阅读说明：本技术 一种氧化二硫化钼-氧化石墨烯-pei复合陶瓷纳滤膜及其制备方法 (Molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane and preparation method thereof ) 是由 陈云强 洪昱斌 方富林 蓝伟光 于 2020-06-12 设计创作，主要内容包括：本发明公开了一种氧化二硫化钼-氧化石墨烯-PEI复合陶瓷纳滤膜及其制备方法,包括多孔陶瓷膜支撑体和设于该多孔陶瓷膜支撑体上的有机功能层,该多孔陶瓷膜支撑体的表面负载有硅烷偶联剂,该有机功能层以氧化二硫化钼和氧化石墨烯的混合水溶液和聚乙烯亚胺水溶液为原料通过层层自组装交替复合于多孔陶瓷膜支撑体上形成。本发明通过在负载有交联剂的无机陶瓷膜上制备氧化二硫化钼/氧化石墨烯/PEI复合陶瓷纳滤膜,使得本发明对硫酸镁溶液具有较高的脱盐率,纯水通量高且耐酸碱性能良好。(The invention discloses a molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane and a preparation method thereof. According to the invention, the molybdenum disulfide oxide/graphene oxide/PEI composite ceramic nanofiltration membrane is prepared on the inorganic ceramic membrane loaded with the cross-linking agent, so that the magnesium sulfate nanofiltration membrane has high desalination rate on magnesium sulfate solution, high pure water flux and good acid and alkali resistance.)

1. A molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane is characterized in that: the organic functional layer is formed by taking a mixed aqueous solution of molybdenum disulfide oxide and graphene oxide and a polyethyleneimine aqueous solution as raw materials and alternately compounding the raw materials on the porous ceramic membrane support layer by layer in a self-assembly manner; and the amino group on the silane coupling agent is reacted and connected with the hydroxyl groups on the graphene oxide and the molybdenum disulfide oxide.

2. The molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane of claim 1, wherein: the silane coupling agent is 3-aminopropyl triethoxysilane.

3. The molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane of claim 1, wherein: the aperture of the porous ceramic membrane support is 10-100 nm.

4. The molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane of claim 1, wherein: the material of the porous ceramic membrane support body is alumina, titanium oxide or zirconium oxide.

5. The nanofiltration membrane of any one of claims 1 to 4, wherein the nanofiltration membrane comprises molybdenum disulfide oxide, graphene oxide and PEI: the mass ratio of the molybdenum disulfide oxide to the graphene oxide in the mixed aqueous solution is 1: 2-5.

6. The method for preparing the molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane as claimed in any one of claims 1 to 5, wherein the method comprises the following steps: the method comprises the following steps: preparing molybdenum disulfide oxide and graphene oxide by an improved Hummers method, and further obtaining a mixed aqueous solution of the molybdenum disulfide oxide and the graphene oxide; and (2) taking the mixed aqueous solution and a polyethyleneimine aqueous solution as raw materials, and forming the organic functional layer on the porous ceramic membrane support activated by strong base and grafted with the silane coupling agent by layer-by-layer self-assembly, wherein amino on the silane coupling agent is reacted and connected with hydroxyl on graphene oxide and molybdenum disulfide oxide, so that the molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane is obtained.

7. The method of claim 6, wherein: the method comprises the following steps:

(1) respectively preparing a molybdenum disulfide oxide aqueous solution and a graphene oxide aqueous solution by using an improved Hummers method, and mixing to obtain a mixed aqueous solution of molybdenum disulfide oxide and graphene oxide;

(2) preparing a polyethyleneimine aqueous solution;

(3) after ultrasonic treatment, soaking the ceramic membrane support body in a strong alkali solution for activation treatment, and then drying to obtain an activated ceramic membrane support body;

(4) soaking the activated ceramic membrane support body in a silane coupling agent solution, then cleaning with ethanol and water, and drying to obtain a grafted ceramic membrane support body;

(5) soaking the grafted ceramic membrane support body in the mixed aqueous solution at room temperature for reaction, removing unreacted mixed aqueous solution by using RO water after reaction, soaking in the polyethyleneimine aqueous solution for reaction, and removing unreacted polyethyleneimine aqueous solution by using RO water after reaction; repeating the steps 1 to 3 times;

(6) and (5) drying the material obtained in the step (5) in the shade, then carrying out heat treatment at 50-80 ℃, and then cooling along with a furnace to obtain the molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane.

