CN115445439A - Pervaporation membrane and preparation method and application thereof - Google Patents

Abstract

The invention provides a pervaporation membrane and a preparation method and application thereof, and the pervaporation membrane comprises the following components: a polymer matrix; graphene oxide nanosheets doped in the polymer matrix and comprising hydrophilic functional groups; wherein the graphene oxide nanoplatelets are oriented in the thickness direction of the film. The pervaporation membrane is an organic-inorganic hybrid membrane prepared by doping Graphene Oxide (GO) nanosheets into a polymer matrix, and the Graphene nanosheets in the polymer matrix are arranged by applying an external alternating current electric field, so that the Graphene nanosheets are oriented in the membrane, and the permeation flux of the pervaporation membrane is improved.

Description

A kind of pervaporation membrane and its preparation method and application

technical field

The invention belongs to the field of separation of azeotrope and near-boiler, trace water removal, brine desalination, etc., and in particular relates to a pervaporation membrane and its preparation method and application.

Background technique

Pervaporation is a mass transfer driving force based on the chemical potential gradient of a certain component in the liquid mixture on both sides of the membrane, so that the component absorbs and dissolves on the surface of the membrane, diffuses in the membrane, and finally vaporizes on the downstream side of the membrane. It is an emerging separation technology that realizes the separation by the difference in the dissolution and diffusion process. Pervaporation has the advantages of low energy consumption, low pollution, simple equipment, and convenient operation. It can be applied to the fields of azeotrope and near-boiler separation, trace water removal, and salt water desalination. One of the research hotspots.

At present, the pervaporation membrane has insufficient flux, which limits the large-scale industrial application of pervaporation technology.

Contents of the invention

In view of this, the object of the present invention is to provide a pervaporation membrane and its preparation method and application. The pervaporation membrane of the present invention has improved permeation flux.

According to one aspect of the present invention, the pervaporation membrane includes the following components: a polymer matrix; and graphene oxide nanosheets dispersed in the polymer matrix, and the graphene oxide nanosheets contain hydrophilic functional groups ; Wherein, the graphene oxide nanosheets are oriented along the thickness direction of the film.

In the present invention, by doping graphene oxide (Graphene Oxide, hereinafter abbreviated as GO) nanosheets into the polymer matrix, and applying an external AC electric field to arrange the graphene oxide nanosheets in the polymer matrix, so that Orientation occurs in the membrane, and the prepared organic-inorganic hybrid membrane (ie, pervaporation membrane) has enhanced permeation flux than the membrane prepared without an applied electric field.

According to some embodiments of the present invention, the polymer matrix includes: polyetheramide, polyvinyl alcohol, chitosan, cellulose triacetate, polyhydroxymethylene, sulfonated polyethylene, polyamide, polyethersulfone, alginic acid One or more of sodium, polyacrylonitrile and polydimethylaminoethyl methacrylate; preferably, the polymer matrix includes cellulose triacetate.

According to some embodiments of the present invention, the diameter of the graphene oxide nanosheets is 0.05-5 μm, preferably 0.1-3 μm, more preferably 0.2-1.5 μm. In the present invention, the term "sheet diameter" refers to the straight-line distance between the two farthest points on the same surface of the graphene oxide nanosheet.

According to some embodiments of the present invention, the hydrophilic functional groups of the graphene oxide nanosheets include one or more of carboxyl groups, hydroxyl groups and epoxy groups. For example, graphene oxide nanosheets available from Sigma-Aldrich, product number 796034, are used.

According to some embodiments of the present invention, the mass fraction of the graphene oxide nanosheets relative to the pervaporation membrane is 0.05-25 wt%, preferably 0.5-20 wt%, more preferably 2.5-15 wt%.

According to the second aspect of the present invention, there is also provided a method for preparing a pervaporation membrane as described above, comprising the following steps:

Step a) dispersing graphene oxide nanosheets in a solvent to form a graphene oxide nanosheet dispersion, wherein the content of graphene oxide nanosheets in the graphene oxide nanosheet dispersion is 0.001 to 0.7 wt%, preferably It is 0.01～0.5wt%, more preferably 0.05～0.3wt%;

Step b) adding a polymer matrix to the graphene oxide nanosheet dispersion described in step a), stirring and dissolving to form a casting solution;

Step c) Casting the film-casting liquid described in step b) into a film, placing it under the action of an electric field, and drying to obtain an electric-field-oriented pervaporation film.

