CN115090136A - High-flux high-selectivity material membrane and preparation method and application thereof - Google Patents

Abstract

The invention discloses a high-flux high-selectivity material membrane and a preparation method and application thereof, wherein the preparation method comprises the following steps: (1) preparing aqueous phase liquid from homopiperazine, an acid absorbing agent and water; (2) dipping the basement membrane in aqueous phase liquid; (3) dissolving trimesoyl chloride in an organic solvent to prepare an oil phase liquid; (4) soaking the base membrane subjected to the first soaking in oil phase liquid for interfacial polymerization reaction, cleaning, and soaking in alkali liquor to obtain a wet membrane covering the polyamide separation layer; (5) preparing a pore-protecting liquid from glycerol, polyglycerol and water; (6) dipping the wet film covering the polyamide separation layer in a pore-preserving solution; (7) mixing polycarbodiimide and water to prepare a post-treatment solution; (8) and (4) dropwise coating the post-treatment solution on the surface of the membrane after the third immersion, and drying to obtain the high-flux high-selectivity material membrane. The application comprises the following steps: the material membrane is used in the field of wastewater treatment for selective separation of organic matters and inorganic salts or the field of material separation or the field of treatment of nanofiltration concentrated solution of landfill leachate.

Description

High-flux high-selectivity material membrane and preparation method and application thereof

Technical Field

The invention relates to the technical field of water treatment membranes, in particular to a high-flux high-selectivity material membrane and a preparation method and application thereof.

Background

The landfill leachate is high-concentration organic wastewater generated in the process of treating and disposing domestic garbage, and has the characteristics of high pollutant concentration, high hardness, high alkalinity, large water quality and water quantity fluctuation and the like. At present, the mainstream treatment process of landfill leachate is a combined process of pretreatment, biological treatment and a double-membrane method (NF + RO). The process is mature, stable in operation and good in effluent quality, but biochemical effluent can generate a large amount of membrane concentrated solution after nanofiltration, concentration and separation. The concentrated solution mainly contains macromolecular humic acid and divalent salt, belongs to high-salt and high-organic matter waste liquid, has high treatment difficulty, and is the problem of the difficulty in effectively treating nanofiltration concentrated solution.

Humic acid is a complex mixture, which is divided into fulvic acid, ulmic acid and fulvic acid. Humic acid contains more functional groups, has good biological activity, and can be used as fertilizer, medicine additive, adsorbent, etc. If the humic acid in the nanofiltration concentrated solution can be separated and extracted, and the residual concentrated solution returns to the biochemical system, the discharge of the nanofiltration concentrated solution can be avoided, the overall recovery rate of a membrane system is improved, and the recycling of the humic acid can be realized.

The material membrane has the molecular weight cutoff of about 800Da (800 +/-200 Da), the removal rate of COD is about 65% (65 +/-20%), and the material membrane has no divalent salt rejection capacity basically. The material membrane is connected with a feed pipe of the landfill leachate nanofiltration concentrate, and is used for intercepting humic acid in the concentrate to recycle resources, the light-phase liquid obtained after passing through the material membrane returns to a biochemical system for cyclic treatment again, and no concentrate is discharged in the whole treatment process, so that zero emission of the landfill leachate nanofiltration concentrate is realized.

Compared with the traditional nanofiltration membrane, the material membrane has high retention rate for small molecular weight, is more focused on separating substances with specific molecular weight, and enables the separation layer to react within a certain pore diameter range by controlling related parameters in the preparation process so as to achieve the purpose of limiting the retention molecular weight. Most of the existing preparation methods of material membranes are similar to the traditional nanofiltration membranes, and separation layers are prepared by an interfacial polymerization method, a phase inversion method or a codeposition method, so that although the prepared material membranes can control the trapped molecular weight within a corresponding range to a certain degree, the distribution of the whole pore diameter is not uniform enough, the surface charge of the membranes can be changed, and the phenomenon that part of substances smaller than the trapped molecular weight still have higher trapping rate can be caused. Therefore, a simple and efficient material membrane preparation method is urgently needed, and a high-flux and high-selectivity material membrane capable of effectively treating the landfill leachate nanofiltration concentrated solution is prepared without changing the surface charge of the membrane while the pore diameter uniformity of the membrane is enhanced.

