Hollow fiber membrane based on metal polyphenol coordination, preparation method and application thereof, and membrane module

Abstract

The invention provides a hollow fiber membrane based on metal polyphenol coordination, a preparation method and application of the hollow fiber membrane and a membrane module. The invention relates to a preparation method of a hollow fiber membrane based on metal polyphenol coordination, which comprises the following steps: mixing polyvinylidene fluoride, polyvinylpyrrolidone, a polyphenol ligand, a metal ion solution and an organic solvent, heating and stirring, standing and defoaming to form a membrane casting solution; spinning the membrane casting solution and entering a coagulating bath to obtain a formed hollow fiber membrane; the formed hollow fiber membrane is soaked in deionized water, then soaked in a glycerin aqueous solution and dried, and the hollow fiber membrane based on the metal polyphenol coordination effect is obtained. The preparation method of the hollow fiber membrane is simple in steps, easy to control and low in equipment requirement. The hollow fiber membrane provided by the invention has high retention rate, high flux and high permeation flux, specifically, the retention rate can reach 99.8% or above; the maximum water flux can reach 804L m <-2 > h <-1 > bar <-1 >; the permeation flux of the emulsified oil can be up to 438L m <-2 > h <-1 > bar <-1 >.

Description

Technical Field

[0001] The present disclosure relates to the technical field of water treatment, and in particular to a hollow fiber membrane based on metal polyphenol coordination, a preparation method and application thereof, and a membrane component. Background Art

[0002] With the rapid development of industry, a large amount of oily wastewater has been generated in the petrochemical, food, textile and other industries. Conventional separation methods are difficult to effectively separate, causing urgent water pollution problems, especially for emulsified oil with small oil droplet size and strong adhesion. Membrane separation technology has received increasing attention in the field of emulsified oil wastewater treatment due to its advantages such as high separation efficiency, low energy consumption, simple operation procedures, no secondary pollution, and environmental friendliness. However, various organic components present in wastewater inevitably accumulate on the membrane surface, which usually leads to serious membrane pollution and reduces the permeability of the membrane, bringing thorny challenges to the basic research and practical application of membrane separation technology.

[0003] The anti-pollution mechanism of the membrane surface is crucial to the anti-pollution modification of the membrane. According to different principles, the anti-pollution mechanism is divided into "pollution resistance" mechanism and "pollution removal" mechanism. The former is mainly through the construction of a hydrophilic membrane surface, through the spatial repulsion effect and the formation of a hydration layer to prevent the contact between oil droplets and the membrane surface and the further spreading of oil droplets on the membrane surface. The latter is to reduce the membrane surface energy so that pollutants attached to the membrane surface can be more easily desorbed from the membrane surface. However, in the current membrane separation technology, there are problems such as severe membrane pollution and low separation efficiency in the process of oily wastewater treatment. Summary of the invention

[0004] The present disclosure provides a hollow fiber membrane based on metal polyphenol coordination, a preparation method and application thereof, and a membrane component, so as to at least solve one of the technical problems existing in the prior art.

[0005] According to a first aspect of the present disclosure, a method for preparing a hollow fiber membrane based on metal polyphenol coordination is provided, the preparation method comprising:

[0006] The polyvinylidene fluoride, polyvinyl pyrrolidone, polyphenol ligand, metal ion solution and organic solvent are mixed, heated and stirred, and allowed to stand for degassing to form a film casting solution;

[0007] Spinning the casting solution and placing it into a coagulation bath to obtain a formed hollow fiber membrane;

[0008] The formed hollow fiber membrane is immersed in deionized water, then immersed in a glycerol aqueous solution and then air-dried to obtain the hollow fiber membrane based on the coordination effect of metal polyphenols.

[0009] In one embodiment, based on the mass fraction of the casting solution being 100%, the polyvinylidene fluoride comprises 15% to 20%, polyvinyl pyrrolidone comprises 1% to 10%, polyphenol ligand comprises 0.1% to 1.2%, metal ion solution comprises 0.01% to 0.2%, and organic solvent comprises 70% to 80%.

