Self-cleaning anti-blocking three-dimensional ultrafiltration membrane and application thereof in wastewater treatment

Abstract

The application provides a self-cleaning anti-blocking three-dimensional ultrafiltration membrane and application thereof in wastewater treatment, and a preparation method thereof, which comprises the following steps: mixing polyvinyl alcohol, wood pulp fiber and water, heating and stirring to obtain a mixed solution; mixing tetrabutyl titanate, triethanolamine, glacial acetic acid and anhydrous ethanol, and uniformly stirring to obtain a transparent solution; mixing the mixed solution and the transparent solution, slowly dropping into a hydrochloric acid solution, and defoaming to obtain an electrostatic spinning solution; performing electrostatic spinning to obtain an electrostatic spinning membrane; and freeze-drying; and irradiating with ultraviolet rays after taking out to obtain the self-cleaning anti-blocking three-dimensional ultrafiltration membrane. The ultrafiltration membrane prepared by the application has a suitable pore size and a good filtering and retaining effect, and the freeze-drying method is used to form nano-pores on the surface of the ultrafiltration membrane, thereby increasing the adsorption property, and thus the ultrafiltration membrane has a good effect on removal of heavy metal ions. Therefore, the ultrafiltration membrane has the effects of ultrafiltration, adsorption and self-cleaning and anti-blocking.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane and its application in wastewater treatment. Background Technology

[0002] Ultrafiltration membranes are a type of porous membrane that primarily utilizes transmembrane pressure difference to trap larger molecules, such as colloids, microorganisms, and proteins, through the microporous structure of the membrane surface. This allows water and smaller solute molecules to permeate, ultimately achieving separation, concentration, and purification. During ultrafiltration membrane use, fouling is inevitable. Membrane fouling refers to the adsorption and deposition of particles, colloids, and biomolecules in the feed solution on the membrane surface or within the pores due to complex chemical or physical interactions. This results in a reduction in the effective pore size of the membrane, and may even lead to the formation of a filter cake, causing a significant decrease in membrane flux. When ultrafiltration membranes are applied in wastewater treatment, seawater desalination, and the food industry, membrane fouling is a particularly challenging problem, increasing operating costs and reducing efficiency, severely hindering the widespread application of ultrafiltration technology. Hydrophilic modification of the membrane surface can improve the hydrophobicity of ultrafiltration membranes, making them highly hydrophilic. When TiO2 membranes are used as ultrafiltration membranes, ultraviolet light irradiation is usually applied to enhance their hydrophilicity. However, if the ultrafiltration membrane is placed in the dark for several days, its hydrophilicity will weaken and it will revert to hydrophobicity unless continuously irradiated with ultraviolet light. Therefore, its superhydrophilicity is not sustainable, which seriously limits the application of TiO2 ultrafiltration membranes. Thus, how to maintain its superhydrophilic properties and achieve self-cleaning and anti-clogging effects during ultrafiltration is an urgent problem to be solved. Summary of the Invention

[0003] The technical problem to be solved: The purpose of this invention is to provide a self-cleaning and anti-clogging three-dimensional ultrafiltration membrane and its application in wastewater treatment. The ultrafiltration membrane is made from polyvinyl alcohol, wood pulp fiber and tetrabutyl titanate, and has a suitable pore size and a good filtration and retention effect. At the same time, the freeze-drying method is used to form nanopores on the surface of the ultrafiltration membrane, which increases the adsorption capacity. Therefore, it also has a good effect on the removal of heavy metal ions. Thus, the ultrafiltration membrane of this invention has the effects of ultrafiltration + adsorption + self-cleaning and anti-clogging.

[0004] Technical solution: A method for preparing a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane, comprising the following steps (parts by weight):

[0005] S1: Mix 10-15 parts polyvinyl alcohol, 5-10 parts wood pulp fiber and 100 parts water, place in a water bath at 95°C and heat and stir for 8 hours, then sonicate to remove bubbles to obtain a mixed solution.

[0006] S2: Mix 10-13 parts tetrabutyl titanate, 2 parts triethanolamine, 4 parts glacial acetic acid and 12-15 parts anhydrous ethanol, stir well to obtain a transparent solution;

[0007] S3: Mix concentrated hydrochloric acid with an aqueous ethanol solution and adjust the pH to 1 to obtain a hydrochloric acid solution;

[0008] S4: Mix the mixed solution and the clear solution, and slowly add hydrochloric acid solution dropwise under vigorous stirring. After the addition is complete, continue stirring for 0.5 h. After degassing, the solution is the electrospinning solution.

