阅读说明：本技术 一种多巴胺改性二氧化钛氧化石墨烯聚酰胺纳滤膜及其制备方法 (Dopamine-modified titanium dioxide graphene oxide polyamide 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：本发明公开了一种多巴胺改性二氧化钛氧化石墨烯聚酰胺纳滤膜及其制备方法,包括聚醚砜支撑体和设于该聚醚砜支撑体上的有机功能层,该有机功能层以水相单体、有机相单体和酸接受剂为原料通过界面聚合反应于聚醚砜支撑体上形成。本发明在室温和0.6MPa的测试条件下,对0.2wt％的硫酸镁溶液具有较高的截留率(96％以上),纯水通量为50-60LHM。(The invention discloses a dopamine modified titanium dioxide graphene oxide polyamide nanofiltration membrane and a preparation method thereof. The invention has higher retention rate (more than 96 percent) for 0.2wt percent of magnesium sulfate solution and pure water flux of 50-60LHM under the test conditions of room temperature and 0.6 MPa.)

1. A dopamine modified titanium dioxide graphene oxide polyamide nanofiltration membrane is characterized in that: the polyether sulfone composite material comprises a polyether sulfone support body and an organic functional layer arranged on the polyether sulfone support body, wherein the organic functional layer is formed by taking a water phase monomer, an organic phase monomer and an acid acceptor as raw materials through an interfacial polymerization reaction on the polyether sulfone support body;

the aqueous phase monomer contains dopamine modified titanium dioxide, graphene oxide and piperazine;

the organic phase monomer is trimesoyl chloride;

the acid acceptor is a polyamine.

2. The dopamine-modified titanium dioxide graphene oxide polyamide nanofiltration membrane of claim 1, wherein: the polyamine is diethylamine.

3. The dopamine-modified titanium dioxide graphene oxide polyamide nanofiltration membrane of claim 1, wherein: the pore diameter of the polyether sulfone support body is 20-50 KD.

4. The dopamine-modified titanium dioxide graphene oxide polyamide nanofiltration membrane of claim 1, wherein: the mass ratio of the dopamine to the titanium dioxide in the dopamine modified titanium dioxide is 1: 0.6-1.5.

5. The dopamine-modified titanium dioxide graphene oxide polyamide nanofiltration membrane of claim 4, wherein: the mass ratio of the dopamine modified titanium dioxide to the graphene oxide to the piperazine is 1-2: 240: 320.

6. The method for preparing the dopamine-modified titanium dioxide graphene oxide polyamide nanofiltration membrane according to any one of claims 1 to 5, wherein the method comprises the following steps: the method comprises the following steps: preparing titanium dioxide nanoparticles by a sol-gel method, and modifying by dopamine to obtain dopamine modified titanium dioxide; and forming the organic functional layer on the polyether sulfone support body through interfacial polymerization reaction by taking the mixture of the dopamine modified titanium dioxide, the graphene oxide and the piperazine as an aqueous phase monomer, taking phthaloyl chloride as an organic monomer and taking polyamine as an acid acceptor, thus obtaining the dopamine modified titanium dioxide graphene oxide polyamide nanofiltration membrane.

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

(1) preparing titanium oxide sol by a sol-gel method;

(2) mixing the titanium oxide sol with a dopamine aqueous solution, and reacting at 60-90 ℃ for 1-3h to obtain a dopamine modified titanium dioxide solution;

(3) preparing a graphene oxide aqueous solution by using a modified Hummers method;

(4) uniformly stirring and mixing the dopamine modified titanium dioxide solution, the graphene oxide aqueous solution and the piperazine aqueous solution, adding PEG1000 and polyamine, and performing ultrasonic treatment to obtain an aqueous phase solution;

(5) soaking the polyether sulfone support body subjected to ethanol and water washing in a normal hexane solution of trimesoyl chloride, carrying out soaking and blow-drying after room temperature reaction, soaking in the aqueous phase solution prepared in the step (4), and carrying out soaking and blow-drying after room temperature reaction; repeating the step at least 1 time;

(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 dopamine modified titanium dioxide graphene oxide polyamide nanofiltration membrane.

8. The method of claim 7, wherein: in the step (4), the concentration of the dopamine modified titanium dioxide solution is 0.25-0.5mg/L, the concentration of the graphene oxide aqueous solution is 0.25-0.5mg/L, and the concentration of the piperazine aqueous solution is 0.8-1.2 wt%.

