Zwitterionic modified piezoelectric ceramic membrane and preparation method thereof

Abstract

The invention relates to a dual anti-pollution modified piezoelectric ceramic membrane and a preparation method thereof, and belongs to the field of membrane materials. The ceramic membrane takes piezoelectric ceramic as a support body, the surface of the ceramic membrane is coated with a membrane layer with a small aperture, and one side of the ceramic membrane is modified by zwitterions and is used for separation and pollution resistance. A main body is a porous piezoelectric medium, the pore diameter is large, and self-cleaning is achieved through in-situ ultrasonic cavitation. The preparation method comprises the following steps: sintering to prepare a piezoelectric support body, coating a film layer, sintering to obtain a composite film, and strengthening the binding force by using dopamine hydrochloride to generate sulfanilamide zwitterions. Experiments show that in-situ ultrasound and the zwitter-ion hydration layer have a synergistic effect, and the anti-pollution performance is remarkably improved.

Description

Technical Field

[0001] The present invention relates to an amphoteric ion-modified piezoelectric ceramic membrane and a preparation method thereof, belonging to the technical field of membrane material preparation. Background Art

[0002] Membrane technology is a new and efficient separation technology. Membrane separation technology uses a selectively permeable membrane as the separation medium. Through the driving force of the transmembrane pressure difference, the raw material selectively permeates through the membrane to achieve the purpose of separation and purification. Among them, ceramic membrane materials have the characteristics of no phase change, low energy consumption, high mechanical strength, high efficiency, etc., and have been more and more widely used in various fields. However, membrane fouling is one of the most main problems faced in membrane separation. Pollutants will accumulate on the membrane surface or in the membrane pores, causing membrane fouling. This not only severely attenuates the membrane filtration flux, but may also affect the retention performance of the membrane for the separated substances, directly affecting the economy and reliability of the membrane separation process.

[0003] Piezoelectric materials are a class of crystalline materials that will generate voltage at both ends when subjected to pressure. This process is reversible. Applying an alternating electric field to it can make it vibrate. At this time, applying an alternating electric field at both ends can make the piezoelectric material generate mechanical vibration. According to the characteristic that the piezoelectric material can convert alternating current into mechanical vibration, the piezoelectric material can be prepared into a separation membrane, making the membrane material an in-situ ultrasonic emission source, generating mechanical vibration during the separation process, thereby playing a role in alleviating or even avoiding membrane fouling.

[0004] However, when the piezoelectric ceramic separation membrane is applied to some filtration and purification systems, there is still a problem that membrane fouling cannot be completely avoided. The purified components may interact with the membrane surface and adsorb on the pore surface or the surface of the membrane. This will cause the blockage of the membrane pores and irreversible fouling, and then lead to a decrease in the membrane flux and affect the filtration effect. Summary of the Invention

[0005] The present invention aims to solve the problem of serious fouling of existing ceramic membranes during the filtration process, and provides an amphoteric ion piezoelectric ceramic membrane for dual anti-fouling and a preparation method thereof. The support of the ceramic membrane prepared by the present invention uses a piezoelectric ceramic material, which can generate ultrasound for in-situ anti-fouling while maintaining the basic performance of the ceramic membrane; the modification of the piezoelectric membrane can form a relatively thick hydration layer during separation and filtration.

[0006] An amphoteric ion-modified piezoelectric ceramic membrane includes a piezoelectric ceramic membrane body and a modification layer on one side of the body. The modification layer has the following compounds, where n refers to the number of repeating units:

[0007]

[0008] And a PDA layer is further included between the modification layer and the piezoelectric ceramic membrane body.

[0009] The value range of n is 50 - 2000.

[0010] The pore size range of the piezoelectric ceramic membrane body is 20 - 500 nm, and at 20 V alternating current voltage, it has a piezoelectric response of 10 - 30 mV;

[0011] The material of the piezoelectric ceramic membrane body is selected from one of silicon oxide, lead zirconate titanate, sodium potassium niobate, and barium titanate; on the piezoelectric ceramic membrane body, there is or is not a selective separation layer made of ceramic material.