[0009] S5: Transfer the electrospinning solution into the syringe of the electrospinning device, perform electrospinning, and obtain an electrospinned membrane;

[0010] S6: Remove the electrospun membrane, place it at room temperature for 12 hours, and then freeze it at -30 to -20°C for 1 hour.

[0011] S7: Place in a vacuum freeze dryer and freeze dry for 3-4 hours;

[0012] S8: After removal, irradiation with ultraviolet light will produce a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane.

[0013] Furthermore, the ratio of ethanol to water in the ethanol-water solution in S3 is 2:1.

[0014] Furthermore, the volume ratio of the mixed solution to the hydrochloric acid solution in S4 is 3.6:1.

[0015] Furthermore, the electrospinning conditions in S5 are as follows: the electrospinning solution flow rate is 0.2–0.5 mm / min, the spinning voltage is 18 kV, the spinning temperature is 20–25 °C, and the receiving distance is 15 cm.

[0016] Furthermore, the ultraviolet irradiation time in S8 is 10-12 hours.

[0017] The self-cleaning, anti-clogging three-dimensional ultrafiltration membrane prepared by the above preparation method.

[0018] Furthermore, the ultrafiltration membrane has a pore size of 30–70 nm and a thickness of 10–50 μm.

[0019] The above-mentioned self-cleaning and anti-clogging three-dimensional ultrafiltration membrane is used in wastewater treatment.

[0020] Beneficial effects:

[0021] 1. The self-cleaning and anti-clogging three-dimensional ultrafiltration membrane of the present invention uses polyvinyl alcohol, wood pulp fiber and tetrabutyl titanate as raw materials. The ultrafiltration membrane has a suitable pore size and a good filtration and retention effect. At the same time, the freeze-drying method is used to form nanopores on the surface of the ultrafiltration membrane, which increases the adsorption capacity. Therefore, it also has a good effect on the removal of heavy metal ions. Thus, the ultrafiltration membrane of the present invention has the effects of ultrafiltration + adsorption + self-cleaning and anti-clogging.

[0022] 2. This invention uses tetrabutyl titanate as a raw material. The nano-TiO2 film prepared solely from it exhibits superhydrophilicity upon ultraviolet light irradiation, but this superhydrophilicity is short-lived; it disappears after a few days in the dark. This invention incorporates wood pulp fibers. Upon ultraviolet irradiation, the oxygen bonds between titanium atoms detach, creating oxygen vacancies. Some of these vacancies combine with water molecules in the air to form chemically adsorbed water, forming uniformly distributed nano-sized hydrophilic microdomains on the TiO2 surface. Simultaneously, the hydroxyl groups on the wood pulp fibers intervene, while others combine with oxygen vacancies to form an irreversible structure, maintaining its permanent hydrophilicity. During ultrafiltration, when contaminants adhere to the ultrafiltration membrane surface, the superhydrophilicity causes a water film to form between the membrane surface and the contaminants. As water flows, the contaminants automatically detach, preventing adhesion and achieving an anti-clogging effect.

[0023] 3. In this invention, wood pulp fiber itself has extremely strong water absorption and oil removal and decontamination capabilities, which can reduce the initial contact angle of the ultrafiltration membrane and improve hydrophilicity. At the same time, wood pulp fiber also has a certain adsorption effect on heavy metal ions.

[0024] 4. The addition of wood pulp fiber in this invention can also inhibit the transformation of TiO2 crystal form from anatase to rutile, improve the activity of TiO2, and further reduce the contact angle. Detailed Implementation

[0025] Example

[0026] A method for preparing a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane, characterized by comprising the following steps (parts by weight):

[0027] S1: Mix 10 parts polyvinyl alcohol, 8 parts wood pulp fiber and 100 parts water, place in a water bath at 95°C and heat and stir for 8 hours, then sonicate to remove bubbles to obtain a mixed solution;

[0028] S2: Mix 12 parts tetrabutyl titanate, 2 parts triethanolamine, 4 parts glacial acetic acid and 15 parts anhydrous ethanol, stir well to obtain a transparent solution;

[0029] S3: Mix concentrated hydrochloric acid with an aqueous ethanol solution, wherein the ratio of ethanol to water in the aqueous ethanol solution is 2:1, and adjust the pH to 1 to obtain a hydrochloric acid solution.

[0030] S4: Mix the mixed solution and the clear solution, and slowly add hydrochloric acid solution dropwise under vigorous stirring. The volume ratio of the mixed solution to the hydrochloric acid solution is 3.6:1. After the addition is complete, continue stirring for 0.5 h. After degassing, the solution is the electrospinning solution.

