CN105126653B - Three-dimensional fusion sediment polyamide forward osmosis membrane, preparation method and applications - Google Patents

Abstract

The invention provides a three-dimensional fused deposition polyamide forward osmosis membrane, a preparation method and an application thereof. According to an embodiment of the present invention, the forward osmosis membrane includes: a support layer, and a forward osmosis skin membrane, the forward osmosis skin membrane is formed on the surface of the support layer, the support layer is formed of polysulfone, and the The support layer has a cross-linked layer, and the forward osmosis skin membrane is formed by 3D printing of polyamide. Therefore, polysulfone can provide good support for the forward osmosis membrane, and by using 3D printing technology, a forward osmosis skin layer with a uniform thickness and a controllable three-dimensional multi-layer network structure is formed on the surface of the support layer. The membrane can further increase the porosity of the forward osmosis membrane, reduce the influence of concentration polarization on the separation performance of the forward osmosis membrane to achieve higher water flux and higher rejection rate, thereby improving the performance of the forward osmosis membrane.

Description

Three-dimensional fused deposition polyamide forward osmosis membrane, preparation method and application thereof

technical field

The invention relates to the field of materials, in particular, the invention relates to a three-dimensional fused deposition polyamide forward osmosis membrane, a preparation method and an application thereof. More specifically, the present invention relates to a method for preparing a forward osmosis membrane, a forward osmosis membrane, and the use of the osmosis membrane in sewage treatment or seawater desalination.

Background technique

The shortage of water resources is an important problem facing our country and even the world at present. Diverting the source of seawater and sewage is an important means to solve the shortage of water resources. Osmotic membrane separation technology plays an important role in the field of water treatment. Currently, nanofiltration membranes (Nanoflitration, NF), reverse osmosis membranes (Reverse Osmosis, RO), and forward osmosis membranes (Forward osmosis, FO) are mainly used. Among them, the forward osmosis membrane (also known as FO membrane) has been widely used in the field of water treatment because of its advantages of using the principle of osmosis, no external pressure, high recovery rate, low membrane pollution, and less wastewater discharge.

However, the current forward osmosis membranes and their preparation methods still need to be improved.

Contents of the invention

The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

The present invention has been accomplished based on the following findings of the inventors:

The current forward osmosis membrane has relatively serious concentration polarization phenomenon, which seriously affects the water flux of the forward osmosis membrane, and further affects the application of the forward osmosis membrane in the field of water treatment. After in-depth research, the inventors found that this is because the thickness, thickness uniformity and surface roughness of the forward osmosis membrane cannot be well controlled.

In view of this, in the first aspect of the present invention, the present invention proposes a method for preparing a forward osmosis membrane. According to an embodiment of the present invention, the method includes: (1) forming a cross-linked layer on the surface of the support layer; (2) using polyamide, photo-cross-linking agent, photo-initiator and antioxidant, through 3D printing, in the The surface of the cross-linked layer forms a forward osmosis skin membrane, so as to obtain the support layer-forward osmosis skin membrane composite; Forward osmosis membrane. The inventors have found that by using 3D printing technology, a forward osmosis skin membrane with a uniform thickness and a controllable three-dimensional multilayer network structure can be formed on the surface of the support layer in step (1), thereby increasing the porosity of the forward osmosis membrane. rate, reducing the impact of concentration polarization on the separation performance of forward osmosis membranes. Moreover, through the heating and ultraviolet light treatment in step (3), the cross-linking of the skin membrane molecules can be achieved to achieve the purpose of improving chemical stability and maintaining the degree of hydrophilicity of the membrane surface, and then the forward osmosis membrane can be maintained for a long time. The operation of high water flux is maintained in the interior, thereby improving the performance of the forward osmosis membrane. According to an embodiment of the present invention, the forward osmosis membrane obtained by using the method for preparing a forward osmosis membrane of the present invention may have a thickness of 5-8 microns, and at the same time have a thickness deviation of no more than 5% on the thickness level.

According to an embodiment of the present invention, the forward osmosis membrane further has the following additional technical features:

According to an embodiment of the present invention, the supporting layer is formed of polysulfone, optionally, the supporting layer is pre-dried, and optionally, the drying is performed at 90 degrees Celsius for 2 hours. Thus, polysulfone can provide good support for the forward osmosis membrane, and the performance of the support layer can be improved through heat treatment, and the treatment effect of the subsequent steps can be improved.