8. The production method according to claim 6 or 7, characterized in that: the concentration of the molybdenum disulfide oxide aqueous solution is 1-5g/L, and the concentration of the graphene oxide aqueous solution is 1-5 g/L.

9. The production method according to claim 6 or 7, characterized in that: the concentration of the polyethyleneimine aqueous solution is 2-6 g/L.

10. The production method according to claim 6 or 7, characterized in that: the concentration of the molybdenum disulfide oxide aqueous solution is 1-5g/L, the concentration of the graphene oxide aqueous solution is 1-5g/L, and the concentration of the polyethyleneimine aqueous solution is 2-6 g/L.

Technical Field

The invention belongs to the technical field of membrane separation, and particularly relates to a molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane and a preparation method thereof.

Background

The nanofiltration membrane technology is a means for effectively solving the problem of water purification due to simple operation and high efficiency. Nanofiltration membrane operation is at lower pressure and higher flux relative to RO membranes. The organic nanofiltration membrane widely used at present has the advantages of high air permeability, low density, good film forming property, low cost, good flexibility and the like, so the organic nanofiltration membrane is widely used in water treatment.

Research on nanofiltration membranes in recent years shows that the nanofiltration membranes prepared from graphene oxide materials are more and more concerned. Graphene oxide utilizes its lamellar structure ability self-assembly to receive the filter membrane, can realize the quick effective purification to the pollutant through its interlamellar spacing, however graphene oxide leads to the rete spacing grow in aqueous owing to its surface hydrophilic effect to it is unstable in aqueous, dissolves in aqueous easily, therefore the effect between the reinforcing graphene oxide is seem to be especially important.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane.

The invention also aims to provide a preparation method of the molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane.

The technical scheme of the invention is as follows:

a molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane is characterized in that: the organic functional layer is formed by taking a mixed aqueous solution of molybdenum disulfide oxide and graphene oxide and a polyethyleneimine aqueous solution as raw materials and alternately compounding the raw materials on the porous ceramic membrane support layer by layer through self-assembly; and the amino group on the silane coupling agent is reacted and connected with the hydroxyl groups on the graphene oxide and the molybdenum disulfide oxide.

In a preferred embodiment of the present invention, the silane coupling agent is 3-aminopropyltriethoxysilane.

In a preferred embodiment of the present invention, the pore size of the porous ceramic membrane support is 10 to 100 nm.

In a preferred embodiment of the present invention, the material of the porous ceramic membrane support is alumina, titania or zirconia.

In a preferred embodiment of the invention, the mass ratio of the molybdenum disulfide oxide to the graphene oxide in the mixed aqueous solution is 1: 2-5.

The preparation method of the molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane comprises the following steps: preparing molybdenum disulfide oxide and graphene oxide by an improved Hummers method, and further obtaining a mixed aqueous solution of the molybdenum disulfide oxide and the graphene oxide; and (2) taking the mixed aqueous solution and a polyethyleneimine aqueous solution as raw materials, and forming the organic functional layer by layer-by-layer self-assembly on the porous ceramic membrane support activated by strong base and grafted with the silane coupling agent, wherein amino on the silane coupling agent is reacted and connected with hydroxyl on graphene oxide and molybdenum disulfide oxide, so that the molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane is obtained.

