阅读说明：本技术 一种氧化二硫化钼-氧化石墨烯复合纳滤膜及其制备方法 (Molybdenum disulfide oxide-graphene oxide composite 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-氧化石墨烯复合纳滤膜及其制备方法,包括经聚乙烯醇改性的有机超滤膜支撑体和设于该有机超滤膜支撑体上的功能层,该功能层以氧化二硫化钼和氧化石墨烯的混合水溶液为原料通过抽滤自组装于有机超滤膜支撑体上而形成。本发明通过氧化石墨烯中引入氧化二硫化钼片层,并通过简单的压力辅助方法抽滤在有机超滤膜支撑体上自组装成氧化二硫化钼-氧化石墨烯纳滤膜,在低压操作下提高了膜层通量。(The invention discloses a molybdenum disulfide oxide-graphene oxide composite nanofiltration membrane and a preparation method thereof. According to the invention, the molybdenum disulfide oxide lamella is introduced into the graphene oxide, and the molybdenum disulfide oxide-graphene oxide nanofiltration membrane is self-assembled on the organic ultrafiltration membrane support body through a simple pressure auxiliary method in a suction filtration manner, so that the membrane flux is improved under the low-pressure operation.)

1. The utility model provides a molybdenum disulfide of oxidation-compound nanofiltration membrane of oxidation membrane which characterized in that: the functional layer is formed by taking a mixed aqueous solution of a molybdenum disulfide oxide aqueous solution and a graphene oxide aqueous solution as a raw material and self-assembling the mixed aqueous solution on the organic ultrafiltration membrane support body through suction filtration, and the molecular weight of polyvinyl alcohol in the polyvinyl alcohol solution is 50000-100000.

2. The molybdenum disulfide oxide-graphene oxide composite nanofiltration membrane of claim 1, wherein: the organic ultrafiltration membrane support body is made of polyvinylidene fluoride, polyether sulfone or polycarbonate.

3. The molybdenum disulfide oxide-graphene oxide composite nanofiltration membrane of claim 1, wherein: the molecular weight cut-off of the organic ultrafiltration membrane support body is 50-60 KD.

4. The molybdenum disulfide oxide-graphene oxide composite nanofiltration membrane of claim 1, wherein: the molecular weight of the polyvinyl alcohol is 75000-85000, and the concentration of the polyvinyl alcohol solution is 2-3 wt%.

5. The nanofiltration membrane of any one of claims 1 to 4, wherein the nanofiltration membrane comprises the following components in parts by weight: the mass ratio of molybdenum disulfide oxide to graphene oxide in the mixed aqueous solution is 1: 2-5, the concentration of the molybdenum disulfide oxide aqueous solution is 0.08-0.12g/L, and the concentration of the graphene oxide aqueous solution is 0.08-0.12 g/L.

6. A preparation method of a molybdenum disulfide oxide-graphene oxide composite nanofiltration membrane is characterized by comprising the following steps: the method comprises the following steps: preparing a molybdenum disulfide oxide aqueous solution and a graphene oxide aqueous solution by an improved Hummers method, and further obtaining a mixed aqueous solution of molybdenum disulfide oxide and graphene oxide; the mixed aqueous solution is taken as a raw material, and is subjected to suction filtration and self-assembly on an organic ultrafiltration membrane support body modified by a polyvinyl alcohol solution to form the functional layer, so that the molybdenum disulfide oxide-graphene oxide composite nanofiltration membrane is obtained, wherein the molecular weight of polyvinyl alcohol in the polyvinyl alcohol solution is 50000-100000.

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) soaking the organic ultrafiltration membrane support body with the molecular weight cutoff of 50-60KD in a polyvinyl alcohol solution for modification to obtain a modified organic ultrafiltration membrane support body;

(3) filtering the mixed aqueous solution on the modified organic ultrafiltration membrane support body at room temperature, and removing unreacted mixed aqueous solution by using RO water;

(4) and (4) carrying out heat treatment on the material obtained in the step (3) at 50-65 ℃, and then cooling along with the furnace to obtain the molybdenum disulfide oxide-graphene oxide composite 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 0.08-0.12g/L, and the concentration of the graphene oxide aqueous solution is 0.08-0.12 g/L.