According to some embodiments of the present invention, the graphene oxide nanosheet dispersion is prepared by ultrasonication in the step a), and the ultrasonic dispersion time is 30 to 60 minutes; and/or wherein, the diameter of the graphene oxide nanosheet is 0.05-5 μm, preferably 0.1-3 μm, more preferably 0.2-1.5 μm; and/or the hydrophilic functional groups of the graphene oxide nanosheets include one or more of carboxyl, hydroxyl and epoxy groups; and /or the solvent includes 1,4-dioxane, 1,2-dichloroethane, isopropanol, o-xylene, cyclohexanone, m-xylene, absolute ethanol, petroleum ether, tetrahydrofuran, One or more of glacial acetic acid, preferably 1,4-dioxane.

According to some embodiments of the present invention, in the step b), the casting solution is prepared with a polymer matrix concentration of 0.1-15wt%, preferably 0.5-10wt%, more preferably 1-5wt%; and/or stirring temperature 40-80°C, and the time is 8-15 hours; wherein, the polymer matrix includes polyetheramide, polyvinyl alcohol, chitosan, cellulose triacetate, polyhydroxymethylene, sulfonated polyethylene, polyamide , polyethersulfone, sodium alginate, polyacrylonitrile and polydimethylaminoethyl methacrylate or one or more, preferably cellulose triacetate.

According to some embodiments of the present invention, the electric field strength in step c) is 400-5000V/cm, preferably 500-3000V/cm, more preferably 600-1000V/cm; and/or the frequency is 400-1000Hz, so The electric field action time is 10-120 minutes; and/or the drying time is 2-24 hours.

According to the third aspect of the present invention, the above pervaporation membrane and the pervaporation membrane prepared by the above pervaporation membrane preparation method are provided. applications in other fields.

The beneficial effects of the present invention are:

There are hydrophilic functional groups on the graphene oxide nanosheets of the present invention, which can be doped in polymers to prepare organic-inorganic hybrid films, gaps between graphene oxide nanosheets and gaps formed between organic and inorganic phases. The interface can become the mass transfer channel of the permeate in the membrane.

Furthermore, the present invention arranges the graphene oxide nanosheets in the polymer matrix by applying an external AC electric field, so that the GO nanosheets are oriented in the membrane, shortening the mass transfer pathway of the permeate molecules in the membrane, and improving the permeability. The permeate flux of vaporized membranes.

Description of drawings

Fig. 1A is a micrograph of the dispersion of graphene oxide nanosheets in 1,4-dioxane prepared according to Example 1 of the present invention under the action of an electric field at 0 seconds, 60 seconds, 90 seconds, 120 seconds and 150 seconds Observe the diagram.

FIG. 1B is a microscope observation diagram of the dispersion of graphene oxide nanosheets in 1,2-dichloroethane prepared according to Example 2 of the present invention under the action of an electric field for 0 seconds and 150 seconds.

1C is a microscopic observation diagram of the dispersion of graphene oxide nanosheets in isopropanol prepared according to Example 2 of the present invention under the action of an electric field for 0 seconds and 150 seconds.

FIG. 1D is a microscope observation diagram of the dispersion of graphene oxide nanosheets in o-xylene prepared according to Example 2 of the present invention under the action of an electric field for 0 seconds and 150 seconds.

FIG. 1E is a microscope observation diagram of the dispersion of graphene oxide nanosheets in cyclohexanone prepared according to Example 2 of the present invention under the action of an electric field for 0 seconds and 150 seconds.

FIG. 1F is a microscope observation diagram of the dispersion of graphene oxide nanosheets in m-xylene prepared according to Example 2 of the present invention under the action of an electric field for 0 seconds and 150 seconds.

FIG. 1G is a microscope observation diagram of the dispersion of graphene oxide nanosheets in absolute ethanol prepared according to Example 2 of the present invention under the action of an electric field for 0 seconds and 150 seconds.