According to an embodiment of the present invention, the cross-linked layer is formed by trimesoyl chloride, optionally, the cross-linked layer is obtained by immersing the support layer in a n-hexane solution of 0.5% by weight of trimesoyl chloride Formed in 20 seconds. Thus, trimesoyl chloride can be used to provide a good cross-linked layer for the support layer, preventing the use effect of the forward osmosis membrane prepared according to the embodiment of the present invention from being affected due to the excessively large pores of the support layer.

According to an embodiment of the present invention, the photocrosslinking agent is triallyl isocyanurate, the photoinitiator is benzophenone and benzoin dimethyl ether, the antioxidant is antioxidant 1010, and The mass ratio of the polyamide, the triallyl isocyanurate, the benzophenone, the benzoin dimethyl ether and the antioxidant is (85-95): (2-6) :(1~5):(0.1~2):(0.1~1). Thus, the materials are thoroughly mixed to serve as raw materials for subsequent 3D printing steps. And by adjusting the ratio of the linking agent, photoinitiator and antioxidant, a better photocrosslinking effect can be achieved, and then a forward osmosis membrane with good chemical stability and hydrophilization degree can be obtained.

According to an embodiment of the present invention, in step (3), double distilled water is used for cleaning before and after the heat treatment, and the heat treatment is carried out at 90 degrees Celsius. Thus, the stability of the forward osmosis membrane prepared by the method according to the embodiment of the present invention can be further improved by heating, and the residual impurities in the above steps can be removed by washing with twice distilled water. Thus, the treatment effect of the subsequent steps can be further improved, and the performance of the forward osmosis membrane prepared according to the embodiment of the present invention can be improved.

According to an embodiment of the present invention, in step (3), the ultraviolet treatment adopts F300/F300SQ microwave-excited ultraviolet lamp with a power density of 120W/cm ² and a dominant wavelength of 365nm, and the distance between the ultraviolet lamp and the sample surface is 7cm. Thus, the cross-linking reaction of the support layer-forward osmosis skin membrane complex can be induced by ultraviolet light treatment, and the chemical stability and compactness of the polyamide skin membrane can be moderately improved, thereby improving the forward osmosis membrane's resistance to salt ions. The rejection rate further improves the performance of the forward osmosis membrane prepared according to the embodiments of the present invention.

According to an embodiment of the present invention, the thickness of the forward osmosis skin membrane is 5-8 microns. Thus, the thickness of the forward osmosis membrane can be controlled by setting relevant parameters in the 3D printing step, such as printing accuracy, thickness and shape of the polyamide layer to be printed. Moreover, when the thickness of the forward osmosis membrane is 5 to 8 microns, it can achieve the effect of reducing the concentration polarization and increasing the water flux of the forward osmosis membrane, thereby improving the forward osmosis membrane prepared according to the embodiment of the present invention. Membrane performance.

In a second aspect of the present invention, the present invention provides a forward osmosis membrane. According to an embodiment of the present invention, the forward osmosis membrane is obtained by the method for preparing a forward osmosis membrane according to the above-mentioned present invention. As mentioned above, the inventors found that by using 3D printing technology, a forward osmosis skin membrane with a uniform thickness and a controllable three-dimensional multilayer network structure can be formed on the surface of the support layer in step (1), thereby improving the The porosity of the forward osmosis membrane reduces the influence of concentration polarization on the separation performance of the forward osmosis membrane. Moreover, through the heating and ultraviolet light treatment in step (3), the cross-linking of the skin membrane molecules can be achieved to achieve the purpose of improving chemical stability and maintaining the degree of hydrophilicity of the membrane surface, and then the forward osmosis membrane can be maintained for a long time. The operation of high water flux is maintained in the interior, thereby improving the performance of the forward osmosis membrane. According to an embodiment of the present invention, the forward osmosis membrane obtained by using the method for preparing a forward osmosis membrane of the present invention may have a thickness of 5-8 microns, and at the same time have a thickness deviation of no more than 5% on the thickness level.

