A double-layer functionalized hollow fiber membrane and preparation method thereof

Abstract

The present invention relates to the research field of functional membrane materials and preparation methods thereof, and in particular to a double-layer functionalized hollow fiber membrane and a preparation method thereof. The present invention provides a preparation method of a double-layer functionalized hollow fiber membrane, comprising preparing a casting liquid, transversely extruding the casting liquid and longitudinally stretching the casting liquid, a first coagulation bath, a second coagulation bath, and a third coagulation bath. The double-layer functionalized hollow fiber membrane prepared by the present invention has a double-functional layer structure of a dense cortical antibacterial layer and a macroporous structure adsorption layer. The double-layer functionalized hollow fiber membrane has both separation and purification functions and antibacterial and adsorption functions. The double-layer functionalized hollow fiber membrane has high strength, is not easy to break, and has a wide range of applications.

Description

Technical Field

[0001] The invention relates to the research field of functional membrane materials and preparation methods thereof, and in particular to a double-layer functionalized hollow fiber membrane and a preparation method thereof. Background Art

[0002] Extracting uranium from seawater and treating nuclear wastewater require a large amount of adsorption and separation materials. Invention patent application number: 202311770819.1 A polyacrylonitrile hollow fiber membrane modified with amidoxime for extracting uranium from seawater and its preparation method were prepared, and an antibacterial layer was introduced into its outer layer, so that the hollow fiber membrane has a dual-functional layer. The introduction of the antibacterial layer caused the following problems:

[0003] The antibacterial component is used as the casting liquid 1 and is prepared separately into the antibacterial layer of the hollow fiber membrane. The adsorption active component is used as the casting liquid 2 and is prepared separately into the adsorption layer of the hollow fiber membrane. The antibacterial layer is coated on the already formed adsorption layer. The two have poor compatibility and the antibacterial layer can easily fall off from the adsorption layer. Even if the antibacterial layer does not fall off from the adsorption layer, since the adsorption layer has been formed, there is a dense layer on the surface of the adsorption layer. Then an antibacterial layer is coated on the adsorption layer, and another dense layer is formed when the antibacterial layer is formed. Due to the existence of two dense layers, the flux of the prepared hollow fiber membrane is significantly reduced, affecting the application field of the hollow fiber membrane.

[0004] If no antibacterial ingredients are added to the adsorption layer of the hollow fiber membrane, bacteria are likely to grow on the membrane surface, causing the adsorption sites on the surface of the adsorption material to be wrapped by bacteria, which is not conducive to adsorption; if antibacterial ingredients are added to the adsorption layer of the hollow fiber membrane, there is a problem of compatibility between the adsorption layer and the antibacterial layer. Adding or not adding an antibacterial layer to the adsorption layer of the hollow fiber membrane is a contradiction. Therefore, how to introduce an antibacterial layer into the adsorption material to prevent bacteria from growing on the surface of the adsorption material and ensure that the adsorption layer and the antibacterial layer are well organically combined into a whole is a technical problem.

[0005] The above problems affect and restrict each other, which seriously hinders the industrialization process of adsorption materials and must be solved comprehensively and systematically. The existing technology has the following technical difficulties in comprehensively solving the above problems:

[0006] The antibacterial component is used as the casting liquid 1, and is prepared separately as the antibacterial layer of the hollow fiber membrane. The adsorption active component is used as the casting liquid 2, and is prepared separately as the adsorption layer of the hollow fiber membrane. It is difficult to organically combine the antibacterial layer and the adsorption layer. First, whether the antibacterial layer is prepared first and then the adsorption layer is coated on the antibacterial layer, or the adsorption layer is prepared first and then the antibacterial layer is coated on the adsorption layer, there will be an initial skin layer on the first preparation, resulting in two skins of the membrane material, and the antibacterial layer and the adsorption layer are not firmly combined, and the antibacterial layer and the adsorption layer are easily peeled off, resulting in the functionalized hollow fiber membrane not being a whole, resulting in the functionalized hollow fiber membrane being unusable; second, after preparing one layer, another layer is immediately coated on it. At this time, the first layer is still in the liquid state, and the second layer is easy to penetrate into the first layer under the action of gravity, which will cause the adsorption site to be buried, causing the adsorption active site in the adsorption component to be inactivated, and the antibacterial layer and the adsorption layer cannot function independently, and the antibacterial component layer and the adsorption active layer cannot achieve a good organic composite.

[0007] Since the adsorption layer has been formed, there is a dense layer on the surface of the adsorption layer, and then an antibacterial layer is coated on the adsorption layer. When the antibacterial layer is formed, another dense layer is formed. Due to the existence of the dense layer between the antibacterial layer and the adsorption layer, the flux of the prepared hollow fiber membrane is significantly reduced.

[0008] On the basis of the existing adsorption layer, the introduction of the antibacterial layer will increase the resistance of water passing through the hollow fiber membrane, which is not conducive to the passage of water through the hollow fiber membrane, thereby causing the hollow fiber membrane flux to decrease. If the antibacterial component layer is coated too thickly, the prepared hollow fiber membrane can play a good antibacterial role, but the hollow fiber membrane has a low water flux due to the large resistance to water passing through; if the antibacterial component layer is coated too thinly, the antibacterial components retained in the membrane will be too few and will not play an antibacterial role.

