, during the separation of water-in-oil emulsions, the rough surface can better capture and retain oil droplets, promoting the rapid passage of the water phase and increasing the separation flux.

[0040] The selection of mixing a 2 mg / ml PEI solution with a 1.5 mg / ml TA solution is determined through experimental optimization. The appropriate concentration ratio can ensure the formation of an appropriate amount of PT nano-complexes, enabling them to effectively adhere to the membrane surface for roughness modification without affecting the overall performance of the membrane due to excessive or too low concentration. If the concentration of PEI or TA is too high, it may lead to excessive aggregation of nano-complexes or the formation of an uneven coating on the membrane surface, affecting the stability and permeability of the membrane; conversely, if the concentration is too low, the expected roughness modification effect and functional improvement may not be achieved.

[0041] The intermediate membrane is immersed in the mixed solution and reacted for 25 minutes (the first specified duration). This time is to ensure that PEI and TA have sufficient time to interact and form a stable nano-complex attachment layer on the membrane surface. During the reaction, the pH value of the mixed solution is adjusted to 2 - 4 with hydrochloric acid (preferably, the pH value can be 3). At this time, the acidic environment is conducive to promoting the electrostatic complexation reaction between PEI and TA, accelerating the formation of nanoparticles (in an acidic environment, the electrostatic attraction between the positive charges of PEI and the negative charges of TA is enhanced, promoting the self-assembly formation of PT nanoparticles). At the same time, the appropriate acidic conditions help the nanoparticles better adhere to the surface of the intermediate membrane, increasing the surface roughness of the membrane.

[0042] It should also be noted that after the intermediate membrane is immersed in the PEI and TA mixed solution and reacted for 25 minutes, the pH value is adjusted with hydrochloric acid, and an effective reaction can be achieved within the pH value adjustment range of 2 - 4. When the pH value is lower than 2, the acidity of the solution is too strong, which may cause changes in the structures of PEI and TA, affecting the formation and attachment of nanoparticles; when the pH value is higher than 4, the rate of the electrostatic complexation reaction will decrease, which is not conducive to the self-assembly of nanoparticles and their attachment to the membrane surface. In this application, the pH value is selected to be adjusted to 3, at which time the electrostatic complexation reaction between PEI and TA can be better promoted, accelerating the formation of nanoparticles.

[0043] S104. Adjust the pH value of the mixed solution to 6 - 7, and continue to soak the intermediate membrane in the mixed solution for a second specified period of time to obtain the three-dimensional porous mycelium membrane.

[0044] It should be noted that NaOH can be used to adjust the pH value of the mixed solution to 6.5. This step is to neutralize the acidic environment, make the chemical environment on the membrane surface more stable, and also help to further stabilize and solidify the NaOH-MM network structure. Continuing to soak the intermediate membrane for 30 minutes (the second specified period of time) under the condition of pH 6.5 can make the nanocomplex adhere more firmly to the membrane surface, enhance the durability and stability of the membrane, and finally obtain a three-dimensional porous mycelium membrane (MM@N-PT) with excellent performance.

[0045] It should also be noted that when using NaOH to adjust the pH value of the mixed solution to about 6.5 for subsequent soaking, in fact, a good membrane performance optimization effect can be achieved within the range of 6 - 7 for this pH value. When the pH value is lower than 6, the chemical environment on the membrane surface is not stable enough, and the binding between PT nanoparticles and the membrane surface is not firm enough; when the pH value is higher than 7, it may cause changes in the charge distribution on the membrane surface, affecting the balance of hydrophilicity and underwater oleophobicity of the membrane. In this application, when the pH value is determined to be 6.5, the nanocomplex can adhere more firmly to the membrane surface, enhancing the stability of the membrane.

[0046] It should also be noted that during the pH adjustment process, when using the PEI solution and the TA solution to perform the roughness modification treatment on the intermediate membrane, the specific timing of pH adjustment is as follows: After the intermediate membrane is immersed in the mixed solution (a mixture of 2 mg / ml PEI solution and 1.5 mg / ml TA solution) and reacts for 25 minutes, at this time, start to adjust the pH value of the mixed solution to 3 with hydrochloric acid; after completing this adjustment, immediately adjust the pH value of the mixed solution to 6.5 with NaOH, and then continue to soak the intermediate membrane in this mixed solution for 30 minutes, thereby completing the entire roughness modification treatment process to obtain the three-dimensional porous mycelium membrane (MM@N-PT). Such a clear operation timing can ensure the accuracy and repeatability of the pH adjustment process, and guarantee the preparation of a three-dimensional porous mycelium membrane with stable performance.

[0047] It should also be noted that the hydrophilicity and underwater oleophobicity of the three-dimensional porous mycelium membrane reach an equilibrium, and the underwater oil contact angle, membrane flux, and separation efficiency of the three-dimensional porous mycelium membrane remain stable under various different environmental conditions and after multiple cycles. Among them, water droplets can quickly infiltrate into the three-dimensional porous mycelium membrane within 1 second, and the underwater oil contact angle of the three-dimensional porous mycelium membrane is greater than 150°; the underwater oil contact angle of the three-dimensional porous mycelium membrane is greater than 150°C under various different environmental conditions and after multiple cycles, and the membrane flux of the three-dimensional porous mycelium membrane is greater than 300Lm -2 h -1 , and the separation efficiency of the three-dimensional porous mycelium membrane is greater than 99% under various different environmental conditions and after multiple cycles. Moreover, the removal rate of heavy metal ions in the emulsion by the three-dimensional porous mycelium membrane is greater than 70%.

[0048] Next, a series of analytical tests were carried out on the samples (such as OR-MM, NaOH-MM, MM@N-PT, etc.) prepared by the preparation method of the three-dimensional porous mycelium membrane to understand their physical and chemical properties. The specific measurement methods and measuring instruments used are as follows:

[0049] Scanning electron microscope (SEM): The surface morphology of the samples was observed using ZEISSSigma300 (Germany). Through SEM, the microscopic structure of the mycelium membrane at different preparation stages can be intuitively seen, such as the entangled filament network membrane formed by Ganoderma lucidum mycelium on the birch wood board matrix in OR-MM, the retention of the microscopic network structure after alkaline treatment of NaOH-MM, and the nanoparticles attached due to chemical treatment on MM@N-PT, etc., which helps to analyze the structural characteristics and changes of the membrane.