[0031] S5: Transfer the electrospinning solution into the syringe of the electrospinning device for electrospinning. The electrospinning conditions are: electrospinning solution flow rate of 0.4 mm / min, spinning voltage of 18kV, spinning temperature of 24℃, and receiving distance of 15cm to obtain an electrospinned membrane.

[0032] S6: Remove the electrospun membrane, place it at room temperature for 12 hours, and then freeze it at -30℃ for 1 hour;

[0033] S7: Place in a vacuum freeze dryer and freeze dry for 3 hours;

[0034] S8: After removal, irradiate with ultraviolet light for 11 hours to obtain a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane.

[0035] Example 2

[0036] A method for preparing a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane, characterized by comprising the following steps (parts by weight):

[0037] S1: Mix 13 parts polyvinyl alcohol, 8 parts wood pulp fiber and 100 parts water, heat and stir in a water bath at 95°C for 8 hours, and remove bubbles by ultrasonication to obtain a mixed solution;

[0038] S2: Mix 12 parts tetrabutyl titanate, 2 parts triethanolamine, 4 parts glacial acetic acid and 15 parts anhydrous ethanol, stir well to obtain a transparent solution;

[0039] S3: Mix concentrated hydrochloric acid with an aqueous ethanol solution, wherein the ratio of ethanol to water in the aqueous ethanol solution is 2:1, and adjust the pH to 1 to obtain a hydrochloric acid solution.

[0040] S4: Mix the mixed solution and the clear solution, and slowly add hydrochloric acid solution dropwise under vigorous stirring. The volume ratio of the mixed solution to the hydrochloric acid solution is 3.6:1. After the addition is complete, continue stirring for 0.5 h. After degassing, the solution is the electrospinning solution.

[0041] S5: Transfer the electrospinning solution into the syringe of the electrospinning device for electrospinning. The electrospinning conditions are: electrospinning solution flow rate of 0.4 mm / min, spinning voltage of 18kV, spinning temperature of 25℃, and receiving distance of 15cm to obtain an electrospinned membrane.

[0042] S6: Remove the electrospun membrane, place it at room temperature for 12 hours, and then freeze it at -30℃ for 1 hour;

[0043] S7: Place in a vacuum freeze dryer and freeze dry for 3 hours;

[0044] S8: After removal, irradiate with ultraviolet light for 11 hours to obtain a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane.

[0045] Example 3

[0046] A method for preparing a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane, characterized by comprising the following steps (parts by weight):

[0047] S1: Mix 15 parts polyvinyl alcohol, 8 parts wood pulp fiber and 100 parts water, place in a water bath at 95°C and heat and stir for 8 hours, then sonicate to remove bubbles to obtain a mixed solution;

[0048] S2: Mix 12 parts tetrabutyl titanate, 2 parts triethanolamine, 4 parts glacial acetic acid and 15 parts anhydrous ethanol, stir well to obtain a transparent solution;

[0049] S3: Mix concentrated hydrochloric acid with an aqueous ethanol solution, wherein the ratio of ethanol to water in the aqueous ethanol solution is 2:1, and adjust the pH to 1 to obtain a hydrochloric acid solution.

[0050] S4: Mix the mixed solution and the clear solution, and slowly add hydrochloric acid solution dropwise under vigorous stirring. The volume ratio of the mixed solution to the hydrochloric acid solution is 3.6:1. After the addition is complete, continue stirring for 0.5 h. After degassing, the solution is the electrospinning solution.

[0051] S5: Transfer the electrospinning solution into the syringe of the electrospinning device for electrospinning. The electrospinning conditions are: electrospinning solution flow rate of 0.4 mm / min, spinning voltage of 18kV, spinning temperature of 20℃, and receiving distance of 15cm to obtain an electrospinned membrane.

[0052] S6: Remove the electrospun membrane, place it at room temperature for 12 hours, and then freeze it at -30℃ for 1 hour;

[0053] S7: Place in a vacuum freeze dryer and freeze dry for 3 hours;

[0054] S8: After removal, irradiate with ultraviolet light for 11 hours to obtain a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane.

[0055] Example 4

[0056] A method for preparing a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane, characterized by comprising the following steps (parts by weight):

[0057] S1: Mix 13 parts polyvinyl alcohol, 5 parts wood pulp fiber and 100 parts water, heat and stir in a water bath at 95°C for 8 hours, and remove bubbles by ultrasonication to obtain a mixed solution.

