CN114874488A

CN114874488A - Anti-pollution separation net and preparation method and application thereof

Info

Publication number: CN114874488A
Application number: CN202210594354.8A
Authority: CN
Inventors: 罗建泉; 黄嘉臣; 万印华
Original assignee: Institute of Process Engineering of CAS
Current assignee: Institute of Process Engineering of CAS
Priority date: 2022-05-27
Filing date: 2022-05-27
Publication date: 2022-08-09
Anticipated expiration: 2042-05-27
Also published as: CN114874488B

Abstract

The invention relates to an anti-pollution separation net and a preparation method and application thereof, wherein the anti-pollution separation net comprises a separation net and an anti-pollution polymer brush arranged on the surface of the separation net; the anti-pollution polymer brush comprises a temperature-sensitive hydrogel polymer brush and a fluorine-containing polymer brush grafted at the tail end of the temperature-sensitive hydrogel polymer brush; the temperature-sensitive hydrogel polymer brush is in direct contact with the separation net. The anti-pollution separation net has good anti-pollution capacity to organic pollutants and biological pollutants, self-cleaning capacity of temperature response, and fluid drag reduction function. The anti-pollution separation net is simple in preparation process, can be repeatedly used, and has a huge application prospect in the preparation of roll-type membrane components.

Description

Anti-pollution separation net and preparation method and application thereof

Technical Field

The invention relates to the technical field of separation nets, in particular to an anti-pollution separation net and a preparation method and application thereof.

Background

The membrane technology is a separation technology with a membrane material having separation selectivity as a core. The separation membrane can realize the purposes of separation, concentration, purification and the like of materials by taking pressure, concentration difference, vapor pressure difference and the like as driving forces. The membrane module is taken as the core of membrane technology and mainly has plate frame type, tubular type, hollow fiber type and roll type 4 structures. Due to higher packing density and lower cost, industrial material separation membranes often take the form of an assembly of wound membranes. The main components of the spiral wound membrane module comprise an interception side and a permeation side separation net, a separation membrane, a permeation side flow passage, a module shell, a sealing component and the like. As a green and efficient separation technology, the membrane technology is widely applied to the fields of drinking water purification, wastewater treatment, food and medicine processing and the like.

However, the components of the feed liquid treated by the membrane technology are complex, and organic matters, thalli and fermentation metabolites contained in the feed liquid can be adsorbed on the separation net or the surface of the membrane at the feed side, so that the membrane flux and the separation selectivity are reduced due to serious membrane pollution. Taking a commercial polypropylene mesh (PP) as an example, bacteria are liable to attach to its surface and form a biofilm during long-term membrane separation. Bacteria are easy to grow at the connecting point of the feed side separation net and the membrane, so that serious biological pollution is formed, and the loss of feed side pressure (FCP) and transmembrane pressure (TMP) is caused.

CN113041841A discloses a preparation method and application of an anti-pollution dense water separation net, wherein the disclosed method comprises the following steps: 1) preparing a solution A: dissolving polyazaheterocycle polycarboxylic acid in water to prepare a solution A with the mass concentration of 0.01-0.1%; 2) preparing a solution B: dissolving a cross-linking agent in water to prepare a solution with the mass concentration of 0.1-1%, and marking as a solution B; 3) mixing the solution A and the solution B according to a mass ratio of 1:1, regulating the pH value to 2-4, and immersing the concentrated water separation net into the mixed solution to obtain the anti-pollution concentrated water separation net. The selected polyazaheterocycle polycarboxylic acid structure has reactive amino and carboxyl, the polyazaheterocycle polycarboxylic acid structure is fixed on the surface of a concentrated water separation net through a cross-linking agent, hydrophilic anti-fouling carboxyl groups can be introduced, and a stable hydration layer is formed on the surface of the concentrated water separation net through the unique three-dimensional cage-shaped structure of the polyazaheterocycle polycarboxylic acid, so that the anti-fouling performance of the concentrated water separation net is greatly improved. However, the method disclosed by the method can only inhibit the adsorption of hydrophobic pollutants, and has poor anti-pollution performance on biological pollutants such as thalli.

CN113549272A discloses a durable hydrophilic polypropylene barrier net material and a preparation method thereof, the disclosed method combines a magnesium sulfate whisker stiffening modification technology with a hydrophilic substance slow-release traction technology, utilizes the self-polymerization capacity of dopamine to pull a hydrophilic agent to the surface of the material to form a uniform hydrophilic layer, and utilizes the slow-release and occlusion effects of sustained-release agents such as EAA sodium salt and the like to lock the hydrophilic substance, so that the barrier net material has good appearance, stiffness, solvent resistance and mechanical comprehensive performance, and also has permanent hydrophilic performance and durable anti-pollution performance. The method disclosed by the invention is simple, excellent in performance, obvious in effect and good in industrial application prospect, the prepared screen material has the advantages of good supporting and shunting effects, corrosion resistance, high-efficiency and durable pollution resistance and easiness in cleaning, the problem of fine particle adhesion can be greatly improved, the service efficiency and the service life of a fluid treatment part are greatly improved, and the screen material disclosed by the invention is suitable for the fluid treatment part which is in close contact with a hydrophilic fluid and needs the supporting and shunting effects. However, the disclosed separation net can not inhibit the formation of biological pollution, and meanwhile, the acting force between the surface of the high-hydrophilicity separation net and water molecules is strong, so that the pressure drop of the inlet and the outlet of the membrane component can be increased.