FIG. 1H is a microscope observation diagram of the dispersion of graphene oxide nanosheets in petroleum ether prepared according to Example 2 of the present invention at 0 seconds and 150 seconds under the action of an electric field.

FIG. 1I is a microscope observation diagram of the dispersion of graphene oxide nanosheets in tetrahydrofuran prepared according to Example 2 of the present invention at 0 seconds and 150 seconds under the action of an electric field.

FIG. 1J is a microscope observation diagram of the dispersion of graphene oxide nanosheets in glacial acetic acid prepared according to Example 2 of the present invention under the action of an electric field for 0 seconds and 150 seconds.

FIG. 1K is a schematic diagram of a microscope device for observing a pervaporation membrane according to an exemplary embodiment of the present invention.

Fig. 2 is a flowchart of a method for preparing a pervaporation membrane according to an exemplary embodiment of the present invention.

Fig. 3 is a schematic diagram of a pervaporation membrane performing electric field orientation according to an exemplary embodiment of the present invention.

Fig. 4 is a graph showing the relationship between the performance of the pervaporation membrane and the electric field strength of the electric field orientation according to an exemplary embodiment of the present invention.

Explanation of reference signs

101 Microscope

103 electrode plate

105 High voltage pulse power supply

107 glass tank

109 Graphene oxide nanosheet dispersion

301 power supply

303 Dust-free box

305 electrode plate

307 backing plate

309 Casting solution

311 glass plate

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The polarizability of graphene oxide nanosheets is anisotropic, and when subjected to an external electric field, the external electric field will generate an induced dipole moment on its plane. The interaction of the external electric field with the dipole moment produces a torque that acts on the GO nanosheets, turning the dipoles and aligning them with the direction of the external field so that the GO nanosheets are parallel to the direction of the electric field. Therefore, in the process of preparing the membrane using a polymer solution containing GO, an external electric field with the direction of the electric field perpendicular to the membrane sheet is applied on both sides of the membrane, and the graphene oxide nanosheets in the polymer can be oriented along the thickness direction of the membrane.

[1] Besharat F, Manteghian M, Gallone G, et al. Electric field induced alignment of graphene oxide nanoplatelets in polyethersulfone matrix [J]. Nanotechnology, 2020, 31(15): 155701(16pp).

It should be noted that the reagents used in each embodiment of the present invention are commercially available conventional products, and the reagents are all analytical or chemical pure.

Example 1

The preparation process of the graphene oxide nanosheet dispersion used in Example 1 includes adding graphene oxide nanosheets (product number is 796034; manufacturer Sigma-Aldrich; molecular weight 4239.48g/mol, and the average value of sheet diameter is 0.8 μm) to 1, In 4-dioxane (Dioxane, manufacturer Tianjin Kemiou Chemical Reagent Co., Ltd., analytically pure), the content of graphene oxide nanosheets in the dispersion is made into a graphene oxide nanosheet dispersion of 0.02wt%. , ultrasonically disperse the graphene oxide nanosheet dispersion for 1 h.

Figure 1A is a microscope observation diagram of the 1,4-dioxane dispersion of graphene oxide nanosheets prepared according to Example 1 of the present invention under the action of an electric field at 0 seconds, 60 seconds, 90 seconds, 120 seconds and 150 seconds .

In this embodiment, the observation environment in Figure 1A is that the concentration of the graphene oxide nanosheet dispersion is 0.02wt%, the electric field strength is 1000V/cm, and the frequency is 1000Hz, and the observation device used is shown in Figure 1K.

In this embodiment, under the condition of the electric field, the orientation of the graphene oxide nanosheets in the solvent is more obvious as the time of the electric field is prolonged.

