A method and device for desalination of saline-alkali water with resistance to fouling and clogging

Abstract

The present invention relates to a method and apparatus for desalination of saline-alkali water that is resistant to fouling and clogging. The method comprises the following steps: initial precipitation of saline-alkali water, heating, micro-nano desalination, and water production; the micro-nano desalination column comprises a micro-nano support column and a desalination membrane wrapped around the micro-nano support column, with a polyurethane elastomer layer disposed between the micro-nano support column and the desalination membrane. In the method, the carbon nanotubes, silicon carbide, and other components of the desalination membrane form composite water channels, preventing hydrated ions from passing through the membrane. Only water and a small number of ions can pass through the membrane, achieving separation of water from salt.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to a saline-alkali water desalination method and equipment that is resistant to fouling and clogging. Background Art

[0002] Saline-alkali land refers to land where the salt content in the soil is so high that it affects the growth of crops. Most saline-alkali lands cannot be used to grow crops. In order to utilize the land resources of saline-alkali land, the existing technology requires the desalination of the saline-alkali water in the soil of saline-alkali land to meet the growth needs of crops or other plants. After long-term agricultural practice, salt washing is still an important means to improve saline-alkali land. However, a large amount of saline-alkali water will be produced in the process of salt washing. Saline-alkali water has the characteristics of high pH value, high carbonate alkalinity, high ion coefficient and various water quality types. If the saline-alkali water is directly discharged as wastewater, it will cause serious waste of water resources. The high salt content in the saline-alkali water will also damage the ecological environment.

[0003] At present, the commonly used method is to purify saline water by using reverse osmosis membrane and nanofiltration as the core water purification technology. However, there are problems such as complex equipment, large floor space and high purification cost. Therefore, the existing technology constructs a micro-nano desalination column with a composite tube cavity structure by mixing carbon nanotubes, graphene oxide and silicon carbide. It recognizes the charge and ion diameter and combines the micro-nano flow of micro-nano tubes to achieve the targeted passage of water and salt. However, the organic macromolecules in saline water will be trapped on the surface of the micro-nano desalination column, thereby clogging the ion screening membrane. At the same time, due to the Ca in saline water, the 2+ Mg 2+ Higher concentrations, Ca 2+ Mg 2+ It is easy to cause scaling on the surface of the micro-nano desalination column located on the saline water side. Summary of the Invention

[0004] The first purpose of the present invention is to provide a method for desalination of saline water with anti-fouling and clogging to solve the problem of micro-nano desalination column due to organic macromolecules and Ca in saline water. 2+ Mg 2+ Technical problems caused by scaling and clogging.

[0005] The second object of the present invention is to provide a saline-alkali water desalination device that is resistant to fouling and clogging.

[0006] In order to achieve the above objectives, the technical solution adopted by the present invention is:

[0007] A method for desalinating saline water that is resistant to fouling and clogging comprises the following steps: initial precipitation of saline water, heating, micro-nano desalination, and water production; the micro-nano desalination adopts a micro-nano desalination column for desalination, the micro-nano desalination column comprising a micro-nano support column and a desalination membrane wrapped around the outside of the micro-nano support column, and a polyurethane elastomer layer is provided between the micro-nano support column and the desalination membrane.

[0008] Furthermore, the preparation method of the desalination membrane is:

[0009] S1: alkali-washing graphene oxide to obtain alkali-washed graphene oxide; dispersing γ-(2,3-epoxypropoxy)propyltrimethoxysilane in a mixed solvent to obtain a mixed solution, then adding the alkali-washed graphene oxide to the mixed solution and heating under reflux, centrifuging to obtain a solid, washing the solid, dispersing it in water, and ultrasonically dispersing it to obtain dispersion 1;

[0010] S2: placing silicon carbide and carbon nanotubes in ethanol and ultrasonically dispersing them to obtain a second dispersion, coating the second dispersion on a polyethersulfone membrane, and drying to obtain a base membrane;

[0011] S3: coating the dispersion in S1 onto the base membrane in S2 to obtain the desalination membrane.