[0050] Fourier transform infrared spectroscopy (FTIR): ThermoFisherScientificNicoletiS20 (USA) was used to detect the functional groups of the samples. By analyzing the position and intensity changes of different absorption peaks in the FTIR spectrum, the presence of components such as chitin, chitosan, and PT nanoparticles in the samples and the changes in their chemical structures can be determined, such as the -OH stretching vibration of some polysaccharide fragments of chitin and chitosan, and the appearance of new absorption peaks caused by the attachment of PT nanoparticles, etc., providing a basis for studying the interactions between different components.

[0051] X-ray photoelectron spectroscopy (XPS): The surface chemical composition of the samples was tested using a Thermo Scientific K-Alpha (USA). X-ray photoelectron spectroscopy can further verify the changes in the elemental composition and chemical state of the sample surface. For example, after the OR-MM was treated with alkali and compounded with PT nanoparticles, the changes in the characteristic peaks of C1S, O1S, N1S, etc. reflected the changes in the surface chemical composition, including the increase or decrease in the number of functional groups such as hydroxyl and amino groups, and the formation of new chemical bonds, which helped to deeply understand the chemical properties and composite structure of the membrane.

[0052] Contact angle measurement: The water and oil contact angles of the samples were measured using a JY-82 contact angle meter (Chengde Dingsheng Co., Ltd., China). The water contact angle can reflect the hydrophilicity of the membrane, and the oil contact angle is used to evaluate the underwater oleophobicity of the membrane. By measuring these contact angles, the changes in the surface wettability of the membrane at different stages can be judged, such as the hydrophobicity of OR-MM, the improvement of hydrophilicity after the alkaline treatment of NaOH-MM, and the superhydrophilicity and underwater superoleophobicity of MM@N-PT, which are crucial for the performance evaluation of its applications in oil-water separation and other fields.

[0053] Other tests: It also includes measuring the oil concentration in the solution using an infrared oil content analyzer (JC-OIL-8, Qingdao Juchuang Instrument Co., Ltd.) to evaluate the oil separation effect of the membrane; testing the specific surface area and pore size distribution of MM@N-PT using a fully automatic specific surface area and porosity analyzer (Micromeritics ASAP 2460, USA) to understand its porous structure characteristics; observing the distribution of oil droplets in the filtrate and permeate using a biological microscope (XD-303LEDCOLDLIGHTSOURCE, China) to visually verify the separation effect of the membrane; analyzing dynamic light scattering (DLS) using a Malvern Zetasizer Nano ZS90 (UK); testing the concentration of Pb 2+ using an ultraviolet-visible spectrophotometer (Shanghai Unico Instrument Co., Ltd., China) to study the removal ability of the membrane for heavy metal ions, etc. These methods comprehensively analyzed the properties of the samples from multiple angles and provided important data support for the research on the preparation process, performance optimization and application of the membrane.

[0054] The experimental principles involved in this application are introduced below:

[0055] Separation experiments of water-in-oil emulsions, oil-water mixtures and methylene blue solutions:

[0056] To prepare a series of surfactant-stabilized oil-in-water emulsions, 0.3 g of oil, 0.015 g of CTAB, and 150 mL of deionized water were mixed and stirred at 1500 rpm for 3 h. To prepare the oil-water mixture, 20 g of oil and 20 g of water were mixed. In addition, the oil was stained with Sudan red. The separation effect of MB could be observed using a spectroscopic instrument (FT-IR, VECTOR22, Bruker, Germany). In the experiment, a conventional glass filter kit was used to separate the oil-in-water emulsion and the oil-water mixture, with the self-weight separation height maintained at 15 cm and the effective separation radius of 5 mm. The filtration flux was calculated using the following formula:

[0057] ;

[0058] where J represents the filtration flux, with the unit of Lm -2 h -1 . V represents the volume of the liquid after passing through the MM@N-PT membrane, with the unit of L. A represents the effective filtration area, with the unit of m 2 . △t represents the effective separation time, with the unit of h.

[0059] The separation efficiency of the oil-in-water emulsion and the oil-water mixture was calculated using the following formula:

[0060] 100%;

[0061] where R represents the separation efficiency, C f represents the oil content in the filtrate, C p represents the oil content in the permeate.

[0062] Durability experiment of MM@N-PT:

[0063] The durability of MM@N-PT was evaluated in terms of salt tolerance, acid and alkali resistance, etc. After MM@N-PT was immersed in 3.5 wt% NaCl solution for different times, its filtration flux, separation efficiency, and underwater oil contact angle were measured. After MM@N-PT was immersed in different pH values for 4 h, its filtration flux and separation efficiency were tested. In addition, by separating the oil-water mixture and the oil-in-water emulsion for 10 cycles, the reusability of the sample was evaluated, with each cycle lasting 2 min.

[0064] Pb 2+ Removal experiment:

[0065] To evaluate the removal ability of MM@N-PT for Pb 2+ in the oil-in-water emulsion, mixed emulsions with Pb 2+ concentrations ranging from 50 mg / L to 300 mg / L were prepared, and the initial Pb 2+ concentration in the filtrate and the residual Pb 2+Concentration, calculate Pb 2+ removal efficiency. In the experiment of removing Pb 2+ solution, a conventional glass filter kit was used, the self-weight separation height was maintained at about 2 cm, and the effective separation radius was 5 mm. The calculation formula for the removal efficiency is as follows:

[0066] ;

[0067] wherein, R represents the removal efficiency, C0 represents the initial concentration of Pb 2+ , C 60 represents the concentration of Pb in the permeate after filtering for 60 minutes 2+ . The same batch of MM@N-PT was used to remove Pb at different concentrations 2+ .

