A semi-permeable membrane for seawater desalination and a method for preparing the same

Abstract

The application relates to the field of water treatment, and particularly discloses a semi-permeable membrane for seawater desalination and a preparation method thereof; the semi-permeable membrane for seawater desalination is composed of an aromatic polyamide membrane and an adsorption layer; the adsorption layer is composed of a chitosan membrane and rebound particles; the chitosan membrane comprises: a chitosan solution, graphene modified flexible fibers, glycerol and glutaraldehyde; the preparation method is as follows: the chitosan solution, the graphene modified flexible fibers, the glycerol and the glutaraldehyde are uniformly mixed and stirred, and are cast into a film; the rebound particles are uniformly sprayed on the surface of the film layer to obtain the adsorption layer; the aromatic polyamide membrane is uniformly sprayed with an ethyl cellulose solution around the periphery; then, the side of the adsorption layer provided with the rebound particles is adhered to one side of the aromatic polyamide membrane which is sprayed with the ethyl cellulose solution; and the semi-permeable membrane is prepared through drying; under the condition of long-time use, the semi-permeable membrane still has high separation efficiency, and the surface of the semi-permeable membrane is not easy to attach bacteria, viruses, aquatic organisms and other substances, so that the semi-permeable membrane has a long service life.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of water treatment, more particularly, it relates to a semi-permeable membrane for seawater desalination and a preparation method thereof. BACKGROUND

[0002] Seawater desalination refers to separating pollutants, bacteria, viruses, aquatic organisms and other substances in seawater from water, and common methods include seawater freezing method, electrodialysis method, distillation method, reverse osmosis method and ammonium carbonate ion exchange method, etc., wherein the reverse osmosis method is the most common method.

[0003] The reverse osmosis method is also called membrane separation desalination method, which separates the seawater by adjusting the osmotic pressure so that fresh water can pass through the semi-permeable membrane; the semi-permeable membrane commonly uses aromatic polyamide membrane as the reverse osmosis membrane, the surface of the aromatic polyamide membrane has carboxyl groups and is negatively charged, and in the process of seawater separation, bacteria, viruses, aquatic organisms and colloidal particles in seawater are easily attached to the surface of the semi-permeable membrane, which not only easily blocks the pores to affect the flow of water, resulting in the influence of seawater desalination efficiency, but also easily shortens the service life of the semi-permeable membrane due to the metabolic acid of the organisms attached to the surface of the semi-permeable membrane and the corrosion of other substances in seawater to the semi-permeable membrane.

[0004] Therefore, how to prepare a semi-permeable membrane for efficiently separating bacteria, viruses, aquatic organisms and fresh water in seawater, and even under the condition of long-term use, the semi-permeable membrane still has high separation efficiency and the surface is not easy to attach bacteria, viruses, aquatic organisms and other substances, so that the semi-permeable membrane has a long service life. SUMMARY

[0005] In order to prepare a semi-permeable membrane for efficiently separating bacteria, viruses, aquatic organisms and fresh water in seawater, and even under the condition of long-term use, the semi-permeable membrane still has high separation efficiency and the surface is not easy to attach bacteria, viruses, aquatic organisms and other substances, so that the semi-permeable membrane has a long service life; the present application provides a semi-permeable membrane for seawater desalination and a preparation method thereof.

[0006] In a first aspect, the present application provides a semi-permeable membrane for seawater desalination, which adopts the following technical scheme:

[0007] A semi-permeable membrane for seawater desalination, which is composed of an aromatic polyamide membrane and an adsorption layer;

[0008] The adsorption layer is composed of a chitosan membrane and a rebound particle;

[0009] The chitosan membrane contains the following raw materials by weight: chitosan solution 80-100 parts, graphene modified flexible fiber 20-30 parts, glycerol 0.5-1 part, and glutaraldehyde 0.2-0.5 part.

[0010] By adopting the technical scheme, the chitosan solution is used as a film-forming base material, and the filling and dispersion effect of the graphene modified flexible fiber is combined to construct a network structure of the chitosan solution and the graphene modified flexible fiber. When seawater is filtered, the bacteriostatic and bactericidal effect of the chitosan solution is combined with the blocking effect of the network structure to block marine organisms and colloid ions in seawater and intercept and repel viruses and bacteria. Meanwhile, the high fiber content and the large porosity between the fiber and the chitosan solution facilitate the flow of water and ensure the filtering efficiency of fresh water.