[0009] The existing technology for preparing double-layer membranes generally adopts a process in which two functional layer materials undergo phase transformation at the same time to form a shape. This preparation process is generally difficult to achieve two functional materials with different shapes and structures. The reasons are as follows: First, after preparing the adsorption layer, another antibacterial layer is immediately coated on it. At this time, the first prepared adsorption layer is still in a liquid state. The antibacterial layer can easily penetrate into the adsorption layer under the action of gravity, which will cause the antibacterial layer and the adsorption layer to mix together and cannot function independently, and it is impossible to obtain a double-layer functional hollow fiber membrane with a dense cortical antibacterial layer and a macroporous structure adsorption layer; second, the antibacterial layer and the adsorption layer are immersed in water and undergo phase transformation at the same time. There is no control over the order of phase transformation, which causes the adsorption layer to form a dense cortical layer, and thus it is impossible to prepare a double-layer functional hollow fiber membrane with a dense cortical antibacterial layer and a macroporous structure adsorption layer. Summary of the invention

[0010] In view of the above technical problems and technical difficulties, the following technical ideas are proposed:

[0011] Regarding technical difficulty 1: the present invention first prepares casting liquid 1 and casting liquid 2, wherein casting liquid 1 is a uniform casting liquid of polyacrylonitrile polymer material containing antibacterial components, and casting liquid 2 is a uniform casting liquid with adsorption components grafted onto polyacrylonitrile polymer material; secondly, casting liquid 1 and casting liquid 2 are simultaneously ejected laterally from a spinneret, and then a longitudinal stretching film-forming process is adopted, thereby avoiding mutual penetration between the two casting liquids due to gravity; finally, an inner liner is used instead of the core liquid, and the curing and molding sequence of the casting liquid is controlled to start with the antibacterial layer first, and the adsorption layer is formed last, and at the same time, the time for the casting liquid to be exposed to the air is controlled, and the casting liquid directly enters the coagulation bath after coming out of the spinneret, thereby ensuring that the two layers will not be stratified, and at the same time, the antibacterial layer can be cured first and the adsorption layer can be cured later, thereby achieving the goal that the antibacterial components will not penetrate into the adsorption layer. By utilizing the synergistic effect of various processes, complementing each other and interacting with each other to form a whole, it is fully guaranteed that the antibacterial layer and the adsorption layer of the hollow fiber membrane are well organically combined, and the phenomenon of two layers of membrane material being prevented, the antibacterial layer and the adsorption layer being not firmly combined, and the two layers being easily peeled off is prevented, thereby fully ensuring that the prepared functionalized hollow fiber membrane is a whole.

[0012] Regarding technical difficulty 2: The present invention uses a casting liquid 1 containing an antibacterial component and a casting liquid 2 containing an adsorption component to extrude the liquid laterally through a spinneret, and controls the thickness of the mold between the two layers of casting liquid on the spinneret. At the same time, an inner lining is introduced and then longitudinal stretch spinning is adopted. The curing and molding sequence of the casting liquid can be controlled. The casting liquid 1 is cured first, and the casting liquid 2 is cured later. Such regulation can eliminate the dense cortex between the antibacterial layer and the adsorption layer, thereby reducing the resistance of water passing through the double-layer functionalized hollow fiber membrane and increasing the water flux.

[0013] Regarding technical difficulty 3: the present invention first prepares casting liquid 1 and casting liquid 2 with the antibacterial component and the adsorption active component respectively, so as to ensure the uniformity and stability of the casting liquid; secondly, the two casting liquids are extruded through the spinneret together, and the liner is introduced and then longitudinal stretching and spinning are adopted, so as to control the curing and molding sequence of the casting liquids, firstly, the casting liquid 1 is cured, so that the prepared double-layer functionalized hollow fiber membrane has an antibacterial layer with a dense cortical structure, and then the casting liquid 2 is cured again, so that the prepared double-layer functionalized hollow fiber The membrane has an adsorption layer with a macroporous structure, so that a double-layer functionalized hollow fiber membrane with a dense cortical antibacterial layer and a macroporous adsorption layer can be prepared. The second is to increase the strength of the functionalized hollow fiber membrane, and the third is to make the double-layer functionalized hollow fiber membrane easier to form; finally, through multiple different coagulation baths, coagulation bath compositions and temperature control, the double-layer functionalized hollow fiber membrane is formed to prevent the loss of antibacterial components and the diffusion of antibacterial components to the adsorption layer during the later membrane curing, so that the antibacterial layer and the adsorption layer can independently play the antibacterial and adsorption effects. The synergistic effect between the processes is utilized to complement each other and interact with each other to form a whole, which fully ensures that the double-layer functionalized hollow fiber membrane has a double-layer structure with a dense cortical antibacterial layer and a macroporous adsorption layer.

[0014] The present invention is based on the above-mentioned inventive concept, and makes full use of the synergistic effect between the various components and processes, complementing each other, and interacting with each other to form a whole, rather than a simple combination. The composition and proportion of the casting liquid, the extrusion and stretching method of the casting liquid, the composition and temperature of the coagulation bath are systematically adjusted, and the membrane making process is coordinated to finally prepare a functionalized hollow fiber membrane.