[0068] The following is an illustration of the specific experimental process and results of this application:

[0069] Figure 2 is a schematic diagram of the results of scanning electron microscope tests on the surface and cross-section of OR-MM, NaOH-MM, and MM@N-PT shown in this application. Among them, Figure 2 each sub-figure (a1), (a2) in is the top surface morphology of OR-MM; (b1), (b2) are the top surface morphologies of NaOH-MM; (c1), (c2) are the top surface morphologies of MM@N-PT; (a3) is the cross-sectional morphology of OR-MM; (b3) is the cross-sectional morphology of NaOH-MM; (c3) is the cross-sectional morphology of MM@N-PT. As shown in (a1) in Figure 2 , Ganoderma lucidum hyphae can form a winding filament network membrane on the birch wood board matrix, and the viscous substances (polysaccharides) secreted by the hyphae can make some hyphae adhere to each other. The naturally controllable porous structure of the OR-MM membrane is beneficial to applications in the water treatment field. In addition, the SEM image of the cross-section shows that the hyphae grow and wind themselves to form a three-dimensional porous structure. In addition, the hyphae have a porous structure composed of tubular hyphae. The hollow tubular morphology of Ganoderma lucidum mycelium is beneficial to water transmission, and secondly, it increases the specific surface area, which is beneficial to the adsorption of heavy metal ions. The formation of the porous structure of the hyphae may be due to the degeneration or apoptosis of some internal cells as the volume of the hyphae increases, resulting in a hollow phenomenon; on the birch wood board matrix, the hyphae may grow and branch in different ways to form a unique hollow tubular structure. As shown in (a2) in Figure 2 , small cubic particles are shown in the SEM image of the OR-MM membrane, which may be caused by the powder particles left when sawing the birch wood board. Since the surface of the OR-MM membrane naturally has hydrophobic properties, it is not conducive to the preparation of superhydrophilic / underwater superoleophobic membranes. Therefore, the surface hydrophobicity can be adjusted by treatment with an appropriate concentration of sodium hydroxide. As shown in Figure 2As shown in (b1) and (b2), after OR-MM alkaline treatment, the microscopic network structure of the membrane remains intact, and the wood chip particles on the surface are also removed. In addition, appropriate high surface roughness can effectively increase the filtration area of the NaOH-MS membrane, thereby promoting the faster penetration of water through the filter membrane. As Figure 2 It can be seen from (c2) that a large number of nanoparticles are attached to the hyphae. This is because under acidic conditions, the electrostatic complexation of TA and PEI forms nano-coupled substances. At the same time, the weak acidic conditions in the later stage neutralize the Ganoderma lucidum hypha membrane after alkaline treatment, which can further stabilize and solidify the NaOH-MM network structure, so that the finally formed MM@N-PT has good mechanical strength and can effectively separate oil-in-water emulsions for a long time.

[0070] Chemical composition analysis:

[0071] Figure 3 are the ATR-FTIR spectra of OR-MM, NaOH-MM and MM@N-PT; Figure 4 are the X-ray photoelectron spectra of OR-MM, NaOH-MM and MM@N-PT; Figure 5 are the high-resolution C1S, O1S and N1S spectra of OR-MM; Figure 6 are the high-resolution C1S, O1S and N1S spectra of NaOH-MM; Figure 7 are the high-resolution C1S, O1S and N1S spectra of MM@N-PT.

[0072] As Figure 3 shown, the FTIR spectra of OR-MM, NaOH-MM and MM@N-PT all show a broad absorption band centered at ~3270 cm -1 , and this absorption band is attributed to the -OH stretching vibration of chitin and some polysaccharide fragments of chitosan. The absorption peak near 2920 cm -1 is mainly related to the stretching vibration of C-H in the alkyl chain, and these alkyl chains usually have hydrophobicity. The peak absorbance of NaOH-MM and MM@N-PT gradually decreases at around 2920 cm -1 because the denaturation of hydrophobin on the membrane surface leads to a reduction in the exposure of the hydrophobic region. In addition, the peak at ~1630 cm -1 is due to the C=O functional group in acetamide, and its absorption intensity will decrease with the increase of the degree of deacetylation, which also indicates that more chitin has been converted into chitosan with hydrophilic properties. A new absorption peak appears at ~1320 cm -1 in the MM@N-PT membrane, which originates from the C-O stretching vibration, confirming the attachment of TA to the membrane. At the same time, at ~1200 cm -1 and ~1540 cm -1Absorption peaks of C-N and N-H molecular deformation vibrations were respectively found at the [specific positions], indicating that PT nanoparticles have been successfully introduced into NaOH-MM, thus forming the MM@N-PT film.

[0073] X-ray photoelectron spectroscopy can further verify the changes in the surface chemical composition of OR-MM after alkaline treatment and composite with PT nanoparticles. As Figure 4 shown, X-ray photoelectron spectroscopy analyzed C1S, O1S, and N1S of OR-MM, NaOH-MM, and MM@N-PT. The O1S characteristic peak of NaOH-MM has the highest binding energy at about 532 eV, which is due to the formation of a large number of hydroxyl groups and other hydrophilic groups on the surface after the OR-MM film is treated with NaOH. The O1S characteristic peak value of MM@N-PT is lower than that of NaOH-MM because the PT nanoparticles cover the film surface, reducing the exposed hydrophilic oxygen groups. In addition, the C1S characteristic peak value of MM@N-PT is higher than that of NaOH-MM, which may be due to the new chemical interaction between the groups in the PT nanoparticles (such as the amino group of PEI and the hydroxyl group of TA) and the carbon atoms in the film, resulting in an increase in the binding energy. In addition, the atomic ratios and the contents of O, N, and C elements of each sample were also tested, and the results showed that PT nanoparticles were successfully attached to the surface of the MM@N-PT film.