[0011] The rebound particles are attached to one side of the adsorption layer. Under the action of the pressure of seawater separation, the graphene modified flexible fiber is prone to fiber filament deformation, that is, the fiber filament is prone to deformation and bending of the fiber filament end toward the side of the aromatic polyamide membrane with the flow of water, which can further ensure the separation efficiency of seawater. Under the action of the pressure, the chitosan membrane formed by the chitosan solution and the graphene modified flexible fiber is prone to deformation and indentation to extrude the rebound particles. When the pressure is removed, the rebound particles rebound the chitosan membrane by using the good rebound elasticity, so as to rebound the killed viruses, bacteria and other aquatic organisms attached to the surface of the chitosan membrane out of the surface of the adsorption layer. Thus, the semi-permeable membrane has a long service life while maintaining a high separation efficiency and the surface is not easy to attach bacteria, viruses and aquatic organisms under the condition of long-time use.

[0012] Preferably, the rebound particles are composed of carrier sepiolite and multi-aperture silica gel particles with a mass ratio of 1:0.2-0.4.

[0013] By adopting the technical scheme, the carrier sepiolite and the multi-aperture silica gel particles are combined to use the flexibility and elasticity of the sepiolite and the elasticity and rebound elasticity of the multi-aperture silica gel particles. After being subjected to the pressure, the rebound particles are prone to deformation. After the pressure is removed, the rebound particles can rebound the chitosan membrane by using the rebound elasticity to rebound the bacteria and viruses on the surface of the chitosan membrane out of the surface of the chitosan membrane, so as to meet the long-time use of the semi-permeable membrane.

[0014] Both the sepiolite and the multi-aperture silica gel particles contain multi-aperture structures to meet the flow of water and the attachment of bacteria and viruses in the internal pores of the sepiolite and the multi-aperture silica gel particles, so as to further filter the bacteria and viruses in seawater and ensure the sterility of fresh water.

[0015] Preferably, the carrier sepiolite is composed of multi-aperture sepiolite, cellulose fiber and chitosan quaternary ammonium salt solution with a mass ratio of 1:0.2-0.5:0.4-0.8.

[0016] By adopting the technical scheme, the pored sepiolite, the cellulose fiber and the chitosan quaternary ammonium salt solution are matched, the cellulose fiber is dispersed in the chitosan quaternary ammonium salt solution, that is, the chitosan quaternary ammonium salt solution carries the cellulose fiber and is attached to the surface of the pored sepiolite, the positive charge of the chitosan quaternary ammonium salt is used to attract the negative charge of the graphene in the graphene modified flexible fiber, the loaded sepiolite is easily attached to the surface of the graphene modified flexible fiber, the positive charge of the chitosan quaternary ammonium salt is easily repelled from the positive charge of the chitosan, and therefore the rebound particles are easily located near the graphene modified flexible fiber.

[0017] When the pressure is extruded, the elastic particles are compressed with the deformation of the flexible fiber, the support effect of the cellulose fiber is used to avoid the occlusion of the open porosity of the pored sepiolite after compression as much as possible, and therefore the filtration of seawater is ensured, the adsorption layer is not easily attached to aquatic organisms, bacteria, viruses and the like through the rebound of the rebound particles after the pressure is removed, and the service life of the semi-permeable membrane is prolonged.

[0018] The pored sepiolite, the chitosan quaternary ammonium salt solution and the cellulose fiber are matched, the support structure of the cellulose fiber is used, the hydroxyl on the surface of the cellulose fiber is connected with the amino in the chitosan quaternary ammonium salt, the cellulose fiber is dispersed and filled in the chitosan quaternary ammonium salt, the porosity after the chitosan quaternary ammonium salt solution is formed into a film is increased, the filtration and circulation effect of water is ensured in cooperation with the porous structure of the pored sepiolite, and the filtration and circulation effect of water is further ensured in cooperation with the water absorption and expansion effect of the pored sepiolite.

[0019] Preferably, the pored sepiolite is prepared by treating pored sepiolite particles with a menthol solution.