9. The production method according to claim 6 or 7, characterized in that: in the mixed aqueous solution, the mass ratio of molybdenum disulfide oxide to graphene oxide is 1: 2-5.

10. The production method according to claim 6 or 7, characterized in that: the concentration of the polyvinyl alcohol solution is 2-3 wt%, wherein the molecular weight of the polyvinyl alcohol is 75000-85000.

Technical Field

The invention belongs to the technical field of membrane separation, and particularly relates to a molybdenum disulfide oxide-graphene oxide composite 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. The nanofiltration membrane operates at lower pressure and higher flux than 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 can be self-assembled into a nanofiltration membrane by utilizing the lamellar structure of graphene oxide, and can realize quick and effective purification of pollutants through the interlayer spacing of graphene oxide, however, graphene oxide is too compact in prepared membrane layer and low in membrane flux, and the distance between the lamellar layers can be increased by introducing organic matters or inorganic particles, so that the membrane flux is improved, and therefore, the preparation of the graphene oxide composite membrane is a hotspot concerned by researchers.

Disclosure of Invention

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

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

The technical scheme of the invention is as follows:

the functional layer is formed by taking a mixed aqueous solution of a molybdenum disulfide oxide aqueous solution and a graphene oxide aqueous solution as a raw material and self-assembling the mixed aqueous solution on the organic ultrafiltration membrane support body through suction filtration, and the molecular weight of polyvinyl alcohol in the polyvinyl alcohol solution is 50000-100000.

In a preferred embodiment of the present invention, the material of the organic ultrafiltration membrane support is polyvinylidene fluoride, polyethersulfone or polycarbonate.

In a preferred embodiment of the invention, the molecular weight cut-off of the organic ultrafiltration membrane support is 50-60 KD.

In a preferred embodiment of the present invention, the molecular weight of the polyvinyl alcohol is 75000-85000, and the concentration of the polyvinyl alcohol solution is 2 to 3 wt%.

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 concentration of the molybdenum disulfide oxide aqueous solution is 0.08-0.12g/L, and the concentration of the graphene oxide aqueous solution is 0.08-0.12 g/L.

The other technical scheme of the invention is as follows:

a preparation method of a molybdenum disulfide oxide-graphene oxide composite nanofiltration membrane comprises the following steps: preparing a molybdenum disulfide oxide aqueous solution and a graphene oxide aqueous solution by an improved Hummers method, and further obtaining a mixed aqueous solution of the molybdenum disulfide oxide aqueous solution and the graphene oxide aqueous solution; the mixed aqueous solution is taken as a raw material, and is subjected to suction filtration and self-assembly on an organic ultrafiltration membrane support body modified by a polyvinyl alcohol solution to form the functional layer, so that the molybdenum disulfide oxide-graphene oxide composite nanofiltration membrane is obtained, wherein the molecular weight of polyvinyl alcohol in the polyvinyl alcohol solution is 50000-100000.

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) soaking the organic ultrafiltration membrane support body with the molecular weight cutoff of 50-60KD in a polyvinyl alcohol solution for modification to obtain a modified organic ultrafiltration membrane support body;

(3) filtering the mixed aqueous solution on the modified organic ultrafiltration membrane support body at room temperature, and removing unreacted mixed aqueous solution by using RO water;

(4) and (4) carrying out heat treatment on the material obtained in the step (3) at 50-65 ℃, and then cooling along with the furnace to obtain the molybdenum disulfide oxide-graphene oxide composite nanofiltration membrane.

In a preferred embodiment of the invention, the concentration of the molybdenum disulfide oxide aqueous solution is 0.08-0.12g/L, and the concentration of the graphene oxide aqueous solution is 0.08-0.12 g/L.

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.