[0012] A preparation method of zwitterionic modified piezoelectric ceramic membrane, comprising the following steps:

[0013] Step 1, prepare a buffer solution containing polydopamine and polyethyleneimine as the first modification solution; prepare a solution containing haloethyl sulfonate as the second modification solution;

[0014] Step 2, contact the piezoelectric ceramic membrane body with the first modification solution, after the surface is loaded with polydopamine and polyethyleneimine, wash and dry;

[0015] Step 3, contact the voltage ceramic membrane body obtained in Step 2 with the second modification solution, after a nucleophilic substitution reaction, a modification layer is formed on the surface.

[0016] In the first modification solution, the concentration range of polydopamine and polyethyleneimine is 0.01 - 20 g / L, and the buffer solution is a Tris - HCl buffer solution with pH = 1 - 13.

[0017] The reaction conditions in Step 2: the temperature is 5 - 90 °C, and the time is 1 - 48 h.

[0018] In the second modification solution, the concentration range of haloethyl sulfonate is 0.5 - 20 mol / L.

[0019] The reaction conditions in Step 2: the temperature is 5 - 90 °C, and the reaction time is 1 - 96 h.

[0020] The use of zwitterionic modified piezoelectric ceramic membrane in liquid filtration.

[0021] When performing liquid filtration, an alternating current electric field of 20 - 200 V and 50 - 500 kHz needs to be applied; the liquid contains organic matter and /

[0022] or suspended matter.

[0023] The ceramic membrane of the present invention is composed of a piezoelectric ceramic as a support or a membrane layer with a smaller pore size coated on the surface of the support, and one side of the ceramic membrane is modified with zwitterions; on the modified side of the ceramic membrane, it plays a role in separation and anti-pollution; the main body of the ceramic membrane is a porous piezoelectric medium with a larger pore size, which plays a supporting role and realizes self-cleaning of the membrane surface through cavitation caused by in-situ ultrasound. The preparation process of the ceramic membrane mainly includes the following processes: First, the piezoelectric material is sintered by dry pressing molding or gel casting and other processes to prepare a piezoelectric support, and a membrane layer is coated on the surface of the porous ceramic by dip coating and sintering to obtain a piezoelectric composite membrane; then, dopamine hydrochloride (PDA) is used to strengthen the modification binding force, and sulfonamide-type zwitterions are generated by polyethyleneimine (PEI) and 2-bromoethylsulfonate sodium (SBES). The zwitterion-modified piezoelectric membrane prepared by the present invention realizes an anti-pollution strategy through the synergistic effect of in-situ ultrasonic vibration and the zwitterion hydration layer. Experiments show that the coupling of the two amplifies the effect of a single mechanism and significantly improves the anti-pollution performance through dynamic complementarity.

[0024] The beneficial effects of the present invention are as follows:

[0025] 1. After applying alternating current at both ends of the support of the modified piezoelectric ceramic membrane, electrical energy can be converted into mechanical energy, and the cavitation effect generated by vibration slows down the adsorption and accumulation of pollutants on the membrane surface, playing an anti-pollution role.

[0026] 2. The coating layer of the modified piezoelectric ceramic membrane can design the separation accuracy by coating a membrane layer on the support to achieve the expected separation effect.

[0027] 3. The modified layer of the modified piezoelectric ceramic membrane forms a hydration layer on the membrane surface through zwitterion modification, enhancing hydrophilicity, increasing the flux and preventing the entry of pollutants into the pores.

[0028] 4. The modified piezoelectric ceramic membrane adopts the dual-function coupling of in-situ ultrasonic anti-pollution and hydration layer anti-pollution, achieving a better effect than single-function anti-pollution and realizing double anti-pollution in the membrane separation process.