Example 2

The preparation process of the graphene oxide nanosheet dispersion used in Example 2 includes adding graphene oxide nanosheets (the product number is 796034; manufacturer Sigma-Aldrich; molecular weight 4239.48g/mol, average sheet diameter is 0.8 μm) to 1 , 2-dichloroethane (manufacturer Tianjin Kemiou Chemical Reagent Co., Ltd., analytically pure), isopropanol (manufacturer Tianjin Fengchuan Chemical Reagent Technology Co., Ltd., analytically pure), o-xylene (manufacturer Tianjin Kemiou Chemical Reagent Co., Ltd., analytically pure), m-xylene (produced by Tianjin Kemiou Chemical Reagent Co., Ltd., analytically pure), cyclohexanone (produced by Tianjin Kemiou Chemical Reagent Co., Ltd., Analytical pure), absolute ethanol (produced by Tianjin Kemiou Chemical Reagent Co., Ltd., analytically pure), petroleum ether (produced by Tianjin Fengchuan Chemical Reagent Technology Co., Ltd., analytically pure), tetrahydrofuran (produced by Tianjin Fengchuan Chuan Chemical Reagent Technology Co., Ltd., analytically pure), glacial acetic acid (manufacturer Tianjin Fengchuan Chemical Reagent Technology Co., Ltd., analytically pure), make the graphite oxide whose content of graphene oxide nanosheets in the dispersion is 0.02wt%. Graphene oxide nanosheet dispersion, ultrasonically disperse the graphene oxide nanosheet dispersion for 1 h.

1B to 1J are microscopic observations of the graphene oxide nanosheet dispersion prepared according to Example 2 of the present invention under the action of an electric field for 0 seconds and 150 seconds.

In this embodiment, the observation environment in Figures 1B to 1J is that the concentration of the graphene oxide nanosheet dispersion is 0.02wt%, the electric field strength is 1000V/cm, and the frequency is 1000Hz. The observation device used is shown in the schematic diagram of the microscope device in Figure 1K.

In this embodiment, under the condition of the electric field, the orientation of the graphene oxide nanosheets in the solvent is more obvious as the time of the electric field is prolonged.

Example 3

Fig. 2 is a flowchart of a method for preparing a pervaporation membrane according to an exemplary embodiment of the present invention.

Referring to Fig. 2, in step S201 of the present embodiment, 0.05g of graphene oxide nanosheets (product number is 796034; manufacturer Sigma-Aldrich; molecular weight 4239.48g/mol, average sheet diameter is 0.8μm) and 97.95g of 1,4-dioxane (Dioxane, produced by Tianjin Kemiou Chemical Reagent Co., Ltd., analytically pure) is blended to make a graphene oxide nanosheet whose content of graphene oxide nanosheets in the dispersion is 0.05wt%. Sheet dispersion liquid, the graphene oxide nanosheet dispersion liquid was ultrasonically dispersed for 1 h. Then transfer to S203.

In step S203, 2 g of cellulose triacetate (analytical pure; manufacturer ACROS; molecular weight 966.845 g/mol) is added to the graphene oxide nanosheet dispersion liquid as a polymer matrix, stirred and dissolved to form a casting solution, and the Stir and dissolve in a water bath for 8 hours to obtain a casting solution with GO/CTA=0.025. Then transfer to S205.

In step S205, the film-casting solution was scraped on a glass plate to form a film, and placed in a high-voltage AC electric field with an electric field strength of 1000 V/cm and a frequency of 1000 Hz. The electric field application device is shown in FIG. 3 . After 50 minutes of application of the electric field, stop, and let it dry naturally for 24 hours to evaporate the solvent to form a cured film. The pervaporation membrane of this example was obtained.

The pervaporation test conditions for the pervaporation membrane obtained in this example include: the raw material liquid is 35g/L NaCl aqueous solution, the flow rate is 1000mL/min, the temperature is 50°C, and the absolute pressure on the permeate side is 0kPa.

The results of the pervaporation experiment in this embodiment are: the water flux is 8.10 kg/(m ² ·h), and the salt rejection rate of NaCl is 99.9%.

Example 4

In the same way as in Example 3, referring to Fig. 2, in step S201 of the present embodiment, 0.1g of graphene oxide nanosheets (product number is 796034; manufacturer Sigma-Aldrich; molecular weight 4239.48g/mol, average sheet diameter is 0.8 μm) and 97.9g of 1,4-dioxane (Dioxane, manufacturer Tianjin Kemiou Chemical Reagent Co., Ltd., analytically pure) blended to make the content of graphene oxide nanosheets in the dispersion liquid is 0.1 wt% graphene oxide nanosheet dispersion liquid, and ultrasonically disperse the graphene oxide nanosheet dispersion liquid for 1 h. Then transfer to S203.