[0010] In one embodiment, the polyphenol ligand is one or more of phytic acid, tannic acid, gallic acid, salicylic acid, caffeic acid, and p-hydroxybenzoic acid;

[0011] The metal ion solution is one or more of ferric chloride, copper chloride, manganese chloride, titanium chloride, zirconium chloride, and aluminum chloride;

[0012] The organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone;

[0013] The coagulation bath and the core liquid during spinning are both deionized water.

[0014] In one embodiment, the casting solution temperature is 30-40°C;

[0015] The coagulation bath temperature is 20-30°C, and the core liquid temperature during spinning is 20-30°C.

[0016] In one embodiment, the casting solution is spun in a spinning machine, wherein the winding speed is 10-20 m / min, the spinning pump flow rate is 10-30 mL / min, and the core liquid flow rate is 10-30 mL / min.

[0017] In one embodiment, the formed hollow fiber membrane is immersed in deionized water for 24 hours, the deionized water is replaced every 2 hours for the first 6 hours, and the deionized water is replaced again after immersion for 24 hours.

[0018] In one embodiment, the molded hollow fiber membrane is immersed in the glycerol aqueous solution for 24 hours, and the mass fraction of glycerol in the glycerol aqueous solution is 10% to 20%.

[0019] According to a second aspect of the present disclosure, there is provided a hollow fiber membrane based on metal polyphenol coordination, which is prepared by the preparation method described in any one of the above-mentioned embodiments.

[0020] According to a second aspect of the present disclosure, a membrane component is provided, comprising the hollow fiber membrane based on metal polyphenol coordination.

[0021] According to a third aspect of the present disclosure, there is provided an application of a hollow fiber membrane based on metal polyphenol coordination in oil-water separation.

[0022] Compared with the prior art, the advantages of the present invention are: 1) The preparation steps of the hollow fiber membrane of the present invention are simple, easy to control, and low in equipment requirements. 2) More importantly, the hollow fiber membrane of the present invention has high rejection rate, high flux, and high permeation flux. Specifically, the rejection rate can reach more than 99.8%; the water flux can reach up to 804L m -2 h -1 bar -1 ; The maximum permeation flux of emulsified oil can reach 438L m -2 h -1 bar -1 . 3) The present invention uses metal polyphenol coordination technology for the preparation of hollow fiber membranes. By constructing a hydrophilic membrane surface, the water flux and permeation flux of the membrane are greatly increased. No complicated synthesis process is required, and the preparation can be completed in one step. It is easy to carry out large-scale and industrial production on existing hollow fiber membrane production equipment, which has certain guiding significance for the large-scale preparation of hollow fiber membranes in the future. In summary, from the perspective of separation performance and preparation process, the hollow fiber membrane of the present invention has good application prospects.

[0023] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and other objects, features and advantages of the exemplary embodiments of the present disclosure will become readily understood by reading the detailed description below with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present disclosure are shown in an exemplary and non-limiting manner, in which:

[0025] In the drawings, the same or corresponding reference numerals represent the same or corresponding parts.

[0026] Figure 1 A scanning electron microscope image (overall) of a cross section of a hollow fiber membrane prepared in Example 1 of the present disclosure is shown;

[0027] Figure 2 A scanning electron microscope image (partial) of a cross section of a hollow fiber membrane prepared in Example 1 of the present disclosure is shown;

[0028] Figure 3 The pure water flux diagram of the hollow fiber membrane prepared in Examples 1 to 6 and Comparative Examples 1 to 2 of the present disclosure is shown;

[0029] Figure 4 The permeation flux diagram of the hollow fiber membranes prepared in Examples 1 to 6 and Comparative Examples 1 to 2 of the present disclosure is shown. DETAILED DESCRIPTION

[0030] In order to make the purpose, features, and advantages of the present disclosure more obvious and easy to understand, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present disclosure.