[0015] In order to achieve the purpose of the present invention, the present invention adopts the following technical scheme:

[0016] A method for preparing a double-layer functionalized hollow fiber membrane comprises the following steps:

[0017] Step 1: Prepare casting solution: The formula of casting solution 1 is calculated by mass percentage: 10%-16% polyacrylonitrile powder, 0.5%-5% water-insoluble antibacterial component, 0.5%-10% thickener, 6%-15% porogen, 54%-83% solvent, and the sum of each component is 100%. The preparation order of casting solution 1 is as follows: first, add a certain amount of solvent into a three-necked flask, add porogen and thickener in turn according to the formula ratio of casting solution 1, heat and stir, and heat to temperature The mixture was stirred at 40-80°C for 0.5 h, and then polyacrylonitrile powder and water-insoluble antibacterial ingredients were added according to the ratio of casting liquid 1, heated and stirred at 60-80°C for 0.5 h, and finally the remaining solvent was added according to the ratio of casting liquid 1, heated and stirred at 60-80°C for 8 h, and then the temperature of casting liquid 1 was adjusted to 50°C, and the mixture was heated at 10 rpm under a negative pressure of 0.05 MPa. / min speed, stirring and degassing for 1h-6h to obtain casting liquid 1; the formula of casting liquid 2 is calculated by mass percentage: 8%-12% polyacrylonitrile powder, 1%-8% polyethyleneimine, 10%-15% porogen, 65%-81% solvent, the sum of each component is 100%, and the preparation order of casting liquid 2 is as follows: first, a certain amount of solvent is added into a three-necked flask, and the porogen is added according to the formula ratio of casting liquid 2, heated and stirred, the heating temperature is 50℃-80℃, and then polyacrylonitrile powder is added according to the formula ratio of casting liquid 2, heated and stirred, the heating temperature is 50℃-80℃, and the stirring time is 0.5h, and then polyethyleneimine is added according to the formula ratio of casting liquid 2, and finally the remaining solvent is added according to the formula ratio of casting liquid 2, heated and stirred, the heating temperature is 60℃-80℃, and the stirring time is continued for 8h, and then the temperature of casting liquid 2 is adjusted to 50℃, and under a negative pressure of 0.05MPa, it is allowed to stand and degas for 1h-6h to obtain casting liquid 2;

[0018] Step 2: the inner liner enters the spinneret through the wire feeding device, the inner liner replaces the core liquid, the casting liquid 1 and the casting liquid 2 enter the feed pump at 0.3MPa, and the feed pump controls the speed to simultaneously and transversely drive different amounts of the casting liquid 1 and the casting liquid 2 into the spinneret, the casting liquid 2 is coated on the inner liner, the casting liquid 1 is coated on the outside of the casting liquid 2, and the inner liner is longitudinally stretched and directly enters the first coagulation bath;

[0019] Step 3: The first coagulation bath is composed of a mixture of 95%-99.5% pure water and 0.5%-5% water-soluble antibacterial components. The temperature of the mixture in the first coagulation bath is controlled at 41°C-50°C. The functionalized hollow fiber membrane stays in the first coagulation bath for 10s-30s. The functionalized hollow fiber membrane enters the second coagulation bath after coming out of the first coagulation bath.

[0020] Step 4: The second coagulation bath is composed of a mixture of 50%-90% pure water and 10%-50% chelating agent, the temperature of the pure water in the second coagulation bath is controlled at 41°C-50°C, and the functionalized hollow fiber membrane enters the third coagulation bath after coming out of the second coagulation bath;

[0021] Step 5: The third coagulation bath is composed of pure water, and the temperature of the third coagulation bath is controlled at 50° C.-80° C. to obtain a functionalized hollow fiber membrane;

[0022] The water-insoluble antibacterial component is one or both of cuprous oxide and cupric oxide, the water-soluble antibacterial component is one or both of cupric chloride and cupric sulfate, the thickener is one or more of PVPK90, PVPK60, PVPK30, POLYOXWSR N-750, POLYOX WSR N-80, POLYOX WSR N-10, POLYOX WSR N-308, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose; and the chelating agent is one or both of disodium ethylenediaminetetraacetate and tetrasodium ethylenediaminetetraacetate.

[0023] Technical description: Step 1: The purpose of preparing casting liquid 1 and casting liquid 2 separately in step 1 is to ensure the uniformity and stability of the casting liquid; adding water-insoluble antibacterial components to casting liquid 1 is: first, to make the prepared functionalized membrane have antibacterial function, and second, to prevent the antibacterial components from being lost to the first coagulation bath when casting liquid 1 enters the first coagulation bath, so that the prepared functionalized hollow fiber membrane has more antibacterial components; adding thickener to casting liquid 1 is to increase the viscosity of casting liquid 1, thereby preventing the aggregation or stratification of water-insoluble antibacterial components in the prepared casting liquid 1, and stirring and degassing casting liquid 1 at a speed of 10 rpm for 1h-6h is to prevent the aggregation or stratification of water-insoluble antibacterial components due to gravity; adding polyethyleneimine to casting liquid 2 is: first, to make the prepared functionalized hollow fiber membrane have adsorption function, and second, to enable polyethyleneimine to be grafted onto polyacrylonitrile during the preparation of casting liquid 2, so that polyethyleneimine can stably exist in the functionalized hollow fiber membrane body.