[0074] In Figure 5 the high-resolution C1S spectrum, the C=O peak appearing in the NaOH-MM sample is caused by the oxidation of sodium hydroxide. The C-N bond appears in the MM@N-PT sample, indicating that PEI is introduced into the film, and the increase in the O-C=O peak value at about 288 eV is due to the reaction of the phenolic hydroxyl group of TA with functional groups such as amino or carboxyl groups on the surface of the NaOH-MM film. At the same time, both PEI and TA contain a large number of C-C bonds, so the C-C peak value in the X-ray photoelectron spectrum of the MM@N-PT film also increases. These phenomena indicate that the composite nanostructured coating PT effectively covers the surface of the NaOH-MM film through electrostatic complexation. Figure 6 The increase in the number of oxygen-containing hydrophilic functional groups in MM@N-PT in [[section]] can prove that the membrane material has good hydrophilicity. Figure 7 -N-C and -NH2 bonds appear in the N1S spectra of the X-ray photoelectron spectra of each sample in [[section]], mainly attributed to the inherent protein and amino acid structures in the film, and may also be related to the presence of amino compounds and surface-adsorbed nitrogen compounds. As Figure 7 shown, NaOH treatment may lead to the degradation of nitrogen compounds, resulting in the weakening of the signal of nitrogen groups in the NaOH-MM film in the X-ray photoelectron spectrum and the decrease of the peak value. In addition, the characteristic peak of the MM@N-PT film at about 401 eV is -NH3 +, which is caused by the protonation of amino groups in the introduced PEI under weakly acidic conditions. These amino groups can form hydrogen bonds with water molecules, thus enhancing the hydrophilicity of the MM@N-PT membrane.

[0075] Synthesis mechanism of MM@N-PT:

[0076] It should be noted that the OR-MM membrane was prepared by a controllable self-growth strategy by allowing Ganoderma lucidum mycelial spores to grow on a birch wood board, thus forming a three-dimensional porous membrane structure. The reasons for the formation of this structure are mainly as follows: First, Ganoderma lucidum mycelia have a high ability to branch and grow and expand, and can grow rapidly along the surface and pores of the birch wood board; Second, the natural microporous structure of the birch wood board provides a growth channel for the mycelia, enabling them to expand in both the up and down directions; In addition, the SDA medium provides sufficient nutrients for the mycelia; Finally, the mycelia can self-assemble to form a complex three-dimensional porous network during growth, further promoting the formation of the OR-MM membrane structure. In order to enable the prepared OR-MM membrane to be applied to wastewater treatment research, the following chemical treatments were carried out: NaOH treatment can deacetylate the main chitin component in the OR-MM membrane and convert it into chitosan. In the deacetylation reaction, the acetyl group (–COCH3) in the chitin molecule is removed under the action of hydroxide ions (OH - ), and a higher proportion of amino groups (-NH2) are generated through alkaline hydrolysis, thus converting part of the chitin into chitosan. In addition, NaOH treatment can also increase the number of -OH in the chitin molecule, thereby improving the hydrophilicity of the OR-MM membrane. However, the hydrophilicity of the formed NaOH-MM membrane is still insufficient. In order to further improve the hydrophilicity of this membrane, PT nanoparticles are self-assembled through the electrostatic attraction and hydrogen bond between the positive charge of PEI and the negative charge of TA to increase the surface roughness of the NaOH-MM membrane, thereby further enhancing the hydrophilicity of the NaOH-MM membrane. Although under normal circumstances, nanoparticles are easily detached from the membrane surface, due to the -NH2 and -OH in the chitosan formed after NaOH treatment can react with the -OH of TA in the PT nanoparticles and form stable hydrogen bonds. Therefore, the PT nanoparticles can firmly adhere to the surface of the MM@N-PT membrane, enhancing the durability of the membrane. Finally, the strong hydrogen bond network formed by the MM@N-PT membrane not only enhances the hydrophilicity of the membrane, but also improves the stability of the membrane. In addition, due to the rich hydrophilic groups (-NH2, -OH, etc.) in the MM@N-PT membrane, it can not only efficiently achieve oil-water separation, but also effectively remove heavy metal ions.

[0077] Surface wettability test:

[0078] The surface wettability, oil anti-adhesion, self-cleaning, underwater oil resistance and other properties of MM@N-PT are key indicators for treating oily wastewater. The water contact angle (WCA) of OR-MM in air is 150°, and the water droplet can remain for 60 s without immersion, indicating that the OR-MM membrane has strong hydrophobicity. This high water contact angle is related to the hydrophobicity of the hydrophobin on the outermost layer of the fungal hyphal cell wall. Sodium hydroxide can denature the hydrophobin of the OR-MM membrane and convert its chitin into chitosan, thereby realizing the hydrophilic modification of the OR-MM surface. Specifically, the water droplet can infiltrate into the NaOH-MM membrane within 2 s, indicating that alkaline treatment can significantly improve the hydrophilicity of OR-MM. In addition, MM@N-PT has superhydrophilicity, and the water droplet can quickly infiltrate into the MM@N-PT membrane within 1 s. This is because the PT nanocomplex is introduced on the surface of the NaOH-MM membrane, increasing the surface roughness and hydrophilic groups of the membrane. It should also be noted that the underwater oil contact angles of NaOH-MM and MM@N-PT are both greater than 150°, indicating that even simple alkaline treatment can endow the membrane with underwater superoleophobic properties. To further test the oil anti-adhesion properties of NaOH-MM and MM@N-PT, tetrachloroethylene solvent stained with Sudan red was used as the oil agent. Specifically, the oil droplet can fall and bounce from the membrane surface with the needle without adhesion, indicating that the NaOH-MM and MM@N-PT membranes have excellent oil anti-adhesion properties. In addition, when MM@N-PT was immersed in a large amount of red oil and then the membrane was cleaned with water, it was found that its surface was not adhered by the red oil. Furthermore, when a large number of oil jets were dropped onto the MM@N-PT membrane immersed in water, the oil droplets would quickly slide off without adhesion. It can be clearly found through experiments that the MM@N-PT membrane was not contaminated by oil droplets. The above shows that MM@N-PT has excellent self-cleaning performance and underwater oil resistance performance.

[0079] Controllable self-growth, stability, durability:

[0080] The filtration flux and separation efficiency of the finally formed three-dimensional porous mycelial membrane are controlled by the growth duration of the Ganoderma lucidum mycelium; the generation duration of the Ganoderma lucidum mycelium is related to the pore size of the initial mycelial membrane and the content of surface hydrophobin; the step of statically culturing the petri dish at 28°C for a specified number of days includes: statically culturing the petri dish at 28°C for 6 days.