[0020] By adopting the technical scheme, the pored sepiolite, the menthol solution, the chitosan solution and the chitosan quaternary ammonium salt solution are matched, the menthol is loaded by using the porous structure of the pored sepiolite, the bacteria and viruses in seawater first contact the chitosan, the bacteriostatic and bactericidal effect of the chitosan is used to kill the bacteria and viruses in seawater, the bacteria and viruses in seawater are killed again by using the chitosan quaternary ammonium salt, even if the bacteria enter the rebound particles, the bacteria in the pored sepiolite can be killed by using the menthol, the menthol is not easily affected to the filtration of seawater because the menthol is insoluble in water, the attachment stability of the chitosan quaternary ammonium salt on the surface of the pored sepiolite is further improved by matching the hydroxyl on the surface of the pored sepiolite with the hydroxyl in the menthol, and the heavy metal ions in seawater can be complexed, and the seawater desalination treatment is facilitated.

[0021] Preferably, the cellulose fiber is prepared by treating cellulose fiber filaments with a sophoramine solution.

[0022] By adopting the technical scheme, the cellulose fiber and the matrine solution are combined, the matrine solution has the sterilization and bacteriostasis effect, and the bacteria and viruses in seawater are further killed, and when water flows around the cellulose fiber, the water purification effect can be achieved.

[0023] Preferably, the graphene modified flexible fiber is composed of alumina fiber, carbon fiber, graphene and ethyl cellulose solution with a mass ratio of 1:0.2-0.5:0.1-0.2:0.05-0.1.

[0024] By adopting the technical scheme, the alumina fiber, carbon fiber, graphene and ethyl cellulose solution are combined, the flexibility of the alumina fiber and the partial flexibility of the carbon fiber are utilized, the graphene is adhered to the surface of the alumina fiber and the carbon fiber by the trace amount of ethyl cellulose solution, the graphene surface is negatively charged, the graphene modified flexible fiber is crosslinked with the chitosan solution to build a network, and the graphene modified flexible fiber is adhered to the rebound particles, the structure stability of the semi-permeable membrane is improved, the network structure with multiple voids facilitates water flow, and the service life of the semi-permeable membrane is prolonged.

[0025] Preferably, the length of the alumina fiber is 60-100 microns, and the length of the carbon fiber is 20-40 microns.

[0026] By adopting the technical scheme, the alumina fiber is used as the basic support, and the carbon fiber is attached to the surface, so that the flexibility, elasticity and rebound of the graphene modified flexible fiber are ensured.

[0027] Preferably, the chitosan solution is composed of chitosan dilute acetic acid solution, talcum powder and titanium dioxide with a mass ratio of 1:0.1-0.2:0.05-0.1.

[0028] By adopting the technical scheme, the chitosan dilute acetic acid solution, talcum powder and titanium dioxide are combined, the lubricating effect of the talcum powder and the titanium dioxide is utilized, the adhesion of the water organisms, bacteria, viruses and other substances in seawater to the surface of the adsorption layer is prevented, the adhered water organisms are bounced off under the rebound effect of the rebound particles, even under the use condition for a long time, the semi-permeable membrane has high separation efficiency, the bacteria, viruses and other substances are not easily adhered to the surface of the semi-permeable membrane, and the semi-permeable membrane has a long service life.

[0029] Preferably, the particle size of the talcum powder is 40-80 nm, and the particle size of the titanium dioxide is 10-40 nm.

[0030] By adopting the technical scheme, the particle sizes of the talcum powder and the titanium dioxide are limited, the separation effect is ensured, and the adhesion of the microorganisms in seawater to the surface of the semi-permeable membrane is prevented as much as possible.

[0031] In a second aspect, the application provides a preparation method of a semi-permeable membrane for seawater desalination, which adopts the following technical scheme:

[0032] A preparation method of a semi-permeable membrane for seawater desalination, comprising the following steps:

[0033] S1, uniformly mix and stir a chitosan solution, graphene modified flexible fiber, glycerol and glutaraldehyde, flow cast a film, and uniformly spray elastic particles on the surface of the film layer to obtain an adsorption layer;

[0034] S2, uniformly spray an ethyl cellulose solution around the aromatic polyamide membrane, then adhere the side of the adsorption layer provided with the elastic particles to the side of the aromatic polyamide membrane sprayed with the ethyl cellulose solution, and dry to obtain a finished semi-permeable membrane.

[0035] By adopting the above technical scheme, the elastic particles are used as a barrier of the chitosan film and the aromatic polyamide film, the porous film layer formed by cross-linking the graphene modified flexible fiber and the chitosan solution cooperates with the pores around the elastic particles to ensure the circulation of water, so that the semi-permeable membrane still has a high water permeability when blocking water organisms, bacteria, viruses and other substances in seawater; and even under a long-term use condition, the semi-permeable membrane still has a high separation efficiency and the surface is not easy to attach bacteria, viruses, water organisms and other substances, so that the semi-permeable membrane has a long service life.