[0024] Step 2: In step 2, the inner lining replaces the core liquid: first, to control the curing and molding order of the casting liquids, first let the casting liquid 1 solidify, and then the casting liquid 2 solidify, so as to prevent the antibacterial components from diffusing to the adsorption layer in the initial ecological membrane; second, to increase the strength of the functionalized hollow fiber membrane; third, to ensure that the prepared functionalized hollow fiber membrane has an antibacterial layer with a dense skin and an adsorption layer with a macroporous structure; fourth, to make the functionalized hollow fiber membrane easy to form; the feed pump simultaneously and horizontally injects different amounts of casting liquid 1 and casting liquid 2 into the spinneret by adjusting the rotation speed: first, to control the thickness of the antibacterial layer and the adsorption layer respectively; second, to ensure that the antibacterial layer and the adsorption layer are well organically combined to prevent the formation of two layers of skin, the antibacterial layer and the adsorption layer from being firmly combined, and the antibacterial layer and the adsorption layer from being peeled off, so as to fully ensure that the prepared functionalized hollow fiber membrane is a whole; the inner lining is longitudinally stretched and directly enters the first coagulation bath to avoid penetration between the two casting liquids due to gravity.

[0025] Step 3: The composition of the first coagulation bath in step 3 is a mixture of 95%-99.5% pure water and 0.5%-5% water-soluble antibacterial components. This is to fully ensure that when the casting liquid enters the first coagulation bath and undergoes an instantaneous phase transformation into an initial membrane, on the one hand, the antibacterial components will not diffuse into the first coagulation bath, and on the other hand, the functionalized hollow fiber membrane forms a dense cortex on the outer surface of the antibacterial layer to prevent the loss of antibacterial components in the later stage; the temperature of the mixture in the first coagulation bath is controlled at 41°C-50°C in order to regulate the instantaneous phase transformation rate and prevent the antibacterial components from diffusing into the first coagulation bath; the residence time of the functionalized hollow fiber membrane in the first coagulation bath is controlled to be 10s-30s in order to prevent the water-soluble antibacterial components in the first coagulation bath from entering the adsorption layer.

[0026] Step 4: The second coagulation bath in step 4 is composed of a mixture of 50%-90% pure water and 10%-50% chelating agent, firstly to remove the residual water-soluble antibacterial components in the first coagulation bath on the functionalized hollow fiber membrane, and secondly to make the insoluble antibacterial components in the casting liquid 1 migrate to the outer surface and prevent the insoluble antibacterial components from diffusing to the adsorption layer; the temperature of the pure water in the second coagulation bath is controlled at 41°C-50°C, in order to regulate the rate of phase transformation of the casting liquid 1 and the casting liquid 2, to ensure that the prepared functionalized hollow fiber membrane has an antibacterial layer with a dense skin and an adsorption layer with a macroporous structure, and at the same time to prevent the formation of two layers of skin, the loose bonding between the antibacterial layer and the adsorption layer, and the peeling off of the antibacterial layer and the adsorption layer, so as to further ensure that the prepared functionalized hollow fiber membrane is a whole.

[0027] Step 5: The third coagulation bath composition in step 5 is pure water in order to fully elute the solvent in the casting liquid; the temperature of the third coagulation bath is controlled at 50°C-80°C, firstly to make the antibacterial layer and the adsorption layer more firmly bonded and more difficult to peel off, and secondly to make the adsorption layer and the inner lining bond more tightly, so that the antibacterial layer, the adsorption layer and the inner lining are more tightly bonded, fully ensuring that the prepared functional hollow fiber membrane is a whole.

[0028] Beneficial effects: (1) The prepared double-layer functionalized hollow fiber membrane has a three-layer structure with the outermost layer being an antibacterial layer, the middle layer being an adsorption layer, and the innermost layer being a support layer. The three-layer structure is an organic whole; (2) The structure of the functionalized hollow fiber membrane can be regulated so that the double-layer functionalized hollow fiber membrane has a dense cortex with antibacterial function and a macroporous structure with adsorption function; (3) The double-layer functionalized hollow fiber membrane has both separation and purification functions and antibacterial and adsorption functions; (4) The double-layer functionalized hollow fiber membrane has high strength, is not easy to break, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 : Microscope photos of different antibacterial layer thicknesses of the double-layer functionalized hollow fiber membrane prepared in Example 1.

[0030] Figure 2 : Scanning electron micrograph of the cross section of the double-layer functionalized hollow fiber membrane prepared in Example 2.

[0031] Figure 3 : Infrared image of the double-layer functionalized hollow fiber membrane prepared in Example 3.

[0032] Figure 4 : XPS spectrum of the double-layer functionalized hollow fiber membrane Cu2p prepared in Example 4.

[0033] Figure 5 : Scanning electron micrograph of the cross section of the double-layer functionalized hollow fiber membrane prepared in Example 8.