[0058] S2: Mix 12 parts tetrabutyl titanate, 2 parts triethanolamine, 4 parts glacial acetic acid and 15 parts anhydrous ethanol, stir well to obtain a transparent solution;

[0059] S3: Mix concentrated hydrochloric acid with an aqueous ethanol solution, wherein the ratio of ethanol to water in the aqueous ethanol solution is 2:1, and adjust the pH to 1 to obtain a hydrochloric acid solution.

[0060] S4: Mix the mixed solution and the clear solution, and slowly add hydrochloric acid solution dropwise under vigorous stirring. The volume ratio of the mixed solution to the hydrochloric acid solution is 3.6:1. After the addition is complete, continue stirring for 0.5 h. After degassing, the solution is the electrospinning solution.

[0061] S5: Transfer the electrospinning solution into the syringe of the electrospinning device for electrospinning. The electrospinning conditions are: electrospinning solution flow rate of 0.4 mm / min, spinning voltage of 18kV, spinning temperature of 20℃, and receiving distance of 15cm to obtain an electrospinned membrane.

[0062] S6: Remove the electrospun membrane, place it at room temperature for 12 hours, and then freeze it at -20°C for 1 hour.

[0063] S7: Place in a vacuum freeze dryer and freeze dry for 3 hours;

[0064] S8: After removal, irradiate with ultraviolet light for 10-12 hours to obtain a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane.

[0065] Example 5

[0066] A method for preparing a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane, characterized by comprising the following steps (parts by weight):

[0067] S1: Mix 13 parts polyvinyl alcohol, 10 parts wood pulp fiber and 100 parts water, heat and stir in a water bath at 95°C for 8 hours, and remove bubbles by ultrasonication to obtain a mixed solution.

[0068] S2: Mix 12 parts tetrabutyl titanate, 2 parts triethanolamine, 4 parts glacial acetic acid and 15 parts anhydrous ethanol, stir well to obtain a transparent solution;

[0069] S3: Mix concentrated hydrochloric acid with an aqueous ethanol solution, wherein the ratio of ethanol to water in the aqueous ethanol solution is 2:1, and adjust the pH to 1 to obtain a hydrochloric acid solution.

[0070] S4: Mix the mixed solution and the clear solution, and slowly add hydrochloric acid solution dropwise under vigorous stirring. The volume ratio of the mixed solution to the hydrochloric acid solution is 3.6:1. After the addition is complete, continue stirring for 0.5 h. After degassing, the solution is the electrospinning solution.

[0071] S5: Transfer the electrospinning solution into the syringe of the electrospinning device for electrospinning. The electrospinning conditions are: electrospinning solution flow rate of 0.4 mm / min, spinning voltage of 18kV, spinning temperature of 20℃, and receiving distance of 15cm to obtain an electrospinned membrane.

[0072] S6: Remove the electrospun membrane, place it at room temperature for 12 hours, and then freeze it at -20°C for 1 hour.

[0073] S7: Place in a vacuum freeze dryer and freeze dry for 3 hours;

[0074] S8: After removal, irradiate with ultraviolet light for 11 hours to obtain a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane.

[0075] Example 6

[0076] A method for preparing a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane, characterized by comprising the following steps (parts by weight):

[0077] S1: Mix 13 parts polyvinyl alcohol, 8 parts wood pulp fiber and 100 parts water, heat and stir in a water bath at 95°C for 8 hours, and remove bubbles by ultrasonication to obtain a mixed solution;

[0078] S2: Mix 10 parts tetrabutyl titanate, 2 parts triethanolamine, 4 parts glacial acetic acid and 15 parts anhydrous ethanol, stir well to obtain a transparent solution.

[0079] S3: Mix concentrated hydrochloric acid with an aqueous ethanol solution, wherein the ratio of ethanol to water in the aqueous ethanol solution is 2:1, and adjust the pH to 1 to obtain a hydrochloric acid solution.

[0080] S4: Mix the mixed solution and the clear solution, and slowly add hydrochloric acid solution dropwise under vigorous stirring. The volume ratio of the mixed solution to the hydrochloric acid solution is 3.6:1. After the addition is complete, continue stirring for 0.5 h. After degassing, the solution is the electrospinning solution.

[0081] S5: Transfer the electrospinning solution into the syringe of the electrospinning device for electrospinning. The electrospinning conditions are: electrospinning solution flow rate of 0.4 mm / min, spinning voltage of 18kV, spinning temperature of 20℃, and receiving distance of 15cm to obtain an electrospinned membrane.