[0012] Furthermore, in S1, 1 to 2 g of the γ-(2,3-epoxypropoxy)propyltrimethoxysilane is added to every 100 mg of the alkali-washed graphene oxide; 180 to 200 mL of a mixed solvent is added to every gram of the γ-(2,3-epoxypropoxy)propyltrimethoxysilane; the mixed solvent is a mixed solvent of water and ethanol, and the volume ratio of water to ethanol is 1:2.5 to 1:3.5.

[0013] Furthermore, the heating reflux temperature in S1 is 60-75° C. and the time is 3-4 h.

[0014] Furthermore, the preparation method of the micro-nano desalting column is:

[0015] S1: preparing a micro-nano support column matrix by 3D printing technology on straw; soaking the micro-nano support column matrix in a polyurethane elastomer soaking liquid to obtain a micro-nano support column, wherein the soaking temperature is 60-90° C. and the soaking time is 1-2 hours;

[0016] S2: coating the polyurethane elastomer emulsion on the side of the desalination membrane coated with the dispersion 1, and then wrapping the desalination membrane coated with the polyurethane elastomer emulsion around the outside of the micro-nano support column, and drying to obtain the result.

[0017] Furthermore, the preparation method of the polyurethane elastomer emulsion is as follows: dehydrating 50 to 90 parts by weight of polyethylene glycol at 100 to 120° C. for 60 to 90 minutes, cooling to 70 to 85° C., adding 5 to 50 parts by weight of diisocyanate and 0.1 to 1 parts by weight of a catalyst, reacting for 50 to 90 minutes to obtain a prepolymer, cooling to 50 to 60° C., adding 2 to 9 parts by weight of a chain extender, 0.2 to 4 parts by weight of a foaming agent, and 0.05 to 2 parts by weight of a foam stabilizer to extend the chain for 100 to 150 minutes, and emulsifying with water to obtain an aqueous polyurethane elastomer emulsion.

[0018] Furthermore, the catalyst is dibutyltin dilaurate, the chain extender is 1,4-butanediol, the foaming agent is water, and the foam stabilizer is an organosilicon foam stabilizer.

[0019] Furthermore, the concentration of the polyurethane elastomer soaking solution is 0.2-0.5 mg / mL, and the polyurethane elastomer soaking solution is obtained by diluting the polyurethane elastomer latex with water.

[0020] Furthermore, the heating temperature is 30-70°C.

[0021] A saline-alkali water desalination device that is resistant to fouling and clogging, wherein the micro-nano desalination column comprises a micro-nano support column and a desalination membrane wrapped around the outside of the micro-nano support column, wherein a polyurethane elastomer layer is provided between the micro-nano support column and the desalination membrane; the micro-nano support column comprises a micro-nano support column matrix and a polyurethane elastomer, wherein the structure of the micro-nano support column matrix is a highly ordered porous structure, and the polyurethane elastomer is embedded in the porous structure of the micro-nano support column matrix; the structure of the desalination membrane is a structure with a composite tube cavity, wherein the tube cavity structure of the desalination membrane is composited by carbon nanotubes and silicon carbide, and the inner diameter of the tube cavity structure is 0.4 to 0.5 nm.

[0022] Beneficial effects of the present invention:

[0023] In the anti-fouling and anti-clogging saline-alkali water desalination method of the present invention, the carbon nanotubes, silicon carbide and the like of the desalination membrane form a composite water channel, hydrated ions cannot pass through the desalination membrane, and only water and a small number of ions can pass through the desalination membrane, thereby achieving separation of water and salt.

[0024] The anti-fouling and anti-clogging saline-alkali water desalination method of the present invention is provided with a polyurethane elastomer layer on the desalination membrane. The polyurethane elastomer layer has a porous structure, water can pass through, and the polyurethane elastomer has a low glass transition temperature and is highly fluid at room temperature. When the Ca in the saline-alkali water 2+ Mg 2+ When organic matter adheres to the desalination membrane or micro-nano support column, the high fluidity of the polyurethane elastomer can make the scale and organic matter fall off, avoiding Ca 2+ Mg2+ , organic matter adheres to the desalination membrane, improving the anti-scaling and anti-fouling properties of the desalination membrane and the micro-nano support column.