In the third aspect of the present invention, the present invention provides a forward osmosis membrane. According to an embodiment of the present invention, the forward osmosis membrane includes: a support layer, and a forward osmosis skin membrane, the forward osmosis skin membrane is formed on the surface of the support layer, wherein the forward osmosis skin membrane has: Multi-layer network structure; thickness of 5-8 microns; deviation of surface thickness not exceeding 5%; water flux of 30L/m ² h to 60L/m ² h under a water flow pressure of 0.1MPa, among which, for seawater The water flux is 60L/m ² h; the rejection rate for NaCl is not lower than 95%; or the rejection rate for MgSO ₄ is not lower than 99%. Thus, the supporting layer can provide a good supporting structure for the forward osmosis membrane, and the forward osmosis skin membrane can provide the forward osmosis membrane according to the embodiment of the present invention with good porosity and uniform thickness distribution, thereby improving the forward osmosis membrane according to the present invention. The performance of the forward osmosis membrane of the embodiment of the invention, so as to achieve higher water flux and higher rejection rate, and then improve the performance of the forward osmosis membrane.

According to an embodiment of the present invention, the support layer contained in the forward osmosis membrane is formed of polysulfone, and the support layer has a cross-linked structure, and the forward osmosis skin membrane is made of polyamide through 3D printing Forming. Thus, polysulfone can provide good support for the forward osmosis membrane, and the cross-linked layer can prevent the use effect of the forward osmosis membrane from being affected by the excessively large pores of the support layer, and by using 3D printing technology, in the A forward osmosis skin membrane with a uniform thickness and a controllable three-dimensional multilayer network structure is formed on the surface of the support layer, thereby increasing the porosity of the forward osmosis membrane and reducing the influence of concentration polarization on the separation performance of the forward osmosis membrane.

In another aspect of the present invention, the present invention proposes the use of the aforementioned forward osmosis membrane in sewage treatment or seawater desalination. Thus, the characteristics of the forward osmosis membrane according to the embodiments of the present invention can be utilized, such as high porosity, higher water flux, higher rejection rate and good chemical stability, etc., to apply the forward osmosis membrane It can be used in sewage treatment or seawater desalination, so as to obtain better results and improve sewage treatment efficiency or seawater desalination effect.

Description of drawings

Fig. 1 has shown the schematic flow sheet of the method for preparing forward osmosis membrane according to one embodiment of the present invention;

Fig. 2 has shown the schematic flow sheet of the method for preparing forward osmosis membrane according to another embodiment of the present invention;

Fig. 3 has shown the schematic flow sheet of the method for preparing forward osmosis membrane according to another embodiment of the present invention;

Fig. 4 has shown the structural representation of the forward osmosis membrane according to an embodiment of the present invention;

Fig. 5 has shown the partial structural representation of the forward osmosis membrane according to another embodiment of the present invention;

Fig. 6 has shown the partial structural representation of the forward osmosis membrane according to another embodiment of the present invention;

Fig. 7 has shown the partial structural representation of the forward osmosis membrane according to another embodiment of the present invention;

Figure 8 shows a schematic flow diagram of a method for preparing a forward osmosis membrane according to an embodiment of the present invention; and

Fig. 9 shows a schematic structural diagram of a system for testing the performance of a forward osmosis membrane according to an embodiment of the present invention.

Explanation of reference signs:

100: support layer

200: Forward osmosis cortical membrane

210: single layer forward osmosis cortical membrane

300: cross-linked layer

detailed description

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals denote the same or similar modules or modules having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

The present invention has been accomplished based on the following findings of the inventors:

The current forward osmosis membrane has relatively serious concentration polarization phenomenon, which seriously affects the water flux of the forward osmosis membrane, and further affects the application of the forward osmosis membrane in the field of water treatment. The inventor found after in-depth research that this is because the thickness and uniformity of the forward osmosis membrane cannot be well controlled.

Method for preparing forward osmosis membrane

In view of this, in one aspect of the present invention, the present invention proposes a method for preparing a forward osmosis membrane. Referring to Fig. 1, according to an embodiment of the present invention, the method includes:

S100 forms a cross-linked layer

In this step, a crosslinked layer is formed on the surface of the support layer. According to an embodiment of the invention, the support layer is formed of polysulfone. As a thermoplastic resin with excellent mechanical properties, good thermal stability and excellent mechanical properties, polysulfone can provide good support for the forward osmosis membrane prepared by the method according to the embodiment of the present invention. The polysulfone material further includes common bisphenol A type polysulfone (PSF), polyarylsulfone (PAS) and polyethersulfone (PES). According to an embodiment of the present invention, the support layer may be a polysulfone ultrafiltration support layer. Thus, the polysulfone can provide good support for the forward osmosis membrane, thereby improving the use effect of the forward osmosis membrane.