[0029] 5. The modified piezoelectric membrane prepared by the present invention has strong piezoelectric properties. Applying an alternating electric field can generate in-situ ultrasound, weakening or preventing the adsorption of membrane surface pollution; it has a complete zwitterion modification layer. During separation, zwitterions form a hydration layer with water to prevent the entry of target pollutants, achieving an anti-pollution effect far exceeding that of a single mechanism through the coupling of the two mechanisms. Description of the Drawings

[0030] Figure 1 It is a schematic diagram of the zwitterion-modified functionalized ceramic membrane provided by the present invention.

[0031] Figure 2 It is the influence of the first-step modification of the membrane on the anti-pollution performance of yeast and bovine serum albumin

[0032] Figure 3 The influence of the concentration of the modified substance of the present invention on the rejection rates of bovine serum albumin (BSA) and yeast

[0033] Figure 4 The anti-pollution performance diagrams of the present invention and the original membrane for separating and filtering BSA solution

[0034] Figure 5 The anti-pollution performance diagrams of the present invention and the original membrane for separating and filtering yeast solution

[0035] Figure 6 The anti-pollution performance diagrams of the present invention and the original membrane for separating and filtering yeast solution under different transmembrane pressure differences

[0036] Figure 7 The anti-pollution performance diagrams of the present invention and the original membrane for separating and filtering yeast solutions with different concentrations

[0037] ( Figure 2-7 Experimental results of Example 1) Detailed description of the specific implementation mode

[0038] The technical solution of the present invention is described in detail as follows:

[0039] The ceramic membrane is composed of a piezoelectric ceramic as a support or a membrane layer with a smaller pore size is coated on the surface of the support. The ceramic membrane is modified with zwitterions on one side; on the modified side of the ceramic membrane, it plays a role in separation and anti-pollution; the main body of the ceramic membrane is a porous piezoelectric medium with a larger pore size, which plays a supporting role and realizes the self-cleaning effect of the membrane surface through cavitation caused by in-situ ultrasound. The preparation process of the modified piezoelectric membrane is mainly divided into the following processes: Step 1: A green body is formed by dry pressing or gel casting process and sintered to prepare a piezoelectric support; Step 2: A membrane layer is coated on the surface of the porous piezoelectric ceramic by impregnation method and sintered to prepare a piezoelectric membrane; Step 3: A (Tris-HCl) buffer solution prepared by using tris(hydroxymethyl)aminomethane (Tris) and hydrochloric acid (HCl) is used. PDA and PEI are added successively and stirred evenly to obtain the first-step modification solution. The ceramic membrane is immersed in the first-step modification solution for modification, and after completion, it is rinsed and dried; Step 4: An SBES solution is prepared with deionized water, and the second-step modification solution is obtained after magnetic stirring; the ceramic membrane is immersed in the second-step modification solution for modification, and after completion, it is rinsed and dried. After drying, the finished product of the modified piezoelectric membrane is obtained and used for anti-pollution research later.

[0040] The porous ceramic support in Step 1 is formed into a green body by dry pressing or gel casting, and a piezoelectric support is prepared by high-temperature sintering at 600°C - 1400°C. The heating rate is controlled at 0.2 - 5°C / min, the cooling rate is controlled at 0.5 - 5°C / min, and the pore size is 0.1 - 10μm;

[0041] The coating film layer in step 2 is coated by the dip-coating method, and the pulling speed in the dip-coating method is controlled at 5-50 cm / s; the coating film temperature is controlled at 15-30 °C, the coating time is 5-300 s, air-dried at room temperature for 0.5-24 h, dried at 20-200 °C for 0.5-24 h, and then sintered in a furnace. The sintering temperature is 300 °C - 1200 °C, the heating rate is controlled at 0.2-5 °C / min, and the cooling rate is controlled at 0.5-5 °C / min. The pore size of the composite film prepared is 2-2000 nm;