[0025] The micro-nano support column matrix prepared by the 3D printing technology of the present invention is a hard skeleton with a highly ordered porous structure. The porous structure is embedded with a porous polyurethane elastomer material. The polyurethane elastomer material is flexible and will shake back and forth during the flow of water, disturbing the water flow, making it difficult for salt and oil stains in saline water to adhere.

[0026] The present invention improves the solubility of anions and cations in saline-alkali water by heating, thereby increasing the number of hydrated ions in the saline-alkali water. When the saline-alkali water passes through the tube cavity structure, water molecules with a diameter less than 4 nm can pass through the tube cavity structure, while hydrated ions with a larger diameter cannot pass through the tube cavity structure. Heating is used to adjust the proportion of hydrated ions, thereby adjusting the amount of ions passing through, thereby achieving regulation of salt content. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is an electron microscope image of the polyurethane elastomer embedded in the micro-nano support column matrix in Example 1;

[0028] Figure 2 This is a physical picture of the micro-nano desalting column in Example 1;

[0029] Figure 3 This is a photo of the micro-nano desalting column in Comparative Example 1 after three months of use;

[0030] Figure 4 This is a photo of the micro-nano desalting column in Example 1 after three months of use. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to the embodiments of the present invention and the accompanying drawings.

[0032] PF-802 was purchased from Chenhua Company.

[0033] Example 1

[0034] The anti-fouling and anti-clogging saline-alkali water desalination method of Example 1 includes the following steps: the saline-alkali water to be treated undergoes initial precipitation to remove impurities and large particles; the saline-alkali water after initial precipitation is heated to increase the solubility of cations and anions in the saline-alkali water; and the heated saline-alkali water undergoes micro-nano desalination to obtain fresh water. The heating temperature is 70°C.

[0035] Micro-nano desalination uses a micro-nano desalting column for desalination. The preparation method of the micro-nano desalting column is as follows:

[0036] S1: Sodium hydroxide was added to a graphene oxide solution, refluxed at 70°C for 3 h, and then centrifuged. The solution was then acidified with hydrochloric acid under reflux, centrifuged, and washed with water to obtain alkaline-washed graphene oxide. 1.2 g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane was dispersed in 220 mL of a mixed solvent of 55 mL of water and 165 mL of ethanol to obtain a mixed solution. 100 mg of the alkaline-washed graphene oxide was added to the mixed solution and refluxed at 70°C for 4 h. After centrifugation, a solid was obtained. The solid was washed and dispersed in water to obtain dispersion 1.

[0037] S2: Silicon carbide and carbon nanotubes are placed in ethanol and ultrasonically dispersed to obtain dispersion liquid 2, which is then coated on a polyethersulfone membrane and dried to obtain a substrate membrane; the mass fraction of silicon carbide in dispersion liquid 2 is 5 wt%, and the mass fraction of carbon nanotubes is 4 wt%;

[0038] S3: The dispersion in S1 is coated on the base membrane in S2 to obtain a desalting membrane;

[0039] S4: 3D printing the straw to obtain a carbon precursor, carbonizing the carbon precursor to obtain a micro-nano support column matrix; soaking the micro-nano support column matrix in a polyurethane elastomer soaking solution for 1 hour at a soaking temperature of 60°C to obtain a micro-nano support column;

[0040] S5: Coat one side of the desalination membrane dispersion in S3 with polyurethane elastomer emulsion. Wrap the desalination membrane coated with polyurethane elastomer emulsion around the outside of the micro-nano support column in S4. After drying, the micro-nano desalination column is obtained. The side coated with polyurethane elastomer emulsion is located on the inside.

[0041] The polyurethane elastomer emulsion was prepared by dehydrating 70 kg of polyethylene glycol at 120°C for 60 minutes, then cooling to 80°C. 20 kg of diisocyanate and 0.5 kg of dibutyltin dilaurate were added and reacted for 70 minutes to obtain a prepolymer. The prepolymer was then cooled to 60°C, followed by the addition of 4 kg of 1,4-butanediol, 1 kg of water, and 0.1 kg of PF-802 for chain extension for 150 minutes. Water was then added and high-speed shear emulsification was performed to obtain the prepolymer. The concentration of the polyurethane elastomer soaking solution was 0.2 mg / mL, and the prepolymer was prepared by diluting the polyurethane elastomer emulsion with water.