[0034] Figure 6 : Antibacterial photos of the double-layer functionalized hollow fiber membrane prepared in Example 10. DETAILED DESCRIPTION

[0035] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0036] Example 1

[0037] A method for preparing a double-layer functionalized hollow fiber membrane comprises the following steps:

[0038] Step 1: Prepare casting solution: The formula of casting solution 1 is calculated by mass percentage: 10%-16% polyacrylonitrile powder, 0.5%-5% water-insoluble antibacterial component, 0.5%-10% thickener, 6%-15% porogen, 54%-83% solvent, and the sum of each component is 100%. The preparation order of casting solution 1 is as follows: first, add a certain amount of solvent into a three-necked flask, add porogen and thickener in turn according to the formula ratio of casting solution 1, heat and stir, and heat to temperature The mixture was stirred at 40-80°C for 0.5 h, and then polyacrylonitrile powder and water-insoluble antibacterial ingredients were added according to the ratio of casting liquid 1, heated and stirred at 60-80°C for 0.5 h, and finally the remaining solvent was added according to the ratio of casting liquid 1, heated and stirred at 60-80°C for 8 h, and then the temperature of casting liquid 1 was adjusted to 50°C, and the mixture was heated at 10 rpm under a negative pressure of 0.05 MPa. / min speed, stirring and degassing for 1h-6h to obtain casting liquid 1; the formula of casting liquid 2 is calculated by mass percentage: 8%-12% polyacrylonitrile powder, 1%-8% polyethyleneimine, 10%-15% porogen, 65%-81% solvent, the sum of each component is 100%, and the preparation order of casting liquid 2 is as follows: first, a certain amount of solvent is added into a three-necked flask, and the porogen is added according to the formula ratio of casting liquid 2, heated and stirred, the heating temperature is 50℃-80℃, and then polyacrylonitrile powder is added according to the formula ratio of casting liquid 2, heated and stirred, the heating temperature is 50℃-80℃, and the stirring time is 0.5h, and then polyethyleneimine is added according to the formula ratio of casting liquid 2, and finally the remaining solvent is added according to the formula ratio of casting liquid 2, heated and stirred, the heating temperature is 60℃-80℃, and the stirring time is continued for 8h, and then the temperature of casting liquid 2 is adjusted to 50℃, and under a negative pressure of 0.05MPa, it is allowed to stand and degas for 1h-6h to obtain casting liquid 2;

[0039] Step 2: the inner liner enters the spinneret through the wire feeding device, the inner liner replaces the core liquid, the casting liquid 1 and the casting liquid 2 enter the feed pump at 0.3MPa, and the feed pump controls the speed to simultaneously and transversely drive different amounts of the casting liquid 1 and the casting liquid 2 into the spinneret, the casting liquid 2 is coated on the inner liner, the casting liquid 1 is coated on the outside of the casting liquid 2, and the inner liner is longitudinally stretched and directly enters the first coagulation bath;

[0040] Step 3: The first coagulation bath is composed of a mixture of 95%-99.5% pure water and 0.5%-5% water-soluble antibacterial components. The temperature of the mixture in the first coagulation bath is controlled at 41°C-50°C. The functionalized hollow fiber membrane stays in the first coagulation bath for 10s-30s. The functionalized hollow fiber membrane enters the second coagulation bath after coming out of the first coagulation bath.

[0041] Step 4: The second coagulation bath is composed of a mixture of 50%-90% pure water and 10%-50% chelating agent, the temperature of the pure water in the second coagulation bath is controlled at 41°C-50°C, and the functionalized hollow fiber membrane enters the third coagulation bath after coming out of the second coagulation bath;

[0042] Step 5: The third coagulation bath is composed of pure water, and the temperature of the third coagulation bath is controlled at 50° C.-80° C. to obtain a functionalized hollow fiber membrane;

[0043] The water-insoluble antibacterial component is one or both of cuprous oxide and cupric oxide, the water-soluble antibacterial component is one or both of cupric chloride and cupric sulfate, the thickener is one or more of PVPK90, PVPK60, PVPK30, POLYOXWSR N-750, POLYOX WSR N-80, POLYOX WSR N-10, POLYOX WSR N-308, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose; and the chelating agent is one or both of disodium ethylenediaminetetraacetate and tetrasodium ethylenediaminetetraacetate.

[0044] In this example, functionalized hollow fiber membranes with different antibacterial layer thicknesses were prepared. Microscope photos of double-layer functionalized hollow fiber membranes with different antibacterial layer thicknesses are shown in Figure 2. Figure 1 shown.

[0045] Example 2

[0046] This embodiment is basically the same as the method for preparing a double-layer functionalized hollow fiber membrane described in Example 1, except that: in step 1, the water-insoluble antibacterial component of the casting liquid 1 is cuprous oxide, and the ratio is 1%; in step 3, the first coagulation bath is composed of a mixture of 99% pure water and 1% water-soluble antibacterial component cupric chloride, the temperature of the mixture in the first coagulation bath is controlled at 45°C, and the residence time of the functionalized hollow fiber membrane in the first coagulation bath is 10s.

[0047] Technical description: This embodiment regulates the water-insoluble antibacterial component and its proportion, the composition and temperature of the first coagulation bath, and the residence time of the functionalized hollow fiber membrane in the first coagulation bath in order to prevent the water-insoluble antibacterial component cuprous oxide from diffusing into the first coagulation bath, and at the same time prevent the water-soluble antibacterial component in the first coagulation bath from entering the adsorption layer, so as to fully ensure that the prepared functionalized hollow fiber membrane has antibacterial function. The cross-sectional scanning electron microscope image of the double-layer functionalized hollow fiber membrane prepared in Example 2 is shown in FIG. Figure 2 .