In a preferred embodiment of the present invention, the method comprises the following steps:

(1) respectively preparing a molybdenum disulfide oxide aqueous solution and a graphene oxide aqueous solution by using an improved Hummers method, and mixing to obtain a mixed aqueous solution of molybdenum disulfide oxide and graphene oxide;

(2) preparing a polyethyleneimine aqueous solution;

(3) after ultrasonic treatment, soaking the ceramic membrane support body in a strong alkaline solution for activation treatment, and then drying to obtain an activated ceramic membrane support body;

(4) soaking the activated ceramic membrane support body in a silane coupling agent solution, then cleaning with ethanol and water, and drying to obtain a grafted ceramic membrane support body;

(5) soaking the grafted ceramic membrane support body in the mixed aqueous solution at room temperature for reaction, removing unreacted mixed aqueous solution by using RO water after reaction, soaking in the polyethyleneimine aqueous solution for reaction, and removing unreacted polyethyleneimine aqueous solution by using RO water after reaction; repeating the steps 1 to 3 times;

(6) and (5) drying the material obtained in the step (5) in the shade, then carrying out heat treatment at 50-80 ℃, and then cooling along with the furnace to obtain the molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane.

In a preferred embodiment of the invention, the concentration of the molybdenum disulfide oxide aqueous solution is 1-5g/L, and the concentration of the graphene oxide aqueous solution is 1-5 g/L.

In a preferred embodiment of the invention, the concentration of the aqueous polyethyleneimine solution is from 2 to 6 g/L.

In a preferred embodiment of the invention, the concentration of the molybdenum disulfide oxide aqueous solution is 1-5g/L, the concentration of the graphene oxide aqueous solution is 1-5g/L, and the concentration of the polyethyleneimine aqueous solution is 2-6 g/L.

The invention has the beneficial effects that: according to the invention, the molybdenum oxide disulfide/graphene oxide/PEI composite ceramic nanofiltration membrane is prepared on the inorganic ceramic membrane loaded with the cross-linking agent, the molybdenum oxide disulfide is doped into the graphene oxide lamellar to form a loose lamellar structure, and a synergistic effect is formed by a Gibbs-Donnan exclusion mechanism and steric hindrance, so that the roughness of the membrane layer is improved by doping the molybdenum oxide disulfide, the water contact area is improved, and the magnesium sulfate solution desalting rate is higher, the pure water flux is high, and the acid and alkali resistance is good.

Detailed Description

The technical solution of the present invention is further illustrated and described by the following detailed description.

The method for preparing the molybdenum disulfide oxide by the modified Hummers method in the following comparative examples and examples specifically comprises the following steps of:

(1) 1000mL of beaker is taken, cleaned and dried, 3g of molybdenum disulfide is added, and 360mL of concentrated sulfuric acid (98% H) is slowly added under magnetic stirring₂SO₄) And 40mL concentrated phosphoric acid (95% H)₃PO₄) Then 18g of potassium permanganate (KMnO) is slowly added in batches₄) (ii) a The beaker was transferred to a 50 ℃ oil bath and stirred for 12 h. Taking out the beaker, and naturally cooling to room temperature. The reaction solution was slowly poured into 400mL of dilute hydrogen peroxide (containing 18mL of 30% H)₂O₂) On ice, the solution turned bright yellow;

(2) performing cross-flow filtration on the solution by using a tubular ceramic membrane with the aperture of 0.05 mu m to remove impurities to obtain a material after impurity removal

(3) And (3) diluting or concentrating the material obtained in the step (2) according to the required concentration to obtain molybdenum oxide disulfide aqueous solutions with different concentrations.

The method for preparing graphene oxide by the modified Hummers method in the following comparative examples and examples specifically comprises the following steps:

(1) 1000mL of beaker is cleaned and dried, 3g of crystalline flake graphite is added, and 360mL of concentrated sulfuric acid (98% H) is slowly added under magnetic stirring₂SO₄) And 40mL concentrated phosphoric acid (95% H)₃PO₄) Then 18g of potassium permanganate (KMnO) is slowly added in batches₄) (ii) a The beaker was transferred to a 50 ℃ oil bath and stirred for 12 h. Taking out the beaker, and naturally cooling to room temperature. The reaction solution was slowly poured into 400mL of dilute hydrogen peroxide (containing 18mL of 30% H)₂O₂) On ice, the solution turned bright yellow;