In a preferred embodiment of the present invention, the concentration of the polyvinyl alcohol solution is 2 to 3 wt%, wherein the molecular weight of the polyvinyl alcohol is 75000-85000.

The invention has the beneficial effects that: according to the invention, the molybdenum disulfide oxide lamella is introduced into the graphene oxide, and the molybdenum disulfide oxide-graphene oxide nanofiltration membrane is self-assembled on the organic ultrafiltration membrane support body through a simple pressure auxiliary method in a suction filtration manner, so that the membrane flux is improved under the low-pressure operation.

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 the circulation of liquid in a pipeline, membrane holes cannot be blocked, smoothness of the membrane holes is guaranteed, and the GO sheet layer with larger size is crushed and stripped; the ceramic tubular membrane filtration pore size is larger than the impurity ion size of GO solution, so that H is obtained⁺、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 Mn²⁺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 0.1g/L by using a modified Hummers method;

(2) soaking a 50KD polyvinylidene fluoride ultrafiltration membrane in a 1 wt% polyvinyl alcohol (molecular weight is 8 ten thousand) solution for 24h for modification, then cleaning with ethanol and RO water, and drying at 60 ℃ to obtain a modified organic ultrafiltration membrane support body;

(3) at room temperature, carrying out suction filtration on the graphene oxide aqueous solution on the modified organic ultrafiltration membrane support, and then removing unreacted graphene oxide aqueous solution by using RO water;

(4) and (4) carrying out heat treatment on the material obtained in the step (3) at 60 ℃ for 1h, and then cooling along with the furnace 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 0.2MPa, and had a pure water flux of 0.75LHM and a retention of 99% for a 0.2 wt% methylene blue solution.

Comparative example 2

(1) Preparing a molybdenum disulfide oxide aqueous solution with the concentration of 0.1g/L by using a modified Hummers method;

(2) soaking a 50KD polyvinylidene fluoride ultrafiltration membrane in a 1 wt% polyvinyl alcohol (molecular weight is 8 ten thousand) solution for 24h for modification, then cleaning with ethanol and RO water, and drying at 60 ℃ to obtain a modified organic ultrafiltration membrane support body;

(3) at room temperature, carrying out suction filtration on the molybdenum disulfide oxide aqueous solution on the modified organic ultrafiltration membrane support body, and then removing unreacted graphene oxide aqueous solution by using RO water;

(4) and (4) carrying out heat treatment on the material obtained in the step (3) at 60 ℃ for 1h, and then cooling along with the furnace 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 0.2MPa, and had a pure water flux of 10.2LHM and a retention of 96.2% by weight of methylene blue solution.

Comparative example 3

(1) Respectively preparing a molybdenum disulfide oxide aqueous solution with the concentration of 0.1g/L and a graphene oxide aqueous solution with the concentration of 0.1g/L by using an improved Hummers method, and ultrasonically mixing the molybdenum disulfide oxide aqueous solution and the graphene oxide aqueous solution for 10min according to the volume ratio of 1: 6 to obtain a mixed aqueous solution of molybdenum disulfide oxide and graphene oxide;

(2) soaking a 50KD polyvinylidene fluoride ultrafiltration membrane in a 3 wt% polyvinyl alcohol (molecular weight is 8 ten thousand) solution for 24h for modification, then cleaning with ethanol and RO water, and drying at 60 ℃ to obtain a modified organic ultrafiltration membrane support body;

(3) filtering the mixed aqueous solution on the modified organic ultrafiltration membrane support body at room temperature, and removing unreacted mixed aqueous solution by using RO water;

(4) and (4) carrying out heat treatment on the material obtained in the step (3) at 60 ℃ for 1h, and then cooling along with the furnace 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 0.2MPa, and had a pure water flux of 12LHM and a retention of 99% for a 0.2 wt% methylene blue solution.