[0036] In summary, the application has the following beneficial effects:

[0037] 1. The chitosan film in the adsorption layer has a high porosity, and cooperates with the filling and blocking effect of the elastic particles. Under the pressure action of seawater separation, the chitosan film formed by the chitosan solution and the graphene modified flexible fiber is easy to deform, depress and extrude the elastic particles. When the pressure is removed, the elastic particles rebound the chitosan film by using the good elasticity, so as to rebound the killed viruses, bacteria and other water organisms attached to the surface of the chitosan film out of the surface of the adsorption layer. Thus, under a long-term use condition, the semi-permeable membrane still has a high separation efficiency and the surface is not easy to attach bacteria, viruses, water organisms and other substances, so that the semi-permeable membrane has a long service life.

[0038] 2. The chitosan dilute acetic acid solution, talc and titanium dioxide cooperate with each other, and the lubricating effect of the talc and titanium dioxide is used to prevent the adhesion of water organisms, bacteria, viruses and other substances on the surface of the adsorption layer. Under the rebounding effect of the elastic particles, the attached water organisms are easily bounced out. Even under a long-term use condition, the semi-permeable membrane still has a high separation efficiency and the surface is not easy to attach bacteria, viruses, water organisms and other substances, so that the semi-permeable membrane has a long service life.

[0039] 3、Resilient particles, graphene modified flexible fiber, chitosan solution, aromatic polyamide film cooperate, the resilient particles as the barrier of chitosan film and aromatic polyamide film, the porous film layer formed by graphene modified flexible fiber and chitosan solution crosslinking, cooperate with the pores around the resilient particles, ensure the circulation of water, so that the semi-permeable membrane still has high water permeability when blocking seawater organisms, bacteria, viruses and other substances. DETAILED DESCRIPTION

[0040] The application will be further described in detail below in combination with examples.

[0041] The following raw materials are purchased from Nantong Xiang Biological Engineering Co., Ltd. Food grade; Menthol solution and sophoridine solution are also food grade raw materials.

[0042] Preparation Example 1: The carrier sepiolite is prepared by the following method:

[0043] Take 1 kg of multi-opening sepiolite particles and immerse them in 10 kg of menthol solution. The particle size of the multi-opening sepiolite particles is 80 μm, and the porosity is 65-70%. The menthol solution is a 10% menthol ethanol solution by mass fraction, and the ethanol mass fraction is 75%. Stir at a speed of 500 r / min for 20 min, then filter out the multi-opening sepiolite particles, dry them, and obtain the multi-opening sepiolite.

[0044] Take 1 kg of cellulose fiber and immerse it in 10 kg of sophoridine solution. The length of the cellulose fiber is 0.3 mm, and the sophoridine solution is a 5% sophoridine ethanol solution by mass fraction, and the ethanol mass fraction is 75%. Filter out the cellulose fiber, dry it, and obtain the cellulose fiber.

[0045] Take 0.4 kg of cellulose fiber and disperse it in 0.8 kg of chitosan quaternary ammonium salt solution. The chitosan quaternary ammonium salt solution is a 3% chitosan quaternary ammonium salt aqueous solution by mass fraction, and the addition speed of the cellulose fiber is 60 g / min. Stir the chitosan quaternary ammonium salt solution at a speed of 300 r / min during the addition process, then uniformly spray it onto the surface of 1 kg of multi-opening sepiolite, and obtain the finished carrier sepiolite after dispersion.

[0046] Preparation Example 2: The difference between this preparation example and Preparation Example 1 is:

[0047] Take 0.2 kg of cellulose fiber and disperse it in 0.4 kg of chitosan quaternary ammonium salt solution. The chitosan quaternary ammonium salt solution is a 3% chitosan quaternary ammonium salt aqueous solution by mass fraction, and the addition speed of the cellulose fiber is 60 g / min. Stir the chitosan quaternary ammonium salt at a speed of 300 r / min during the addition process, then uniformly spray it onto the surface of 1 kg of multi-opening sepiolite, and obtain the finished carrier sepiolite after dispersion.

[0048] Preparation Example 3: The difference between this preparation example and Preparation Example 1 is that:

[0049] 0.5 kg of cellulose fibers were weighed and dispersed into 0.8 kg of a chitosan quaternary ammonium salt solution which was a 3% chitosan quaternary ammonium salt aqueous solution by mass, and the cellulose fibers were added at a speed of 60 g / min while the chitosan quaternary ammonium salt was stirred at a speed of 300 r / min, and then uniformly sprayed onto the surface of 1 kg of the porous sepiolite prepared in Preparation Example 1, and after dispersion, the finished product, the loaded sepiolite, was prepared.