9. The method of claim 8, wherein: in the step (4), the concentration of the polyamine in the mixture of the dopamine modified titanium dioxide solution, the graphene oxide aqueous solution and the piperazine aqueous solution is 0.8 to 1.2 wt%, and the concentration of the PEG1000 in the mixture of the dopamine modified titanium dioxide solution, the graphene oxide aqueous solution and the piperazine aqueous solution is 0.8 to 1.2 wt%.

10. The method of claim 7, wherein: the concentration of the n-hexane solution of trimesoyl chloride is 1.8-2.2 wt%.

Technical Field

The invention belongs to the technical field of membrane separation, and particularly relates to a dopamine modified titanium dioxide graphene oxide polyamide nanofiltration membrane and a preparation method thereof.

Background

The nanofiltration membrane is a novel pressure-driven membrane, the pore size of the membrane is between that of ultrafiltration and reverse osmosis, and the nanofiltration membrane can be used for separating divalent salt and monovalent salt. The nanofiltration membrane has the characteristics of low operating pressure, high flux, energy conservation and the like, so the nanofiltration membrane is widely applied to the fields of bioengineering, medicine, metallurgy, water treatment, electronics and the like. The nanofiltration membrane commonly used in industry is an organic nanofiltration membrane, which has the advantages of high air permeability, low density, good film forming property, low cost, good flexibility and the like, but the organic nanofiltration membrane has the defects of low flux, poor pollution resistance and the like in industrial application, so the organic nanofiltration membrane needs to be modified to improve the flux and pollution resistance of the membrane layer.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a dopamine-modified titanium dioxide graphene oxide polyamide nanofiltration membrane.

The invention also aims to provide a preparation method of the dopamine modified titanium dioxide graphene oxide polyamide nanofiltration membrane.

The technical scheme of the invention is as follows:

a dopamine modified titanium dioxide graphene oxide polyamide nanofiltration membrane comprises a polyether sulfone support body and an organic functional layer arranged on the polyether sulfone support body, wherein the organic functional layer is formed by taking a water phase monomer, an organic phase monomer and an acid acceptor as raw materials and performing interfacial polymerization reaction on the polyether sulfone support body;

the aqueous phase monomer contains dopamine modified titanium dioxide, graphene oxide and piperazine;

the organic phase monomer is trimesoyl chloride;

the acid acceptor is a polyamine.

In a preferred embodiment of the invention, the polyamine is diethylamine.

In a preferred embodiment of the invention, the pore size of the polyethersulfone support is in the range of 20-50 KD.

In a preferred embodiment of the invention, the dopamine-to-titanium dioxide mass ratio in the dopamine-modified titanium dioxide is 1: 0.6-1.5.

Further preferably, the mass ratio of the dopamine modified titanium dioxide, the graphene oxide and the piperazine is 1-2: 240: 320.

The other technical scheme of the invention is as follows:

the preparation method of the dopamine-modified titanium dioxide graphene oxide polyamide nanofiltration membrane comprises the following steps: preparing titanium dioxide nanoparticles by a sol-gel method, and modifying by dopamine to obtain dopamine modified titanium dioxide; and forming the organic functional layer on the polyether sulfone support body through interfacial polymerization reaction by taking the mixture of the dopamine modified titanium dioxide, the graphene oxide and the piperazine as an aqueous phase monomer, taking phthaloyl chloride as an organic monomer and taking polyamine as an acid acceptor, thus obtaining the dopamine modified titanium dioxide graphene oxide polyamide nanofiltration membrane.

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

(1) preparing titanium oxide sol by a sol-gel method;

(2) mixing the titanium oxide sol with a dopamine aqueous solution, and reacting at 60-90 ℃ for 1-3h to obtain a dopamine modified titanium dioxide solution;

(3) preparing a graphene oxide aqueous solution by using a modified Hummers method;

(4) uniformly stirring and mixing the dopamine modified titanium dioxide solution, the graphene oxide aqueous solution and the piperazine aqueous solution, adding PEG1000 and polyamine, and performing ultrasonic treatment to obtain an aqueous phase solution;

(5) soaking the polyether sulfone support body subjected to ethanol and water washing in a normal hexane solution of trimesoyl chloride, carrying out soaking and blow-drying after room temperature reaction, soaking in the aqueous phase solution prepared in the step (4), and carrying out soaking and blow-drying after room temperature reaction; repeating the step at least 1 time;

(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 dopamine modified titanium dioxide graphene oxide polyamide nanofiltration membrane.

Further preferably, in the step (4), the concentration of the dopamine modified titanium dioxide solution is 0.25 to 0.5mg/L, the concentration of the graphene oxide aqueous solution is 0.25 to 0.5mg/L, and the concentration of the piperazine aqueous solution is 0.8 to 1.2 wt%.