[0048] Example 3

[0049] This embodiment is basically the same as the method for preparing a double-layer functionalized hollow fiber membrane described in Example 2, except that the second coagulation bath in step 4 is composed of a mixture of 50% pure water and 50% chelating agent disodium ethylenediaminetetraacetate.

[0050] Technical description: In this embodiment, the composition of the second coagulation bath is regulated to remove the residual water-soluble antibacterial components in the first coagulation bath on the functionalized hollow fiber membrane, and to make the insoluble antibacterial components in the casting solution 1 migrate to the outer surface to prevent the insoluble antibacterial components from diffusing to the adsorption layer. Figure 3 .

[0051] Example 4

[0052] This embodiment is basically the same as the method for preparing a double-layer functionalized hollow fiber membrane described in Example 3, except that: in step 4, the temperature of the pure water in the second coagulation bath is controlled at 50°C; and in step 5, the temperature of the third coagulation bath is controlled at 80°C.

[0053] Technical description: In this embodiment, the temperature of the second coagulation bath is controlled in order to regulate the rate of phase transformation of casting liquid 1 and casting liquid 2, to ensure that the prepared functionalized hollow fiber membrane has an antibacterial layer with a dense skin and an adsorption layer with a macroporous structure, and to prevent the appearance of two layers of skin, the loose bonding between the antibacterial layer and the adsorption layer, and the peeling of the two layers, to further ensure that the prepared functionalized hollow fiber membrane is a whole; the temperature of the third coagulation bath is regulated, firstly, to make the antibacterial layer and the adsorption layer more firmly bonded, and the antibacterial layer and the adsorption layer less likely to peel off, and secondly, to make the adsorption layer and the inner lining more tightly bonded, so that the antibacterial layer, the adsorption layer and the inner lining are more tightly bonded, to fully ensure that the prepared functionalized hollow fiber membrane is a whole. The XPS spectrum of the double-layer functionalized hollow fiber membrane prepared in Example 4 is shown in Figure 4 .

[0054] Example 5

[0055] This embodiment is basically the same as the method for preparing a double-layer functionalized hollow fiber membrane described in Example 1, except that: in step 1, the water-insoluble antibacterial component copper oxide in the casting liquid 1 is 0.5%, the thickener is POLYOX WSRN-750 in the casting liquid 2, and the polyethyleneimine is 4%.

[0056] Technical description: In this embodiment, the composition and ratio of the casting liquid 1 and the casting liquid 2 are regulated to ensure the uniformity and stability of the casting liquid 1 and the casting liquid 2.

[0057] Example 6

[0058] This embodiment is basically the same as the method for preparing a double-layer functionalized hollow fiber membrane described in Example 5, except that: in step 3, the first coagulation bath composition is a mixture of 99.5% pure water and 0.5% water-soluble antibacterial component copper sulfate.

[0059] Technical description: In this embodiment, the composition of the first coagulation bath is regulated to prevent the water-insoluble antibacterial component copper oxide from diffusing into the first coagulation bath, thereby fully ensuring that the prepared functionalized hollow fiber membrane has antibacterial function.

[0060] Example 7

[0061] This embodiment is basically the same as the method for preparing a double-layer functionalized hollow fiber membrane described in Example 6, except that the second coagulation bath in step 4 is composed of a mixture of 60% pure water and 40% chelating agent tetrasodium ethylenediaminetetraacetate.

[0062] Technical description: In this embodiment, the composition of the second coagulation bath is regulated, firstly to remove the residual water-soluble antibacterial components in the first coagulation bath on the functionalized hollow fiber membrane, and secondly to make the insoluble antibacterial components in the casting liquid 1 migrate to the outer surface and prevent the insoluble antibacterial components from diffusing to the adsorption layer.

[0063] Example 8

[0064] This embodiment is basically the same as the method for preparing a double-layer functionalized hollow fiber membrane described in Example 7, except that: in step 3, the temperature of the mixture in the first coagulation bath is controlled at 50° C., and the residence time of the functionalized hollow fiber membrane in the first coagulation bath is 30 s.

[0065] Technical description: In this embodiment, the temperature of the first coagulation bath and the residence time of the functionalized hollow fiber membrane in the first coagulation bath are regulated in order to regulate the rate of instantaneous phase transformation of the casting solution 1, prevent the water-insoluble antibacterial component copper oxide from diffusing into the first coagulation bath, and prevent the water-soluble antibacterial component in the first coagulation bath from entering the adsorption layer, so as to fully ensure that the prepared functionalized hollow fiber membrane has antibacterial function. The scanning electron microscope image of the cross section of the double-layer functionalized hollow fiber membrane prepared in Example 8 is shown in FIG. Figure 5 .

[0066] Example 9

[0067] This embodiment is basically the same as the method for preparing a double-layer functionalized hollow fiber membrane described in Example 8, except that: in step 4, the temperature of the pure water in the second coagulation bath is controlled at 50°C; in step 5, the temperature of the third coagulation bath is controlled at 50°C.