(2) carrying out cross-flow filtration on the solution by using a tubular ceramic membrane with the aperture of 0.05 mu m to remove impurities, and obtaining an oxidized graphene solution after impurity removal; the basic principle is that the pore size screening effect of the ceramic membrane is utilized, namely the size of the filtering pore size of the ceramic tubular membrane is smaller than that of the GO sheet layer, so that the GO sheet layer cannot flow out through the tubular ceramic membrane and flows back to a material liquid barrel along with liquid in a pipeline in a circulating manner, membrane holes cannot be blocked, smoothness of the membrane holes is guaranteed, and the GO sheet layer with larger size is crushed and stripped; ceramic materialThe pore size of the tubular membrane filter is larger than the size of impurity ions of GO solution, so that H is⁺、K⁺、 Mn²⁺The isoacid radicals and metal ions can be easily discharged through the pore diameter of the ceramic tubular membrane. The GO, the waste acid and the K are repeatedly circulated in the way⁺And Mn^{2 +}Separating metal ions, collecting GO solution, and washing and removing impurities of GO;

(3) and diluting or concentrating according to the required concentration to obtain the graphene oxide aqueous solutions with different concentrations.

Comparative example 1

(1) Preparing a graphene oxide aqueous solution with the concentration of 3mg/mL by using a modified Hummers method;

(2) preparing a polyethyleneimine water solution with the concentration of 3 g/L;

(3) ultrasonically treating an alumina ceramic membrane tube with the aperture of about 50cm after cutting for 5 hours, soaking the alumina ceramic membrane tube with the aperture of 100nm for 24 hours by using 2mol/L sodium hydroxide, drying the tube for 10 hours at the temperature of 100 ℃, washing the ceramic membrane tube by using cellulose after cooling, then washing the ceramic membrane tube by using ethanol and deionized water for a plurality of times in sequence, drying the tube for 12 hours at the temperature set value of 100 ℃ in a drying oven, and cooling the tube along with the oven to obtain an activated ceramic membrane support body;

(4) soaking the activated ceramic membrane support body in a 2 mmol/L3-aminopropyltriethoxysilane ethanol solution, reacting for 12 hours at room temperature, washing with ethanol and deionized water for several times, drying in a drying oven at a temperature set value of 150 ℃ for 12 hours, and cooling with the oven to obtain a grafted ceramic membrane support body;

(5) soaking the grafted ceramic membrane support body in the graphene oxide aqueous solution at room temperature for reaction for 10min, removing unreacted graphene oxide aqueous solution by using RO water after the reaction, soaking in the polyethyleneimine aqueous solution for reaction for 10min, and removing unreacted polyethyleneimine aqueous solution by using RO water after the reaction; repeating the step for 1 time;

(6) and (5) placing the material obtained in the step (4) in a shade place for air drying, then placing the material in a 50 ℃ oven for heat treatment for 15min, and then cooling the material along with the oven to obtain the contrast film.

Testing the performance of the membrane tube: the comparative film obtained in this comparative example was tested at room temperature and a pressure of 0.6MPa, and had a pure water flux of 21LHM and a rejection of 93% for a 0.2 wt% solution of magnesium sulfate.

And (3) acid and alkali resistance test: after the comparative membrane prepared in the comparative example is respectively soaked in a nitric acid solution with the pH value of 2 and a sodium hydroxide solution with the pH value of 12 for 168 hours at the temperature of 85 ℃, the pure water flux is respectively 20 LHM and 18LHM, the retention rates are respectively 91.7 percent and 91.3 percent, and the performance is basically kept unchanged.

Comparative example 2

(1) Respectively preparing a molybdenum disulfide oxide aqueous solution and a graphene oxide aqueous solution with the concentration of 3mg/mL by using an improved Hummers method, and mixing to obtain a mixed aqueous solution of molybdenum disulfide oxide and graphene oxide, wherein the mass ratio of molybdenum disulfide oxide to graphene oxide is 1: 1;

(2) preparing a polyethyleneimine water solution with the concentration of 3 g/L;

(3) ultrasonically treating an alumina ceramic membrane tube with the aperture of about 50cm after cutting for 5 hours, soaking the alumina ceramic membrane tube with the aperture of 100nm for 24 hours by using 2mol/L sodium hydroxide, drying the tube for 10 hours at the temperature of 100 ℃, washing the ceramic membrane tube by using cellulose after cooling, then washing the ceramic membrane tube by using ethanol and deionized water for a plurality of times in sequence, drying the tube for 12 hours at the temperature set value of 100 ℃ in a drying oven, and cooling the tube along with the oven to obtain an activated ceramic membrane support body;