CN113480805A discloses a method for preparing an antibacterial screen, wherein silver ions or quaternary ammonium salt antibacterial agents are added in the preparation process of the disclosed screen, so that the antibacterial performance of the screen can be effectively improved. However, the disclosed separation net can weaken the activity of thalli, is extremely unfavorable for processes such as biological fermentation coupling membrane separation and the like, and meanwhile, the leaching of silver ions can cause the reduction of the antibacterial performance of the separation net.

Therefore, the development of the efficient and stable anti-pollution separation net on the feeding side has important significance for improving the anti-pollution performance of the separation net on organic and biological pollutants and reducing the pressure drop of the inlet and the outlet of the membrane component.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide an anti-pollution separation net and a preparation method and application thereof, wherein the anti-pollution separation net has good anti-pollution capacity on organic pollutants and biological pollutants, self-cleaning capacity of temperature response and fluid drag reduction function.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides an anti-pollution screen, comprising a screen and an anti-pollution polymer brush arranged on the surface of the screen;

the anti-pollution polymer brush comprises a temperature-sensitive hydrogel polymer brush and a fluorine-containing polymer brush grafted at the tail end of the temperature-sensitive hydrogel polymer brush;

the temperature-sensitive hydrogel polymer brush is in direct contact with the separation net.

According to the invention, through the special design of surface grafting of the double-polymer brush, the anti-pollution separation net is endowed with excellent anti-adsorption capacity on organic and biological pollutants, and the anti-pollution performance is remarkably improved; specifically, the temperature-sensitive hydrogel polymer brush directly connected with the surface of the original separation net has the performances of high-temperature structure shrinkage and low-temperature structure extension, and the temperature response type structural change is beneficial to reducing pollutant adsorption and promoting a pollution layer to be stripped from the surface of the separation net, so that the pollution resistance of the separation net is improved. Meanwhile, the fluorine-containing polymer brush can reduce the surface energy of the separation net, so that on one hand, the adsorption of organic and biological pollutants on the surface of the separation net can be inhibited, and on the other hand, the stripping effect of a pollution layer of the temperature-sensitive hydrogel polymer brush can be improved. In addition, due to the excellent hydrophobic and oleophobic performance of the fluorinated polymer brush, the shearing force between the surface of the anti-pollution separation net and the fluid is smaller, so that the anti-pollution separation net has higher interfacial slip velocity and lower fluid mass transfer resistance.

Preferably, the spacer mesh comprises a membrane module retentate side polymeric porous spacer mesh.

Preferably, the screen comprises any one of a planar screen, a woven screen or a screen with a three-dimensional structure or a combination of at least two of the above, wherein typical but non-limiting combinations include: a combination of a planar screen and a knitted screen, a combination of a knitted screen and a screen having a three-dimensional structure, a combination of a planar screen, a knitted screen and a screen having a three-dimensional structure, and the like.

Preferably, the shape of the holes of the screen comprises any one of a circle, a triangle or a quadrilateral or a combination of at least two of the same, wherein typical but non-limiting combinations comprise: a combination of a circle and a triangle, a combination of a triangle and a quadrangle, a combination of a circle, a triangle and a quadrangle, and the like.

Preferably, the surface of the three-dimensional separation net is provided with a wavy curved surface and/or a three-circumference curved surface.

In the present invention, the three-perimeter surface includes a minimum three-perimeter surface feature.

Preferably, the material of the mesh comprises any one or a combination of at least two of polyethylene, polypropylene or polyester, wherein a typical but non-limiting combination comprises: combinations of polyethylene and polypropylene, polypropylene and polyester, polyethylene, polypropylene and polyester, and the like.

Preferably, the raw material for preparing the temperature-sensitive hydrogel polymer brush comprises a temperature-sensitive monomer.

Preferably, the temperature sensitive monomer comprises any one of N-isopropylacrylamide, dimethylaminoethyl methacrylate, or ethylene glycol monomethyl ether methacrylate, or a combination of at least two thereof, wherein typical but non-limiting combinations include: a combination of N-isopropylacrylamide and dimethylaminoethyl methacrylate, a combination of dimethylaminoethyl methacrylate and ethylene glycol monomethyl ether methacrylate, a combination of N-isopropylacrylamide, dimethylaminoethyl methacrylate and ethylene glycol monomethyl ether methacrylate, and the like, with N-isopropylacrylamide being more preferred.

Preferably, the starting material for the fluoropolymer brush comprises a fluoromonomer.

Preferably, the fluoromonomer comprises any one of 2- (perfluorooctyl) ethyl methacrylate, dodecafluoroheptyl methacrylate, or perfluoroalkylethyl methacrylate, or a combination of at least two thereof, wherein typical but non-limiting combinations include: a combination of 2- (perfluorooctyl) ethyl methacrylate and dodecafluoroheptyl methacrylate, a combination of dodecafluoroheptyl methacrylate and perfluoroalkylethyl methacrylate, a combination of 2- (perfluorooctyl) ethyl methacrylate, dodecafluoroheptyl methacrylate and perfluoroalkylethyl methacrylate, and the like, and 2- (perfluorooctyl) ethyl methacrylate is more preferable.

In a second aspect, the present invention provides a method for preparing an anti-pollution partition net according to the first aspect, wherein the method for preparing the anti-pollution partition net comprises the following steps:

(1) grafting a temperature-sensitive monomer on the surface of the halogenated separation net to form a temperature-sensitive hydrogel polymer brush;

(2) and grafting a fluorine-containing monomer at the tail end of the temperature-sensitive hydrogel polymer brush to form a fluorine-containing polymer brush, thereby obtaining the anti-pollution separation net.