Still more preferably, in the step (4), the concentration of the polyamine in the mixture of the dopamine modified titanium dioxide solution, the graphene oxide aqueous solution and the piperazine aqueous solution is 0.8 to 1.2 wt%, and the concentration of the PEG1000 in the mixture of the dopamine modified titanium dioxide solution, the graphene oxide aqueous solution and the piperazine aqueous solution is 0.8 to 1.2 wt%.

Further preferably, the concentration of the n-hexane solution of trimesoyl chloride is 1.8-2.2 wt%.

The invention has the beneficial effects that: according to the preparation method, the dopamine modified titanium dioxide-graphene oxide is added into the water phase monomer, the dopamine modified titanium dioxide-graphene oxide polyamide nanofiltration membrane is prepared through interfacial polymerization, the rejection rate (more than 96%) of 0.2 wt% of magnesium sulfate solution is high under the test conditions of room temperature and 0.6MPa, and the pure water flux is 50-60 LHM.

Detailed Description

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

The modified Hummers process of the following comparative examples and examples specifically includes:

(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 of the ceramic membrane is utilized to screen, namely the pore size of the ceramic tubular membrane is smaller than the size of the GO lamella, so that the GO lamella cannot pass throughThe GO sheets flow out through the pipe type ceramic membrane and circularly flow back to the material liquid barrel along with liquid in the pipeline, membrane holes are not blocked, smoothness of the membrane holes is guaranteed, and the GO sheets with larger sizes are 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 0.25mg/L by using a modified Hummers method;

(2) uniformly stirring 50ml of 0.25mg/L graphene oxide aqueous solution and 300ml of 1 wt% piperazine aqueous solution, adding 1 wt% PEG1000 and 1 wt% diethylamine, and performing ultrasonic treatment for 30min to prepare a uniform aqueous phase solution;

(3) soaking 20KD of polyether sulfone washed by ethanol and water in 2 wt% of TMC n-hexane solution, reacting at room temperature for 10min, taking out, and carrying out water soaking and air gun blow-drying; and soaking in the aqueous phase solution, reacting at room temperature for 10min, taking out, soaking in water, blow-drying with an air gun, repeating the step for 1 time, placing in a shade, air-drying, placing in a 50 ℃ oven, heat-treating for 15min, and cooling with the oven to prepare the graphene oxide polyamide nanofiltration membrane.

The graphene oxide polyamide nanofiltration membrane prepared by the comparative example is tested under the conditions of room temperature and 0.6MPa, the pure water flux is 32LHM, and the rejection rate of 0.2 wt% magnesium sulfate solution is 94.8%.

Comparative example 2

(1) Adding 0.5 wt% of dispersant polyethylene glycol into 0.5mol/L of n-butyl titanate solution, in a sol-gel reaction, the molar ratio of n-butyl titanate to water is 1: 50, adding acid for dispergation, wherein the pH value of the dispergated sol is 4 to obtain titanium dioxide sol, adding 1 wt% of dispersant polyethylene glycol, uniformly mixing to prepare well-dispersed titanium oxide sol with the concentration of 0.5mg/L, and then diluting with water to the concentration of 0.25 mg/L;

(2) preparing a graphene oxide aqueous solution with the concentration of 0.25mg/L by using a modified Hummers method;

(3) uniformly stirring 50ml of 0.25mg/L titanium dioxide solution, 50ml of 0.25mg/L graphene oxide aqueous solution and 300ml of 1 wt% piperazine aqueous solution, adding 1 wt% PEG1000 and 1 wt% diethylamine, and performing ultrasonic treatment for 30min to prepare a uniform aqueous phase solution;

(4) soaking the polyether sulfone support body of 20KD after ethanol and water washing in n-hexane solution of trimesoyl chloride with the concentration of 2 wt%, carrying out water soaking and air gun blow-drying after reacting for 10min at room temperature, then soaking in the aqueous phase solution, and carrying out water soaking and air gun blow-drying after reacting at room temperature; repeating the step for 1 time;

(5) and (5) placing the material obtained in the step (4) in a shade place for air drying, then performing heat treatment in a 50 ℃ oven for 15min, and then cooling along with the oven to obtain the titanium dioxide-graphene oxide polyamide nanofiltration membrane.

Testing the performance of the membrane tube: the titanium dioxide-graphene oxide polyamide nanofiltration membrane prepared by the comparative example is tested under the conditions of room temperature and 0.6MPa, the pure water flux of the nanofiltration membrane is 40LHM, and the rejection rate of the nanofiltration membrane on 0.2 wt% of magnesium sulfate solution is 95%.