According to an embodiment of the present invention, the above cross-linked layer may be formed of trimesoyl chloride. Also, the cross-linked layer can be obtained by immersing the polysulfone support layer in a n-hexane solution of 0.5% by weight of trimesoyl chloride for 20 seconds. Thus, a cross-linked layer provided by trimesoyl chloride can be formed on the above-mentioned support layer to prevent the use effect of the forward osmosis membrane prepared according to the embodiment of the present invention from being affected due to the excessively large pores of the support layer.

According to an embodiment of the present invention, referring to FIG. 2 , before S100 , it may further include: S10 , pre-drying the support layer. According to an embodiment of the present invention, the drying treatment may be heating at 90 degrees Celsius for 2 hours. Therefore, the performance of the polysulfone ultrafiltration support layer as a support layer can be improved through heat treatment, and the treatment effect of subsequent steps can be improved.

S200 forms a forward osmosis skin membrane

In this step, a forward osmosis skin membrane is formed on the surface of the crosslinked layer formed in S100 by 3D printing using polyamide, photocrosslinking agent, photoinitiator and antioxidant, so as to obtain a support layer-forward osmosis skin membrane Complex. In other words, in this step, polyamide, photocrosslinking agent, photoinitiator and antioxidant are first mixed, and then according to the preset printing parameters and procedures, by 3D printing, the crosslinking layer A forward osmosis skin membrane is formed on the surface. The inventors found that the forward osmosis skin membrane formed by the traditional method of polymerizing polyamide usually has a layered structure, and it is difficult to control the uniformity of thickness. Therefore, forward osmosis membranes prepared by traditional methods usually have lower porosity and greater concentration polarization, which in turn leads to lower water flux of forward osmosis membranes. Thus, by adopting 3D printing technology, a forward osmosis skin membrane with a uniform thickness and a controllable three-dimensional multilayer network structure can be formed on the surface of the support layer formed by S100, thereby increasing the porosity of the forward osmosis membrane and reducing The effect of concentration polarization on the separation performance of forward osmosis membranes.

According to an embodiment of the present invention, the polyamide is low molecular weight and low melting point polyamide powder, for example, nylon 6. The photocrosslinking agent is triallyl isocyanurate, the photoinitiator includes benzophenone and benzoin dimethyl ether, and the antioxidant is antioxidant 1010. Specifically, in the mixture for 3D printing, the mass ratio of polyacyltriallylisocyanurate benzophenone, benzoin dimethyl ether and antioxidant is (85～95):(2～6):( 1~5): (0.1~2): (0.1~1). Wherein, according to a specific embodiment of the present invention, in the mixture of nylon 6, photocrosslinking agent, photoinitiator and antioxidant, the content of nylon 6 is 92.5% by weight, and the content of photocrosslinker is 4% by weight, The content of benzophenone in the photoinitiator is 2% by weight, the content of benzoin dimethyl ether is 1% by weight, and the content of antioxidant is 0.5% by weight. Thus, nylon 6 with low molecular weight and low melting point can provide a better forward osmosis membrane structure for the forward osmosis membrane according to the embodiment of the present invention, and can improve the effect of 3D printing; The ratio of initiator and antioxidant can achieve better photocrosslinking effect, and then obtain a forward osmosis skin membrane with good chemical stability and hydrophilization degree, and then obtain a support layer-forward osmosis skin layer with good use effect Membrane complex in order to improve the effect of subsequent treatment.

In addition, those skilled in the art can understand that the materials for forming the forward osmosis skin membrane in the above embodiments according to the present invention, such as polyamide, photocrosslinking agent, photoinitiator and other materials are not particularly limited. Those skilled in the art can choose any other material suitable for the embodiments of the present invention as the material of the forward osmosis skin membrane according to actual needs, for example, cellulose acetate can also be selected. In addition, the selection of photocrosslinking agent, photoinitiator and antioxidant is not particularly limited, as long as a good photocrosslinking effect can be achieved and the chemical stability and compactness of the forward osmosis skin membrane can be improved.

S300 heat treatment and ultraviolet light irradiation

In this step, the support layer-forward osmosis skin membrane complex formed in S200 is sequentially subjected to heat treatment and ultraviolet light irradiation, so as to obtain a forward osmosis membrane. Thus, through heating and ultraviolet light treatment, the cross-linking of molecules in the forward osmosis skin membrane can be achieved, thereby achieving the purpose of improving chemical stability and maintaining the degree of hydrophilicity of the membrane surface, and then maintaining the forward osmosis membrane for a long time. High water flux operation improves the performance of the forward osmosis membrane.