In the invention, the anti-pollution separation net is simple in preparation process, can be repeatedly used and has a huge application prospect.

Preferably, in step (1), the grafting method comprises:

mixing the halogenated separation net with a solution containing metal halide salt and ligand, a temperature-sensitive monomer and a reducing agent solution in sequence, and reacting in a closed space after deoxygenation to obtain the temperature-sensitive hydrogel polymer brush grafted on the surface of the separation net.

Preferably, the mass ratio of the temperature-sensitive monomer to the separation net is 1: (0.5-5), for example 1: 0.6, 1: 0.7, 1: 0.8, 1: 0.9, 1: 1. 1: 1.5, 1: 2. 1: 2.5, 1: 3. 1: 3.5, 1: 4. 1: 4.5, and the specific values therebetween, are not intended to be exhaustive or to limit the invention to the precise values encompassed by the scope, for reasons of brevity and clarity.

In the invention, the mass ratio of the temperature-sensitive monomer to the separation net is controlled to be 1: (0.5-5) range, because: too high a mass ratio of the two results in a reduced monomer conversion; the mass ratio of the two is too low, which causes the grafting amount of the polymer brush to be insufficient, and the temperature-sensitive performance of the polymer brush cannot be effectively exerted.

Preferably, the halogenated barrier comprises a brominated barrier.

Preferably, the metal halide salt comprises copper bromide.

Preferably, the ligand comprises any one of hexamethyltriethylenetetramine, pentamethyldiethylenetriamine or tris (2-dimethylaminoethyl) amine, or a combination of at least two thereof, wherein typical but non-limiting combinations include: hexamethyltriethylenetetramine and pentamethyldiethylenetriamine, pentamethyldiethylenetriamine and tris (2-dimethylaminoethyl) amine, hexamethyltriethylenetetramine, pentamethyldiethylenetriamine and tris (2-dimethylaminoethyl) amine, and the like.

Preferably, the metal halide salt is present in the solution comprising the metal halide salt and the ligand at a mass concentration of 1-10mg/L, such as 1.5mg/L, 2mg/L, 2.5mg/L, 3mg/L, 3.5mg/L, 4mg/L, 4.5mg/L, 5mg/L, 5.5mg/L, 6mg/L, 6.5mg/L, 7mg/L, 7.5mg/L, 8mg/L, 8.5mg/L, 9mg/L, 9.5mg/L, and specific values therebetween, for the sake of brevity and space, the invention is not further limited to the specific values included in the range.

Preferably, the mass concentration ratio of the ligand to the metal halide salt is (1-5):1, wherein 1-5 can be 2, 3, 4, etc.

Preferably, the reducing agent comprises any one of ascorbic acid, glucose or stannous chloride or a combination of at least two of them, with typical but non-limiting combinations including: a combination of ascorbic acid and glucose, a combination of glucose and stannous chloride, a combination of ascorbic acid, glucose and stannous chloride, and the like, with ascorbic acid being more preferred.

Preferably, the ascorbic acid has a mass concentration of 0.1-1.5g/L, such as 0.2g/L, 0.3g/L, 0.4g/L, 0.5g/L, 0.6g/L, 0.7g/L, 0.8g/L, 0.9g/L, 1g/L, 1.1g/L, 1.2g/L, 1.3g/L, 1.4g/L, and specific values therebetween, not to be construed as limiting the space and for brevity, the invention is not exhaustive of the specific values included in the recited ranges.

Preferably, the mixing of the halogenated barrier web with the reducing agent solution is carried out under a protective atmosphere.

In the present invention, the protective atmosphere comprises nitrogen.

Preferably, the means for removing oxygen comprises passing a protective gas.

In the present invention, the protective gas comprises nitrogen.

Preferably, the time for introducing the protective gas is 5-15min, such as 6min, 7min, 8min, 9min, 10min, 11min, 12min, 13min, 14min, etc., and the specific values therebetween are limited by space and for the sake of brevity, and the invention is not exhaustive of the specific values included in the range.

Preferably, the reaction temperature is in the range of 60 to 90 deg.C, such as 65 deg.C, 70 deg.C, 75 deg.C, 80 deg.C, 85 deg.C, and the like, and the specific values therebetween are not exhaustive for the invention and are included for brevity.

Preferably, the reaction time is 0.5 to 5h, such as 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, etc., and the specific values therebetween, are not exhaustive for the invention and are included for brevity.

Preferably, in step (1), the halogenated barrier net is prepared by a method comprising: activating the screen to form hydroxyl functional groups on the surface, and then performing halogenation treatment on the surface of the hydroxylated screen to obtain the halogenated screen.

Preferably, the activated solution comprises an ammonium sulfate solution.

Preferably, the activated solution has a mass concentration of 5% to 20%, such as 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, and specific points therebetween, which are not exhaustive for the invention and are included for brevity.

Preferably, the activation is carried out under a protective atmosphere.

Preferably, the temperature of the activation is 60-80 ℃, such as 62 ℃, 64 ℃, 66 ℃, 68 ℃, 70 ℃, 72 ℃, 74 ℃, 76 ℃, 78 ℃, 80 ℃, and the specific values therebetween, which are not exhaustive and included in the scope of the invention for brevity.

Preferably, the activation time is 1-2h, such as 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, and the specific values therebetween, which are not intended to be exhaustive and included in the scope of the invention for the sake of brevity.