Disclosure of Invention

The invention provides a preparation process of a high-flux high-selectivity material membrane based on a pore size screening effect, solves a plurality of problems in the preparation of the material membrane in the prior art, and has very important economic value and research significance.

The invention is realized by the following technical scheme:

a preparation method of a high-flux high-selectivity material membrane is characterized by comprising the following steps:

(1) preparing a water phase liquid: mixing homopiperazine, an acid-absorbing agent and water to prepare aqueous phase liquid;

(2) first impregnation treatment: soaking the basement membrane in the aqueous liquid, and then separating and removing the liquid on the surface of the basement membrane;

(3) preparing an oil phase liquid: dissolving trimesoyl chloride in an organic solvent to prepare an oil phase liquid;

(4) and (3) second impregnation treatment: soaking the base membrane subjected to the first soaking treatment in the oil phase liquid again for interfacial polymerization reaction, separating and removing the liquid on the surface of the base membrane, cleaning, and soaking in alkali liquor to obtain a wet membrane covering the polyamide separation layer;

(5) preparing a pore-protecting liquid: mixing glycerol, polyglycerol and water to prepare a pore-protecting liquid;

(6) and (3) third impregnation treatment: placing the wet membrane covered with the polyamide separation layer in the pore-preserving solution for dipping treatment, and then separating and removing the liquid on the surface of the membrane;

(7) preparing a post-treatment solution: mixing polycarbodiimide and water to prepare a post-treatment solution;

(8) preparing a dry film sheet: and uniformly dripping the post-treatment solution on the surface of the membrane subjected to the third dipping treatment, separating and removing the liquid on the surface of the membrane, and drying to obtain the high-flux high-selectivity material membrane.

Specifically, polyglycerol is a polyol in which two or more hydroxyl groups among glycerol molecules are dehydrated to form ether bonds, is an important fine chemical product and a synthesis intermediate, and has wide application, but the polyglycerol is not reported to be used for preparing material films at present. In the preparation process of the high-flux high-selectivity material membrane, the polyamide separation layer formed by interfacial polymerization is soaked by using sodium hydroxide (alkali liquor), so that part of the polyamide reticular cross-linked structure can be broken and the size of the cross-linked pore diameter can be effectively enlarged while residual oil is cleaned. Meanwhile, in the process of the invention, polyglycerol with larger molecular weight is introduced into the preparation of the dry film sheet in the later stage, polyglycerol molecules effectively prevent the collapse of polyamide crosslinking holes in the drying process through the space occupying effect, and a polycarbodiimide crosslinking agent is used for repairing partial broken polymer chains, so that the high divalent salt transmittance of the material film is ensured, and the entrapment performance of PEG800 is not reduced.

Specifically, the preparation method of the high-flux high-selectivity material membrane comprises the following steps: introducing a polyglycerol substance as a pore-protecting agent into the preparation process of the material film dry membrane; the preparation method is simple, low in cost, good in compatibility with the traditional interfacial polymerization production process, and easy to produce and amplify. Under the synergistic effect of the polyglycerol and the polycarbodiimide crosslinking agent, the prepared material membrane has the molecular weight cut-off of about 800Da, the cut-off rate of divalent salt is less than 5%, and excellent organic matter/divalent salt selectivity is reflected. The high-flux high-selectivity material membrane prepared by the invention has the water flux more than 100LMH under extremely low pressure (0.2 MPa).

Further, a preparation method of the high-flux high-selectivity material membrane comprises the following steps: preparing aqueous phase liquid: the concentration of homopiperazine in the aqueous phase liquid is 0.1-2.0 wt%, and the concentration of the acid acceptor is 0.5-3.0 wt%; and the acid acceptor is selected from one or more of sodium carbonate, trisodium phosphate, triethylamine and sodium hydroxide. Preferably, the concentration of the homopiperazine in the aqueous phase liquid is 0.2-1.0 wt%, and the concentration of the acid acceptor is 1.0-2.5 wt%; the preferred acid scavenger is trisodium phosphate.

Further, a preparation method of the high-flux high-selectivity material membrane comprises the following steps: step (2) first dipping treatment: wherein the basement membrane is a polysulfone basement membrane; the time of the dipping treatment is 0.5-5 minutes.