[0050] Example 4: The rebound particles were prepared by the following method:

[0051] 0.3 kg of porous silica gel particles with a particle size of 2 μm and a porosity of 60-65% were weighed and uniformly sprayed onto the surface of 1 kg of the loaded sepiolite prepared in Preparation Example 1 at a spraying speed of 30 g / min, and the loaded sepiolite was stirred at a speed of 200 r / min during the spraying process, and after drying and dispersion, the loaded sepiolite was not agglomerated, and the rebound particles were prepared.

[0052] Preparation Example 5: The difference between this preparation example and Preparation Example 4 is that:

[0053] 0.2 kg of porous silica gel particles with a particle size of 2 μm were weighed and uniformly sprayed onto the surface of 1 kg of the loaded sepiolite prepared in Preparation Example 2 at a spraying speed of 30 g / min, and the loaded sepiolite was stirred at a speed of 200 r / min during the spraying process, and after drying and dispersion, the loaded sepiolite was not agglomerated, and the rebound particles were prepared.

[0054] Preparation Example 6: The difference between this preparation example and Preparation Example 4 is that:

[0055] 0.4 kg of porous silica gel particles with a particle size of 2 μm were weighed and uniformly sprayed onto the surface of 1 kg of the loaded sepiolite prepared in Preparation Example 3 at a spraying speed of 30 g / min, and the loaded sepiolite was stirred at a speed of 200 r / min during the spraying process, and after drying and dispersion, the loaded sepiolite was not agglomerated, and the rebound particles were prepared.

[0056] Example 7: The graphene modified flexible fiber was prepared by the following method:

[0057] 1 kg of alumina fibers with a length of 80 μm and 0.4 kg of carbon fibers with a length of 20 μm were mixed and stirred uniformly, and then 0.08 kg of an ethyl cellulose solution which was a 1% ethyl cellulose solution by mass was uniformly sprayed onto the surface of the flexible fiber, and then 0.15 kg of graphene with a particle size of 80 nm was uniformly sprayed, and after drying and dispersion, the finished product, the graphene modified flexible fiber, was prepared.

[0058] Example 8: The difference between this example and example 7 is that:

[0059] Take 1 kg of alumina fiber and 0.2 kg of carbon fiber, mix and stir evenly, the length of alumina fiber is 60 μm, the length of carbon fiber is 20 μm, then evenly spray 0.05 kg of ethyl cellulose solution on the surface of the flexible fiber, the mass fraction of ethyl cellulose solution is 1%, then evenly spray 0.1 kg of graphene, the particle size of graphene is 80 nm, after drying and dispersing, the finished product of graphene modified flexible fiber is obtained.

[0060] Example 9: The difference between this example and example 1 is that:

[0061] Take 1 kg of alumina fiber and 0.5 kg of carbon fiber, mix and stir evenly, the length of alumina fiber is 100 μm, the length of carbon fiber is 40 μm, then evenly spray 0.1 kg of ethyl cellulose solution on the surface of the flexible fiber, the mass fraction of ethyl cellulose solution is 1%, then evenly spray 0.2 kg of graphene, the particle size of graphene is 80 nm, after drying and dispersing, the finished product of graphene modified flexible fiber is obtained.

[0062] Example 10: The chitosan solution is prepared by the following method:

[0063] Take 1 kg of chitosan dilute acetic acid solution and 0.15 kg of talc and 0.08 kg of titanium dioxide, mix and stir evenly to obtain the chitosan solution, the mass fraction of chitosan dilute acetic acid solution is 2%, the mass fraction of dilute acetic acid solution is 2%, the particle size of talc is 60 nm, and the particle size of titanium dioxide is 20 nm.

[0064] Example 11: The chitosan solution is prepared by the following method:

[0065] Take 1 kg of chitosan dilute acetic acid solution and 0.1 kg of talc and 0.05 kg of titanium dioxide, mix and stir evenly to obtain the chitosan solution, the mass fraction of chitosan dilute acetic acid solution is 2%, the mass fraction of dilute acetic acid solution is 2%, the particle size of talc is 40 nm, and the particle size of titanium dioxide is 10 nm.