[0068] Technical description: In this embodiment, the temperature of the second coagulation bath is controlled in order to regulate the rate of phase transformation of the casting liquid 1 and the casting liquid 2, to ensure that the prepared functionalized hollow fiber membrane has an antibacterial layer with a dense skin and an adsorption layer with a macroporous structure, and to prevent the appearance of two layers of skin, the antibacterial layer and the adsorption layer from being loosely bonded, and the antibacterial layer and the adsorption layer from being peeled off, thereby further ensuring that the prepared functionalized hollow fiber membrane is a whole; the temperature of the third coagulation bath is regulated, firstly, to make the antibacterial layer and the adsorption layer more firmly bonded, and the antibacterial layer and the adsorption layer are less likely to be peeled off, and secondly, to make the adsorption layer and the inner lining bonded more tightly, so that the antibacterial layer, the adsorption layer and the inner lining are more tightly bonded, thereby fully ensuring that the prepared functionalized hollow fiber membrane is a whole.

[0069] Example 10

[0070] This embodiment is basically the same as the method for preparing a double-layer functionalized hollow fiber membrane described in Example 1, except that: in step 1, the water-insoluble antibacterial component of the casting liquid 1 is cuprous oxide, the proportion is 5%, and the thickener is PVPK30, the proportion is 10%; in step 3, the first coagulation bath composition is a mixture of 95% pure water and 5% water-soluble antibacterial component copper sulfate, the temperature of the mixture in the first coagulation bath is controlled at 41°C, and the residence time of the functionalized hollow fiber membrane in the first coagulation bath is 20s; in step 4, the second coagulation bath composition is a mixture of 90% pure water and 10% chelating agents disodium ethylenediaminetetraacetic acid and tetrasodium ethylenediaminetetraacetic acid, the pure water temperature in the second coagulation bath is controlled at 41°C; in step 5, the temperature of the third coagulation bath is controlled at 65°C.

[0071] Technical description: In this embodiment, the composition and proportion of the casting liquid 1 are regulated in order to prepare a uniform and stable casting liquid; the composition and temperature of the first coagulation bath are regulated in order to regulate the rate of instantaneous phase transformation of the casting liquid 1, prevent the water-insoluble antibacterial component copper oxide from diffusing into the first coagulation bath, and fully ensure that the prepared functionalized hollow fiber membrane has antibacterial function; the residence time of the functionalized hollow fiber membrane in the first coagulation bath is controlled in order to prevent the water-soluble antibacterial components in the first coagulation bath from entering the adsorption layer; the composition and temperature of the second coagulation bath are regulated in order to regulate the rate of phase transformation of the casting liquid 1 and the casting liquid 2, and ensure that the prepared functionalized hollow fiber membrane has antibacterial function. The functionalized hollow fiber membrane has an antibacterial layer with a dense skin and an adsorption layer with a macroporous structure, and at the same time prevents the formation of two layers of skin, the loose bonding between the antibacterial layer and the adsorption layer, and the peeling of the two layers, further ensuring that the prepared functionalized hollow fiber membrane is a whole; the temperature of the third coagulation bath is regulated, firstly to make the antibacterial layer and the adsorption layer more firmly bonded, and the antibacterial layer and the adsorption layer are less likely to peel off, and secondly to make the adsorption layer and the lining bond more tightly, so that the antibacterial layer, the adsorption layer and the lining are more tightly bonded, fully ensuring that the prepared functionalized hollow fiber membrane is a whole. See the antibacterial photo of the double-layer functionalized hollow fiber membrane prepared in Example 10. Figure 6 .