(4) soaking the activated ceramic membrane support body in a 2 mmol/L3-aminopropyltriethoxysilane ethanol solution, reacting for 12 hours at room temperature, washing with ethanol and deionized water for several times, drying in a drying oven at a temperature set value of 150 ℃ for 12 hours, and cooling with the oven to obtain a grafted ceramic membrane support body;

(5) soaking the grafted ceramic membrane support body in the mixed aqueous solution at room temperature for reaction for 10min, removing unreacted mixed aqueous solution by using RO water after the reaction, soaking in the polyethyleneimine aqueous solution for reaction for 10min, and removing unreacted polyethyleneimine aqueous solution by using RO water after the reaction; repeating the step for 1 time;

(6) and (5) placing the material obtained in the step (5) in a shade place for air drying, then placing the material in a 50 ℃ oven for heat treatment for 15min, and then cooling the material along with the oven to obtain the contrast film.

Testing the performance of the membrane tube: the comparative film obtained in this comparative example was tested at room temperature and a pressure of 0.6MPa, and had a pure water flux of 48LHM and a rejection of 85% for a 0.2 wt% solution of magnesium sulfate.

And (3) acid and alkali resistance test: after the comparative membrane prepared in the comparative example was immersed in a nitric acid solution having a pH of 2 and a sodium hydroxide solution having a pH of 12 at 85 ℃ for 168 hours, pure water fluxes were 47.2 and 47.0LHM, retention rates were 84.2% and 83.6%, respectively, and the performance was substantially maintained.

Comparative example 3

(1) Respectively preparing a molybdenum disulfide oxide aqueous solution and a graphene oxide aqueous solution with the concentration of 3mg/mL by using an improved Hummers method, and mixing to obtain a mixed aqueous solution of molybdenum disulfide oxide and graphene oxide, wherein the mass ratio of molybdenum disulfide oxide to graphene oxide is 1: 6;

(2) preparing a polyethyleneimine water solution with the concentration of 3 g/L;

(3) ultrasonically treating an alumina ceramic membrane tube with the aperture of about 50cm after cutting for 5 hours, soaking the alumina ceramic membrane tube with the aperture of 100nm for 24 hours by using 2mol/L sodium hydroxide, drying the tube for 10 hours at the temperature of 100 ℃, washing the ceramic membrane tube by using cellulose after cooling, then washing the ceramic membrane tube by using ethanol and deionized water for a plurality of times in sequence, drying the tube for 12 hours at the temperature set value of 100 ℃ in a drying oven, and cooling the tube along with the oven to obtain an activated ceramic membrane support body;

(4) soaking the activated ceramic membrane support body in a 2 mmol/L3-aminopropyltriethoxysilane ethanol solution, reacting for 12 hours at room temperature, washing with ethanol and deionized water for several times, drying in a drying oven at a temperature set value of 150 ℃ for 12 hours, and cooling with the oven to obtain a grafted ceramic membrane support body;

(5) soaking the grafted ceramic membrane support body in the mixed aqueous solution at room temperature for reaction for 10min, removing unreacted mixed aqueous solution by using RO water after the reaction, soaking in the polyethyleneimine aqueous solution for reaction for 10min, and removing unreacted polyethyleneimine aqueous solution by using RO water after the reaction; repeating the step for 1 time;

(6) and (5) placing the material obtained in the step (5) in a shade place for air drying, then placing the material in a 50 ℃ oven for heat treatment for 15min, and then cooling the material along with the oven to obtain the contrast film.

Testing the performance of the membrane tube: the comparative film obtained in this comparative example was tested at room temperature and a pressure of 0.6MPa, and had a pure water flux of 35LHM and a retention of 92% for a 0.2 wt% magnesium sulfate solution.

And (3) acid and alkali resistance test: after the comparative membrane prepared in the comparative example was immersed in a nitric acid solution having a pH of 2 and a sodium hydroxide solution having a pH of 12 at 85 ℃ for 168 hours, the pure water fluxes were 34.2 and 33.0LHM, respectively, and the retention rates were 91.2% and 90.6%, respectively, with the properties being substantially maintained.