[0066] Example 12: The chitosan solution is prepared by the following method:

[0067] Take 1 kg of chitosan dilute acetic acid solution and 0.2 kg of talc and 0.1 kg of titanium dioxide, mix and stir evenly to obtain the chitosan solution, the mass fraction of chitosan dilute acetic acid solution is 2%, the mass fraction of dilute acetic acid solution is 2%, the particle size of talc is 80 nm, and the particle size of titanium dioxide is 40 nm. Example

[0068] Example 1: A semi-permeable membrane for seawater desalination:

[0069] Composed of an aromatic polyamide membrane and an adsorption layer;

[0070] The preparation method is as follows:

[0071] S1, 100 kg of chitosan solution, 25 kg of graphene modified flexible fiber, 0.8 kg of glycerol, 0.4 kg of glutaraldehyde are mixed and stirred uniformly, and a film is obtained by casting. 10 kg of rebound particles and 50 kg of water are mixed and placed in a glass jar, and a glass sheet carrying the chitosan film is covered on the glass jar. The chitosan film is in contact with the liquid in the glass jar, and then the glass jar is pressed and compacted and then inverted. After 10 min, the glass sheet is removed, and the chitosan film loaded with rebound particles is taken off. After drying, an adsorption layer is obtained. The chitosan solution is prepared by the preparation example 10, the graphene modified flexible fiber is prepared by the preparation example 7, and the rebound particles are prepared by the preparation example 4.

[0072] S2, evenly spray ethyl cellulose solution on the surface of the aromatic polyamide membrane around the four sides with a width of 0.8-1 cm, then adhere the side of the adsorption layer provided with the rebound particles to the side of the aromatic polyamide membrane sprayed with the ethyl cellulose solution, and dry to obtain the finished semi-permeable membrane. The finished semi-permeable membrane can be directly applied to the seawater desalination equipment. The aromatic polyamide membrane is the base layer, and the thickness is 0.38 mm. The thickness of the adsorption layer is 0.62 mm.

[0073] Example 2: The difference between this example and example 1 is:

[0074] S1, 80 kg of chitosan solution, 20 kg of graphene modified flexible fiber, 0.5 kg of glycerol, and 0.2 kg of glutaraldehyde are mixed and stirred uniformly, and a film is obtained by casting. The chitosan solution is prepared by the preparation example 11, the graphene modified flexible fiber is prepared by the preparation example 8, and the rebound particles are prepared by the preparation example 5.

[0075] Example 3: The difference between this example and example 1 is:

[0076] S1, 100 kg of chitosan solution, 30 kg of graphene modified flexible fiber, 1 kg of glycerol, and 0.5 kg of glutaraldehyde are mixed and stirred uniformly, and a film is obtained by casting. The chitosan solution is prepared by the preparation example 12, the graphene modified flexible fiber is prepared by the preparation example 9, and the rebound particles are prepared by the preparation example 6.

[0077] Example 4: The difference between this example and example 1 is:

[0078] No porous silica gel particles are added to the rebound particles.

[0079] Example 5: This example differs from Example 1 in that:

[0080] No cellulose fibers are added to the carrier sepiolite.

[0081] Example 6: This example differs from Example 1 in that:

[0082] No chitosan quaternary ammonium salt solution is added to the carrier sepiolite.

[0083] Example 7: This example differs from Example 1 in that:

[0084] The porous sepiolite is not treated with a menthol solution.

[0085] Example 8: This example differs from Example 1 in that:

[0086] The cellulose fibers are not treated with a matrine solution.

[0087] Example 9: This example differs from Example 1 in that:

[0088] No talc and titanium dioxide are added to the chitosan solution.

[0089] Comparative Example 1: This comparative example differs from Example 1 in that:

[0090] No graphene-modified flexible fibers and rebound particles are added to the chitosan membrane.

[0091] Comparative Example 2: This comparative example differs from Example 1 in that:

[0092] The graphene-modified flexible fibers are replaced with silica fibers of the same mass in the chitosan membrane, and the silica fibers have a length of 100 μm.

[0093] Comparative Example 3: This comparative example differs from Example 1 in that:

[0094] No rebound particles are added to the chitosan membrane.

[0095] Comparative Example 4: This comparative example differs from Example 1 in that:

[0096] The semi-permeable membrane is an aromatic polyamide membrane, i.e., the semi-permeable membrane has no adsorption layer.