[0081] As the growth time of Ganoderma lucidum mycelium extends, its growth on birch wood boards gradually becomes denser. In the initial growth stage, the mycelium is relatively sparse, and the initial mycelial membrane (OR-MM) formed has relatively large pores and an uneven distribution. As time goes by, the mycelium continuously branches, expands, and intertwines, gradually filling the originally large pore space, making the pores smaller and more evenly distributed. For example, when growing for 4 days, the pores of the membrane are relatively large, which may cause some smaller impurities or particles to pass through the pores during the filtration process, affecting the separation efficiency; while when the growth time reaches 6 days or longer, the smaller and more uniform pores can more effectively intercept impurities and improve the filtration effect. This change in pore size directly affects the filtration flux of the three-dimensional porous mycelial membrane. Smaller and more uniform pores will increase the resistance when liquid passes through the membrane, resulting in a decrease in the filtration flux. In practical applications, it is necessary to balance the relationship between pore size and filtration flux while ensuring a certain separation efficiency, and select an appropriate mycelial growth duration.

[0082] During the growth of Ganoderma lucidum mycelium, the content of surface hydrophobin also changes. In the early stage of mycelial growth, the content of hydrophobin is relatively low, and as the mycelium gradually matures, the concentration of hydrophobin may increase. The increase in the content of surface hydrophobin enhances the hydrophobicity of the surface of the three-dimensional porous mycelial membrane. In water purification or oil-water separation applications, too strong hydrophobicity may affect the affinity of the membrane for the aqueous phase and the rejection ability for the oil phase, which is not conducive to achieving an efficient separation process. Therefore, it is necessary to control the mycelial growth duration to regulate the content of surface hydrophobin in order to obtain the best membrane surface wettability and separation performance.

[0083] Through a large number of experimental studies and data analysis, it is found that when the culture dish is statically cultured at 28 °C for 6 days, the filtration flux and separation efficiency of the three-dimensional porous mycelial membrane can be better balanced. At this time point, the pore size of the initial mycelial membrane and the content of surface hydrophobin reach a relatively appropriate state. Compared with growing for 4 days, the 6-day culture time makes the structure of the membrane more stable, with a moderate pore size, which can not only ensure a certain filtration flux but also achieve a high separation efficiency. Compared with growing for 9 days, it avoids the problem of too small pores and too low filtration flux caused by excessive mycelial growth, and also prevents the negative impact of too high content of surface hydrophobin on the membrane performance. Therefore, considering various factors, it is finally determined that the culture dish is statically cultured at 28 °C for 6 days to obtain an initial mycelial membrane with excellent performance, and then prepare a three-dimensional porous mycelial membrane that meets the application requirements.

[0084] Figure 8 Separation effect diagrams of water-in-oil emulsions obtained by MM@N-PT for different growth times; Figure 9Separation effect diagrams of the water-in-oil emulsion after MM@N-PT was immersed in a NaCl solution (3.5 wt%) for 0–48 h; Figure 10 Underwater oil contact angles of the MM@N-PT membrane after being immersed in a NaCl solution (3.5 wt%) for 0–48 h; Figure 11 Separation effect diagrams of the water-in-oil emulsion after MM@N-PT was immersed for 4 h at different pH values. Specifically, controlling the growth time of the mycelium is crucial for regulating the pore size of the OR-MM membrane and the content of surface hydrophobin. By controlling the growth time of the OR-MM membrane, the flux and separation efficiency of the MM@N-PT membrane are improved. When the OR-MM membrane grows for 4 days, 6 days, and 9 days respectively, it is removed from the birch board and modified to obtain the MM@N-PT membrane. Then, the MM@N-PT membrane is used to filter the water-in-oil emulsion, and the obtained separation fluxes are 1756.07, 496.56, 267.38 Lm -2 h -1 , and the separation efficiencies are 99.82%, 99.99%, 99.85%, as Figure 8 shown. The above results indicate that as the growth time of the mycelium extends, the OR-MM membrane network becomes denser, the pores become smaller and more uniformly distributed, resulting in a gradual decrease in the flux of the MM@N-PT membrane. Secondly, the content of surface hydrophobin also changes with the growth time of the mycelium. As the mycelium gradually matures, the concentration of hydrophobic proteins may increase, enhancing the hydrophobicity of the MM@N-PT membrane surface. Considering the flux and separation efficiency of the MM@N-PT membrane comprehensively, the OR-MM membrane that grows for six days is finally selected as the object for modification treatment for the oil-water separation experimental study.

[0085] In addition, to test the adaptability of the MM@N-PT membrane under various environmental conditions, first, the MM@N-PT membrane was immersed in a 3.5% NaCl solution for 0 h, 6 h, 12 h, 24 h, 48 h, and then the membrane was taken out to test its underwater oleophobic angle, the flux and efficiency of separating the water-in-oil emulsion. As Figure 9 shown, the membrane flux of MM@N-PT is stable at more than 400 Lm -2 h -1 above, and the separation efficiencies are 99.98%, 99.99%, 99.95%, 99.96%, 99.98% respectively. And it can be seen from Figure 10 that after being immersed in a 3.5% NaCl solution for 0–48 h, the underwater oleophobic angle of the MM@N-PT membrane still remains at about 150°. The above research results indicate that MM@N-PT has excellent salt tolerance. In addition, the separation effect of MM@N-PT on the water-in-oil emulsion after being immersed in solutions with pH = 3 to 11 for 4 h was also tested ( Figure 11). The results show that MM@N-PT still has a separation efficiency higher than 99.90% under extreme acid-base conditions. At the same time, after the MM@N-PT membrane was immersed in an environment with pH = 3 to 11 for 7 days, it could still maintain its integrity. In addition, the MM@N-PT membrane has a dense mycelial network fiber structure and can continue to be used after being folded and bent. Therefore, the above research results show that MM@N-PT has excellent durability and stability, and can efficiently purify oily wastewater even under harsh acid-base and high-salt conditions.