Preferably, the halogenation treatment comprises: firstly, carrying out water removal treatment on an acid-binding agent and a halogen-containing compound, then mixing the hydroxylation separation net, the acid-binding agent and the halogen-containing compound in a protective atmosphere, and reacting to obtain the halogenated separation net.

Preferably, the acid scavenger comprises triethylamine.

Preferably, the halogen-containing compound comprises 2-bromoisobutyryl bromide.

Preferably, the mixing comprises: firstly, mixing an acid-binding agent solution and a hydroxylation separation net for the first time, and then mixing the mixture with a halogen-containing compound for the second time.

Preferably, the second mixing comprises: slowly dripping a halogen-containing compound into the solution of the acid-binding agent containing the hydroxylation separation net in a protective atmosphere and an ice-water bath environment to obtain a mixed solution.

Preferably, in the acid scavenger solution, the solvent comprises N, N-dimethylformamide.

Preferably, the molar concentration of the acid-binding agent and the halogen-containing compound in the mixed solution is independently 100-450mM, such as 150mM, 200mM, 250mM, 300mM, 350mM, 400mM, etc., and the specific values therebetween are limited by space and for brevity, the invention does not exhaustive list the specific values included in the range, and further preferably the molar concentrations are the same.

Preferably, the reaction temperature is in the range of 10 to 40 ℃, e.g., 15 ℃, 20 ℃, 25 ℃, 30 ℃, 35 ℃, etc., and the specific values therebetween, are not exhaustive for the invention and for the sake of brevity.

Preferably, the reaction time is 12-15h, such as 12.5h, 13h, 13.5h, 14h, 14.5h, etc., and specific values therebetween are not exhaustive for the invention and for brevity.

Preferably, in step (2), the grafting comprises: mixing the modified separation net with the temperature-sensitive hydrogel polymer brush on the surface with a solution containing metal halide salt and ligand, a fluorine-containing monomer and a reducing agent solution in sequence, and reacting in a closed space after deoxygenation to obtain the temperature-sensitive hydrogel polymer brush grafted on the surface of the separation net.

Preferably, the mass ratio of the fluorine-containing monomer to the screen is 1: (0.5-5), for example 1: 0.6, 1: 0.7, 1: 0.8, 1: 0.9, 1: 1. 1: 1.5, 1: 2. 1: 2.5, 1: 3. 1: 3.5, 1: 4. 1: 4.5, and the specific values therebetween, are not intended to be exhaustive or to limit the invention to the precise values encompassed by the scope, for reasons of brevity and clarity.

In the invention, the mass ratio of the fluorine-containing monomer to the screen is controlled to be 1: (0.5-5) range, because: too high a mass ratio of the two results in a decrease in monomer conversion; the mass ratio of the two components is too low, so that the grafting amount of the polymer brush is insufficient, and the anti-pollution performance of the polymer brush cannot be effectively exerted.

In the invention, the mass ratio of the fluorine-containing monomer to the temperature-sensitive monomer relative to the separation net is simultaneously controlled, and in the range, the grafting rate of the fluorine-containing monomer at the tail end of the temperature-sensitive hydrogel polymer brush can be ensured to be 1.7-1.8% (such as 1.72%, 1.74%, 1.76%, 1.78% and the like), so that the comprehensive performance of the anti-pollution separation net is further improved.

Preferably, the halogenated barrier comprises a brominated barrier.

Preferably, the metal halide salt comprises copper bromide.

Preferably, the reducing agent comprises any one of, or a combination of at least two of, ascorbic acid, glucose or stannous chloride, with typical but non-limiting combinations including: a combination of ascorbic acid and glucose, a combination of glucose and stannous chloride, a combination of ascorbic acid, glucose and stannous chloride, and the like, with ascorbic acid being more preferred.

Preferably, the means for removing oxygen comprises passing a protective gas.

As a preferred technical scheme, the preparation method comprises the following steps:

(1') mixing the screen with 5-20% by mass of ammonium persulfate aqueous solution, and reacting at 60-80 ℃ in a protective atmosphere for 1-2h to form hydroxyl functional groups on the surface of the screen to obtain a hydroxylated screen;

(2') carrying out water removal treatment on an acid-binding agent and a halogen-containing compound in advance, mixing a hydroxylation screen with an acid-binding agent solution containing 100-450mM, then mixing with a halogen-containing compound solution containing 100-450mM in a protective atmosphere and an ice water bath, and reacting for 12-15h at 10-40 ℃ to obtain a halogenated screen;

(3') mixing a halogenated partition net with a solution containing 1-10mg/L of metal halide salt and 1-5 times of ligand, and adding a mixture of the halogenated partition net and the solution with the mass ratio of 1: (0.5-5) adding 0.1-1.5g/L reducing agent solution into the temperature-sensitive monomer under protective atmosphere, sealing the container after the reactor is deaerated, and reacting for 0.5-5h at the temperature of 60-90 ℃ to obtain a modified separation net with a temperature-sensitive hydrogel polymer brush on the surface;

(4') mixing the modified separation net with the surface provided with the temperature-sensitive hydrogel polymer brush with a solution containing 1-10mg/L of metal halide salt and 1-5 times of ligand, and adding a mixture of the mixture and the separation net according to the mass ratio of 1: (0.5-5) adding 0.1-1.5g/L reducing agent solution into the fluorine-containing monomer under protective atmosphere, sealing the container after the reactor is deaerated, and reacting for 0.5-5h at the temperature of 60-90 ℃ to obtain the anti-pollution separation net with the temperature-sensitive hydrogel polymer brush and the fluorine-containing polymer brush on the surfaces.