Further, a preparation method of the high-flux high-selectivity material membrane comprises the following steps: preparing oil phase liquid: wherein the organic solvent is at least one selected from n-hexane, cyclohexane, ethylcyclohexane, n-heptane and isoparaffin solvent; the concentration of the trimesoyl chloride in the oil phase liquid is 0.05-0.5 wt%.

Further, a preparation method of the high-flux high-selectivity material membrane comprises the following steps: step (4) second dipping treatment: and soaking the base membrane subjected to the first soaking treatment in the oil phase liquid for 5-20 seconds for interfacial polymerization, separating and removing the liquid on the surface of the membrane, cleaning, and soaking in a sodium hydroxide aqueous solution with the concentration of 0.1-4.0 wt% for 0.5-5 minutes to obtain the wet membrane covering the polyamide separation layer.

Further, a preparation method of the high-flux high-selectivity material membrane comprises the following steps: preparing a pore-protecting liquid: the concentration of glycerol in the pore-protecting liquid is 1.0-15.0 wt%, and the concentration of polyglycerol is 0.2-3.0 wt%; the polyglycerol is n-polyglycerol, wherein n is 6-10, and preferably octaglycerol. Preferably, the concentration of glycerol in the pore-keeping solution is 3.0-8.0 wt%, and the concentration of polyglycerol is 0.5-1.5 wt%.

Further, a preparation method of the high-flux high-selectivity material membrane comprises the following steps: step (6) third impregnation treatment: and (3) placing the wet membrane covered with the polyamide separation layer in the pore-preserving solution for immersion treatment for 0.5-5 minutes, and then separating and removing the liquid on the surface of the membrane.

Further, the preparation method of the high-flux high-selectivity material membrane comprises the following steps: preparing a post-treatment solution in the step (7): the concentration of the polycarbodiimide in the post-treatment solution is 0.05 to 1.0 wt%.

Further, the preparation method of the high-flux high-selectivity material membrane comprises the following steps: step (8) dry film sheet preparation: the drying temperature is 30-90 ℃, and the drying time is 2-10 minutes.

The high-flux high-selectivity material membrane is characterized by being prepared by the preparation method.

The application of the high-flux high-selectivity material membrane is characterized in that the high-flux high-selectivity material membrane prepared by the preparation method is used in the field of wastewater treatment or material separation requiring selective separation of organic matters and inorganic salts, and is preferably used in the field of landfill leachate nanofiltration concentrate treatment.

The invention has the beneficial effects that:

(1) the preparation process is simple, the molecular weight cut-off of the prepared high-flux high-selectivity material membrane is about 800Da, the cut-off rate of the divalent salt magnesium sulfate is less than 5%, and the precise separation of organic matters and divalent salt can be realized.

(2) The polyglycerol introduced in the preparation process has a swelling effect on a polyamide layer cross-linked structure, the pore size in the cross-linked network structure can be uniformly expanded under the actions of soaking in alkali liquor and the polyglycerol, the water permeation efficiency is effectively improved, and the prepared high-flux high-selectivity material membrane has the water flux of more than 100LMH under extremely low pressure (0.2 MPa).

(3) The preparation method of the high-flux high-selectivity material membrane provided by the invention is simple, has low cost, has good compatibility with the traditional interfacial polymerization production process, is easy to produce and amplify, and has very important economic benefits.

(4) The preparation method of the high-flux high-selectivity material membrane provided by the invention comprises the following steps: on the basis of traditional interfacial polymerization operation, alkali liquor (sodium hydroxide solution) is used for soaking and destroying part of a polyamide reticular cross-linked structure, polyglycerol is introduced in the preparation of a dry film, the aperture size of a polyamide layer is enlarged by utilizing the occupying effect of the polyglycerol, and finally a polycarbodiimide cross-linking agent is used for repairing part of fractured macromolecular chains, so that the molecular weight cut-off of the prepared material membrane is about 800Da, the cut-off rate of divalent salt magnesium sulfate is less than 5%, and higher water flux can be still kept under extremely low pressure, so that the material membrane has good application prospect and economic value in the wastewater treatment field or the material separation field of selective separation of organic matters and inorganic salts and the treatment field of nanofiltration concentrated solution of garbage percolate.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to specific embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

A preparation method of a high-flux high-selectivity material membrane comprises the following steps:

(1) preparing a water phase liquid: mixing homopiperazine, acid absorbent and water to prepare aqueous phase liquid; the concentration of homopiperazine in the aqueous phase liquid is 0.1-2.0 wt% (preferably 0.2-1.0 wt%), and the concentration of acid acceptor is 0.5-3.0 wt% (preferably 1.0-2.5 wt%); the acid scavenger is selected from one or more of sodium carbonate, trisodium phosphate, triethylamine and sodium hydroxide, and the preferred acid scavenger is trisodium phosphate;

(2) first dipping treatment: immersing a basement membrane (polysulfone basement membrane) in the aqueous phase liquid for 0.5-5 minutes, and then separating and removing the liquid on the surface of the basement membrane;

(3) preparing an oil phase liquid: dissolving trimesoyl chloride in an organic solvent to prepare an oil phase liquid; the concentration of trimesoyl chloride in the oil phase liquid is 0.05 to 0.5 weight percent; wherein the organic solvent can be one or more selected from n-hexane, cyclohexane, ethylcyclohexane, n-heptane and isoparaffin solvent;

(4) and (3) second impregnation treatment: soaking the base membrane subjected to the first soaking treatment in the oil phase liquid again for 5-20 seconds of interfacial polymerization reaction, separating and removing the liquid on the surface of the base membrane, cleaning, and soaking in a sodium hydroxide aqueous solution with the concentration of 0.1-4.0 wt% for 0.5-5 minutes to obtain a wet membrane covering a polyamide separation layer;

(5) preparing a hole retaining solution: mixing glycerol, polyglycerol and water to prepare a pore-protecting liquid; the concentration of glycerol in the pore-protecting liquid is 1.0-15.0 wt% (preferably 3.0-8.0 wt%), and the concentration of polyglycerol is 0.2-3.0 wt% (preferably 0.5-1.5 wt%); the polyglycerol is n polyglycerol, n is 6-10, n is a positive integer, and the polyglycerol can be preferably octaglycerol;

(6) and (3) third impregnation treatment: placing the wet membrane covered with the polyamide separation layer in the pore-preserving solution for dipping treatment for 0.5-5 minutes, and then separating and removing the liquid on the surface of the membrane;

(7) preparing a post-treatment solution: mixing polycarbodiimide and water to prepare a post-treatment solution; the concentration of the polycarbodiimide in the post-treatment solution is 0.05 to 1.0 weight percent;

(8) preparing a dry film sheet: uniformly dripping the post-treatment solution on the surface of the membrane subjected to the third dipping treatment, separating and removing the liquid on the surface of the membrane, and drying at 30-90 ℃ for 2-10 minutes to obtain the high-flux high-selectivity material membrane.

Example 1

A preparation method of a high-flux high-selectivity material membrane comprises the following specific steps:

(1) preparing aqueous phase liquid: mixing Homopiperazine (HPIP), trisodium phosphate (acid acceptor) and water to prepare aqueous phase liquid; the concentration of homopiperazine in the aqueous phase liquid is 0.6 wt%, and the concentration of trisodium phosphate is 2.0 wt%;

(2) first impregnation treatment: soaking the polysulfone basal membrane in the aqueous phase liquid for 1 minute, and then separating and removing the liquid on the surface of the polysulfone basal membrane;

(3) preparing oil phase liquid: dissolving trimesoyl chloride (TMC) in ethylcyclohexane to prepare an oil phase liquid; and the concentration of trimesoyl chloride in the oil phase liquid is 0.15 wt%;

(4) and (3) second impregnation treatment: soaking the polysulfone base membrane subjected to the first soaking treatment in the oil phase liquid for interfacial polymerization reaction for 10 seconds, separating and removing membrane surface liquid, cleaning, and soaking in a 1.0 wt% sodium hydroxide aqueous solution for 1 minute to obtain a wet membrane covering a polyamide separation layer;

(5) preparing a pore-protecting liquid: mixing glycerol, octaglycerol and water to prepare a pore-protecting liquid; the concentration of glycerol in the pore-preserving solution is 5.0 wt%, and the concentration of octaglycerol is 1.0 wt%;

(6) and (3) third impregnation treatment: soaking the wet membrane covered with the polyamide separation layer in the pore-preserving solution for 1 minute, and then separating and removing the liquid on the surface of the membrane;

(7) preparing a post-treatment solution: mixing polycarbodiimide and water to prepare a post-treatment solution; and the concentration of the polycarbodiimide in the post-treatment solution is 0.2 wt%;

(8) preparing a dry film sheet: and uniformly dripping the post-treatment solution on the surface of the membrane subjected to the third dipping treatment, separating and removing the liquid on the surface of the membrane, and drying in an oven at 60 ℃ for 5 minutes to obtain the high-flux high-selectivity material membrane.