[0042] The blocked saline-alkali water desalination equipment of Example 1 includes a micro-nano desalination column, which includes a micro-nano support column and a desalination membrane wrapped around the outside of the micro-nano support column, with a polyurethane elastomer layer provided between the micro-nano support column and the desalination membrane. The micro-nano support column includes a micro-nano support column matrix and a polyurethane elastomer. The structure of the micro-nano support column matrix is a highly ordered porous structure, the polyurethane elastomer is embedded in the porous structure of the micro-nano support column matrix, and the polyurethane elastomer coated on the desalination membrane is connected to the -NH2 on the polyurethane elastomer through the epoxy group of the desalination membrane. The structure of the desalination membrane is a structure with a composite tube cavity. The tube cavity structure of the desalination membrane is composed of a composite of carbon nanotubes and silicon carbide, and the inner diameter of the tube cavity structure is 0.4 to 0.5 nm. The tube cavity structure is the established composite water channel, and water molecules pass through the composite water channel.

[0043] Example 2

[0044] The anti-fouling and anti-clogging saline-alkali water desalination method of Example 2 includes the following steps: the saline-alkali water to be treated undergoes initial precipitation to remove impurities and large particles; the saline-alkali water after initial precipitation is heated to increase the solubility of cations and anions in the saline-alkali water; and the heated saline-alkali water undergoes micro-nano desalination to obtain fresh water. The heating temperature is 50°C.

[0045] Micro-nano desalination uses a micro-nano desalting column for desalination. The preparation method of the micro-nano desalting column is as follows:

[0046] S1: Sodium hydroxide was added to a graphene oxide solution, refluxed at 70°C for 3 h, and then centrifuged. The solution was then acidified with hydrochloric acid under reflux, centrifuged, and washed with water to obtain alkaline-washed graphene oxide. 1.5 g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane was dispersed in 300 mL of a mixed solvent of 80 mL of water and 220 mL of ethanol to obtain a mixed solution. 100 mg of the alkaline-washed graphene oxide was added to the mixed solution and refluxed at 60°C for 4 h. After centrifugation, a solid was obtained. The solid was washed and dispersed in water to obtain dispersion 1.

[0047] S2: Silicon carbide and carbon nanotubes are placed in ethanol and ultrasonically dispersed to obtain dispersion liquid 2, which is then coated on a polyethersulfone membrane and dried to obtain a substrate membrane; the mass fraction of silicon carbide in dispersion liquid 2 is 5 wt%, and the mass fraction of carbon nanotubes is 6 wt%;

[0048] S3: The dispersion in S1 is coated on the base membrane in S2 to obtain a desalting membrane;

[0049] S4: 3D printing the straw to obtain a carbon precursor, carbonizing the carbon precursor to obtain a micro-nano support column matrix; soaking the micro-nano support column matrix in a polyurethane elastomer soaking solution for 2 h at a soaking temperature of 70°C to obtain a micro-nano support column;

[0050] S5: Coat one side of the desalination membrane dispersion in S3 with polyurethane elastomer emulsion. Wrap the desalination membrane coated with polyurethane elastomer emulsion around the outside of the micro-nano support column in S4. After drying, the micro-nano desalination column is obtained. The side coated with polyurethane elastomer emulsion is located on the inside.

[0051] The polyurethane elastomer emulsion was prepared by dehydrating 50 kg of polyethylene glycol at 100°C for 90 minutes, then cooling to 70°C. 15 kg of diisocyanate and 0.1 kg of dibutyltin dilaurate were added and reacted for 50 minutes to obtain a prepolymer. The prepolymer was then cooled to 50°C and chain-extended with 2 kg of 1,4-butanediol, 0.2 kg of water, and 0.05 kg of PF-802 for 100 minutes. Water was then added and high-speed shear emulsification was performed to obtain the prepolymer. The concentration of the polyurethane elastomer soaking solution was 0.3 mg / mL, and the prepolymer was prepared by diluting the polyurethane elastomer emulsion with water.