In order to further improve the performance of the forward osmosis membrane prepared by the method according to the embodiment of the present invention, the following steps may be further included before and after S300: Referring to FIG. Impurities attached to the surface of the forward osmosis skin membrane. The above washing steps can be repeatedly washed with double distilled water to remove residual impurities and improve the treatment effect of the subsequent heat treatment step S320. The cleaned forward osmosis skin membrane is further subjected to S320 heat treatment. The heat treatment step can be carried out at 90 degrees centigrade, and the treatment time can be 15-20 minutes. Therefore, the stability of the forward osmosis membrane can be further improved by heating, and the combination of the polyamide forward osmosis skin membrane and the polysulfone support layer can be improved, thereby improving the performance of the forward osmosis membrane prepared according to the embodiment of the present invention. In addition, after the heat treatment at S320, a cleaning step S330 may be further included to further remove impurities remaining in the above steps and improve the treatment effect of subsequent steps. The above features and advantages in the cleaning step of S310 are also applicable to S330, and will not be repeated here.

After the cleaning step of S330, the above-mentioned forward osmosis skin membrane may be subjected to S340 ultraviolet irradiation treatment. The ultraviolet irradiation can adopt F300/F300SQ type microwave excitation ultraviolet lamp, the power density is 120W/cm ² , the dominant wavelength is 365nm, and the ultraviolet lamp tube is 7cm away from the sample surface. Moreover, the ultraviolet light irradiation time can be adjusted according to the specific thickness of the polyamide forward osmosis skin membrane. For example, when the forward osmosis membrane has a thickness of 5-8 microns, the light treatment time may be 5-10 seconds. Thus, the polyamide forward osmosis skin membrane complex can be induced to undergo cross-linking reaction through ultraviolet light treatment, and the chemical stability and compactness of the polyamide skin membrane can be moderately improved, so as to improve the interception of salt ions by the forward osmosis membrane. rate, thereby improving the performance of the forward osmosis membrane prepared according to the embodiments of the present invention.

According to an embodiment of the present invention, the thickness of the forward osmosis skin membrane is 5-8 microns. Precise control of the thickness of the forward osmosis membrane can be achieved by setting relevant parameters in the 3D printing step, for example, by designing parameters such as the thickness, shape, and printing accuracy of the polyamide layer based on CAD digital model software. Moreover, when the thickness of the polyamide forward osmosis membrane is 5 to 8 microns, the effect of reducing the concentration polarization and increasing the water flux of the forward osmosis membrane can be achieved, thereby improving the efficiency of using the forward osmosis membrane prepared according to the embodiment of the present invention. performance.

Thus, by adopting the method for preparing a forward osmosis membrane according to an embodiment of the present invention, a forward osmosis skin membrane with a uniform thickness and a controllable three-dimensional multilayer network structure can be formed on the surface of the support layer by 3D printing technology, thereby improving The porosity of the forward osmosis membrane reduces the influence of concentration polarization on the separation performance of the forward osmosis membrane. Moreover, through the heating and ultraviolet light treatment according to the embodiment of the present invention, the crosslinking of the skin membrane molecules can be achieved to achieve the purpose of improving chemical stability and maintaining the degree of hydrophilicity of the membrane surface, thereby maintaining the forward osmosis membrane in a long time. The operation of maintaining a high water flux, thereby improving the performance of the forward osmosis membrane according to the embodiment of the present invention.

Forward osmosis membrane

In another aspect of the present invention, the present invention provides a forward osmosis membrane. According to an embodiment of the present invention, the forward osmosis membrane is prepared by the above method for preparing a forward osmosis membrane according to the embodiment of the present invention. Thus, by adopting the 3D printing technology according to the embodiment of the present invention, a forward osmosis skin membrane with a uniform thickness and a controllable three-dimensional multi-layer network structure can be formed on the surface of the support layer, thereby increasing the porosity of the forward osmosis membrane. Reduce the effect of concentration polarization on the separation performance of forward osmosis membranes. Moreover, through the heating and ultraviolet light treatment according to the embodiment of the present invention, the crosslinking of the skin membrane molecules can be achieved to achieve the purpose of improving chemical stability and maintaining the degree of hydrophilicity of the membrane surface, thereby maintaining the forward osmosis membrane in a long time. The operation of maintaining a high water flux, thereby improving the performance of the forward osmosis membrane according to the embodiment of the present invention.