In the present invention, the solvent in each solution includes any one or a combination of at least two of N, N-dimethylformamide, toluene or tetrahydrofuran, wherein typical but non-limiting combinations include: a combination of N, N-dimethylformamide and toluene, a combination of toluene and tetrahydrofuran, a combination of N, N-dimethylformamide, toluene and tetrahydrofuran, and the like, and N, N-dimethylformamide is more preferable.

Further, as a preferred technical scheme, the preparation method comprises the following steps:

(1') mixing the original screen with 5-20% ammonium persulfate aqueous solution, and reacting for 1-2h at 60-80 ℃ in nitrogen atmosphere to form hydroxyl functional groups on the surface of the original screen;

(2') carrying out water removal treatment on an acid-binding agent and a halogen-containing compound in advance, mixing a hydroxylation screen with an acid-binding agent solution containing 100-450mM, then mixing with a halogen-containing compound solution with the same concentration as the acid-binding agent in a protective atmosphere and an ice water bath, and reacting for 12-15h at 10-40 ℃ to obtain a bromination screen;

(3') mixing a brominated partition net with an N, N-dimethylformamide solution containing 1-10mg/L of copper bromide and 1-5 times of pentamethyldiethylenetriamine, and adding a mixture of the copper bromide and the N, N-dimethylformamide solution, wherein the mass ratio of the mixture to the partition net is 1: (0.5-5) adding 0.1-1.5g/L ascorbic acid N, N-dimethylformamide solution into N-isopropylacrylamide in a nitrogen atmosphere, deoxidizing the reactor, sealing the reactor, and reacting for 0.5-5h at the temperature of 60-90 ℃ to obtain a modified separation net with a poly-N-isopropylacrylamide temperature-sensitive polymer brush on the surface;

(4') mixing the modified separation net with the poly N-isopropylacrylamide temperature-sensitive polymer brush on the surface and an N, N-dimethylformamide solution containing 1-10mg/L of copper bromide and 1-5 times of pentamethyldiethylenetriamine, and adding the mixture into a stirring device, wherein the mass ratio of the mixture to the separation net is 1: and (0.5-5) adding 0.1-1.5g/L ascorbic acid N, N-dimethylformamide solution into 2- (perfluorooctyl) ethyl methacrylate in the nitrogen atmosphere, sealing the container after the reactor is deoxygenated, and reacting for 0.5-5h at the temperature of 60-90 ℃ to obtain the anti-pollution separation net with the temperature-sensitive polymer brush and the fluorinated polymer brush on the surface.

In a third aspect, the invention provides a liquid separation spiral wound membrane module, which comprises the anti-pollution separation net in the first aspect.

In the invention, the specific types of the liquid separation spiral-wound membrane module include, but are not limited to, a microfiltration membrane module, an ultrafiltration membrane module, a nanofiltration membrane module, a reverse osmosis membrane module, a forward osmosis membrane module, an electrodialysis membrane module, a pervaporation membrane module, a membrane distillation module and the like.

Compared with the prior art, the invention has the following beneficial effects:

(1) the temperature sensitive polymer brush in the anti-pollution separation net is expanded and promotes the stripping of pollutants when the temperature is reduced to be below the critical temperature, so that the anti-pollution separation net has stronger self-cleaning capability, meanwhile, the pressure difference of a side inlet and an outlet of a interception side is relatively lower after 12h pollution experiments, and in addition, the anti-pollution separation net is adopted for cross-flow membrane filtration, so that the pressure drop of a feed side is relatively lower.

(2) In a preferable range, the anti-pollution separation net has the bovine serum albumin pollution desorption efficiency of more than 41.05% at 25 ℃ and the bovine serum albumin pollution desorption efficiency of more than 33.85% at 40 ℃; the yeast pollution desorption efficiency of the anti-pollution separation net is above 56.79% at 25 ℃, and the yeast pollution desorption efficiency is above 45.35% at 40 ℃; the cross-flow pollution pressure difference of yeast liquid of the anti-pollution separation net is between 0.49 and 0.55bar, and in addition, the reduction percentage of the pressure drop of the feeding side of the anti-pollution separation net for cross-flow membrane filtration is more than 14 percent.

Drawings

FIG. 1 is a schematic view of the construction of an anti-contamination barrier as described in example 1;

wherein, 1-polypropylene separation net; 2-poly N-isopropylacrylamide temperature-sensitive polymer brush; 3-poly 2- (perfluorooctyl) ethyl methacrylate polymer brush;

FIG. 2a is a graph showing the resistance-reducing performance of the anti-fouling barrier net prepared in comparative example 1;

FIG. 2b is a graph showing the resistance-reducing performance of the anti-fouling barrier net prepared in comparative example 2;

FIG. 2c is a graph showing the resistance-reducing performance of the anti-fouling barrier net prepared in comparative example 3;

FIG. 2d is a plot showing the resistance-reducing performance of the anti-fouling barrier net prepared in comparative example 4;

FIG. 2e is a graph showing the resistance-reducing performance of the anti-fouling barrier net prepared in comparative example 5;

FIG. 2f is a graph showing the evaluation of the drag reduction performance of the anti-fouling barrier net prepared in example 1.