In step S203, 2 g of cellulose triacetate (analytical pure; manufacturer ACROS; molecular weight 966.845 g/mol) is added to the graphene oxide nanosheet dispersion liquid as a polymer matrix, stirred and dissolved to form a casting solution, and the Stir and dissolve in a water bath for 8 hours to obtain a casting solution with GO/CTA=0.05. Then transfer to S205.

In step S205, the film-casting solution is scraped on a glass plate to form a film, and placed in a high-voltage AC electric field with an electric field strength of 600-1000V/cm (a sample is prepared at an interval of 100V/cm, so there are 5 samples in total in this embodiment) samples), the frequency is 1000 Hz, and the electric field device is shown in Figure 3. The electric field was stopped after 50 minutes of application and dried for 24 hours. The pervaporation membrane of this example was obtained.

The pervaporation test conditions for the pervaporation membrane obtained in this example include: the raw material liquid is 35g/L NaCl aqueous solution, the flow rate is 1000mL/min, the temperature is 50°C, and the absolute pressure on the permeate side is 0kPa.

The results of the pervaporation experiment in this embodiment are:

The electric field strength is 600V/cm sample: the water flux is 7.63kg/(m ² ·h), and the salt rejection rate of NaCl is 99.9%;

The electric field strength is 700V/cm sample: the water flux is 7.76kg/(m ² ·h), and the salt rejection rate of NaCl is 99.9%;

The electric field strength is 800V/cm sample: the water flux is 7.93kg/(m ² ·h), and the salt rejection rate of NaCl is 99.9%;

The electric field strength is 900V/cm sample: the water flux is 8.12kg/(m ² h), and the salt rejection rate of NaCl is 99.9%;

The electric field intensity is 1000V/cm sample: the water flux is 8.59kg/(m ² ·h), and the salt rejection rate of NaCl is 99.9%.

This example proves that the higher the electric field intensity is, the higher the orientation degree of GO is, and the water flux is improved more, as shown in Fig. 4 .

Example 5

In the same way as above-mentioned embodiment 3, referring to Fig. 2, in step S201 of the present embodiment, the graphene oxide nanosheet of 0.15g (commercial number is 796034; manufacturer Sigma-Aldrich; molecular weight 4239.48g/mol, sheet diameter mean value 0.8 μm) and 97.85g of 1,4-dioxane (Dioxane, manufacturer Tianjin Kemiou Chemical Reagent Co., Ltd., analytically pure) blends to make the content of graphene oxide nanosheets in the dispersion liquid is 0.15wt% graphene oxide nanosheet dispersion, and ultrasonically disperse the graphene oxide nanosheet dispersion for 1 hour. Then transfer to S203.

In step S203, 2 g of cellulose triacetate (analytical pure; manufacturer ACROS; molecular weight 966.845 g/mol) is added to the graphene oxide nanosheet dispersion liquid as a polymer matrix, stirred and dissolved to form a casting solution, and the Stir and dissolve in a water bath for 8 hours to obtain a casting solution with GO/CTA=0.075. Then transfer to S205.

In step S205, the film-casting solution was scraped on a glass plate to form a film, and placed in a high-voltage AC electric field with an electric field strength of 1000 V/cm and a frequency of 1000 Hz. The electric field application device is shown in FIG. 3 . The electric field was stopped after 50 minutes of application and dried for 24 hours. The pervaporation membrane of this example was obtained.

The pervaporation test conditions for the pervaporation membrane obtained in this example include: the raw material liquid is 35g/L NaCl aqueous solution, the flow rate is 1000mL/min, the temperature is 50°C, and the absolute pressure on the permeate side is 0kPa.

The results of the pervaporation experiment in this embodiment are: the water flux is 9.06 kg/(m ² ·h), and the NaCl salt rejection rate is 99.9%.