Example 2

Example 2 differs from example 1 above in that the concentration of glycerol in the pore-retaining solution described in step (5) of example 2 is 1.0 wt%; the other preparation conditions of example 2 were the same as in example 1.

Example 3

Example 3 differs from example 1 above in that the concentration of glycerol in the pore-retaining solution described in step (5) of example 3 is 3.0 wt%; the other preparation conditions of example 3 were the same as in example 1.

Example 4

Example 4 differs from example 1 above in that the concentration of glycerol in the pore-retaining solution described in step (5) of example 4 is 12.0 wt%; the other preparation conditions of example 4 were the same as in example 1.

Example 5

Example 5 differs from example 1 above in that the concentration of octaglycerol in the pore-retaining solution described in step (5) of example 5 is 0.2 wt%; the other preparation conditions of example 5 were the same as in example 1.

Example 6

Example 6 differs from example 1 above in that the concentration of octaglycerol in the pore-retaining solution described in step (5) of example 6 is 1.5 wt%; the other preparation conditions of example 6 were the same as in example 1.

Example 7

Example 7 differs from example 1 above in that the concentration of octaglycerol in the pore-retaining solution described in step (5) of example 7 is 3.0 wt%; the other preparation conditions of example 7 were the same as in example 1.

Example 8

Example 8 differs from example 1 above in that the interfacial polymerization reaction time in step (4) of example 8 is 20 seconds; the other preparation conditions of example 8 were the same as in example 1.

Example 9

Example 9 differs from example 1 above in that the concentration of polycarbodiimide in the post-treatment solution described in step (7) of example 9 was 0.05 wt%; the other preparation conditions of example 9 were the same as in example 1.

Example 10

Example 10 differs from example 1 above in that the concentration of polycarbodiimide in the post-treatment solution described in step (7) of example 10 was 1.0 wt%; the other preparation conditions of example 10 were the same as in example 1.

Example 11

Example 11 differs from example 1 above in that the pore-retaining solution described in step (5) of example 11 is prepared by mixing glycerol, hexa-polyglycerol and water; i.e. replacing the octaglycerol of example 1 with hexaglycerol; example 11 the concentration of glycerol and the concentration of hexaglycerol in the pore-preserving solution were 5.0 wt% and 1.0 wt%, respectively; the other preparation conditions of example 11 were the same as in example 1.

Example 12

Example 12 differs from example 1 above in that the pore-retaining solution described in step (5) of example 12 is prepared by mixing glycerol, decaglycerol and water; i.e., replacing the octaglycerol of example 1 with decaglycerol; example 12 the concentration of glycerol and the concentration of decaglycerol in the pore-preserving fluid were 5.0 wt% and 1.0 wt%, respectively; the other preparation conditions of example 12 were the same as in example 1.

Comparative example 1

Comparative example 1 differs from example 1 above in that no octaglycerol was added to the pore-preserving solution described in step (5) of comparative example 1; the remaining preparation conditions of comparative example 1 were the same as in example 1.

Comparative example 2

Comparative example 2 differs from example 2 above in that no octaglycerol was added to the pore-preserving solution described in step (5) of comparative example 2; the remaining preparation conditions of comparative example 2 were the same as in example 2.

Comparative example 3

Comparative example 3 differs from example 3 above in that no octaglycerol was added to the pore-preserving solution described in step (5) of comparative example 3; the remaining preparation conditions of comparative example 3 were the same as those of example 3.

Comparative example 4

Comparative example 4 differs from example 4 above in that no octaglycerol was added to the pore-preserving solution described in step (5) of comparative example 4; the remaining preparation conditions of comparative example 4 were the same as in example 4.

Comparative example 5

Comparative example 5 differs from example 1 above in that the interfacial polymerization reaction time in step (4) of comparative example 5 is 40 seconds; the remaining preparation conditions of comparative example 5 were the same as in example 1.