Claims

1. A method for preparing a double-layer functionalized hollow fiber membrane, comprising the following steps: Step 1: Prepare casting solution: The formula of casting solution 1 is calculated by mass percentage: 10%-16% polyacrylonitrile powder, 0.5%-5% water-insoluble antibacterial component, 0.5%-10% thickener, 6%-15% porogen, 54%-83% solvent, and the sum of each component is 100%. The preparation order of casting solution 1 is as follows: first, add a certain amount of solvent into a three-necked flask, add porogen and thickener in turn according to the formula ratio of casting solution 1, heat and stir, and heat to temperature The mixture was stirred at 40-80°C for 0.5 h, and then polyacrylonitrile powder and water-insoluble antibacterial ingredients were added according to the ratio of casting liquid 1, heated and stirred at 60-80°C for 0.5 h, and finally the remaining solvent was added according to the ratio of casting liquid 1, heated and stirred at 60-80°C for 8 h, and then the temperature of casting liquid 1 was adjusted to 50°C, and the mixture was heated at 10 rpm under a negative pressure of 0.05 MPa. / min speed, stirring and degassing for 1h-6h to obtain casting liquid 1; the formula of casting liquid 2 is calculated by mass percentage: 8%-12% polyacrylonitrile powder, 1%-8% polyethyleneimine, 10%-15% porogen, 65%-81% solvent, the sum of each component is 100%, and the preparation order of casting liquid 2 is as follows: first, a certain amount of solvent is added into a three-necked flask, and the porogen is added according to the formula ratio of casting liquid 2, heated and stirred, the heating temperature is 50℃-80℃, and then polyacrylonitrile powder is added according to the formula ratio of casting liquid 2, heated and stirred, the heating temperature is 50℃-80℃, and the stirring time is 0.5h, and then polyethyleneimine is added according to the formula ratio of casting liquid 2, and finally the remaining solvent is added according to the formula ratio of casting liquid 2, heated and stirred, the heating temperature is 60℃-80℃, and the stirring time is continued for 8h, and then the temperature of casting liquid 2 is adjusted to 50℃, and under a negative pressure of 0.05MPa, it is allowed to stand and degas for 1h-6h to obtain casting liquid 2; Step 2: the inner liner enters the spinneret through the wire feeding device, the inner liner replaces the core liquid, the casting liquid 1 and the casting liquid 2 enter the feed pump at 0.3MPa, and the feed pump controls the speed to simultaneously and transversely drive different amounts of the casting liquid 1 and the casting liquid 2 into the spinneret, the casting liquid 2 is coated on the inner liner, the casting liquid 1 is coated on the outside of the casting liquid 2, and the inner liner is longitudinally stretched and directly enters the first coagulation bath; Step 3: The first coagulation bath is composed of a mixture of 95%-99.5% pure water and 0.5%-5% water-soluble antibacterial components. The temperature of the mixture in the first coagulation bath is controlled at 41°C-50°C. The functionalized hollow fiber membrane stays in the first coagulation bath for 10s-30s. The functionalized hollow fiber membrane enters the second coagulation bath after coming out of the first coagulation bath. Step 4: The second coagulation bath is composed of a mixture of 50%-90% pure water and 10%-50% chelating agent, the temperature of the pure water in the second coagulation bath is controlled at 41°C-50°C, and the functionalized hollow fiber membrane enters the third coagulation bath after coming out of the second coagulation bath; Step 5: The third coagulation bath is composed of pure water, and the temperature of the third coagulation bath is controlled at 50° C.-80° C. to obtain a functionalized hollow fiber membrane; in, The water-insoluble antibacterial component is one or both of cuprous oxide and cupric oxide, the water-soluble antibacterial component is one or both of cupric chloride and cupric sulfate, the thickener is one or more of PVPK90, PVPK60, PVPK30, POLYOX WSRN-750, POLYOX WSR N-80, POLYOX WSR N-10, POLYOX WSR N-308, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose; the chelating agent is one or both of disodium ethylenediaminetetraacetate and tetrasodium ethylenediaminetetraacetate.

2. A method for preparing a double-layer functionalized hollow fiber membrane according to claim 1, characterized in that: In step 1, the water-insoluble antibacterial component of the casting solution 1 is cuprous oxide, and the ratio is 1%; in step 3, the first coagulation bath is composed of a mixture of 99% pure water and 1% water-soluble antibacterial component cupric chloride, the temperature of the mixture in the first coagulation bath is controlled at 45°C, and the functionalized hollow fiber membrane stays in the first coagulation bath for 10s.

3. A method for preparing a double-layer functionalized hollow fiber membrane according to claim 2, characterized in that: The second coagulation bath in step 4 is composed of a mixture of 50% pure water and 50% chelating agent disodium ethylenediaminetetraacetate.

4. A method for preparing a double-layer functionalized hollow fiber membrane according to claim 3, characterized in that: In step 4, the temperature of pure water in the second coagulation bath is controlled at 50°C; in step 5, the temperature of the third coagulation bath is controlled at 80°C.

5. The method for preparing a double-layer functionalized hollow fiber membrane according to claim 1, characterized in that: In step 1, the water-insoluble antibacterial component copper oxide in the casting liquid 1 is 0.5%, the thickener is POLYOX WSR N-750, the proportion is 2%, and the casting liquid 2 polyethyleneimine is 4%.

6. A method for preparing a double-layer functionalized hollow fiber membrane according to claim 5, characterized in that: In step 3, the first coagulation bath is composed of a mixture of 99.5% pure water and 0.5% water-soluble antibacterial component copper sulfate.

7. A method for preparing a double-layer functionalized hollow fiber membrane according to claim 6, characterized in that: The second coagulation bath in step 4 is composed of a mixture of 60% pure water and 40% chelating agent tetrasodium ethylenediaminetetraacetate.

8. A method for preparing a double-layer functionalized hollow fiber membrane according to claim 7, characterized in that: Step 3: The temperature of the mixture in the first coagulation bath is controlled at 50° C., and the residence time of the functionalized hollow fiber membrane in the first coagulation bath is 30 seconds.

9. A method for preparing a double-layer functionalized hollow fiber membrane according to claim 8, characterized in that: In step 4, the temperature of pure water in the second coagulation bath is controlled at 50°C; in step 5, the temperature of the third coagulation bath is controlled at 50°C.

10. The method for preparing a double-layer functionalized hollow fiber membrane according to claim 1, characterized in that: In step 1, the water-insoluble antibacterial component of the casting liquid 1 is cuprous oxide, the proportion is 5%, and the thickener is PVPK30, the proportion is 10%; in step 3, the first coagulation bath composition is a mixture of 95% pure water and 5% water-soluble antibacterial component copper sulfate, the temperature of the mixture in the first coagulation bath is controlled at 41°C, and the residence time of the functionalized hollow fiber membrane in the first coagulation bath is 20s; in step 4, the second coagulation bath composition is a mixture of 90% pure water and 10% chelating agents disodium ethylenediaminetetraacetic acid and tetrasodium ethylenediaminetetraacetic acid, and the pure water temperature in the second coagulation bath is controlled at 41°C; in step 5, the temperature of the third coagulation bath is controlled at 65°C.

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