Example 6

Referring to Fig. 2, in step S201 of the present embodiment, 0.2g of graphene oxide nanosheets (product number is 796034; manufacturer Sigma-Aldrich; molecular weight 4239.48g/mol, average sheet diameter is 0.8μm) and 97.8g of 1,4-dioxane (Dioxane, produced by Tianjin Kemiou Chemical Reagent Co., Ltd., analytically pure) is blended to make a graphene oxide nanosheet whose content of graphene oxide nanosheets in the dispersion is 0.2wt%. Sheet dispersion liquid, the graphene oxide nanosheet dispersion liquid was ultrasonically dispersed for 1 h. Then transfer to S203.

In step S203, 2 g of cellulose triacetate (analytical pure; manufacturer ACROS; molecular weight 966.845 g/mol) is added to the graphene oxide nanosheet dispersion liquid as a polymer matrix, stirred and dissolved to form a casting solution, and the Stir and dissolve in a water bath for 8 hours to obtain a casting solution with GO/CTA=0.1. Then transfer to S205.

In step S205, the film-casting solution was scraped on a glass plate to form a film, and placed in a high-voltage AC electric field with an electric field strength of 1000 V/cm and a frequency of 1000 Hz. The electric field application device is shown in FIG. 3 . The electric field was stopped after 50 minutes of application and dried for 24 hours. The pervaporation membrane of this example was obtained.

The pervaporation test conditions for the pervaporation membrane obtained in this example include: the raw material liquid is 35g/L NaCl aqueous solution, the flow rate is 1000mL/min, the temperature is 50°C, and the absolute pressure on the permeate side is 0kPa.

The results of the pervaporation experiment in this embodiment are: the water flux is 9.07 kg/(m ² ·h), and the salt rejection rate of NaCl is 99.9%.

Example 7

Referring to Fig. 2, in step S201 of the present embodiment, 0.25g of graphene oxide nanosheets (product number is 796034; manufacturer Sigma-Aldrich; molecular weight 4239.48g/mol, average sheet diameter is 0.8μm) and 97.75g of 1,4-Dioxane (Dioxane, produced by Tianjin Kemiou Chemical Reagent Co., Ltd., analytically pure) is blended to make a graphene oxide nanosheet whose content of graphene oxide nanosheets in the dispersion is 0.25wt%. Sheet dispersion liquid, the graphene oxide nanosheet dispersion liquid was ultrasonically dispersed for 1 h. Then transfer to S203.

In step S203, 2 g of cellulose triacetate (analytical pure; manufacturer ACROS; molecular weight 966.845 g/mol) is added to the graphene oxide nanosheet dispersion liquid as a polymer matrix, stirred and dissolved to form a casting solution, and the Stir and dissolve in a water bath for 8 hours to obtain a casting solution with GO/CTA=0.125. Then transfer to S205.

In step S205, the film-casting solution was scraped on a glass plate to form a film, and placed in a high-voltage AC electric field with an electric field strength of 1000 V/cm and a frequency of 1000 Hz. The electric field application device is shown in FIG. 3 . The electric field was stopped after 50 minutes of application and dried for 24 hours. The pervaporation membrane of this example was obtained.

The pervaporation test conditions for the pervaporation membrane obtained in this example include: the raw material liquid is 35g/L NaCl aqueous solution, the flow rate is 1000mL/min, the temperature is 50°C, and the absolute pressure on the permeate side is 0kPa.

The results of the pervaporation experiment in this embodiment are: the water flux is 9.11 kg/(m ² ·h), and the NaCl salt rejection rate is 99.9%.

Example 8

Referring to Fig. 2, in step S201 of the present embodiment, 0.3g of graphene oxide nanosheets (product number is 796034; manufacturer Sigma-Aldrich; molecular weight 4239.48g/mol, mean value of sheet diameter is 0.8μm) and 97.7g of 1,4-Dioxane (Dioxane, produced by Tianjin Kemiou Chemical Reagent Co., Ltd., analytically pure) is blended to make a graphene oxide nanosheet whose content of graphene oxide nanosheets in the dispersion is 0.3wt%. Sheet dispersion liquid, the graphene oxide nanosheet dispersion liquid was ultrasonically dispersed for 1 h. Then transfer to S203.

In step S203, 2 g of cellulose triacetate (analytical pure; manufacturer ACROS; molecular weight 966.845 g/mol) is added to the graphene oxide nanosheet dispersion liquid as a polymer matrix, stirred and dissolved to form a casting solution, and the Stir and dissolve in a water bath for 8 hours to obtain a casting solution with GO/CTA=0.15. Then transfer to S205.