[0086] Separation of oil-water mixture and purification of dyes:

[0087] Figure 12 is the schematic diagram of the cyclic separation of pure water by MM@N-PT; Figure 13 is the schematic diagram of the cyclic separation of methyl silicone oil-water mixture by MM@N-PT; Figure 14 is the process diagram of the MM@N-PT membrane used for separating oil-water mixture; Figure 15 is the membrane flux and separation efficiency diagram of MM@N-PT for separating different types of oil-water mixtures; Figure 16 is the process diagram of MM@N-PT used for separating methylene blue solution; Figure 17 is the absorbance spectrum of MM@N-PT before and after separating methylene blue solution. First, in order to explore the anti-swelling performance of the MM@N-PT membrane, 10 water cycle tests were carried out. The membrane flux of MM@N-PT decreased with the increase of the number of cycles, but it could still remain above 400 Lm -2 h -1 above ( Figure 12 ). This result proves that the MM@N-PT membrane has good anti-swelling properties, which is beneficial to its repeated use. In order to verify the reusability of MM@N-PT for separating methyl silicone oil-water mixture, ten cycle tests were carried out. As Figure 13 shown, it was found that the filtration flux of MM@N-PT could remain above 400 Lm -2 h -1 above, and the separation efficiency was greater than 99.99%. This result may be because the good mechanical properties and excellent hydrophilicity of the MM@N-PT membrane make it difficult for oil to adhere to its surface under multiple cycle filtration conditions. Through Figure 14 it can be found that after pouring the oil-water mixture into the self-separation device by gravity, the oil and water can quickly separate into layers. The water in the lower layer will permeate through the MM@N-PT membrane, while the oil in the upper layer is successfully intercepted, and the oil does not adhere to the surface of the membrane, indicating that the MM@N-PT membrane has excellent self-cleaning performance.

[0088] This application studied the use of MM@N-PT membrane for methyl silicone oil (MS), lubricating oil (LO), sunflower oil (SO), cyclohexane (C6H 12), five kinds of oil-water mixtures such as vacuum pump oil (VPO) were separated and tested. The results showed that the membrane filtration fluxes were 649.35, 763.94, 630.25, 687.55, and 725.75 Lm -2 h -1 , and the separation efficiency was greater than 99.99% ( Figure 15 ). The research results prove that the MM@N-PT membrane can effectively purify various oil-water mixtures and has broad application prospects.

[0089] In addition, this application also carried out purification tests on solutions containing methylene blue (MB). The absorbance of the original MB solution and the filtered solution was measured using ultraviolet-visible spectroscopy to evaluate the separation efficiency of the MM@N-PT membrane for dyes (biomimetic high strength). Figure 16 shows the process of filtering the MB solution with the MM@N-PT membrane. The absorbance spectra of the MM@N-PT before and after separating the methylene blue solution are as Figure 17 shown. As can be seen from the figure, the original MB solution shows a special peak at a wavelength of 660 nm, while the absorbance of the filtered solution approaches 0 in the wavelength range of 400 - 800 nm. This result indicates that the MM@N-PT can effectively filter the MB solution because the membrane can adsorb and bind to MB molecules through its natural porous structure and abundant hydrophilic groups (such as hydroxyl, amino, and carboxyl groups), and utilize mechanisms such as physical adsorption, chemical adsorption, electrostatic interaction, and enhanced mass transfer by hydrophilicity to achieve efficient removal of dyes in the solution.

[0090] Therefore, the novel porous membrane MM@N-PT can efficiently separate oil-water mixtures and purify dyes in wastewater due to its good anti-swelling performance and excellent hydrophilicity.

[0091] Separation of oil-in-water emulsions:

[0092] Due to the small droplet size and high stability of emulsified oil, it is difficult to purify emulsified oil. Figure 18 shows the experimental process and microscopic images of separating the oil-in-water emulsion. Among them, Figure 18 Figure (a) in is the microscopic image of the oil-in-water emulsion before separation, (b) is the process diagram of separating the oil-in-water emulsion using MM@N-PT, and (c) is the microscopic image of the oil-in-water emulsion after separation; Figure 19 is the pore size distribution diagram of MM@N-PT; Figure 20 is the cyclic separation result diagram of NaOH-MM for the oil-in-water emulsion; Figure 21 is the cyclic separation result diagram of MM@N-PT for the oil-in-water emulsion; Figure 22 is the membrane flux and separation efficiency diagram of MM@N-PT separating different types of oil-in-water emulsions; Figure 23Particle size distribution diagrams of oil droplets in the oil-in-water emulsion before and after separation. To further explore the application of MM@N-PT in oil-water separation, methyl silicone oil was used as a representative to prepare an oil-in-water emulsion. A self-gravity separation device ( Figure 18 in (b)) was used to conduct a series of separation tests on the oil-in-water emulsion. As Figure 18 shown, after self-gravity separation, the oil-water emulsion was effectively purified. It can be seen from the microscope images that the emulsion before separation contained a large number of oil droplets, while no oil droplets were found in the emulsion after separation, proving that MM@N-PT can efficiently separate the oil-in-water emulsion.

[0093] In addition, the average pore size of the MM@N-PT membrane was about 11 nm ( Figure 19 ), and this pore size was beneficial to the demulsification of the filter membrane. The demulsification mechanism of the MM@N-PT membrane is as follows: the superhydrophilic property of the MM@N-PT membrane will cause a stable hydration layer to form on its surface, which can selectively allow the water phase to pass through the membrane under the drive of gravity, while the oil phase is blocked on the membrane surface. This makes the emulsion present an unstable state, and the small droplets of the oil phase (dispersed phase) in the oil-in-water emulsion aggregate into clusters to form large droplets, and finally the oil and water phases are separated and precipitated.