Comparative example 4

(1) Respectively preparing a molybdenum disulfide oxide aqueous solution with the concentration of 0.1g/L and a graphene oxide aqueous solution with the concentration of 0.1g/L by using an improved Hummers method, and ultrasonically mixing the molybdenum disulfide oxide aqueous solution and the graphene oxide aqueous solution for 10min at a volume ratio of 1: 5 to obtain a mixed aqueous solution of molybdenum disulfide oxide and graphene oxide;

(2) soaking a 50KD polyvinylidene fluoride ultrafiltration membrane in a 5 wt% polyvinyl alcohol (molecular weight is 8 ten thousand) solution for 24h for modification, then cleaning with ethanol and RO water, and drying at 60 ℃ to obtain a modified organic ultrafiltration membrane support body;

(3) filtering the mixed aqueous solution on the modified organic ultrafiltration membrane support body at room temperature, and removing unreacted mixed aqueous solution by using RO water;

(4) and (4) carrying out heat treatment on the material obtained in the step (3) at 60 ℃ for 1h, and then cooling along with the furnace 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 0.2MPa, and had a pure water flux of 8LHM and a retention of 99% for a 0.2 wt% methylene blue solution.

Example 1

(1) Respectively preparing a molybdenum disulfide oxide aqueous solution with the concentration of 0.1g/L and a graphene oxide aqueous solution with the concentration of 0.1g/L by using an improved Hummers method, and ultrasonically mixing the molybdenum disulfide oxide aqueous solution and the graphene oxide aqueous solution for 10min at the volume ratio of 2.5: 5 to obtain a mixed aqueous solution of molybdenum disulfide oxide and graphene oxide;

(2) soaking a 50KD polyvinylidene fluoride ultrafiltration membrane in a 2 wt% polyvinyl alcohol (molecular weight is 8 ten thousand) solution for 24h for modification, then cleaning with ethanol and RO water, and drying at 60 ℃ to obtain a modified organic ultrafiltration membrane support body;

(3) filtering the mixed aqueous solution on the modified organic ultrafiltration membrane support body at room temperature, and removing unreacted mixed aqueous solution by using RO water;

(4) and (4) carrying out heat treatment on the material obtained in the step (3) at 60 ℃ for 1h, and then cooling along with a furnace to obtain the molybdenum disulfide oxide-graphene oxide composite nanofiltration membrane.

Testing the performance of the membrane tube: the molybdenum disulfide oxide-graphene oxide composite nanofiltration membrane prepared in the embodiment is tested under the conditions of room temperature and 0.2MPa, the pure water flux of the nanofiltration membrane is 15LHM, and the rejection rate of the nanofiltration membrane on 0.2 wt% of methylene blue solution is 99%.

Example 2

(1) Respectively preparing a molybdenum disulfide oxide aqueous solution with the concentration of 0.1g/L and a graphene oxide aqueous solution with the concentration of 0.1g/L by using an improved Hummers method, and ultrasonically mixing the molybdenum disulfide oxide aqueous solution and the graphene oxide aqueous solution for 10min at a volume ratio of 1: 5 to obtain a mixed aqueous solution of molybdenum disulfide oxide and graphene oxide;

(2) soaking a 50KD polyvinylidene fluoride ultrafiltration membrane in a 3 wt% polyvinyl alcohol (molecular weight is 8 ten thousand) solution for 24h for modification, then cleaning with ethanol and RO water, and drying at 60 ℃ to obtain a modified organic ultrafiltration membrane support body;

(3) filtering the mixed aqueous solution on the modified organic ultrafiltration membrane support body at room temperature, and removing unreacted mixed aqueous solution by using RO water;

(4) and (4) carrying out heat treatment on the material obtained in the step (3) at 60 ℃ for 1h, and then cooling along with a furnace to obtain the molybdenum disulfide oxide-graphene oxide composite nanofiltration membrane.

Testing the performance of the membrane tube: the molybdenum disulfide oxide-graphene oxide composite nanofiltration membrane prepared in the embodiment is tested under the conditions of room temperature and 0.2MPa, the pure water flux of the nanofiltration membrane is 16LHM, and the rejection rate of the nanofiltration membrane on 0.2 wt% of methylene blue solution is 99%.

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.