Example 1

(1) Respectively preparing a molybdenum disulfide oxide aqueous solution and a graphene oxide aqueous solution with the concentration of 3mg/mL by using an improved Hummers method, and mixing to obtain a mixed aqueous solution of molybdenum disulfide oxide and graphene oxide, wherein the mass ratio of molybdenum disulfide oxide to graphene oxide is 1: 2;

(2) preparing a polyethyleneimine water solution with the concentration of 3 g/L;

(3) ultrasonically treating an alumina ceramic membrane tube with the aperture of about 50cm after cutting for 5 hours, soaking the alumina ceramic membrane tube with the aperture of 100nm for 24 hours by using 2mol/L sodium hydroxide, drying the tube for 10 hours at the temperature of 100 ℃, washing the ceramic membrane tube by using cellulose after cooling, then washing the ceramic membrane tube by using ethanol and deionized water for a plurality of times in sequence, drying the tube for 12 hours at the temperature set value of 100 ℃ in a drying oven, and cooling the tube along with the oven to obtain an activated ceramic membrane support body;

(4) soaking the activated ceramic membrane support body in a 2 mmol/L3-aminopropyltriethoxysilane ethanol solution, reacting for 12 hours at room temperature, washing with ethanol and deionized water for several times, drying in a drying oven at a temperature set value of 150 ℃ for 12 hours, and cooling with the oven to obtain a grafted ceramic membrane support body;

(5) soaking the grafted ceramic membrane support body in the mixed aqueous solution at room temperature for reaction for 10min, removing unreacted mixed aqueous solution by using RO water after the reaction, soaking in the polyethyleneimine aqueous solution for reaction for 10min, and removing unreacted polyethyleneimine aqueous solution by using RO water after the reaction; repeating the step for 1 time;

(6) and (3) placing the material obtained in the step (5) in a shade place for air drying, then placing the material in a 50 ℃ oven for heat treatment for 15min, and then cooling the material along with the oven to obtain the molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane.

Testing the performance of the membrane tube: the molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane prepared in the embodiment is tested at room temperature and under the pressure of 0.6MPa, the pure water flux is 45LHM, and the retention rate of 0.2 wt% magnesium sulfate solution is 94%.

And (3) acid and alkali resistance test: the molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane prepared in the embodiment is respectively placed in a nitric acid solution with the pH value of 2 and a sodium hydroxide solution with the pH value of 12, after the nanofiltration membrane is soaked for 168 hours at the temperature of 85 ℃, pure water fluxes are respectively 44 LHM and 43.5LHM, retention rates are respectively 93.7% and 93.4%, and performances are basically kept unchanged.

Example 2

(1) Respectively preparing a molybdenum disulfide oxide aqueous solution and a graphene oxide aqueous solution with the concentration of 5mg/mL by using an improved Hummers method, and mixing to obtain a mixed aqueous solution of molybdenum disulfide oxide and graphene oxide, wherein the mass ratio of molybdenum disulfide oxide to graphene oxide is 1: 3;

(2) preparing a polyethyleneimine water solution with the concentration of 5 g/L;

(3) ultrasonically treating a titanium oxide ceramic membrane tube with the length of about 50cm and the aperture of 80nm after cutting for 5 hours, soaking the titanium oxide ceramic membrane tube in 2mol/L sodium hydroxide for 24 hours, drying the titanium oxide ceramic membrane tube for 10 hours at the temperature of 100 ℃, washing the ceramic membrane tube by using cellulose after cooling, then sequentially washing the ceramic membrane tube by using ethanol and deionized water for a plurality of times, drying the ceramic membrane tube for 12 hours at the temperature set value of 100 ℃ in a drying oven, and cooling the ceramic membrane tube along with the oven to obtain an activated ceramic membrane support body;

(4) soaking the activated ceramic membrane support body in a 2 mmol/L3-aminopropyltriethoxysilane ethanol solution, reacting for 12 hours at room temperature, washing with ethanol and deionized water for several times, drying in a drying oven at a temperature set value of 150 ℃ for 12 hours, and cooling with the oven to obtain a grafted ceramic membrane support body;

(5) soaking the grafted ceramic membrane support body in the mixed aqueous solution at room temperature for reaction for 10min, removing unreacted mixed aqueous solution by using RO water after the reaction, soaking in the polyethyleneimine aqueous solution for reaction for 10min, and removing unreacted polyethyleneimine aqueous solution by using RO water after the reaction; repeating the step for 1 time;

(6) and (3) placing the material obtained in the step (5) in a shade place for air drying, then placing the material in a 50 ℃ oven for heat treatment for 15min, and then cooling the material along with the oven to obtain the molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane.