[0094] The cyclic separation of the oil-in-water emulsion by the NaOH-MM and MM@N-PT membranes is shown in Figure 20 and 21 . After multiple oil-water separations, the filtration flux of the NaOH-MM membrane decreased from 267.38 to 190.99 Lm -2 h -1 , but the separation efficiency remained above 99.55%. In contrast, after 10 cyclic separations, the filtration flux of the MM@N-PT membrane decreased from 477.46 to 324.68 Lm -2 h -1 , and the separation efficiency still remained above 99.93%. The above results show that the MM@N-PT membrane exhibits excellent repeatability during multiple cyclic uses, which is mainly attributed to its excellent superhydrophilicity, dense porous structure and high surface roughness. In addition, to further verify the application potential of the MM@N-PT membrane in the oil-in-water emulsion, its separation performance for various emulsions was tested. As Figure 22 shown, the filtration fluxes of the MM@N-PT membrane for five emulsions of methyl silicone oil (MS), lubricating oil (LO), sunflower oil (SO), cyclohexane (C6H 12 ) and vacuum pump oil (VPO) were 458.37, 485.10, 401.07, 439.27 and 477.46 Lm -2 h -1, the separation efficiency is as high as 99.99%. To further verify the high-efficiency separation performance of MM@N-PT for oil-in-water emulsions, the oil droplet size distribution before and after emulsion separation was tested. As Figure 23 shown, the oil droplet size range in the emulsion before separation was 100 nm to 400 nm, the oil droplet size in the emulsion before separation was between 100 and 400 nm, and no oil droplet distribution was found in the emulsion after separation. This result indicates that the MM@N-PT membrane can achieve high-efficiency separation of oil-in-water emulsions. In addition, MM@N-PT can separate oily bilge wastewater with a concentration of 5400 mg / L, and its separation efficiency can reach 99.85%. Therefore, this superhydrophilic / underwater superoleophobic porous mycelium membrane-MM@N-PT with a simple preparation method, low cost, and controllable self-growth characteristics has broad application prospects in the field of oil-water separation and is expected to achieve large-scale popularization and application.

[0095] Removal of Pb 2+ :

[0096] Figure 24 This is the removal efficiency diagram of the NaOH-MM membrane and the MM@N-PT membrane shown in this application for Pb 2+ in different environments. In recent years, the use of fungi to remove heavy metal ions has attracted increasing attention from researchers (fungal detoxification). Among them, Figure 24 each subfigure in is (a) the removal efficiency of the NaOH-MM membrane and the MM@N-PT membrane for Pb 2+ ions; (b) the removal efficiency of the MM@N-PT membrane for different initial concentrations of Pb 2+ ; (c) the removal efficiency of the MM@N-PT membrane for Pb 2+ under different acid-base conditions. Among them, the charged functional groups such as hydroxyl and amino groups on the fungal cell wall can make the cell wall surface negatively charged, which is beneficial for fungi to purify metal ions in wastewater through ion exchange or electrostatic adsorption (modified microorganisms). This application mainly studied the use of MM@N-PT to remove Pb 2+ in oil-in-water emulsions. As Figure 24 shown in (a) of, the removal efficiency of the NaOH-MS membrane for Pb 2+ is 88.5%, while the removal efficiency of the MM@N-PT membrane for Pb 2+ is 92.8%. Among them, the removal effect of the NaOH-MS membrane on Pb 2+ mainly stems from the fact that the chitin rich in the mycelium undergoes a deacetylation reaction to form chitosan, and the hydroxyl and amino groups in chitosan have strong heavy metal ion adsorption capabilities (with heavy metal adsorption properties). To further improve the membrane's removal of Pb 2+removal ability, the NaOH-MM membrane was modified with the PT nanocomplex formed by PEI and TA, generating more -NH2 and -OH active groups, thus enhancing the chelation ability for Pb 2+ .

[0097] Pb 2+ The initial concentration of Pb is a key factor affecting the removal efficiency of Pb by the MM@N-PT membrane. As shown in (b) of 2+ , when the concentration of Pb in the water-in-oil emulsion ranges from 50 mg / L to 250 mg / L, with the increase of the Pb Figure 24 concentration, the removal efficiency of the MM@N-PT membrane for Pb 2+ gradually increases. However, when the Pb 2+ concentration increases to 300 mg / L, the removal efficiency of the MM@N-PT membrane decreases instead (lead-induced). This may be because the higher concentration of lead ions enhances the mass transfer driving force of lead, overcomes the mass transfer limitation between the surface of the bacteria and the liquid phase, thus increasing the adsorption amount of lead on the filter membrane. In addition, the higher concentration of lead ions also increases the effective collision times between the filter membrane and lead ions, strengthening the adsorption ability of the bacteria for lead (Optimizing the removal of lead ions by fungi: Explanation of the fungal adsorption mechanism). Therefore, when the concentration of lead ions in the water-in-oil emulsion is 250 mg / L, the removal efficiency of the MM@N-PT membrane for Pb 2+ reaches the maximum value (94.4%). However, when the concentration of lead ions is too high, it will cause insufficient binding sites on the surface of the MM@N-PT membrane, resulting in competitive adsorption between metal ions, thus reducing the removal efficiency (Biofilm). 2+ 2+

[0098] In addition, the pH of the solution is also an important factor affecting the removal efficiency of MM@N-PT for Pb 2+ . For this reason, the removal efficiency of the MM@N-PT membrane for lead ions under different pH conditions was tested when the concentration of lead ions in the water-in-oil emulsion was 50 mg / L. As shown in (c) of Figure 24 , when pH = 5, the removal efficiency of MM@N-PT for Pb 2+ reaches 77.1%, while under strong acid or strong base conditions, the removal efficiency of MM@N-PT for Pb 2+ is relatively low. This is because when the pH value is too small, the surface of the MM@N-PT membrane will be occupied by H3O + , and due to the electrostatic repulsion, it is difficult for metal ions to bind to the adsorption sites on the membrane surface; when the pH value is too high, the heavy metal ions will reach their precipitation equilibrium constant, and then hydroxide precipitates will form and precipitate out, thus affecting the removal effect (Optimizing the removal of lead ions by fungi: Explanation of the fungal adsorption mechanism).

[0099] ​​Removal of Pb by MM@N-PT Membrane 2+ The mechanism is that the membrane has achieved the efficient removal of Pb through the synergistic effect (to the maximum extent) of complexation, electrostatic adsorption and hydrogen bonding. 2+ The removal mechanism is as follows: First, after alkaline treatment, more active groups such as -OH and -NH2 are generated on the membrane surface. At the same time, the -NH2 and -OH rich in the PT nano-complex further enrich the types and quantities of active adsorption sites of the MM@N-PT membrane. These groups can form stable complexes with Pb 2+ through coordination, thus achieving the efficient removal of heavy metal ions; Second, in an acidic solution, the -NH2 part in PEI is protonated to -NH3 + , making the MM@N-PT membrane surface positively charged. At the same time, certain negatively charged groups (such as -COO - ) still remain on the membrane surface, and combine with Pb 2+ through electrostatic attraction to become the main adsorption sites. -NH3 + indirectly enhances the adsorption efficiency of Pb 2+ by adjusting the surface charge distribution; In addition, the formation of hydrogen bonds in the MM@N-PT membrane can enhance the binding ability of hydrogen-containing polar groups (such as -OH, -NH2, -COOH, etc.) to Pb 2+ . Therefore, the MM@N-PT membrane can effectively remove Pb 2+ in the oil-in-water emulsion.