[0042] The buffer solution in step 3 is a Tris-HCl buffer solution with pH = 1-13, and the concentrations of PDA and PEI added successively are both in the range of 0.01-20 g / L;

[0043] The temperature for soaking the composite film in step 3 is 5-90 °C, the soaking time is 1-48 h, and the rinsing is carried out with deionized water and absolute ethanol;

[0044] The concentration of the second-step modification liquid SBES in step 4 is 0-20 mol / L;

[0045] The temperature for soaking the composite film in the second-step modification in step 4 is 5-90 °C, the soaking time is 1-96 h, and the rinsing is carried out with deionized water and absolute ethanol.

[0046] Example 1 Modified piezoelectric ceramic membrane supported by porous piezoelectric SiO2 and its preparation

[0047] Using silicon oxide (α-quartz) as the raw material, a piezoelectric chip-type ceramic membrane is prepared by the gel-casting process. The sintering temperature is 1250 °C, the heating rate is 2 °C / min, the cooling rate is 3 °C / min, the average pore size is 0.83 μm, the pore size distribution is 0.2-1.5 μm, and the pure water permeability is 534 ± 30 L·m -2 ·h -1 ·bar -1 , and the strength is 11.8 ± 3.23 MPa; under 60 V alternating voltage, the piezoelectric response is 11.5 ± 0.5 mV.

[0048] Prepare a Tris-HCl buffer solution with pH = 8.5, and the concentrations of PDA and PEI added successively are both 0.2 g / L. Stir evenly to obtain the first-step modification liquid;

[0049] The temperature for soaking the piezoelectric membrane is 25 °C, the soaking time is 4 h, and the first-step modified membrane is rinsed with deionized water and absolute ethanol, then dried and reserved;

[0050] Prepare solutions with concentrations of 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, and 0.2 mol / L SBES as the second-step modification liquid;

[0051] The piezoelectric film that has completed the first-step modification is immersed in the second-step modification solution at a temperature of 50 °C for 12 h. After completion, it is rinsed with deionized water and absolute ethanol and air-dried for later use;

[0052] Performance tests are conducted on the finished modified piezoelectric ceramic membrane. The separation experiments are all carried out under a transmembrane pressure difference of 1 bar and a membrane surface flow rate of 0.5 m / s. As Figure 2 can be seen, after the original membrane completes the first-step modification, the permeabilities of the yeast and protein systems during filtration are basically the same as those of the original membrane, indicating that the first-step modification has little effect on the anti-fouling performance of the membrane. By changing the concentration of the SBES modification solution, the influence law of the modified membrane on the rejection rates of the permeating component (BSA) and the retained component (yeast) is investigated. As Figure 3 can be seen, the decrease in the rejection rate of the protein after modification indicates that the modified membrane can relieve the fouling caused by the components entering the pores and will not affect the pore size. In addition, the increase in the retention of yeast indicates that there is less fouling on the membrane surface and the fouling on the membrane surface is relieved. When filtering a 500 ppm BSA protein solution, the stable flux of the original membrane is 43 L·m -2 ·h -1 ·bar -1 ; when an alternating electric field of 60 V and 178 kHz is applied, the stable flux of the membrane increases to 50 L·m -2 ·h -1 ·bar -1 ; the stable flux of the modified membrane without applying voltage is 58 L·m -2 ·h -1 ·bar -1 ; when the same alternating electric field is applied, the stable flux of the modified membrane without applying voltage is 81 L·m -2 ·h -1 ·bar -1 , and the stable flux of the modified membrane increases to 2 - 3 times that of the original membrane when the electric field is applied. When filtering a 500 ppm yeast solution, the stable flux of the modified membrane increases to 3 - 4 times that of the original membrane when the electric field is applied.