Detailed Description

For the purpose of facilitating an understanding of the present invention, the present invention will now be described by way of examples. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

Example 1

The embodiment provides an anti-pollution separation net, the structural schematic diagram of which is shown in fig. 1, wherein the anti-pollution separation net comprises a polypropylene separation net 1 and an anti-pollution polymer brush arranged on the surface of the separation net;

the anti-pollution polymer brush comprises a poly N-isopropyl acrylamide temperature-sensitive polymer brush 2 and a poly 2- (perfluorooctyl) ethyl methacrylate polymer brush 3 grafted to the tail end of the poly N-isopropyl acrylamide temperature-sensitive polymer brush;

the poly N-isopropyl acrylamide temperature-sensitive polymer brush is directly contacted with the separation net.

The anti-pollution separation net is prepared by the following method, and the method comprises the following steps:

(1) dissolving 7g of ammonium persulfate in 30mL of deionized water to prepare an ammonium persulfate solution with the concentration of 18.9%;

placing 0.2g of polypropylene separation net (taken from a brand-new roll-type membrane module and purchased from Ankusan Membrane separation technology engineering (Beijing) Co., Ltd.) in 30mL of ammonium persulfate solution, and reacting for 1h at the temperature of 60 ℃ to obtain the separation net with the surface provided with hydroxyl functional groups;

the solution of ammonium persulfate on the surface of the screen was eluted by shaking with deionized water at 200rpm for 30 min.

(2) Adding 1.7mL of anhydrous triethylamine which is dried by a molecular sieve into 30mL of anhydrous N, N-dimethylformamide to obtain 407mM triethylamine solution;

mixing the hydroxylation separation net with the solution under the nitrogen atmosphere; slowly dropwise adding 2-bromoisobutyryl bromide with equal molar amount into the solution in a nitrogen atmosphere and an ice-water bath environment to obtain a solution containing triethylamine and 2-bromoisobutyryl bromide;

reacting for 15h at 25 ℃, and then sequentially washing the separation net by using acetone and deionized water to obtain the separation net with the brominated surface.

(3) Adding 500mg of ascorbic acid into 25mL of N, N-dimethylformamide solution to obtain 20g/L ascorbic acid solution;

sequentially adding 40mg of copper bromide and 180 mu L of pentamethyl diethylenetriamine into the N, N-dimethylformamide solution, and oscillating until the copper bromide and the pentamethyl diethylenetriamine are uniformly mixed to obtain a solution containing the copper bromide and the pentamethyl diethylenetriamine;

adding 2mL of solution containing copper bromide and pentamethyldiethylenetriamine into 23mL of N, N-dimethylformamide solution, and adding a brominated spacer screen and 0.1g of N-isopropylacrylamide into the solution;

adding 5mL of ascorbic acid solution into the solution under the nitrogen atmosphere, introducing nitrogen into the reactor for 15min, and reacting for 1h at 90 ℃ to obtain the modified separation net with the surface provided with the poly N-isopropylacrylamide temperature-sensitive polymer brush.

(4) Adding 500mg of ascorbic acid into 25mL of N, N-dimethylformamide solution to obtain 20g/L ascorbic acid solution;

adding 2mL of solution containing copper bromide and pentamethyldiethylenetriamine into 23mL of N, N-dimethylformamide solution, and adding a brominated spacer screen and 0.1g of 2- (perfluorooctyl) ethyl methacrylate into the solution;

and adding 5mL of ascorbic acid solution into the solution under the nitrogen atmosphere, introducing nitrogen into the reactor for 15min, and reacting for 3h at 90 ℃ to obtain the anti-pollution separation net with the temperature-sensitive polymer brush and the fluorinated polymer brush on the surface.

Example 2

This example provides an anti-fouling barrier net, which is different from example 1 in that the poly-N-isopropylacrylamide temperature-sensitive polymer brush is a poly (dimethylaminoethyl methacrylate) brush; the preparation method differs from example 1 in that N-isopropylacrylamide in step (3) is replaced with an equimolar amount of dimethylaminoethyl methacrylate.

Example 3

This example provides an anti-fouling barrier net that differs from example 1 in that the poly N-isopropylacrylamide temperature-sensitive polymer brush is a polyethylene glycol monomethyl ether methacrylate brush; the preparation process differs from example 1 in that the N-isopropylacrylamide in step (3) is replaced by an equimolar amount of ethylene glycol monomethyl ether methacrylate.

Example 4

This example provides an anti-fouling barrier net that differs from example 1 in that the poly 2- (perfluorooctyl) ethyl methacrylate polymer brush is a poly dodecafluoroheptyl methacrylate brush; the preparation method differs from example 1 in that 2- (perfluorooctyl) ethyl methacrylate in step (4) is replaced with an equimolar amount of dodecafluoroheptyl methacrylate.

Example 5

This example provides an anti-fouling barrier net that differs from example 1 in that the poly 2- (perfluorooctyl) ethyl methacrylate polymer brushes are polyperfluoroalkylethyl methacrylate brushes; the preparation method differs from example 1 in that 2- (perfluorooctyl) ethyl methacrylate in step (4) is replaced with an equimolar amount of perfluoroalkylethyl methacrylate.

Example 6

This example is different from example 1 in that in step (3), N-isopropylacrylamide was added in an amount of 0.02g, respectively, in a mass ratio to the polypropylene spacer mesh of 1:10, and the rest was the same as in example 1.

Example 7

This example is different from example 1 in that in step (4), 2- (perfluorooctyl) ethyl methacrylate was added in an amount of 0.02g in a mass ratio to the polypropylene spacer net of 1:10, respectively, and the rest was the same as in example 1.