[0031] According to a first aspect of the present disclosure, the present invention provides a method for preparing a hollow fiber membrane based on metal polyphenol coordination, the preparation method comprising:

[0032] (1) mixing polyvinylidene fluoride, polyvinyl pyrrolidone, polyphenol ligand, metal ion solution and organic solvent, heating and stirring, standing and degassing to form a casting solution;

[0033] (2) spinning the casting solution and placing it into a coagulation bath to obtain a shaped hollow fiber membrane, and keeping the temperatures of the coagulation bath, the casting solution and the core solution constant;

[0034] (3) soaking the formed hollow fiber membrane in deionized water, replacing the deionized water to fully remove the organic solvent remaining on the membrane surface, and then soaking it in a glycerol aqueous solution and drying it to obtain the hollow fiber membrane based on the coordination effect of metal polyphenols.

[0035] The present application uses metal polyphenol coordination chemistry for hollow fiber ultrafiltration membrane preparation, without the need for complex synthesis process, the raw material source is easily available, and it is easy to carry out large-scale and industrialized production on existing hollow fiber membrane production equipment, which has certain guiding significance for the large-scale preparation of future hollow fiber membranes. In addition, since metal polyphenol coordination chemistry is currently only used to prepare flat membranes for laboratory pilot studies, it has not yet been explored in the preparation of hollow fiber membranes. The present invention uses metal polyphenol coordination chemistry for the preparation of hollow fiber membranes, by constructing a hydrophilic membrane surface, the water flux and permeation flux of the membrane are greatly increased, and without the need for a complex synthesis process, a one-step method can be prepared.

[0036] The preparation steps of the hollow fiber membrane of the present invention are simple, easy to control, and have low requirements on equipment. The hollow fiber membrane of the present invention has high retention rate, high flux, and high permeation flux. Specifically, the retention rate can reach more than 99.8%; the water flux can reach up to 804L m -2 h -1 bar -1 ; The maximum permeation flux of emulsified oil can reach 438L m -2 h -1 bar -1 .

[0037] The present invention applies metal polyphenol coordination technology to the preparation of hollow fiber membranes. By constructing a hydrophilic membrane surface, the water flux and permeation flux of the membrane are greatly increased. No complicated synthesis process is required and the preparation can be completed in one step. It is easy to carry out large-scale and industrial production on existing hollow fiber membrane production equipment, which has certain guiding significance for the large-scale preparation of hollow fiber membranes in the future.

[0038] In some embodiments, based on the mass fraction of the casting solution being 100%, the mass fractions of polyvinylidene fluoride are 15% to 20%, polyvinyl pyrrolidone is 1% to 10%, polyphenol ligands are 0.1% to 1.2%, metal ion solution is 0.01% to 0.2%, and organic solvents are 70% to 80%. Exemplarily, the mass fraction of polyvinylidene fluoride is 15%, 16%, 17%, 18%, 19%, 20%. The mass fraction of polyvinyl pyrrolidone is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%. The mass fraction of polyphenol ligands is 0.1%, 0.2%, 0.3%, 0.6%, 0.8%, 1%, 1.2%. The mass fraction of the metal ion solution is 0.01%, 0.05%, 0.10%, 0.15%, and 0.2%, and the mass fraction of the organic solvent is 70%, 72%, 74%, 76%, 78%, and 80%.

[0039] In some embodiments, the polyphenol ligand is one or more of phytic acid, tannic acid, gallic acid, salicylic acid, caffeic acid, and p-hydroxybenzoic acid;

[0040] The metal ion solution is one or more of ferric chloride, copper chloride, manganese chloride, titanium chloride, zirconium chloride, and aluminum chloride;

[0041] The organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone;

[0042] The coagulation bath and the core liquid during spinning are both deionized water.

[0043] In the present application, polyphenolic compounds such as phytic acid, tannic acid and gallic acid have more phenolic hydroxyl groups, have strong chelating ability with various metal ions, and can form a metal-polyphenol coordination network. Therefore, the use of metal-polyphenol coordination chemistry to prepare hydrophilic and anti-pollution hollow fiber membranes is of great significance in the field of oil-water separation.