[0052] The anti-fouling and anti-clogging saline water desalination equipment of Example 2 includes a micro-nano desalination column, and the structure of the micro-nano desalination column of Example 2 is the same as that of the micro-nano desalination column of Example 1. The micro-nano desalination column of Example 2 is prepared using the preparation method of the micro-nano desalination column of Example 2.

[0053] Example 3

[0054] The anti-fouling and anti-clogging saline-alkali water desalination method of Example 3 includes the following steps: the saline-alkali water to be treated undergoes initial precipitation to remove impurities and large particles; the saline-alkali water after initial precipitation is heated to increase the solubility of cations and anions in the saline-alkali water; and the heated saline-alkali water undergoes micro-nano desalination to obtain fresh water. The heating temperature is 30°C.

[0055] Micro-nano desalination uses a micro-nano desalting column for desalination. The preparation method of the micro-nano desalting column is as follows:

[0056] S1: Sodium hydroxide was added to a graphene oxide solution, and the mixture was refluxed at 70°C for 3 h and then centrifuged. The mixture was then acidified with hydrochloric acid under reflux, centrifuged, and washed with water to obtain alkali-washed graphene oxide. 2 g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane was dispersed in 380 mL of a mixed solvent to obtain a mixed solution. 100 mg of the alkali-washed graphene oxide was added to the mixed solution, and the mixture was refluxed at 65°C for 3 h. The solid was obtained after centrifugation. The solid was washed and dispersed in water to obtain dispersion 1.

[0057] S2: Silicon carbide and carbon nanotubes are placed in ethanol and ultrasonically dispersed to obtain dispersion liquid 2, which is then coated on a polyethersulfone membrane and dried to obtain a substrate membrane; the mass fraction of silicon carbide and carbon nanotubes in dispersion liquid 2 is 6 wt%, and the mass fraction of carbon nanotubes is 6 wt%;

[0058] S3: The dispersion in S1 is coated on the base membrane in S2 to obtain a desalting membrane;

[0059] S4: 3D printing the straw to obtain a carbon precursor, carbonizing the carbon precursor to obtain a micro-nano support column matrix; soaking the micro-nano support column matrix in a polyurethane elastomer soaking solution for 1 hour at a soaking temperature of 90°C to obtain a micro-nano support column;

[0060] S5: Coat one side of the desalination membrane dispersion in S3 with polyurethane elastomer emulsion. Wrap the desalination membrane coated with polyurethane elastomer emulsion around the outside of the micro-nano support column in S4. After drying, the micro-nano desalination column is obtained. The side coated with polyurethane elastomer emulsion is located on the inside.

[0061] The mixed solvent is a mixed solvent of water and ethanol, the volume of water is 90 mL, and the volume of ethanol is 290 mL.

[0062] The polyurethane elastomer emulsion was prepared by dehydrating 90 kg of polyethylene glycol at 110°C for 70 minutes, then cooling to 85°C. 50 kg of diisocyanate and 1 kg of dibutyltin dilaurate were added and reacted for 90 minutes to obtain a prepolymer. The prepolymer was then cooled to 60°C, and chain extension was performed by adding 9 kg of 1,4-butanediol, 4 kg of water, and 2 kg of PF-802 for 150 minutes. Water was then added and high-speed shear emulsification was performed to obtain the prepolymer. The concentration of the polyurethane elastomer soaking solution was 0.5 mg / mL, and the prepolymer was prepared by diluting the polyurethane elastomer emulsion with water.

[0063] The anti-fouling and anti-clogging saline water desalination equipment of Example 3 includes a micro-nano desalination column, and the structure of the micro-nano desalination column of Example 3 is the same as that of the micro-nano desalination column of Example 1. The micro-nano desalination column of Example 3 is prepared using the preparation method of the micro-nano desalination column of Example 3.

[0064] Comparative Example 1

[0065] The anti-fouling and anti-clogging saline-alkali water desalination method of Comparative Example 1 includes the following steps: the saline-alkali water to be treated undergoes initial precipitation to remove impurities and large particles; the saline-alkali water after initial precipitation is heated to increase the solubility of cations and anions in the saline-alkali water; and the heated saline-alkali water undergoes micro-nano desalination to obtain fresh water. The heating temperature is 70°C.