[0082] S6: Remove the electrospun membrane, place it at room temperature for 12 hours, and then freeze it at -30℃ for 1 hour;

[0083] S7: Place in a vacuum freeze dryer and freeze dry for 3 hours;

[0084] S8: After removal, irradiate with ultraviolet light for 11 hours to obtain a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane.

[0085] Example 7

[0086] A method for preparing a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane, characterized by comprising the following steps (parts by weight):

[0087] S1: Mix 13 parts polyvinyl alcohol, 8 parts wood pulp fiber and 100 parts water, heat and stir in a water bath at 95°C for 8 hours, and remove bubbles by ultrasonication to obtain a mixed solution;

[0088] S2: Mix 13 parts tetrabutyl titanate, 2 parts triethanolamine, 4 parts glacial acetic acid and 15 parts anhydrous ethanol, stir well to obtain a transparent solution;

[0089] S3: Mix concentrated hydrochloric acid with an aqueous ethanol solution, wherein the ratio of ethanol to water in the aqueous ethanol solution is 2:1, and adjust the pH to 1 to obtain a hydrochloric acid solution.

[0090] S4: Mix the mixed solution and the clear solution, and slowly add hydrochloric acid solution dropwise under vigorous stirring. The volume ratio of the mixed solution to the hydrochloric acid solution is 3.6:1. After the addition is complete, continue stirring for 0.5 h. After degassing, the solution is the electrospinning solution.

[0091] S5: Transfer the electrospinning solution into the syringe of the electrospinning device for electrospinning. The electrospinning conditions are: electrospinning solution flow rate of 0.4 mm / min, spinning voltage of 18kV, spinning temperature of 25℃, and receiving distance of 15cm to obtain an electrospinned membrane.

[0092] S6: Remove the electrospun membrane, place it at room temperature for 12 hours, and then freeze it at -20°C for 1 hour.

[0093] S7: Place in a vacuum freeze dryer and freeze dry for 3 hours;

[0094] S8: After removal, irradiate with ultraviolet light for 11 hours to obtain a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane.

[0095] Example 8

[0096] A method for preparing a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane, characterized by comprising the following steps (parts by weight):

[0097] S1: Mix 13 parts polyvinyl alcohol, 8 parts wood pulp fiber and 100 parts water, heat and stir in a water bath at 95°C for 8 hours, and remove bubbles by ultrasonication to obtain a mixed solution;

[0098] S2: Mix 12 parts tetrabutyl titanate, 2 parts triethanolamine, 4 parts glacial acetic acid and 15 parts anhydrous ethanol, stir well to obtain a transparent solution;

[0099] S3: Mix concentrated hydrochloric acid with an aqueous ethanol solution, wherein the ratio of ethanol to water in the aqueous ethanol solution is 2:1, and adjust the pH to 1 to obtain a hydrochloric acid solution.

[0100] S4: Mix the mixed solution and the clear solution, and slowly add hydrochloric acid solution dropwise under vigorous stirring. The volume ratio of the mixed solution to the hydrochloric acid solution is 3.6:1. After the addition is complete, continue stirring for 0.5 h. After degassing, the solution is the electrospinning solution.

[0101] S5: Transfer the electrospinning solution into the syringe of the electrospinning device for electrospinning. The electrospinning conditions are: electrospinning solution flow rate of 0.2 mm / min, spinning voltage of 18kV, spinning temperature of 23℃, and receiving distance of 15cm to obtain an electrospinned membrane.

[0102] S6: Remove the electrospun membrane, place it at room temperature for 12 hours, and then freeze it at -30℃ for 1 hour;

[0103] S7: Place in a vacuum freeze dryer and freeze dry for 4 hours;

[0104] S8: After removal, irradiate with ultraviolet light for 11 hours to obtain a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane.

[0105] Example 9

[0106] A method for preparing a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane, characterized by comprising the following steps (parts by weight):

[0107] S1: Mix 13 parts polyvinyl alcohol, 8 parts wood pulp fiber and 100 parts water, heat and stir in a water bath at 95°C for 8 hours, and remove bubbles by ultrasonication to obtain a mixed solution;

[0108] S2: Mix 12 parts tetrabutyl titanate, 2 parts triethanolamine, 4 parts glacial acetic acid and 12-15 parts anhydrous ethanol, stir well to obtain a transparent solution;

[0109] S3: Mix concentrated hydrochloric acid with an aqueous ethanol solution, wherein the ratio of ethanol to water in the aqueous ethanol solution is 2:1, and adjust the pH to 1 to obtain a hydrochloric acid solution.