[0053] Example 2 Modified piezoelectric ceramic membrane supported by porous piezoelectric PZT and its preparation

[0054] Using lead zirconate titanate as the raw material, a sheet-type PZT ceramic membrane is prepared by a dry pressing process. The sintering temperature is 1000 °C, the heating rate is 2 °C / min, the cooling rate is 3 °C / min, the average pore diameter is 270 nm, the pore size distribution is 130 - 530 nm, and the pure water permeability is 280 ± 5.6 L·m -2 ·h -1 ·bar -1The strength is 37.8 ± 4.38 MPa; under 20V AC voltage, the piezoelectric response is 29.6 ± 1.5 mV.

[0055] Prepare a Tris-HCl buffer solution with pH = 9, and the concentrations of PDA and PEI added successively are both 0.3 g / L. Stir evenly to obtain the first-step modification solution.

[0056] The temperature for soaking the piezoelectric film is 30 °C, and the soaking time is 8 h. The first-step modified film is rinsed with deionized water and absolute ethanol, dried, and reserved for use.

[0057] Prepare a solution with a concentration of 0.3 mol / L SBES as the second-step modification solution.

[0058] The piezoelectric film completed the first-step modification is soaked in the second-step modification solution at a temperature of 60 °C for 12 h. After completion, it is rinsed with deionized water and absolute ethanol, dried, and reserved for use.

[0059] Perform performance tests on the finished modified piezoelectric ceramic film. The separation experiments are all carried out under a transmembrane pressure difference of 0.5 bar and a membrane surface flow rate of 1.5 m / s. It is found that the influence law of the modification concentration on the rejection rate of the rejected components (oil and water) is the same as that in Example 1. When filtering a 500 pm oil-water solution, the stable flux of the original membrane is 54 L·m -2 ·h -1 ·bar -1 ; when an AC electric field of 60V and 210 kHz is applied, the stable flux of the membrane is increased to 93 L·m -2 ·h -1 ·bar -1 ; the stable flux of the modified membrane without applying voltage is 84 L·m -2 ·h -1 ·bar -1 ; when a 60V AC electric field is applied, the stable flux of the modified membrane under the energized condition is 167 L·m -2 ·h -1 ·bar -1 The stable flux of the modified membrane under the energized condition is increased to 3 - 4 times that of the original membrane.

[0060] Example 3 Modified piezoelectric ceramic membrane supported by sodium potassium niobate (KNN) and its preparation

[0061] Prepare KNN powder by the solid-phase reaction method and prepare a sheet-type piezoelectric ceramic membrane by the dry pressing process; the sintering temperature is 1050 °C, the heating rate is 2 °C / min, the cooling rate is 3 °C / min, the average pore diameter is 300 nm, and the pure water permeability is 220.7 ± 20.0 L·m -2 ·h -1 ·bar -1, the strength is 20.8 ± 1.23 MPa; under 20 V alternating current voltage, the piezoelectric response is 20.6 ± 0.5 mV.

[0062] Prepare a Tris-HCl buffer solution with pH = 3, and the concentrations of PDA and PEI added successively are both 0.5 g / L. Stir evenly to obtain the first-step modification solution.

[0063] The temperature for soaking the piezoelectric film is 25 °C, and the soaking time is 8 h. The first-step modified film is rinsed with deionized water and absolute ethanol, dried, and reserved for use.

[0064] Prepare a solution with a concentration of 0.2 mol / L SBES as the second-step modification solution.

[0065] The piezoelectric film that has completed the first-step modification is soaked in the second-step modification solution at a temperature of 60 °C for 24 h. After completion, it is rinsed with deionized water and absolute ethanol, dried, and reserved for use.