[0066] Micro-nano desalination uses a micro-nano desalting column for desalination. The preparation method of the micro-nano desalting column is as follows:

[0067] S1: 100 mg of graphene oxide was dispersed in 220 mL of water and ultrasonically dispersed to obtain dispersion 1;

[0068] S2: Silicon carbide and carbon nanotubes are placed in ethanol and ultrasonically dispersed to obtain dispersion liquid 2, which is then coated on a polyethersulfone membrane and dried to obtain a substrate membrane; the mass fraction of silicon carbide in dispersion liquid 2 is 5 wt%, and the mass fraction of carbon nanotubes is 4 wt%;

[0069] S3: The dispersion in S1 is coated on the base membrane in S2 to obtain a desalting membrane;

[0070] S4: 3D printing the straw to obtain a carbon precursor, and carbonizing the carbon precursor to obtain micro-nano support pillars;

[0071] S5: Wrap the desalting membrane on the outside of the micro-nano support column in S4 to obtain a micro-nano desalting column.

[0072] Test Example 1

[0073] The pure water flux of the micro-nano desalination columns of Examples 1 to 3 and the micro-nano desalination column of Comparative Example 1 was tested (test temperature 25° C., test pressure 15 bar), and the results are shown in Table 1.

[0074] Table 1 Pure water flux test results of the micro-nano desalination columns of Examples 1 to 3 and Comparative Example 1

[0075]

[0076] As can be seen from Table 1, the pure water flux of the micro-nano desalination columns of Examples 1 to 3 is not much different from that of the micro-nano desalination column of Comparative Example 1, indicating that the micro-nano desalination columns coated with polyurethane elastomer in Examples 1 to 3 do not affect the pure water flux.

[0077] After three months of use, the pure water flux of the micro-nano desalination columns of Example 1 and Comparative Example 1 was tested (test temperature: 25° C., test pressure: 15 bar), and the results are shown in Table 2.

[0078] Table 2 Pure water flux test results of the micro-nano desalination columns of Example 1 and Comparative Example 1

[0079]

[0080] As can be seen from Table 2, after three months of use, the micro-nano desalination column of Example 1 still has a large pure water flux, while the micro-nano desalination column of Comparative Example 1 has a small pure water flux. This is because Comparative Example 1 uses a conventional micro-nano desalination column, which has weak anti-scaling and anti-fouling capabilities.2+ Mg 2+ Scaling on the micro-nano desalination column affects the pure water flux of the micro-nano desalination column of Comparative Example 1.

[0081] Test Example 2

[0082] The saline-alkali water discharged from a saline-alkali land after the salt washing method is taken. The water quality indicators of the saline-alkali water are shown in Table 3.

[0083] Table 3 Water quality indicators of saline-alkali water (concentration unit: mg / L)

[0084]

[0085] The saline-alkali water was desalinated using the anti-fouling and anti-clogging saline-alkali water desalination method and equipment of Example 1 and Comparative Example 1. The water quality indicators of the treated saline-alkali water are shown in Table 4.

[0086] Table 4. Results of saline-alkali water treatment (concentration unit: mg / L)

[0087]

[0088] As can be seen from Table 4, the saline water treated by the anti-fouling and anti-clogging saline water desalination method and equipment of Example 1 can be directly recycled for domestic use. However, the anti-scaling ability of the micro-nano desalination column of Comparative Example 1 is weak, resulting in Ca 2+ Mg 2+ Scaling on the micro-nano desalination column affects the separation effect of the micro-nano desalination column, which in turn leads to a higher ion content in the treated saline water.