[0110] S4: Mix the mixed solution and the clear solution, and slowly add hydrochloric acid solution dropwise under vigorous stirring. The volume ratio of the mixed solution to the hydrochloric acid solution is 3.6:1. After the addition is complete, continue stirring for 0.5 h. After degassing, the solution is the electrospinning solution.

[0111] S5: Transfer the electrospinning solution into the syringe of the electrospinning device for electrospinning. The electrospinning conditions are: electrospinning solution flow rate of 0.5 mm / min, spinning voltage of 18kV, spinning temperature of 22℃, and receiving distance of 15cm to obtain an electrospinned membrane.

[0112] S6: Remove the electrospun membrane, place it at room temperature for 12 hours, and then freeze it at -30℃ for 1 hour;

[0113] S7: Place in a vacuum freeze dryer and freeze dry for 4 hours;

[0114] S8: After removal, irradiate with ultraviolet light for 11 hours to obtain a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane.

[0115] Example 10

[0116] A method for preparing a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane, characterized by comprising the following steps (parts by weight):

[0117] S1: Mix 13 parts polyvinyl alcohol, 8 parts wood pulp fiber and 100 parts water, heat and stir in a water bath at 95°C for 8 hours, and remove bubbles by ultrasonication to obtain a mixed solution;

[0118] S2: Mix 12 parts tetrabutyl titanate, 2 parts triethanolamine, 4 parts glacial acetic acid and 15 parts anhydrous ethanol, stir well to obtain a transparent solution;

[0119] S3: Mix concentrated hydrochloric acid with an aqueous ethanol solution, wherein the ratio of ethanol to water in the aqueous ethanol solution is 2:1, and adjust the pH to 1 to obtain a hydrochloric acid solution.

[0120] S4: Mix the mixed solution and the clear solution, and slowly add hydrochloric acid solution dropwise under vigorous stirring. The volume ratio of the mixed solution to the hydrochloric acid solution is 3.6:1. After the addition is complete, continue stirring for 0.5 h. After degassing, the solution is the electrospinning solution.

[0121] S5: Transfer the electrospinning solution into the syringe of the electrospinning device for electrospinning. The electrospinning conditions are: electrospinning solution flow rate of 0.4 mm / min, spinning voltage of 18kV, spinning temperature of 20℃, and receiving distance of 15cm to obtain an electrospinned membrane.

[0122] S6: Remove the electrospun membrane, place it at room temperature for 12 hours, and then freeze it at -20°C for 1 hour.

[0123] S7: Place in a vacuum freeze dryer and freeze dry for 3 hours;

[0124] S8: After removal, irradiate with ultraviolet light for 10 hours to obtain a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane.

[0125] Example 11

[0126] A method for preparing a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane, characterized by comprising the following steps (parts by weight):

[0127] S1: Mix 13 parts polyvinyl alcohol, 8 parts wood pulp fiber and 100 parts water, heat and stir in a water bath at 95°C for 8 hours, and remove bubbles by ultrasonication to obtain a mixed solution;

[0128] S2: Mix 12 parts tetrabutyl titanate, 2 parts triethanolamine, 4 parts glacial acetic acid and 12-15 parts anhydrous ethanol, stir well to obtain a transparent solution;

[0129] S3: Mix concentrated hydrochloric acid with an aqueous ethanol solution, wherein the ratio of ethanol to water in the aqueous ethanol solution is 2:1, and adjust the pH to 1 to obtain a hydrochloric acid solution.

[0130] S4: Mix the mixed solution and the clear solution, and slowly add hydrochloric acid solution dropwise under vigorous stirring. The volume ratio of the mixed solution to the hydrochloric acid solution is 3.6:1. After the addition is complete, continue stirring for 0.5 h. After degassing, the solution is the electrospinning solution.

[0131] S5: Transfer the electrospinning solution into the syringe of the electrospinning device for electrospinning. The electrospinning conditions are: electrospinning solution flow rate of 0.4 mm / min, spinning voltage of 18kV, spinning temperature of 25℃, and receiving distance of 15cm to obtain an electrospinned membrane.

[0132] S6: Remove the electrospun membrane, place it at room temperature for 12 hours, and then freeze it at -20°C for 1 hour.

[0133] S7: Place in a vacuum freeze dryer and freeze dry for 4 hours;

[0134] S8: After removal, irradiate with ultraviolet light for 12 hours to obtain a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane.