[0097] The finished semi-permeable membranes are prepared using the preparation methods of Examples 1-9 and Comparative Examples 1-4, respectively;

[0098] Take seawater, under the condition of pressure 1.55 MPa and flow rate 3 L / min, pre-press for 1 h, then test for 1 h, and calculate the water permeation flux according to the following formula:

[0099] Formula: J / Vp=At, wherein J represents flux, L·m -2 ·h -1 ; Vp represents the volume passed, L; A represents the effective area of the membrane, m 2 .

[0100] The finished semi-permeable membrane is prepared by the preparation method of Examples 1-9 and Comparative Examples 1-4 respectively; the water permeation flux is detected again after 60 and 180 days of use;

[0101] And after 1 year of use, the total number of microorganisms on the adsorption layer and the aromatic polyamide membrane is detected, including microalgae, fungi, bacteria, viruses, etc.; wherein the number of microorganisms in seawater is about 1.4×10 7 CFU / mL.

[0102] The finished semi-permeable membrane is prepared by the preparation method of Examples 1-3 respectively; the contact angle of the semi-permeable membrane is tested by a video optical contact angle measuring instrument (OCA15EC).

[0103] Table 1 Performance test table

[0104]

[0105] It can be seen from Examples 1-3 and Table 1 that the semi-permeable membrane prepared in the application can efficiently separate bacteria, viruses, aquatic organisms and fresh water in seawater, and even under long-term use conditions, the semi-permeable membrane still has high separation efficiency and the surface is not easy to attach bacteria, viruses, aquatic organisms and other substances, thereby prolonging the service life of the semi-permeable membrane.

[0106] It can be seen from Examples 1 and Examples 4-9 and Table 1 that no multi-aperture silica gel particles are added in the rebound particles of Example 4, compared with Example 1, the difference between the water permeation flux and the initial flux of the semi-permeable membrane prepared in Example 4 after 60 d and 180 d of use is greater than the corresponding difference value of Example 1, and the number of microorganisms on the adsorption layer and the base layer surface is greater than that of Example 1; it is explained that the multi-aperture silica gel particles have a certain elasticity, which is convenient for filtering aquatic organisms and rebounding part of the attached surface organisms after pressure removal, thereby reducing the blockage of microorganisms in seawater and prolonging the service life of the semi-permeable membrane.

[0107] Example 5: The cellulose fiber is not added in the carrier sepiolite. Compared with Example 1, the difference between the water permeation flux after 60d, 180d and the initial flux of the semi-permeable membrane prepared in Example 5 is greater than the corresponding difference of Example 1, and the number of microorganisms on the surface of the adsorption layer and the base layer is greater than that of Example 1; It shows that the cellulose fiber plays a supporting role, ensuring water passing while blocking bacteria, thereby reducing the number of microorganisms in seawater adhering to the surface of the base layer, ensuring seawater desalination.

[0108] Example 6: The chitosan quaternary ammonium salt solution is not added in the carrier sepiolite. Compared with Example 1, the water permeation flux of the semi-permeable membrane prepared in Example 6 is less than that of Example 1, the difference between the water permeation flux after 60d, 180d and the initial flux is greater than the corresponding difference of Example 1, and the number of microorganisms on the surface of the adsorption layer and the base layer is greater than that of Example 1; It shows that chitosan quaternary ammonium salt not only has bactericidal effect, but also facilitates the bonding of carrier sepiolite with graphene modified flexible fiber and aromatic polyamide membrane, and the bacteria after sterilization no longer secrete sticky substances, so as to prevent microorganisms in seawater from adhering to the surface of the adsorption layer, thereby prolonging the service life of the semi-permeable membrane.

[0109] Example 7: The porous sepiolite is not treated with menthol solution, and Example 8: The cellulose fiber is not treated with sophoramine solution. Compared with Example 1, the difference between the water permeation flux after 60d, 180d and the initial flux of the semi-permeable membrane prepared in Examples 7 and 8 is greater than the corresponding difference of Example 1, and the number of microorganisms on the surface of the adsorption layer and the base layer is greater than that of Example 1; It shows that after sterilization by menthol and sophoramine, the inactivated bacteria are not easy to secrete sticky substances and adhere to the surface of the adsorption layer, and are convenient for removing part of the adhering microorganisms from the surface of the adsorption layer.

[0110] Example 9: The talc and titanium dioxide are not added in the chitosan solution. Compared with Example 1, the difference between the water permeation flux after 60d, 180d and the initial flux of the semi-permeable membrane prepared in Example 9 is greater than the corresponding difference of Example 1, and the number of microorganisms on the surface of the adsorption layer and the base layer is greater than that of Example 1; It shows that talc and carbon dioxide cooperate to make it difficult for microorganisms to adhere to the surface of the adsorption layer.