In another aspect of the present invention, the present invention provides a forward osmosis membrane. According to an embodiment of the present invention, referring to FIG. 4 , the forward osmosis membrane has the following structure: a support layer 100 and a forward osmosis skin membrane 200 . According to an embodiment of the present invention, the forward osmosis skin membrane 200 is formed on the surface of the support layer 100 . Specifically, referring to FIG. 7 , the support layer 100 contained in the aforementioned forward osmosis membrane is formed of polysulfone, and the polysulfone support layer 100 further has a cross-linked layer 300 . And the forward osmosis skin membrane 200 is formed by 3D printing of polyamide. Thus, polysulfone can provide good support for the forward osmosis membrane, and by using 3D printing technology, a forward osmosis skin membrane 200 with a uniform thickness and a controllable three-dimensional multilayer network structure is formed on the surface of the support layer 100 , and then can increase the porosity of the forward osmosis membrane, reduce the impact of concentration polarization on the separation performance of the forward osmosis membrane, thereby achieving higher water flux and higher rejection rate, and then improving the performance of the forward osmosis membrane.

In addition, the forward osmosis skin membrane 200 may further have the following additional technical features: Referring to FIG. 4, the forward osmosis skin membrane 200 has a thickness H, which may be 5-8 microns; the forward osmosis skin membrane 200 further has a multi-layer network structure; Referring to FIG. 5 , the forward osmosis skin membrane 200 is composed of a plurality of membranes having a single-layer forward osmosis skin membrane 210 structure; and, the forward osmosis skin membrane 200 has a thickness deviation of no more than 5%. Referring to FIG. 6 , the above-mentioned thickness deviation is defined as follows: the thickness Hmax at the highest point on the surface of the forward osmosis skin membrane 200 minus the thickness Hmin at the lowest point, and the ratio of the average thickness. The above average thickness is the average value of Hmax and Hmin.

In addition, in order to further improve the performance of the forward osmosis membrane according to the embodiment of the present invention, heat treatment and ultraviolet irradiation treatment may be performed on the above forward osmosis membrane. In addition, before and after the above-mentioned heat treatment, the above-mentioned forward osmosis membrane may be cleaned with twice distilled water, respectively. The characteristics and advantages of the heating and ultraviolet irradiation treatment described above in the method for preparing a forward osmosis membrane according to the embodiment of the present invention are also applicable to the steps described above, and will not be repeated here.

The forward osmosis membrane according to the embodiment of the present invention further has the following technical features: under the water flow pressure of 0.1MPa, the water flux of 30L/m ² h to 60L/m ² h, wherein the water flux for seawater is 60L/m2h m ² h; a rejection rate of not less than 95% for NaCl; or a rejection rate of not less than 99% for MgSO ₄ .

The present invention is described below through specific examples, and those skilled in the art can understand that the following specific examples are only for the purpose of illustration, and do not limit the scope of the present invention in any way. In addition, in the following examples, unless otherwise specified, the materials and equipment used are commercially available. If the specific treatment conditions and treatment methods are not clearly described in the following examples, the conditions and methods known in the art can be used for treatment.

Embodiment 1 prepares forward osmosis membrane

In this embodiment, with reference to Figure 8, a forward osmosis membrane is prepared, wherein the specific steps and conditions are as follows:

Using a polyethersulfone ultrafiltration membrane with a molecular weight cut-off of 80kDa as the base membrane, the surface of the membrane was first washed with deionized water and dried in a 90°C drying oven for 2 hours. Then immediately immersed in n-hexane solution containing 0.5% by weight of trimesoyl chloride (TMC), the immersion time was 20 seconds. Then the membrane was taken out and placed in the air, and dried at room temperature for 1 minute to completely volatilize the n-hexane solvent on the surface of the membrane. Then put the TMC-attached base film into the 3D printer. According to the pre-set program, deposit and print the mixed material of polyamide and photocrosslinking agent on the upper surface of the base film. After cooling, take out the sample and place it in a 90°C drying oven. Dry in medium for 1 hour, then take it out and wash it, and irradiate and cross-link with ultraviolet light with a power density of 120W/cm ² for 10s. Finally, wash it several times with secondary water to remove residual impurities and store it in the sink for later use.