[0044] In some embodiments, in step 1), the step of heating and stirring evenly and then standing is specifically: heating to 60-70° C. and then mechanically stirring for 6-8 hours, and then standing at 60-70° C. for 12-24 hours to degas.

[0045] In some embodiments, in step (1), the casting solution temperature is 30-40°C;

[0046] In the step (2), the coagulation bath temperature is 20-30°C, and the core liquid temperature during the spinning is 20-30°C.

[0047] In some embodiments, in step (2), spinning the casting solution is carried out in a hollow fiber spinning machine, wherein the specific parameters of the spinning process are: the winding speed is 10-20 m / min, the spinning pump flow is 10-30 mL / min, and the core liquid flow is 10-30 mL / min. The spinning pump temperature is constant at 30-35°C, the spinneret temperature is constant at 30-35°C, and the temperature of the core liquid and the coagulation bath is 20-30°C. The inner and outer diameters of the spinneret are 0.7 mm and 1.4 mm, respectively, the distance between the spinneret and the coagulation bath surface is 5 cm, the winding speed is 12 m / min, the spinning pump flow is 10 mL / min, and the core liquid flow is 15 mL / min.

[0048] In some embodiments, in step (3), the deionized water immersion time is 24 hours, the deionized water is replaced every 2 hours in the first 6 hours, and the deionized water is replaced again after immersion for 24 hours.

[0049] In some embodiments, in step (3), the molded hollow fiber membrane is immersed in the glycerol aqueous solution for 24 hours, and the mass fraction of glycerol in the glycerol aqueous solution is 10% to 20%.

[0050] According to the second aspect of the present disclosure, the present application provides a hollow fiber membrane based on metal polyphenol coordination, which is prepared by the preparation method described above.

[0051] According to a third aspect of the present disclosure, a membrane component is provided, comprising the hollow fiber membrane based on metal polyphenol coordination.

[0052] According to the fourth aspect of the present disclosure, the present application also provides the use of the hollow fiber membrane based on metal polyphenol coordination in oil-water separation.

[0053] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings, comparative examples and specific embodiments. The described specific embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0054] Example 1

[0055] A preparation method of a hollow fiber membrane based on the coordination of metal polyphenols (hereinafter referred to as "hollow fiber membrane"), the steps are as follows: 68g of polyvinylidene fluoride (FR904, industrial pure), 20g of polyvinyl pyrrolidone, 2.4g of phytic acid, 0.2g of anhydrous ferric chloride and 309.4g of N,N dimethylacetamide are added to the reactor of a hollow fiber spinning machine, mechanically stirred at 60°C for 8h, and then allowed to stand at 60°C for 15h for degassing to obtain a casting solution. The casting solution is used as a raw material, and a hollow fiber spinning machine is used for spinning. The casting solution is extruded under 0.15MPa nitrogen pressure and introduced into a coagulation bath at room temperature for curing and molding to obtain a molded hollow fiber membrane.

[0056] When spinning in a hollow fiber spinning machine, the spinning pump temperature is 32°C, the inner and outer diameters of the spinneret are 0.7 mm and 1.4 mm respectively, the distance between the spinneret and the water coagulation bath surface is 5 cm, the winding speed is 12 m / min, the spinning pump flow rate is 10 mL / min, and the core liquid flow rate is 15 mL / min.

[0057] The formed hollow fiber membrane was immersed in deionized water for 24 hours, and the deionized water was replaced every 2 hours in the first 6 hours, and the deionized water was replaced for the last time after 24 hours. The immersion time in the glycerol aqueous solution was 24 hours, and the glycerol aqueous solution was 15% by mass.

[0058] The pure water flux of the hollow fiber membrane in Example 1 is 804.1 L·m -2 h -1 bar -1 ,like Figure 3 In the oil-water emulsion (vacuum pump oil 0.1wt%, sodium dodecyl sulfate 0.01wt%, water 99.89wt%, mechanical stirring at 700r / min for 24h) separation test, the membrane permeation flux was maintained at 437.8L·m -2 h -1 bar -1 ,like Figure 4 The rejection rate is 99.8%, indicating that the introduction of phytic acid iron complex greatly improves the water flux and permeation flux of the membrane.