Example 8

The embodiment provides an anti-pollution separation net, which comprises a polypropylene separation net and an anti-pollution polymer brush arranged on the surface of the separation net;

the anti-pollution polymer brush comprises a poly N-isopropyl acrylamide temperature-sensitive polymer brush and a poly 2- (perfluorooctyl) ethyl methacrylate polymer brush grafted to the tail end of the poly N-isopropyl acrylamide temperature-sensitive polymer brush;

(1) dissolving 2g of ammonium persulfate in 30mL of deionized water to prepare a 5.4% ammonium persulfate solution;

reacting for 15h at 10 ℃, and then sequentially washing the separation net by using acetone and deionized water to obtain the separation net with the brominated surface.

Example 9

(2) Adding 0.1mL of anhydrous triethylamine which is dried by a molecular sieve into 30mL of anhydrous N, N-dimethylformamide to obtain a 23.94mM triethylamine solution;

mixing the hydroxylation separation net with the solution under the nitrogen atmosphere; slowly dropwise adding 1.51mL of 2-bromoisobutyryl bromide into the solution in a nitrogen atmosphere and an ice-water bath environment to obtain a solution containing 23.94mM of triethylamine and 407mM of 2-bromoisobutyryl bromide;

reacting for 15h at the temperature of 20 ℃, and then sequentially washing the separation net by using acetone and deionized water to obtain the separation net with the brominated surface.

Comparative example 1

The comparative example provides an anti-fouling screen that was an untreated polypropylene screen.

Comparative example 2

This comparative example provides an anti-contamination barrier net, which is prepared by a method different from that of example 1 in that step (2) is not carried out and step (3) is carried out directly after step (1) is finished; and no bromine is on the surface of the separation net, so that no polymer brush is generated on the surface of the separation net finally.

Comparative example 3

This comparative example provides an anti-pollution barrier net, which is prepared by a method different from that of example 1 in that no reducing agent ascorbic acid is added in step (3); namely, the copper bromide can not be reduced into the cuprous bromide with reactivity to participate in the reaction, and finally, no polymer brush is generated on the surface of the separation net.

Comparative example 4

This comparative example provides an anti-contamination barrier net, which was prepared by a method different from that of example 1 in that the operation of step (4) was not performed; the resulting anti-fouling barrier web was free of fluorinated polymer brushes on its surface.

Comparative example 5

This comparative example provides an anti-contamination barrier net, which was prepared by a method different from that of example 1 in that the operation of step (3) was not performed; the finally obtained anti-pollution separation net is not grafted with a temperature-sensitive polymer brush.

Performance testing

The anti-pollution barrier nets described in examples 1-9 and comparative examples 1-5 were tested as follows:

(1) pollution desorption efficiency: adsorption capacity to 10g/L bovine serum albumin and 30g/L yeast at 40 ℃; and then standing in deionized water at different temperatures for 15min, and evaluating the self-cleaning desorption performance of the anti-pollution separation net.

(2) The pressure difference of the interception side inlet and the interception side outlet of the membrane module changes: after testing that each anti-pollution separation net filters 30g/L yeast fermentation liquid for 12h in a cross flow manner, the pressure difference between the intercepted side inlet and the intercepted outlet of the membrane component changes.

(3) The resistance reducing performance is as follows: and (3) testing the resistance reduction performance of the anti-pollution separation net in a cross flow mode by using deionized water as a feeding liquid.

The test results are summarized in table 1 and fig. 2.

TABLE 1

The data in the analysis table 1 show that the anti-pollution separation net has the bovine serum albumin pollution desorption efficiency of more than 15.11% at 25 ℃ and the bovine serum albumin pollution desorption efficiency of more than 13.59% at 40 ℃; the anti-pollution separation net has the yeast pollution desorption efficiency of more than 14.24% at 25 ℃ and the yeast pollution desorption efficiency of more than 11.64% at 40 ℃; the cross-flow pollution pressure difference of the yeast liquid of the anti-pollution separation net is between 0.49 and 0.67 bar. The temperature-sensitive polymer brush in the anti-pollution separation net is expanded and promotes the stripping of pollutants when the temperature is reduced to be below the critical temperature, so that the anti-pollution separation net has stronger self-cleaning capability, and meanwhile, after 12h pollution experiments, the pressure difference between the interception side inlet and the interception side outlet is relatively lower.

In a further preferred embodiment 1-5 range, the anti-pollution separation net has a bovine serum albumin pollution desorption efficiency of 41.05% or more at 25 ℃ and a bovine serum albumin pollution desorption efficiency of 33.85% or more at 40 ℃; the yeast pollution desorption efficiency of the anti-pollution separation net is above 56.79% at 25 ℃, and the yeast pollution desorption efficiency is above 45.35% at 40 ℃; the cross-flow pollution pressure difference of the yeast liquid of the anti-pollution separation net is between 0.49 and 0.55 bar. The thermosensitive polymer brush in the anti-pollution separation net has the advantages that when the temperature is reduced to be below the critical temperature, the structure is expanded, the stripping of pollutants is promoted, the self-cleaning capability is stronger, and meanwhile, after 12h pollution experiments are carried out on the anti-pollution separation net, the pressure difference between the intercepted side inlet and the intercepted side outlet is relatively lower.

Examples 6-7 had lower resistance to organic and biological contamination than examples 1-5 due to the lower concentration of the reactive monomer. The temperature-sensitive polymer brush of the anti-pollution separation net in the embodiment 6 has a low grafting amount, so that when the temperature is reduced to be below the critical temperature, the structure change of the temperature-sensitive polymer brush is not obvious, and the pollutant can not be effectively stripped. The anti-fouling barrier network described in example 7 had lower levels of fluorinated polymer brush grafts and thus had poorer anti-fouling and drag-reducing properties.