[0135] Comparative Example 1

[0136] The difference between this embodiment and Embodiment 2 is that wood pulp fibers are not added. Specifically:

[0137] A method for preparing a three-dimensional ultrafiltration membrane, characterized by comprising the following steps, by weight:

[0138] S1: Mix 13 parts of polyvinyl alcohol and 100 parts of water, heat and stir in a water bath at 95°C for 8 hours, and remove bubbles by sonication to obtain a mixed solution;

[0139] S2: Mix 12 parts tetrabutyl titanate, 2 parts triethanolamine, 4 parts glacial acetic acid and 15 parts anhydrous ethanol, stir well to obtain a transparent solution;

[0140] S3: Mix concentrated hydrochloric acid with an aqueous ethanol solution, wherein the ratio of ethanol to water in the aqueous ethanol solution is 2:1, and adjust the pH to 1 to obtain a hydrochloric acid solution.

[0141] S4: Mix the mixed solution and the clear solution, and slowly add hydrochloric acid solution dropwise under vigorous stirring. The volume ratio of the mixed solution to the hydrochloric acid solution is 3.6:1. After the addition is complete, continue stirring for 0.5 h. After degassing, the solution is the electrospinning solution.

[0142] S5: Transfer the electrospinning solution into the syringe of the electrospinning device for electrospinning. The electrospinning conditions are: electrospinning solution flow rate of 0.4 mm / min, spinning voltage of 18kV, spinning temperature of 25℃, and receiving distance of 15cm to obtain an electrospinned membrane.

[0143] S6: Remove the electrospun membrane, place it at room temperature for 12 hours, and then freeze it at -30℃ for 1 hour;

[0144] S7: Place in a vacuum freeze dryer and freeze dry for 3 hours;

[0145] S8: After removal, irradiate with ultraviolet light for 11 hours to obtain a three-dimensional ultrafiltration membrane.

[0146] Comparative Example 2

[0147] The difference between this embodiment and Embodiment 2 is that it is not subject to ultraviolet radiation, as detailed below:

[0148] A method for preparing a three-dimensional ultrafiltration membrane, characterized by comprising the following steps, by weight:

[0149] S1: Mix 13 parts polyvinyl alcohol, 8 parts wood pulp fiber and 100 parts water, heat and stir in a water bath at 95°C for 8 hours, and remove bubbles by ultrasonication to obtain a mixed solution;

[0150] S2: Mix 12 parts tetrabutyl titanate, 2 parts triethanolamine, 4 parts glacial acetic acid and 15 parts anhydrous ethanol, stir well to obtain a transparent solution;

[0151] S3: Mix concentrated hydrochloric acid with an aqueous ethanol solution, wherein the ratio of ethanol to water in the aqueous ethanol solution is 2:1, and adjust the pH to 1 to obtain a hydrochloric acid solution.

[0152] S4: Mix the mixed solution and the clear solution, and slowly add hydrochloric acid solution dropwise under vigorous stirring. The volume ratio of the mixed solution to the hydrochloric acid solution is 3.6:1. After the addition is complete, continue stirring for 0.5 h. After degassing, the solution is the electrospinning solution.

[0153] S5: Transfer the electrospinning solution into the syringe of the electrospinning device for electrospinning. The electrospinning conditions are: electrospinning solution flow rate of 0.4 mm / min, spinning voltage of 18kV, spinning temperature of 25℃, and receiving distance of 15cm to obtain an electrospinned membrane.

[0154] S6: Remove the electrospun membrane, place it at room temperature for 12 hours, and then freeze it at -30℃ for 1 hour;

[0155] S7: Place in a vacuum freeze dryer and freeze dry for 3 hours to obtain a three-dimensional ultrafiltration membrane.

[0156] Determining the pore size of a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane;

[0157] The contact angle of the self-cleaning, anti-clogging three-dimensional ultrafiltration membrane was measured on the day of preparation, and after 10 and 30 days of storage.

[0158] The results are shown in Table 1 below:

[0159] Table 1

[0160]

[0161] As can be seen from Table 1, the contact angle of the self-cleaning and anti-clogging three-dimensional ultrafiltration membranes in the various embodiments of the present invention is close to 0°, which is a superhydrophilic material. Furthermore, the contact angle remains basically unchanged after 30 days of storage. In contrast, the contact angle of the comparative example begins to change after 10 days of storage, shifting from hydrophilic to hydrophobic, and the hydrophilic properties cannot be maintained. However, the hydrophilicity of the ultrafiltration membrane of the present invention can be maintained indefinitely.