[0059] Example 2

[0060] Example 2 prepares a hollow fiber membrane based on metal polyphenol coordination. The steps of Example 2 are basically the same as those of Example 1, except that among the raw materials constituting the casting solution, the mass of phytic acid is 0.4 g and the mass of N,N-dimethylacetamide is 311.4 g.

[0061] The pure water flux of the hollow fiber membrane of Example 2 is 617.2 L·m -2 h -1 bar -1,like Figure 3 In the oil-water emulsion (vacuum pump oil 0.1wt%, sodium dodecyl sulfate 0.01wt%, water 99.89wt%, mechanical stirring at 700r / min for 24h) separation test, the membrane permeation flux was 216.3L·m -2 h -1 bar -1 ,like Figure 4 The rejection rate is 93.7%, indicating that the introduction of phytic acid iron complex greatly improves the water flux and permeation flux of the membrane.

[0062] Example 3

[0063] Example 3 prepares a hollow fiber membrane based on metal polyphenol coordination. The steps of Example 3 are basically the same as those of Example 1, except that among the raw materials constituting the casting solution, the mass of phytic acid is 0.8 g and the mass of N,N-dimethylacetamide is 311 g.

[0064] The pure water flux of the hollow fiber membrane of Example 3 is 556.6 L·m -2 h -1 bar -1 ,like Figure 3 In the oil-water emulsion (vacuum pump oil 0.1wt%, sodium dodecyl sulfate 0.01wt%, water 99.89wt%, mechanical stirring at 700r / min for 24h) separation test, the membrane permeation flux was 262.7L·m -2 h -1 bar -1 ,like Figure 4 The rejection rate is 97.1%, indicating that the introduction of phytic acid iron complex greatly improves the water flux and permeation flux of the membrane.

[0065] Example 4

[0066] Example 4 prepares a hollow fiber membrane based on metal polyphenol coordination. The steps of Example 4 are substantially the same as those of Example 1, except that among the raw materials constituting the casting solution, the mass of phytic acid is 1.2 g, and the mass of N,N-dimethylacetamide is 310.6 g.

[0067] The pure water flux of the hollow fiber membrane of Example 4 is 783.5 L·m -2 h -1 bar -1 ,like Figure 3 In the oil-water emulsion (vacuum pump oil 0.1wt%, sodium dodecyl sulfate 0.01wt%, water 99.89wt%, mechanical stirring at 700r / min for 24h) separation test, the membrane permeation flux was 295.2L·m -2 h -1 bar-1 ,like Figure 4 The rejection rate is 97.49%, indicating that the introduction of phytic acid iron complex greatly improves the water flux and permeation flux of the membrane.

[0068] Example 5

[0069] Example 5 prepares a hollow fiber membrane based on metal polyphenol coordination. The steps of Example 5 are substantially the same as those of Example 1, except that among the raw materials constituting the casting solution, the mass of phytic acid is 3.2 g, and the mass of N,N-dimethylacetamide is 308.6 g.

[0070] The pure water flux of the hollow fiber membrane of Example 5 is 447.8 L·m -2 h -1 bar -1 ,like Figure 3 In the oil-water emulsion (vacuum pump oil 0.1wt%, sodium dodecyl sulfate 0.01wt%, water 99.89wt%, mechanical stirring at 700r / min for 24h) separation test, the membrane permeation flux was 237.1L·m -2 h -1 bar -1 ,like Figure 4 As shown in the figure, the retention rate is 99.5%, indicating that the introduction of phytic acid iron complex greatly improves the water flux and permeation flux of the membrane.

[0071] Example 6

[0072] Example 6 prepares a hollow fiber membrane based on metal polyphenol coordination. The steps of Example 6 are substantially the same as those of Example 1, except that among the raw materials constituting the casting solution, the mass of phytic acid is 4.8 g, and the mass of N,N-dimethylacetamide is 307 g.