In step S205, the film-casting solution was scraped on a glass plate to form a film, and placed in a high-voltage AC electric field with an electric field strength of 1000 V/cm and a frequency of 1000 Hz. The electric field application device is shown in FIG. 3 . The electric field was stopped after 50 minutes of application and dried for 24 hours. The pervaporation membrane of this example was obtained.

The pervaporation test conditions for the pervaporation membrane obtained in this example include: the raw material liquid is 35g/L NaCl aqueous solution, the flow rate is 1000mL/min, the temperature is 50°C, and the absolute pressure on the permeate side is 0kPa.

The results of the pervaporation experiment in this embodiment are: the water flux is 9.23 kg/(m ² ·h), and the NaCl salt rejection rate is 99.9%.

Comparative example 1

In the same way as the casting solution prepared in Example 3, it was dried for 24 hours in an environment without an electric field to obtain a pervaporation film without electric field orientation.

The pervaporation test conditions for the pervaporation membrane obtained in Comparative Example 1 include: the raw material liquid is 35g/L NaCl aqueous solution, the flow rate is 1000mL/min, the temperature is 50°C, and the absolute pressure on the permeate side is 0kPa.

The pervaporation test results of Comparative Example 1 are: the water flux is 7.07 kg/(m ² ·h), and the NaCl salt rejection rate is 99.9%.

Comparative example 2

In the same way as the casting solution prepared in Example 4, it was dried for 24 hours in an environment without an electric field to obtain a pervaporation film without electric field orientation.

The pervaporation test conditions for the pervaporation membrane obtained in Comparative Example 2 include: the raw material liquid is 35g/L NaCl aqueous solution, the flow rate is 1000mL/min, the temperature is 50°C, and the absolute pressure on the permeate side is 0kPa.

The pervaporation test results of Comparative Example 2 are: the water flux is 7.24 kg/(m ² ·h), and the salt rejection rate of NaCl is 99.9%.

Comparative example 3

In the same way as the casting solution prepared in Example 5, it was dried for 24 hours in an environment without an electric field to obtain a pervaporation film without electric field orientation.

The pervaporation test conditions for the pervaporation membrane obtained in Comparative Example 3 include: the raw material liquid is 35g/L NaCl aqueous solution, the flow rate is 1000mL/min, the temperature is 50°C, and the absolute pressure on the permeate side is 0kPa.

The pervaporation test results of Comparative Example 3 are: the water flux is 7.36 kg/(m ² ·h), and the NaCl salt rejection rate is 99.9%.

Comparative example 4

In the same way as the casting solution prepared in Example 6, it was dried for 24 hours in an environment without an electric field to obtain a pervaporation film without electric field orientation.

The pervaporation test conditions for the pervaporation membrane obtained in Comparative Example 4 include: the raw material liquid is 35g/L NaCl aqueous solution, the flow rate is 1000mL/min, the temperature is 50°C, and the absolute pressure on the permeate side is 0kPa.

The pervaporation test results of Comparative Example 4 are: the water flux is 7.69 kg/(m ² ·h), and the NaCl salt rejection rate is 99.9%.

Comparative example 5

In the same way as the casting solution prepared in Example 7, it was dried for 24 hours in an environment without an electric field to obtain a pervaporation film without electric field orientation.

The pervaporation test conditions for the pervaporation membrane obtained in Comparative Example 5 include: the raw material liquid is 35g/L NaCl aqueous solution, the flow rate is 1000mL/min, the temperature is 50°C, and the absolute pressure on the permeate side is 0kPa.

The pervaporation test results of Comparative Example 5 are: the water flux is 7.95 kg/(m ² ·h), and the NaCl salt rejection rate is 99.9%.

Comparative example 6

In the same way as the casting solution prepared in Example 8, it was dried for 24 hours in an environment without an electric field to obtain a pervaporation film without electric field orientation.

The pervaporation test conditions for the pervaporation membrane obtained in Comparative Example 6 include: the raw material liquid is 35g/L NaCl aqueous solution, the flow rate is 1000mL/min, the temperature is 50°C, and the absolute pressure on the permeate side is 0kPa.