Comparative example 6

Comparative example 6 is different from example 1 described above in that the interfacial polymerization described in step (4) of comparative example 6 is not subjected to a soaking treatment with an aqueous sodium hydroxide solution; the remaining preparation conditions of comparative example 6 were the same as those of example 1.

Comparative example 7

Comparative example 7 differs from example 1 above in that the concentration of polycarbodiimide in the post-treatment solution described in step (7) of comparative example 7 was 0; the remaining preparation conditions of comparative example 7 were the same as in example 1.

And (3) testing:

the films of the materials obtained in examples 1 to 12 and comparative examples 1 to 7 were tested for their properties: the membrane separation performance of the prepared material is evaluated and mainly characterized by two characteristic parameters, namely the water flux (LMH) and the solute rejection rate of the membrane.

Water flux (LMH) is defined as: the volume of water per unit time that permeates the active membrane area under certain operating pressure conditions.

Solute rejection calculation formula: r ═ 1-C_p /C_f ) X 100%, wherein R represents the rejection rate, C_f And C_p The concentrations of solutes (ppm) in the permeate and feed solutions, respectively.

The test conditions of the material membrane separation performance are as follows: the feeding liquid is 2000ppm magnesium sulfate aqueous solution and 200ppm polyethylene glycol (PEG) aqueous solution with molecular weight of 800Da respectively, the temperature of the feeding liquid is 25 ℃, and the operation pressure is 0.2 MPa.

The PEG concentration was determined by total organic carbon analyzer (TOC-VCHP, Shimadzu, Japan). It is generally accepted that the relative molecular weight corresponding to a membrane with a 90% PEG cut-off is the cut-off for the membrane.

The above methods were used to perform the performance tests on the material films prepared in examples 1 to 7 and comparative examples 1 to 4, and the test results are shown in table 1 below.

Table 1 shows the results of the membrane separation performance test of the materials prepared in examples 1 to 7 and comparative examples 1 to 4

The test results in the table 1 show that the addition of the octaglycerol in the pore-retaining solution can obviously reduce the retention rate of the material membrane on the magnesium sulfate dibasic salt, the PEG retention is kept about 90%, and the retention molecular weight is accurately controlled about 800 Da; meanwhile, compared with glycerol, octaglycerol has stronger pore-protecting capability and has swelling effect on a polyamide layer cross-linked structure, and the water flux of the membrane can be improved by adding the lower-concentration triglycerol.

The above methods were used to perform the performance tests on the material films prepared in examples 8 to 12 and comparative examples 5 to 7, and the test results are shown in table 2 below.

Table 2 shows the results of the membrane separation performance tests of the materials prepared in examples 8 to 12 and comparative examples 5 to 7

As can be seen from the test results in Table 2, the polyglycerols with different molecular weights have different effects on the performance of the prepared material membrane, for example, the polyglycerols with different molecular weights have stronger swelling effect on the polyamide crosslinking layer, the prepared material membrane has larger water flux but lower PEG interception, and the material membrane prepared by the polyglycerols with smaller molecular weights has smaller pore size and obviously higher PEG and magnesium sulfate interception. In addition, the interfacial polymerization reaction time in the preparation process of the substance membrane is not easy to overlong, otherwise, the formed polyamide layer is compact, and the rejection rate of magnesium sulfate cannot be effectively reduced.

The sources of the raw materials used in examples 1-14 and comparative examples 1-5 above are shown in Table 3 below.

Name of raw materials	Parameter index	Manufacturer of the product
			Homopiperazine	The purity is more than or equal to 98 percent	Aladdin reagent
Trisodium phosphate	The purity is more than or equal to 98 percent	Reagent for treating west longs
			Trimesoyl chloride	The purity is more than or equal to 99 percent	Three-strength bennoco
Sodium hydroxide (NaOH)	The purity is more than or equal to 97 percent	Microphone forest
			Glycerol	The purity is more than or equal to 99 percent	Kangdi' s
Polyglycerol	The purity is more than or equal to 99 percent	Kangdi' s
			Polycarbodiimide UN-557	Industrial grade	Shanghai Yong En
Magnesium sulfate	The purity is more than or equal to 98 percent	Beijing YinuoKai
			Polyethylene glycol 800	The purity is more than or equal to 99 percent	Beijing YinuoKai

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not intended to limit the present invention. Obvious variations or modifications of the present invention are within the scope of the present invention.