[0073] The pure water flux of the hollow fiber membrane of Example 6 is 358.3 L·m -2 h -1 bar -1 ,like Figure 3 In the oil-water emulsion (vacuum pump oil 0.1wt%, sodium dodecyl sulfate 0.01wt%, water 99.89wt%, mechanical stirring at 700r / min for 24h) separation test, the membrane permeation flux was 277.1L·m -2 h -1 bar -1 ,like Figure 4 The retention rate is 99.0%.

[0074] Comparative Example 1

[0075] A conventional method for preparing a hollow fiber membrane with polyvinylidene fluoride as the main material comprises the following steps: 68g polyvinylidene fluoride (FR904, industrial pure), 20g polyvinyl pyrrolidone and 312g N,N-dimethylacetamide are added to a reactor of a hollow fiber spinning machine, mechanically stirred at 60°C for 8h, and then allowed to stand at 60°C for 15h for degassing to obtain a casting solution. The casting solution is used as a raw material, and a hollow fiber spinning machine is used for spinning. The casting solution is extruded under 0.15MPa nitrogen pressure and introduced into a water coagulation bath at room temperature for curing and molding to obtain a molded hollow fiber membrane.

[0076] When spinning in a hollow fiber spinning machine, the spinning pump temperature is 35°C, the inner and outer diameters of the spinneret are 0.7 mm and 1.4 mm respectively, the distance between the spinneret and the water coagulation bath surface is 5 cm, the winding speed is 12 m / min, the spinning pump flow rate is 10 mL / min, and the core liquid flow rate is 15 mL / min.

[0077] The formed hollow fiber membrane was immersed in deionized water for 24 hours, and the deionized water was replaced every 2 hours in the first 6 hours, and the deionized water was replaced for the last time after 24 hours. The immersion time in the glycerol aqueous solution was 24 hours, and the glycerol aqueous solution was 15% by mass.

[0078] The pure water flux of the hollow fiber membrane of Comparative Example 1 is 348.1 L·m -2 h -1 bar -1 ,like Figure 3 In the oil-water emulsion (vacuum pump oil 0.1wt%, sodium dodecyl sulfate 0.01wt%, water 99.89wt%, mechanical stirring at 700r / min for 24h) separation test, the membrane permeation flux was 168.9L·m -2 h -1 bar -1 ,like Figure 4 The retention rate is 91.9%.

[0079] Comparative Example 2

[0080] A method for preparing a hollow fiber membrane for oil-water separation based on reactive surface segregation (hereinafter referred to as "hollow fiber membrane"), the steps are as follows: 68g polyvinylidene fluoride (FR904, industrial pure), 20g polyvinyl pyrrolidone, 2g 1,2,4,5-cyclohexanetetracarboxylic acid and 387.5g N,N-dimethylacetamide are added to the reactor of a hollow fiber spinning machine, mechanically stirred at 60°C for 8h, and then allowed to stand at 60°C for 15h for degassing to obtain a casting solution. The casting solution is used as a raw material, and a hollow fiber spinning machine is used for spinning. The casting solution is extruded under 0.15MPa nitrogen pressure and introduced into a room temperature aqueous solution coagulation bath for curing to obtain a molded hollow fiber membrane.

[0081] When spinning in a hollow fiber spinning machine, the spinning pump temperature is 35°C, the inner and outer diameters of the spinneret are 0.7 mm and 1.4 mm respectively, the distance between the spinneret and the water coagulation bath surface is 5 cm, the spinning speed is 12 m / min, the spinning pump flow rate is 10 mL / min, and the core liquid flow rate is 15 mL / min.

[0082] The formed hollow fiber membrane was immersed in deionized water for 24 hours, and the deionized water was replaced every 2 hours in the first 6 hours, and the deionized water was replaced for the last time after 24 hours. The immersion time in the glycerol aqueous solution was 24 hours, and the glycerol aqueous solution was 15% by mass.