Testing the performance of the membrane tube: the molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane prepared in the embodiment is tested at room temperature and under the pressure condition of 0.6MPa, the pure water flux is 42LHM, and the retention rate of 0.2 wt% magnesium sulfate solution is 95%.

And (3) acid and alkali resistance test: the molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane prepared in the embodiment is respectively placed in a nitric acid solution with the pH value of 2 and a sodium hydroxide solution with the pH value of 12, after the nanofiltration membrane is soaked for 168 hours at the temperature of 85 ℃, pure water fluxes are respectively 41.2LHM and 41.5LHM, retention rates are respectively 94.3% and 94.5%, and performances are basically kept unchanged.

Example 3

(1) Respectively preparing a molybdenum disulfide oxide aqueous solution and a graphene oxide aqueous solution with the concentration of 5mg/mL by using an improved Hummers method, and mixing to obtain a mixed aqueous solution of molybdenum disulfide oxide and graphene oxide, wherein the mass ratio of molybdenum disulfide oxide to graphene oxide is 1: 5;

(2) preparing a polyethyleneimine water solution with the concentration of 6 g/L;

(3) ultrasonically treating an alumina ceramic membrane tube with the length of about 50cm and the aperture of 10nm after cutting for 10 hours, soaking the alumina ceramic membrane tube in 2mol/L sodium hydroxide for 24 hours, drying the tube for 10 hours at the temperature of 100 ℃, washing the ceramic membrane tube by using cellulose after cooling, then washing the ceramic membrane tube by using ethanol and deionized water for a plurality of times in sequence, drying the tube for 12 hours at the temperature of 100 ℃ in a drying oven, and cooling the tube along with the oven to obtain an activated ceramic membrane support body;

(4) soaking the activated ceramic membrane support body in a 2 mmol/L3-aminopropyltriethoxysilane ethanol solution, reacting for 12 hours at room temperature, washing with ethanol and deionized water for several times, drying in a drying oven at a temperature set value of 150 ℃ for 12 hours, and cooling with the oven to obtain a grafted ceramic membrane support body;

(5) soaking the grafted ceramic membrane support body in the mixed aqueous solution at room temperature for reaction for 10min, removing unreacted mixed aqueous solution by using RO water after the reaction, soaking in the polyethyleneimine aqueous solution for reaction for 10min, and removing unreacted polyethyleneimine aqueous solution by using RO water after the reaction; repeating the step for 1 time;

(6) and (3) placing the material obtained in the step (5) in a shade place for air drying, then placing the material in a 50 ℃ oven for heat treatment for 15min, and then cooling the material along with the oven to obtain the molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane.

Testing the performance of the membrane tube: the molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane prepared in the embodiment is tested at room temperature and under the pressure condition of 0.6MPa, the pure water flux of the nanofiltration membrane is 40LHM, and the interception rate of the nanofiltration membrane on 0.2 wt% of magnesium sulfate solution is 94%.

And (3) acid and alkali resistance test: the molybdenum disulfide oxide-graphene oxide-PEI composite ceramic nanofiltration membrane prepared in the embodiment is respectively placed in a nitric acid solution with the pH value of 2 and a sodium hydroxide solution with the pH value of 12, after the nanofiltration membrane is soaked for 168 hours at the temperature of 85 ℃, pure water fluxes are respectively 39.1 LHM and 38.7LHM, retention rates are respectively 93.4% and 92.9%, and performances are basically kept unchanged.

The above description is only a preferred embodiment of the present invention, and therefore should not be taken as limiting the scope of the invention, which is defined by the appended claims.