Claims

1. A method for desalination of saline-alkali water with resistance to fouling and clogging, comprising the following steps: Initial precipitation, heating, micro-nano desalination, and water production of saline-alkali water; characterized in that the micro-nano desalination adopts a micro-nano desalination column for desalination, and the micro-nano desalination column includes a micro-nano support column and a desalination membrane wrapped around the outside of the micro-nano support column, and a polyurethane elastomer layer is provided between the micro-nano support column and the desalination membrane; The preparation method of the desalination membrane is: S1: alkali-washing graphene oxide to obtain alkali-washed graphene oxide; dispersing γ-(2,3-epoxypropoxy)propyltrimethoxysilane in a mixed solvent to obtain a mixed solution, then adding the alkali-washed graphene oxide to the mixed solution and heating under reflux, centrifuging to obtain a solid, washing the solid, dispersing it in water, and ultrasonically dispersing it to obtain dispersion 1; S2: placing silicon carbide and carbon nanotubes in ethanol and ultrasonically dispersing them to obtain a second dispersion, coating the second dispersion on a polyethersulfone membrane, and drying to obtain a base membrane; S3: coating the dispersion in S1 onto the base membrane in S2 to obtain the desalination membrane; In the preparation method of the desalination membrane: in S1, 1 to 2 g of the γ-(2,3-epoxypropoxy)propyltrimethoxysilane is added to every 100 mg of the alkali-washed graphene oxide; 180 to 200 mL of a mixed solvent is added to every gram of the γ-(2,3-epoxypropoxy)propyltrimethoxysilane; the mixed solvent is a mixed solvent of water and ethanol, and the volume ratio of water to ethanol is 1:2.5 to 1:3.5; The preparation method of the micro-nano desalting column is as follows: S1: preparing a micro-nano support column matrix by 3D printing technology on straw; soaking the micro-nano support column matrix in a polyurethane elastomer soaking liquid to obtain a micro-nano support column, wherein the soaking temperature is 60-90°C and the soaking time is 1-2 hours; S2: coating the polyurethane elastomer emulsion on the side of the desalination membrane coated with the dispersion 1, and then wrapping the desalination membrane coated with the polyurethane elastomer emulsion around the outside of the micro-nano support column, and drying to obtain the result.

2. The anti-fouling and anti-clogging saline-alkali water desalination method according to claim 1, characterized in that: The heating reflux temperature in S1 of the desalination membrane preparation method is 60-75° C. and the time is 3-4 h.

3. The anti-fouling and anti-clogging saline-alkali water desalination method according to claim 1, characterized in that: The preparation method of the polyurethane elastomer emulsion comprises the following steps: dehydrating 50 to 90 parts by weight of polyethylene glycol at 100 to 120° C. for 60 to 90 minutes, cooling the mixture to 70 to 85° C., adding 5 to 50 parts by weight of diisocyanate and 0.1 to 1 parts by weight of a catalyst, reacting the mixture for 50 to 90 minutes to obtain a prepolymer, cooling the mixture to 50 to 60° C., adding 2 to 9 parts by weight of a chain extender, 0.2 to 4 parts by weight of a foaming agent, and 0.05 to 2 parts by weight of a foam stabilizer, and chain extending the mixture for 100 to 150 minutes; and emulsifying the mixture with water to obtain the polyurethane elastomer emulsion.

4. The anti-fouling and anti-clogging saline-alkali water desalination method according to claim 3, characterized in that: The catalyst is dibutyltin dilaurate, the chain extender is 1,4-butanediol, the foaming agent is water, and the foam stabilizer is an organic silicon foam stabilizer.

5. The anti-fouling and anti-clogging saline-alkali water desalination method according to claim 3, characterized in that: The concentration of the polyurethane elastomer soaking liquid is 0.2-0.5 mg / mL, and the polyurethane elastomer soaking liquid is obtained by diluting the polyurethane elastomer latex with water.

6. The anti-fouling and anti-clogging saline-alkali water desalination method according to claim 1, characterized in that: The heating temperature is 30-70°C.

7. A saline-alkali water desalination device that is resistant to fouling and clogging, characterized in that: It comprises the micro-nano desalination column according to claim 1, wherein the micro-nano support column comprises a micro-nano support column matrix and a polyurethane elastomer, the structure of the micro-nano support column matrix is a highly ordered porous structure, and the polyurethane elastomer is embedded in the porous structure of the micro-nano support column matrix; the structure of the desalination membrane is a structure with a composite tube cavity, the tube cavity structure of the desalination membrane is composed of a composite of carbon nanotubes and silicon carbide, and the inner diameter of the tube cavity structure is 0.4 to 0.5 nm.

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