[0083] The pure water flux of the hollow fiber membrane of Comparative Example 2 is 335.67 L·m -2 h -1 bar -1 ,like Figure 3 In the oil-water emulsion (vacuum pump oil 0.1wt%, sodium dodecyl sulfate 0.01wt%, water 99.89wt%, mechanical stirring at 700r / min for 24h) separation test, the membrane permeation flux was 237.81L·m -2 h -1 bar -1 ,like Figure 4 As shown. The retention rate is 99.5%.

[0084] In summary, the present invention uses a one-step method to complete the preparation of hollow fiber membrane, by the introduction of phytic acid iron metal coordination network, by the chelating ability between phytic acid and metal ions, the hydrophilicity of membrane surface is increased. By changing the concentration ratio of phytic acid iron, it is formed on the membrane surface The permeation flux of emulsified oil is improved by a hydrophilic layer. It is found by the above-mentioned comparative examples 1 to 2 and embodiments 1 to 6 pure water flux and permeation flux that, compared with the comparative example, the pure water flux and permeation flux of the hollow fiber membrane based on the coordination of metal polyphenols are improved, and the retention rate remains substantially unchanged, and the hollow fiber membrane comprehensive performance prepared by embodiment 1 reaches an optimum value.

[0085] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in this disclosure can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solutions disclosed in this disclosure can be achieved, and this document does not limit this.

[0086] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present disclosure, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0087] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A method for preparing a hollow fiber membrane based on metal polyphenol coordination, characterized in that: The preparation method comprises: The polyvinylidene fluoride, polyvinyl pyrrolidone, polyphenol ligand, metal ion solution and organic solvent are mixed, heated and stirred, and allowed to stand for degassing to form a film casting solution; Spinning the casting solution and placing it into a coagulation bath to obtain a formed hollow fiber membrane; The formed hollow fiber membrane is immersed in deionized water, then immersed in a glycerol aqueous solution and then air-dried to obtain the hollow fiber membrane based on the coordination effect of metal polyphenols.

2. The preparation method according to claim 1, characterized in that: Based on the mass fraction of the casting liquid being 100%, the polyvinylidene fluoride is 15% to 20%, the polyvinyl pyrrolidone is 1% to 10%, the polyphenol ligand is 0.1% to 1.2%, the metal ion solution is 0.01% to 0.2%, and the organic solvent is 70% to 80%.

3. The preparation method according to claim 1, characterized in that: The polyphenol ligand is one or more of phytic acid, tannic acid, gallic acid, salicylic acid, caffeic acid, and p-hydroxybenzoic acid; The metal ion solution is one or more of ferric chloride, copper chloride, manganese chloride, titanium chloride, zirconium chloride, and aluminum chloride; The organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone; The coagulation bath and the core liquid during spinning are both deionized water.

4. The preparation method according to claim 1, characterized in that: The casting liquid temperature is 30-40°C; The coagulation bath temperature is 20-30°C, and the core liquid temperature during spinning is 20-30°C.

5. The preparation method according to claim 1, characterized in that: The casting solution is spun in a spinning machine, wherein the winding speed is 10-20 m / min, the spinning pump flow rate is 10-30 mL / min, and the core liquid flow rate is 10-30 mL / min.

6. The preparation method according to claim 1, characterized in that: The formed hollow fiber membrane is immersed in deionized water for 24 hours, the deionized water is replaced every 2 hours in the first 6 hours, and the deionized water is replaced again after immersion for 24 hours.

7. The preparation method according to claim 6, characterized in that: The molded hollow fiber membrane is immersed in the glycerol aqueous solution for 24 hours, and the mass fraction of glycerol in the glycerol aqueous solution is 10% to 20%.

8. A hollow fiber membrane based on metal polyphenol coordination, characterized in that: It is prepared by the preparation method described in any one of claims 1 to 7.

9. A membrane module, characterized in that: It comprises the hollow fiber membrane based on metal polyphenol coordination as described in claim 8.

10. Use of the hollow fiber membrane based on metal polyphenol coordination as claimed in claim 8 in oil-water separation.

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