[0111] It can be seen from the combination of Example 1 and Comparative Examples 1-4 and Table 1 that, in the chitosan membrane of Comparative Example 1, no graphene modified flexible fiber and rebound particles are added, in the chitosan membrane of Comparative Example 2, the graphene modified flexible fiber is replaced by silica fiber of the same mass, and in the chitosan membrane of Comparative Example 3, no rebound particles are added. Compared with Example 1, the difference between the water permeation flux after 60 days and 180 days and the initial flux of the semi-permeable membrane prepared in Comparative Examples 1, 2 and 3 is greater than the corresponding difference of Example 1, and the number of microorganisms on the surface of the adsorption layer and the base layer is greater than that of Example 1. It is shown that the graphene modified flexible fiber and the rebound particles cooperate with each other, the rebound particles have good rebounding property, the rebounding chitosan membrane is convenient for rebounding the viruses, bacteria and other aquatic organisms attached to the surface of the chitosan membrane from the surface of the adsorption layer, so that the semi-permeable membrane still has high separation efficiency under the condition of long-term use, and the surface is not easy to attach bacteria, viruses, aquatic organisms and other substances, thereby prolonging the service life of the semi-permeable membrane.

[0112] The semi-permeable membrane of Comparative Example 4 is an aromatic polyamide membrane, i.e., the semi-permeable membrane has no adsorption layer. Compared with Example 1, the difference between the water permeation flux after 60 days and 180 days and the initial flux of the semi-permeable membrane prepared in Comparative Example 4 is greater than the corresponding difference of Example 1, and the number of microorganisms on the surface of the adsorption layer and the base layer is greater than that of Example 1. It is shown that the presence of the adsorption layer ensures the water flux, prevents the pores of the aromatic polyamide membrane from being blocked by microorganisms in seawater, and thus guarantees the desalination of seawater.

[0113] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the present specification, and the modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A semipermeable membrane for seawater desalination, characterized by, The semi-permeable membrane is composed of an aromatic polyamide film and an adsorption layer. The adsorption layer is composed of a chitosan film and rebound particles. The chitosan film comprises the following raw materials by weight: 80-100 parts of chitosan solution, 20-30 parts of graphene modified flexible fiber, 0.5-1 part of glycerol, and 0.2-0.5 part of glutaraldehyde. The rebound particles are composed of carrier sepiolite and multi-porous silica gel particles in a mass ratio of 1:0.2-0.4, and the carrier sepiolite is composed of multi-porous sepiolite, cellulose fiber and chitosan quaternary ammonium salt solution in a mass ratio of 1:0.2-0.5:0.4-0.8; the multi-porous sepiolite is prepared by treating multi-porous sepiolite particles with a menthol solution; and the cellulose fiber is prepared by treating cellulose fiber silk with a sophoridine solution. The semi-permeable membrane is prepared by the following method: S1, uniformly mix and stir the chitosan solution, graphene modified flexible fiber, glycerol and glutaraldehyde, flow cast a film, and uniformly spray the rebound particles on the surface of the film layer to obtain an adsorption layer; S2, uniformly spray ethyl cellulose solution around the aromatic polyamide film, then adhere the side of the adsorption layer provided with the rebound particles to the side of the aromatic polyamide film sprayed with the ethyl cellulose solution, and dry to obtain the finished semi-permeable membrane.

2. The semi-permeable membrane for seawater desalination according to claim 1, wherein The graphene modified flexible fiber is composed of aluminum oxide fiber, carbon fiber, graphene and ethyl cellulose solution in a mass ratio of 1:0.2-0.5:0.1-0.2:0.05-0.

1.

3. The semi-permeable membrane for seawater desalination according to claim 2, wherein The length of the aluminum oxide fiber is 60-100 μm, and the length of the carbon fiber is 20-40 μm.

4. The semi-permeable membrane for seawater desalination according to claim 1, wherein The chitosan solution is composed of chitosan dilute acetic acid solution, talc powder and titanium dioxide in a mass ratio of 1:0.1-0.2:0.05-0.

1.

5. The semi-permeable membrane for seawater desalination according to claim 4, wherein The particle size of the talc powder is 40-80 nm, and the particle size of the titanium dioxide is 10-40 nm.

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