The average thickness of the obtained asymmetric forward osmosis membrane polyamide skin layer is 7 microns, the deviation of surface uniformity is 4%, and the cross-linking strength between the skin layer membrane and the matrix membrane is high, and the stability of the membrane is good. It can be used in 2M sodium chloride aqueous solution It is used as the drawing liquid and the secondary water is used as the raw material liquid to run continuously for 2 weeks without falling off or decomposing.

Referring to FIG. 9, the performance of the forward osmosis membrane obtained in Example 1 is tested. Specifically, FIG. 9 shows the flow of the determination device for the water flux and salt ion rejection rate of the composite FO membrane. The test temperature was kept at room temperature (23±0.5° C.), and the pH of the solution was neutral (pH 7-8). As shown in Figure 9, the flow of the aqueous solution in the test system is driven by two peristaltic pumps (YZ1515X). Control a certain water flow speed and water pressure.

The water flux of the FO membrane was calculated by measuring the increment of the draw solution within 30 minutes (recorded every 1 minute) by an electronic analytical balance (AY220). During the test, the skin membrane of the FO composite membrane faced the side of the feed solution (AL-facing-FS), and the support membrane faced the side of the draw solution. For each group of FO composite membranes, each experiment was repeated three times, and the data were averaged to calculate the standard deviation. The calculation formula of FO membrane water flux (J _w ) (L·m ^-2 ·h ^-1 ) is as follows:

Where Δw: change in the mass of the draw solution (kg);

ρ: density of water (kg·L ^-1 );

s: effective area of the membrane (m ² );

t: Operation experiment (h).

The interception rate of the forward osmosis membrane to the draw solution solute (the amount of solute that the draw solution diffuses into the raw material solution through the membrane, RS) is measured by calculating the salt ion concentration of the secondary water of the raw material solution, and the average value of the three test data is obtained, and the standard deviation is calculated. . A standard conductivity meter is used to measure the conductivity value of the solution and calculate the concentration of the solution. The formula for calculating the anti-mixing rejection rate is as follows:

Among them, n _salt : the molar mass (mol) of the solute that enters the raw material solution from the draw solution during the experiment;

V _DI : water penetration (L);

C _d : the concentration of the draw solution (mol·L ^-1 ).

Example 2

With the NaCl aqueous solution of concentration 2mol/L as draw liquid, take twice distilled water as raw material liquid, test the forward osmosis membrane prepared in embodiment 1, test according to the method described in embodiment 1 and according to the formula in embodiment 1 Calculate the water flux and rejection of the forward osmosis membrane. First place the forward osmosis membrane (FO membrane) prepared according to the embodiment of the present invention in the system, at room temperature (23°C), by turning on the peristaltic pump and adjusting the valve, control the draw liquid and raw material liquid to have a certain flow rate, so that The water flow pressure is maintained at 0.1MPa, and the pressure in the system is monitored through a pressure gauge. The quality of the raw material solution consumed through the FO membrane was tested by an electronic balance. By calculation, the water permeation rate per unit area and unit time of the forward osmosis membrane according to the embodiment of the present invention can reach 32 L/m ² h. Use a DDS-307 conductivity meter to test the concentration change before and after the draw solution, and calculate the rejection rate of salt ions by the forward osmosis membrane according to the embodiment of the present invention. The rejection rate of NaCl ions can reach 95%.

Example 3

With the MgSO of concentration _2mol /L Aqueous solution is draw liquid, with twice distilled water as raw material liquid, the forward osmosis membrane prepared in embodiment 1 is tested, test according to the method described in embodiment 1 and according to the method in embodiment 1 The formula calculates the water flux and rejection of forward osmosis membrane. Put the forward osmosis membrane (FO membrane) prepared according to the embodiment of the present invention in the system, at room temperature (23°C), by turning on the peristaltic pump and adjusting the valve, control the draw liquid and raw material liquid to have a certain flow rate, so that the water flow The pressure is maintained at 0.1MPa, and the pressure in the system is monitored through a pressure gauge. The quality of the raw material solution consumed through the FO membrane was tested by an electronic balance. By calculation, the water permeation rate per unit area and unit time of the forward osmosis membrane according to the embodiment of the present invention can reach 48 L/m ² h. Utilize the DDS-307 conductivity meter to test the concentration change before and after the draw solution, and calculate the rejection rate of MgSO ₄ ions by the forward osmosis membrane according to the embodiment of the present invention can reach 99%.