[0066] Perform performance tests on the finished modified piezoelectric ceramic film. The separation experiments are all carried out under a transmembrane pressure difference of 0.5 bar and a membrane surface flow rate of 1 m / s. It is found that the influence law of the modification concentration on the rejection rate of the rejected components (oil and water) is the same as that in Example 1. When filtering a 500 pm oil-water solution, the stable flux of the original membrane is 34 L·m -2 ·h -1 ·bar -1 ; when a 60 V alternating current electric field is applied, the stable flux of the membrane is increased to 63 L·m -2 ·h -1 ·bar -1 ; the stable flux of the modified membrane without applying voltage is 74 L·m -2 ·h -1 ·bar -1 ; when applying an alternating current electric field of 60 V and 190 kHz, the stable flux of the modified membrane without applying voltage is 137 L·m -2 ·h -1 ·bar -1 , and the stable flux of the modified membrane under the condition of applying electricity is increased to 4 - 5 times that of the original membrane.

[0067] Example 4 Modified piezoelectric ceramic membrane supported by barium titanate (BTO) and its preparation

[0068] Using barium titanate as the raw material, a BTO sheet support is prepared by the dry pressing method; the sintering temperature is 1250 °C, the heating rate is 2 °C / min, the cooling rate is 3 °C / min, the average pore diameter is 470 nm, and the pure water permeability is 260 ± 30.0 L·m -2 ·h -1 ·bar -1, the strength is 41.2 ± 2.23 MPa; under 20 V AC voltage, the piezoelectric response is 20.6 ± 0.5 mV.

[0069] Prepare a Tris-HCl buffer solution with pH = 3, and the concentrations of PDA and PEI added successively are both 0.5 g / L. Stir evenly to obtain the first-step modification solution;

[0070] The piezoelectric film is soaked at a temperature of 25 °C for 8 h. The first-step modified film is rinsed with deionized water and anhydrous ethanol and dried for later use;

[0071] Prepare a solution with a concentration of 0.2 mol / L SBES as the second-step modification solution;

[0072] The piezoelectric film that has completed the first-step modification is soaked in the second-step modification solution at a temperature of 60 °C for 24 h. After completion, it is rinsed with deionized water and anhydrous ethanol and dried for later use;

[0073] Perform performance tests on the finished modified piezoelectric ceramic film. The separation experiments are all carried out under a transmembrane pressure difference of 1 bar and a membrane surface flow rate of 0.5 m / s. It is found that the influence law of the modification concentration on the rejection rate of the rejected component (yeast) is the same as that in Example 1. When filtering a 500 pm yeast solution, the stable flux of the original membrane is 33 L·m -2 ·h -1 ·bar -1 ; when a 60 V AC electric field is applied, the membrane stable flux increases to 93 L·m -2 ·h -1 ·bar -1 ; the stable flux of the modified membrane without applying voltage is 54 L·m -2 ·h -1 ·bar -1 ; when a 60 V and 100 kHz AC electric field is applied, the stable flux of the modified membrane without applying voltage is 184 L·m -2 ·h -1 ·bar -1 , and the stable flux of the modified membrane increases to 6-7 times that of the original membrane when the voltage is applied.

[0074] Example 5 Modified piezoelectric ceramic membrane with Al2O3 / BTO as the support and its preparation

[0075] Using BTO as the raw material, prepare a BTO sheet-type piezoelectric support by the dry pressing method; the sintering temperature is 1200 °C, the heating rate is 2 °C / min, the cooling rate is 3 °C / min, and a film-forming solution of Al2O3 is coated on its surface by the dip-coating method for 60 s. After drying, it is sintered at 950 °C. The average pore diameter of the prepared composite membrane is 24 nm, and the pure water permeability is 129 ± 4 L·m -2 ·h -1 ·bar-1 ; Under 20V AC voltage, the piezoelectric response is 36.6 ± 1.5 mV.