Example 1

(1) Adding 0.5 wt% of dispersant polyethylene glycol into 0.5mol/L of n-butyl titanate solution, in a sol-gel reaction, the molar ratio of n-butyl titanate to water is 1: 50, adding acid for dispergation, wherein the pH value of the dispergated sol is 4 to obtain titanium dioxide sol, adding 1 wt% of dispersant polyethylene glycol, uniformly mixing to prepare well-dispersed titanium oxide sol with the concentration of 0.5mg/L, and then diluting with water to the concentration of 0.2 mg/L;

(2) adding 50ml of 1mg/L dopamine aqueous solution into 150ml of 0.2mg/L titanium oxide sol, heating and reacting for 3 hours in an oil bath at 60 ℃ to obtain dopamine modified titanium dioxide solution, and then concentrating to the concentration of 0.25 mg/L;

(3) preparing a graphene oxide aqueous solution with the concentration of 0.25mg/L by using a modified Hummers method;

(4) uniformly stirring 50ml of 0.25mg/L dopamine modified titanium dioxide solution, 50ml of 0.25mg/L graphene oxide aqueous solution and 300ml of 1 wt% piperazine aqueous solution, adding 1 wt% PEG1000 and 1 wt% diethylamine, and carrying out ultrasonic treatment for 30min to prepare a uniform aqueous phase solution;

(5) soaking the polyether sulfone support body of 20KD after ethanol and water washing in n-hexane solution of trimesoyl chloride with the concentration of 2 wt%, carrying out water soaking and air gun blow-drying after reacting for 10min at room temperature, then soaking in the aqueous phase solution, and carrying out water soaking and air gun blow-drying after reacting at room temperature; 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 performing heat treatment in a 50 ℃ oven for 15min, and then cooling along with the oven to obtain the dopamine modified titanium dioxide graphene oxide polyamide nanofiltration membrane.

Testing the performance of the membrane tube: the dopamine modified titanium dioxide graphene oxide polyamide nanofiltration membrane prepared in the embodiment is tested under the conditions of room temperature and 0.6MPa, the pure water flux is 55LHM, and the rejection rate of 0.2 wt% magnesium sulfate solution is 98%.

Example 2

(1) Adding 0.5 wt% of dispersant polyethylene glycol into 0.5mol/L of n-butyl titanate solution, in a sol-gel reaction, adding acid to carry out dispergation, wherein the molar ratio of n-butyl titanate to water is 1: 50, and the pH of the dispergated sol is 4 to obtain titanium dioxide sol, adding 1 wt% of dispersant polyethylene glycol, and uniformly mixing to prepare well-dispersed titanium oxide sol with the concentration of 0.5 mg/L;

(2) adding 50ml of 1mg/L dopamine aqueous solution into 150ml of 0.2mg/L titanium oxide sol, and heating and reacting for 3 hours in an oil bath at the temperature of 60 ℃ to obtain dopamine modified titanium dioxide solution;

(3) preparing a graphene oxide aqueous solution with the concentration of 0.5mg/L by using a modified Hummers method;

(4) uniformly stirring 50ml of 0.5mg/L dopamine modified titanium dioxide solution, 50ml of 0.5mg/L graphene oxide aqueous solution and 300ml of 1 wt% piperazine aqueous solution, adding 1 wt% PEG1000 and 1 wt% diethylamine, and carrying out ultrasonic treatment for 30min to prepare a uniform aqueous phase solution;

(5) soaking a polyether sulfone support body of 50KD after ethanol and water washing in a normal hexane solution of trimesoyl chloride with the concentration of 2 wt%, carrying out water soaking and air gun blow-drying after reacting for 10min at room temperature, soaking in the aqueous phase solution, and carrying out water soaking and air gun blow-drying after reacting at room temperature; 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 performing heat treatment in a 50 ℃ oven for 15min, and then cooling along with the oven to obtain the dopamine modified titanium dioxide graphene oxide polyamide nanofiltration membrane.

Testing the performance of the membrane tube: the dopamine modified titanium dioxide graphene oxide polyamide nanofiltration membrane prepared in the embodiment is tested under the conditions of room temperature and pressure of 0.6MPa, the pure water flux is 58LHM, and the rejection rate of the dopamine modified titanium dioxide graphene oxide polyamide nanofiltration membrane on 0.2 wt% magnesium sulfate solution is 96.5%.

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.