[0162] After comprehensive comparison, Examples 2, 7, Comparative Example 1, and Comparative Example 2 were selected for subsequent wastewater treatment experiments.

[0163] Experiment on the treatment of self-made wastewater (BSA solution and yeast suspension, both at a concentration of 1000 ppm):

[0164] Cut the ultrafiltration membrane to a suitable size and place it in the ultrafiltration cup. Measure the wastewater flux: Measure the self-made wastewater at a pressure of 0.05 MPa for 60 min, record the change in permeation flux during the process, and obtain the steady-state flux Jp.

[0165] The steady-state flux was measured over 5 days and 15 days, and the flux decay rate was calculated.

[0166] The formula for calculating the pollutant rejection rate of the self-cleaning, anti-clogging three-dimensional ultrafiltration membrane is as follows:

[0167]

[0168] In the formula, R is the retention rate (%), and C is the retention rate (%). pC is the permeate concentration (g / L). f The concentration of the retentate is (g / L). The concentration change of the self-made wastewater solution was determined by measuring the absorbance of the pollutants in the solution at the maximum absorption wavelength using a UV-Vis spectrophotometer (the maximum absorption wavelength of BSA is 278 nm, and that of yeast is 600 nm).

[0169] Determination of Cu 2+ Pb 2+ Cr 2+ and Cd 2+ The adsorption rate.

[0170] The flux decay rate is shown in Table 2 below:

[0171] Table 2

[0172]

[0173] As can be seen from Table 2, after 5 days or even 15 days of use, the self-cleaning and anti-clogging three-dimensional ultrafiltration membrane of the present invention has a decay rate of only 0.8%, and its flux is basically unaffected, indicating that it is not contaminated and the pore size is not affected, thus exhibiting a very good anti-clogging effect.

[0174] The retention rate test results are shown in Table 3 below:

[0175] Table 3

[0176]

[0177] For Cu 2+ Pb 2+ Cr 2+ and Cd 2+ The adsorption rate results are shown in Table 4 below:

[0178] Table 4

[0179]

[0180] The above embodiments are provided to clearly and completely describe the technical solution and represent some, but not all, implementations of the present invention. However, the implementations of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention.

Claims

1. A method for preparing a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane, characterized in that: By weight, the following steps are included: S1: Mix 10-15 parts polyvinyl alcohol, 5-10 parts wood pulp fiber and 100 parts water, place in a water bath at 95°C and heat and stir for 8 hours, then sonicate to remove bubbles to obtain a mixed solution. S2: Mix 10-13 parts tetrabutyl titanate, 2 parts triethanolamine, 4 parts glacial acetic acid and 12-15 parts anhydrous ethanol, stir well to obtain a transparent solution; S3: Mix concentrated hydrochloric acid with an aqueous ethanol solution and adjust the pH to 1 to obtain a hydrochloric acid solution; S4: Mix the mixed solution and the clear solution, and slowly add hydrochloric acid solution dropwise under vigorous stirring. After the addition is complete, continue stirring for 0.5 h. After degassing, the solution is the electrospinning solution. S5: Transfer the electrospinning solution into the syringe of the electrospinning device, perform electrospinning, and obtain an electrospinned membrane; S6: Remove the electrospun membrane, place it at room temperature for 12 hours, and then freeze it at -30 to -20°C for 1 hour. S7: Place in a vacuum freeze dryer and freeze dry for 3-4 hours; S8: After removal, irradiation with ultraviolet light will produce a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane.

2. The method for preparing a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane according to claim 1, characterized in that: The volume ratio of the mixed solution to the hydrochloric acid solution in S4 is 3.6:

1.

3. The method for preparing a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane according to claim 1, characterized in that: The electrospinning conditions in S5 are as follows: the electrospinning solution flow rate is 0.2-0.5 mm / min, the spinning voltage is 18kV, the spinning temperature is 20-25℃, and the receiving distance is 15cm.

4. The method for preparing a self-cleaning, anti-clogging three-dimensional ultrafiltration membrane according to claim 1, characterized in that: The ultraviolet irradiation time in S8 is 10-12 hours.

5. The self-cleaning, anti-clogging three-dimensional ultrafiltration membrane prepared by the preparation method according to any one of claims 1 to 4.

6. The self-cleaning, anti-clogging three-dimensional ultrafiltration membrane according to claim 5, characterized in that: The ultrafiltration membrane has a pore size of 30–70 nm and a thickness of 10–50 μm.

7. The application of the self-cleaning, anti-clogging three-dimensional ultrafiltration membrane according to claim 5 in wastewater treatment.

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