[0076] Prepare a Tris-HCl buffer solution with pH = 8.5, and add PDA and PEI successively at a concentration of 0.2 g / L each, and stir evenly to obtain the first-step modification solution;

[0077] Immerse the piezoelectric film at 25 °C for 4 h. The first-step modified film is rinsed with deionized water and absolute ethanol and dried for later use;

[0078] Prepare a solution of 0.2 mol / L SBES as the second-step modification solution;

[0079] Immerse the piezoelectric film that has completed the first-step modification in the second-step modification solution at 50 °C for 12 h. After completion, rinse with deionized water and absolute ethanol and dry for later use;

[0080] Perform performance tests on the finished modified piezoelectric ceramic membrane. The separation experiments are all carried out under a transmembrane pressure difference of 1 bar and a membrane surface flow rate of 0.5 m / s. It is found that the influence law of the modification concentration on the rejection rate of the rejected components (oil and water) is the same as that in Example 1. When filtering a 500 pm oil-water solution, the stable flux of the original membrane is 46 L·m -2 ·h -1 ·bar -1 ; When applying a 60V AC electric field, the stable flux of the membrane is increased to 83 L·m -2 ·h -1 ·bar -1 ; The stable flux of the modified membrane without applying voltage is 64 L·m -2 ·h -1 ·bar -1 ; When applying a 60V and 147 kHz AC electric field, the stable flux of the modified membrane without applying voltage is 124 L·m -2 ·h -1 ·bar -1 , the stable flux of the modified membrane under the condition of applying voltage is increased to 2-3 times that of the original membrane, and the modified membrane is basically not polluted under the condition of applying voltage.

Claims

1. A zwitterionic modified piezoelectric ceramic membrane, characterized in that, It includes a piezoelectric ceramic membrane body and a modification layer on one side of the body. The modification layer has the following compound, where n refers to the number of repeating units: And a PDA layer is also included between the modification layer and the piezoelectric ceramic membrane body.

2. The zwitterionic modified piezoelectric ceramic film according to claim 1, wherein The value range of n is 50 - 2000.

3. The zwitterion-modified piezoelectric ceramic film according to claim 1, wherein The pore size range of the piezoelectric ceramic membrane body is 20 - 500 nm. Under a 20 V alternating voltage, it has a piezoelectric response of 10 - 30 mV. The material of the piezoelectric ceramic membrane body is selected from one of silicon oxide, lead zirconate titanate, sodium potassium niobate, and barium titanate. A selective separation layer made of ceramic material may or may not be contained on the piezoelectric ceramic membrane body.

4. The preparation method of the zwitterionic modified piezoelectric ceramic film according to claim 1, characterized in that, It includes the following steps: Step 1, prepare a buffer solution containing polydopamine and polyethyleneimine as the first modification solution; prepare a solution containing haloethyl sulfonate as the second modification solution. Step 2, contact the piezoelectric ceramic membrane body with the first modification solution. After the surface is loaded with polydopamine and polyethyleneimine, wash and dry it. Step 3, contact the piezoelectric ceramic membrane body obtained in Step 2 with the second modification solution. After a nucleophilic substitution reaction, a modification layer is formed on the surface.

5. The preparation method according to claim 4, characterized in that, In the first modification solution, the concentration range of polydopamine and polyethyleneimine is 0.01 - 20 g / L, and the buffer solution is a Tris - HCl buffer solution with pH = 1 - 13.

6. The preparation method according to claim 5, wherein The reaction conditions in Step 2: the temperature is 5 - 90 °C, and the time is 1 - 48 h.

7. The preparation method according to claim 4, characterized in that, In the second modification solution, the concentration range of haloethyl sulfonate is 0.5 - 20 mol / L.

8. The preparation method according to claim 5, characterized in that, The reaction conditions in Step 2: the temperature is 5 - 90 °C, and the reaction time is 1 - 96 h.

9. Use of the zwitterionic modified piezoelectric ceramic membrane according to claim 1 in liquid filtration.

10. The use according to claim 9, characterized in that, When performing liquid filtration, an alternating electric field of 20 - 200 V and 50 - 500 kHz also needs to be applied; the liquid contains organic substances and / or suspended solids.

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