Claims (10)

1. A preparation method of a high-flux high-selectivity material membrane is characterized by comprising the following steps:

(1) preparing aqueous phase liquid: mixing homopiperazine, acid absorbent and water to prepare aqueous phase liquid;

(2) first impregnation treatment: soaking the basement membrane in the aqueous liquid, and then separating and removing the liquid on the surface of the basement membrane;

(3) preparing an oil phase liquid: dissolving trimesoyl chloride in an organic solvent to prepare an oil phase liquid;

(4) and (3) second impregnation treatment: soaking the base membrane subjected to the first soaking treatment in the oil phase liquid again for interfacial polymerization reaction, separating and removing the liquid on the surface of the base membrane, cleaning, and soaking in an alkali liquor to obtain a wet membrane covering a polyamide separation layer;

(5) preparing a pore-protecting liquid: mixing glycerol, polyglycerol and water to prepare a pore-protecting liquid;

(6) and (3) third impregnation treatment: placing the wet membrane covered with the polyamide separation layer in the pore-preserving liquid for dipping treatment, and then separating and removing the liquid on the surface of the membrane;

(7) preparing a post-treatment solution: mixing polycarbodiimide and water to prepare a post-treatment solution;

(8) preparing a dry film sheet: and uniformly dripping the post-treatment solution on the surface of the membrane subjected to the third dipping treatment, separating and removing the liquid on the surface of the membrane, and drying to obtain the high-flux high-selectivity material membrane.

2. The method for preparing a high flux high selectivity material membrane according to claim 1, wherein the step (1) of preparing the aqueous liquid: the concentration of homopiperazine in the aqueous phase liquid is 0.1-2.0 wt%, and the concentration of the acid acceptor is 0.5-3.0 wt%; and the acid acceptor is selected from one or more of sodium carbonate, trisodium phosphate, triethylamine and sodium hydroxide.

3. The method for preparing a high flux high selectivity material membrane as claimed in claim 1, wherein the step (2) of the first dipping treatment: the basement membrane is a polysulfone basement membrane; the time of the dipping treatment is 0.5-5 minutes.

4. The method for preparing a high flux high selectivity material membrane as claimed in claim 1, wherein the step (3) is to prepare an oil phase liquid: wherein the organic solvent is at least one of n-hexane, cyclohexane, ethylcyclohexane, n-heptane and isoparaffin solvent; the concentration of the trimesoyl chloride in the oil phase liquid is 0.05-0.5 wt%.

5. The method for preparing a high flux high selectivity material membrane as claimed in claim 1, wherein the step (4) of the second dipping treatment: and soaking the base membrane subjected to the first soaking treatment in the oil phase liquid for 5-20 seconds for interfacial polymerization, separating and removing the liquid on the surface of the membrane, cleaning, and soaking in a sodium hydroxide aqueous solution with the concentration of 0.1-4.0 wt% for 0.5-5 minutes to obtain the wet membrane covering the polyamide separation layer.

6. The method for preparing a high flux high selectivity material membrane as claimed in claim 1, wherein the step (5) is to prepare a pore-protecting solution: the concentration of glycerol in the pore-protecting liquid is 1.0-15.0 wt%, and the concentration of polyglycerol is 0.2-3.0 wt%; the polyglycerol is n-polyglycerol, wherein n is 6-10, and preferably octaglycerol.

7. The method for preparing a high flux high selectivity material membrane as claimed in claim 1, wherein the step (7) of preparing the post-treatment solution: the concentration of the polycarbodiimide in the post-treatment solution is 0.05 to 1.0 wt%.

8. The method for preparing a high flux high selectivity material membrane according to claim 1, wherein the step (8) of preparing the dry membrane sheet comprises: the drying temperature is 30-90 ℃, and the drying time is 2-10 minutes.

9. A high flux high selectivity material membrane prepared by the method of any one of claims 1 to 8.

10. The application of the high-flux high-selectivity material membrane prepared by the preparation method of any one of claims 1 to 8 is characterized in that the high-flux high-selectivity material membrane prepared by the preparation method is used in the field of wastewater treatment or material separation requiring selective separation of organic matters and inorganic salts, preferably used in the field of nanofiltration concentrate treatment of landfill leachate.