Example 4

In addition, in order to further illustrate the performance of the forward osmosis membrane according to the embodiment of the present invention when treating seawater, the present invention provides the following test: simulate seawater with a NaCl aqueous solution with a concentration of 1.6mol/L, and use river water as the infiltrate to construct a pressure-damped osmosis ( PRO) power generation system, the water flux and the rejection rate of the forward osmosis membrane that test embodiment 1 prepares. First place the forward osmosis membrane according to the embodiment of the present invention in the PRO performance detection device, at room temperature (23° C.), adjust the valve to control a certain flow rate, and use an electronic balance to test the flow rate of the forward osmosis membrane according to the embodiment of the present invention. The consumption mass of raw material liquid. By calculation, the water permeation rate per unit area and unit time of the forward osmosis membrane according to the embodiment of the present invention can reach 60 L/m ² h. Use the DDS-307 conductivity meter to test the concentration change in front of the draw solution, and calculate the interception rate of salt ions. The rejection rate of the NaCl ion of the forward osmosis membrane according to the embodiment of the present invention can reach 97%.

In another aspect of the present invention, the present invention proposes the use of the forward osmosis membrane according to the embodiment of the present invention in sewage treatment or seawater desalination. Since the forward osmosis membrane is prepared by the method described above according to the embodiment of the present invention, the forward osmosis membrane has the characteristics and advantages of the forward osmosis membrane described above according to the embodiment of the present invention, and will not be repeated here. Therefore, the characteristics of the forward osmosis membrane according to the embodiment of the present invention can be utilized, such as having high porosity, higher water flux, higher rejection rate and good chemical stability, etc., and the forward osmosis membrane can be applied to sewage Treatment or seawater desalination, so as to obtain better results, improve sewage treatment efficiency or seawater desalination effect.

It should be noted that the features and effects described in various aspects of the present invention are mutually applicable and will not be repeated here.

In the description of this specification, description with reference to the terms "one embodiment", "another embodiment", etc. means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention . In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the described specific features, structures, materials or characteristics may be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples and features of different embodiments or examples described in this specification without conflicting with each other.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and those skilled in the art can make the above-mentioned The embodiments are subject to changes, modifications, substitutions and variations.

Claims (11)

1. A kind of 1. method for preparing forward osmosis membrane, it is characterised in that including：

   (1) cross-linked layer is formed on the surface of supporting layer；

   (2) polyamide, photocrosslinking agent, light trigger and antioxidant are used, by 3D printing, on the surface of the cross-linked layer Positive infiltration cortex film is formed, to obtain supporting layer-positive infiltration cortex film composite；And

   (3) it is described to obtain by the supporting layer-positive infiltration cortex film composite is heat-treated successively and ultraviolet light Forward osmosis membrane,

   The photocrosslinking agent is Triallyl isocyanurate, and the light trigger is benzophenone and benzoin dimethylether, institute It is antioxidant 1010 to state antioxidant, and the polyamide, the Triallyl isocyanurate, the benzophenone, The mass ratio of the benzoin dimethylether and the antioxidant is (85~95)：(2~6)：(1~5)：(0.1~2)： (0.1~1).
2. 2. according to the method for claim 1, it is characterised in that the supporting layer is formed by polysulfones.
3. 3. according to the method for claim 2, it is characterised in that the supporting layer is withering in advance.
4. 4. according to the method for claim 3, it is characterised in that the drying process is carried out 2 hours under 90 degrees Celsius.
5. 5. according to the method for claim 1, it is characterised in that the cross-linked layer is formed by pyromellitic trimethylsilyl chloride.
6. 6. according to the method for claim 5, it is characterised in that the cross-linked layer is by the way that the supporting layer is immersed in In the hexane solution of 0.5 weight % pyromellitic trimethylsilyl chlorides 20 seconds and formed.
7. 7. according to the method for claim 1, it is characterised in that in step (3), before the heat treatment is carried out and it Afterwards, redistilled water is respectively adopted to be cleaned, and the heat treatment is carried out under 90 degrees Celsius.
8. 8. according to the method for claim 1, it is characterised in that in step (3), the ultraviolet processing uses F300/ F300SQ type microwave-excitation uviol lamps, power density 120W/cm², dominant wavelength 365nm, ultraviolet lamp tube is away from sample surfaces 7cm.
9. 9. according to the method for claim 1, it is characterised in that the thickness of the positive infiltration cortex film is 5~8 microns.
10. 10. a kind of forward osmosis membrane, it is prepared by method according to any one of claims 1 to 9.
11. 11. purposes of the forward osmosis membrane in sewage disposal or desalinization described in claim 10.