[0100] Corresponding to the embodiment of the preparation method of the foregoing three-dimensional porous mycelial membrane, the present application also provides a three-dimensional porous mycelial membrane, which is prepared based on the preparation method of the three-dimensional porous mycelial membrane. Among them, the hydrophilicity and underwater oleophobicity of the three-dimensional porous mycelial membrane reach an equilibrium, and the underwater oil contact angle, membrane flux and separation efficiency of the three-dimensional porous mycelial membrane remain stable under various different environmental conditions and after multiple cycles.

[0101] Corresponding to the embodiment of the preparation method of the foregoing three-dimensional porous mycelial membrane, the present application also provides an application of the three-dimensional porous mycelial membrane, and the three-dimensional porous mycelial membrane is applied to the fields of water purification, oil-in-water emulsion separation and oil-water mixture separation.

[0102] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for preparing a three-dimensional porous mycelium membrane, characterized in that, The method includes: Using Sabouraud dextrose agar medium as the nutrient source and birch wood board as the carrier to culture Ganoderma lucidum mycelium, so that the Ganoderma lucidum mycelium grows on the birch wood board into an initial mycelial membrane with a three-dimensional porous grid structure; Performing an alkaline treatment on the initial mycelial membrane to convert chitin in the initial mycelial membrane into chitosan, obtaining an intermediate membrane; Soaking the intermediate membrane in a mixed solution composed of a PEI solution and a TA solution for a first specified duration, and after the reaction ends, adjusting the pH value of the mixed solution to 2-4; Adjusting the pH value of the mixed solution to 6-7, and continuing to soak the intermediate membrane in the mixed solution for a second specified duration, obtaining the three-dimensional porous mycelial membrane.

2. The method according to claim 1, wherein The hydrophilicity and underwater oleophobicity of the three-dimensional porous mycelial membrane reach an equilibrium, and the underwater oil contact angle, membrane flux and separation efficiency of the three-dimensional porous mycelial membrane remain stable under various different environmental conditions and after multiple cycles; Among them, water droplets can quickly infiltrate into the three-dimensional porous mycelial membrane within 1 second, and the underwater oil contact angle of the three-dimensional porous mycelial membrane is greater than 150°; The underwater oil contact angle of the three-dimensional porous mycelial membrane is greater than 150 °C under various different environmental conditions and after multiple cycles. The membrane flux of the three-dimensional porous mycelial membrane is greater than 300 Lm -2 h -1 , and the separation efficiency of the three-dimensional porous mycelial membrane is greater than 99% under various different environmental conditions and after multiple cycles.

3. The method according to claim 1, wherein The removal rate of heavy metal ions in the emulsion by the three-dimensional porous mycelial membrane is greater than 70%.

4. The method according to claim 1, characterized in that, Using Sabouraud dextrose agar medium as the nutrient source and birch wood board as the carrier to culture Ganoderma lucidum mycelium, so that the Ganoderma lucidum mycelium grows on the birch wood board into an initial mycelial membrane, including: Preparing mycelial suspension spores; Performing high-temperature and high-pressure sterilization treatment on a birch wood board of a specified size, and placing the treated birch wood board in a petri dish containing sterilized Sabouraud dextrose agar medium; Inoculating the mycelial suspension spores onto the edge of the birch wood board under sterile conditions, obtaining a petri dish inoculated with spores; Static-culturing the petri dish at a first specified temperature for a specified number of days, and after the culture ends, tearing off the Ganoderma lucidum mycelial membrane generated on the birch wood board with tweezers; Rinsing the Ganoderma lucidum mycelial membrane with deionized water, obtaining the initial mycelial membrane.

5. The method according to claim 1, wherein Performing an alkaline treatment on the initial mycelial membrane to convert chitin in the initial mycelial membrane into chitosan, obtaining an intermediate membrane, including: Placing the initial mycelial membrane into a NaOH solution and treating it at a second specified temperature for a specified duration; Washing the treated initial mycelial membrane with deionized water, obtaining the intermediate membrane.

6. The method according to claim 4, wherein The filtration flux and separation efficiency of the three-dimensional porous mycelial membrane are controlled by the growth duration of the Ganoderma lucidum mycelium; the generation duration of the Ganoderma lucidum mycelium is related to the size of the pores and the content of surface hydrophobin in the initial mycelial membrane; the static-culturing the petri dish at a first specified temperature for a specified number of days includes: The petri dish is static-cultured at a first specified temperature for 6 days.

7. The method according to claim 4, characterized in that The preparing the mycelial suspension spores includes: Preparing a liquid medium using corn flour, deionized water, glucose, yeast powder, potassium dihydrogen phosphate and magnesium sulfate; Dispensing the liquid medium into Erlenmeyer flasks, and performing high-temperature and high-pressure sterilization treatment on the Erlenmeyer flasks; Inoculating mycelial pieces into the Erlenmeyer flasks in a laminar flow hood; Let the conical flask inoculated with mycelium be statically cultured for two days, and after the static culture is completed, place the conical flask in a constant temperature incubator and continuously culture it for a specified number of days in a culture environment at the first specified temperature and specified rotation speed to obtain the mycelium suspension spores.

8. The method according to claim 1, characterized in that, The mixed solution is composed of a 2 mg / ml PEI solution and a 1.5 mg / ml TA solution; the first specified duration is 25 minutes, and the second specified duration is 30 minutes.

9. A three-dimensional porous mycelium membrane, characterized in that, The three-dimensional porous mycelium membrane is prepared by the method according to any one of claims 1-8.

10. Application of a three-dimensional porous mycelial membrane, characterized in that, The three-dimensional porous mycelium membrane is applied to the fields of water purification, water-in-oil emulsion separation, and oil-water mixture separation.

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