The pervaporation test results of Comparative Example 6 are: the water flux is 8.53 kg/(m ² ·h), and the NaCl salt rejection rate is 99.9%.

What has been described above are only preferred examples of the present invention. It should be pointed out that for those skilled in the art, under the technical inspiration provided by the present invention, as common knowledge in the field, other equivalent modifications and improvements can also be made, which should also be regarded as the protection scope of the present invention.

Claims (8)

1. A pervaporation membrane, comprising the following components:

a polymer matrix; and

graphene oxide nanoplatelets dispersed in the polymer matrix, the graphene oxide nanoplatelets comprising hydrophilic functional groups;

wherein the graphene oxide nanoplatelets are oriented in the thickness direction of the film.

2. The pervaporation membrane according to claim 1, wherein said polymer matrix comprises: one or more of polyether amide, polyvinyl alcohol, chitosan, cellulose triacetate, polyhydroxymethylene, sulfonated polyethylene, polyamide, polyether sulfone, sodium alginate, polyacrylonitrile and polydimethylaminoethyl methacrylate;

preferably, the polymer matrix comprises cellulose triacetate.

3. Pervaporation membrane according to claim 1 or 2, characterised in that said graphene oxide nanoplatelets have a sheet diameter comprised between 0.05 and 5 μ ι η, preferably between 0.1 and 3 μ ι η, more preferably between 0.2 and 1.5 μ ι η; and/or

The hydrophilic functional group of the graphene oxide nanosheet comprises one or more of a carboxyl group, a hydroxyl group and an epoxy group; and/or

The mass fraction of the graphene oxide nanosheet relative to the pervaporation membrane is 0.05 to 25wt%, preferably 0.5 to 20wt%, and more preferably 2.5 to 15wt%.

4. A method of making a pervaporation membrane according to any of claims 1 to 3, comprising the steps of:

step a), dispersing graphene oxide nanosheets in a solvent to form a graphene oxide nanosheet dispersion liquid; wherein the content of the graphene oxide nanosheet in the graphene oxide nanosheet dispersion liquid is 0.001-0.7 wt%, preferably 0.01-0.5 wt%, and more preferably 0.05-0.3 wt%;

step b) adding a polymer matrix into the graphene oxide nanosheet dispersion liquid obtained in the step a), and stirring and dissolving to form a membrane casting liquid;

and c) casting the casting solution in the step b) into a film, placing the film in an electric field, and drying to obtain the electric field oriented pervaporation film.

5. The preparation method according to claim 4, wherein the graphene oxide nanosheet dispersion liquid is prepared in step a) by ultrasonic action for 30-60 minutes; and/or

Wherein the sheet diameter of the graphene oxide nanosheet is 0.05-5 μm; and/or

The hydrophilic functional groups of the graphene oxide nanoplatelets comprise carboxyl and/or hydroxyl and/or epoxy groups.

6. The method according to claim 4 or 5, wherein the concentration of the polymer matrix in the casting solution in step b) is 0.1 to 15wt%, preferably 0.5 to 10wt%, more preferably 1 to 5wt%; and/or

Stirring at 40-80 deg.c for 8-15 hr;

wherein the polymer matrix comprises one or more of polyether amide, polyvinyl alcohol, chitosan, cellulose triacetate, polyhydroxymethylene, sulfonated polyethylene, polyamide, polyether sulfone, sodium alginate, polyacrylonitrile and polydimethylaminoethyl methacrylate, and preferably the cellulose triacetate.

7. The method according to any one of claims 4 to 6, wherein the electric field strength in step c) is 400 to 5000V/cm, preferably 500 to 3000V/cm, more preferably 600 to 1000V/cm; and/or

The frequency of the electric field is 400-1000 Hz, and the time of the action of the electric field is 10-120 minutes; and/or

The drying time is 2-24 hours.

8. Use of a pervaporation membrane according to any of claims 1-3 and/or a pervaporation membrane prepared according to the method of manufacturing a pervaporation membrane according to any of claims 4-7 in the fields of azeotrope and near-boil separation, trace water removal, desalination of brine and the like.

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