Example 8 the lower concentration of ammonium persulfate in water, i.e., the lower mass fraction of activated solution, used in step (1) resulted in a decrease in the degree of hydroxylation of the surface of the polypropylene spacer, resulting in a decrease in subsequent spacer bromination and in the amount of polymer brush grafts. The anti-organic and anti-biological pollution performance of the anti-pollution separation net is lower than that of the anti-organic and anti-biological pollution performance of the anti-pollution separation net in examples 1-5.

In example 9, the acid-binding agent triethylamine used in step (2) has a low concentration, which results in that the acidic byproduct hydrogen bromide generated by the reaction of 2-bromoisobutyryl bromide and hydroxyl groups cannot be removed in time, so that product inhibition is formed, and the bromination degree of the separation net is inhibited. The anti-organic and anti-biological pollution performance of the anti-pollution separation net is lower than that of the anti-organic and anti-biological pollution performance of the anti-pollution separation net in examples 1-5.

Compared with the polypropylene separation net in the comparative example 1, the anti-pollution separation net prepared in the examples 1 to 5 has stronger organic and biological pollution resistance, higher pollutant desorption efficiency and smaller pressure difference. The anti-pollution performance and the self-cleaning performance of the polypropylene separation net are weak, while the anti-pollution separation net prepared in the embodiment 1-5 is strong in self-cleaning performance, and the amount of adsorbed pollutants in the filtering process is small, so that the pressure drop is low. The composite has certain anti-pollution effect on organic pollutants, bacteria and other microorganisms, the adsorption quantity of the organic pollutants and the biological pollutants can be reduced by more than 85%, the desorption efficiency is obviously increased, and for example, the desorption efficiency of the yeast pollution in example 1 is increased from 1.38% to 65.21% in comparative example 1.

Compared with the anti-pollution separation nets in the comparative examples 2-3, the anti-pollution separation net prepared in the example 1 has stronger organic and biological pollution resistance, higher pollutant desorption efficiency and smaller pressure difference. The subsequent reaction can not be carried out due to no halogenation (bromination) or addition of a reducing agent ascorbic acid, and the polymer brush grafting is not carried out on the surface of the separation net, so that the anti-pollution and self-cleaning performance of the separation net is not remarkably improved.

Compared with the comparative example 4, the anti-pollution separation net prepared in the example 1 has the advantages that the pollutant desorption efficiency is improved obviously, and the pressure difference is smaller, so that the fluorinated polymer brush is a main factor for improving the anti-pollution and self-cleaning performance of the separation net compared with the temperature-sensitive polymer brush.

Although the fluorinated polymer brush part grafted on the surface of the comparative example 5 improves the anti-pollution performance of the separation net, the pressure difference of the separation net after cross-flow pollution of the yeast liquid is smaller than that of the comparative examples 1-4, but still higher than that of the examples 1-5. Meanwhile, compared with the comparative example 5, the anti-pollution separation net prepared in the example 1 has a more obvious improvement on the pollutant desorption efficiency at a low temperature (25 ℃), which shows that the self-cleaning performance of the separation net is further and obviously improved after the temperature-sensitive polymer brush is introduced.

The anti-drag performance of the anti-pollution separation net prepared in example 1 and comparative examples 1-5 was tested in a cross-flow mode using deionized water as a feed liquid, and the results are shown in fig. 2 a-2 f. Since the fluorinated polymer brushes were not grafted in any of comparative examples 1 to 4, the pressure drop on the feed side did not change much. In contrast, comparative example 5 and example 1 both have fluorinated polymer brushes, and therefore the transmembrane pressure difference is reduced compared to comparative examples 1-4, with the transmembrane pressure difference of example 1 being reduced by a minimum of 14%.

The applicant states that the present invention is illustrated by the above examples to show the detailed method of the present invention, but the present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be carried out. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims

1. An anti-pollution separation net is characterized in that the anti-pollution separation net comprises a separation net and anti-pollution polymer brushes arranged on the surface of the separation net;

2. The anti-contamination barrier web of claim 1 wherein the barrier web comprises a membrane module retentate side polymeric porous barrier web;

preferably, the separation net comprises any one of a plane separation net, a woven separation net or a separation net with a three-dimensional structure or a combination of at least two of the plane separation net, the woven separation net and the separation net;

preferably, the shape of the holes of the separation net comprises any one or a combination of at least two of a circle, a triangle or a quadrangle;

preferably, the surface of the separation net with the three-dimensional structure is provided with a wavy curved surface and/or a three-circumference curved surface;

preferably, the material of the separation net comprises any one or a combination of at least two of polyethylene, polypropylene or polyester.

3. The anti-pollution barrier net according to claim 1 or 2, wherein the temperature-sensitive hydrogel polymer brush is prepared from a temperature-sensitive monomer;

preferably, the temperature-sensitive monomer comprises any one of N-isopropylacrylamide, dimethylaminoethyl methacrylate or ethylene glycol monomethyl ether methacrylate or a combination of at least two of the N-isopropylacrylamide and the dimethylaminoethyl methacrylate;

preferably, the fluoropolymer brush is prepared from raw materials including a fluoromonomer;

preferably, the fluorine-containing monomer comprises any one of 2- (perfluorooctyl) ethyl methacrylate, dodecafluoroheptyl methacrylate or perfluoroalkylethyl methacrylate or a combination of at least two thereof.

4. A method of making an anti-pollution barrier web according to any of claims 1 to 3, comprising the steps of:

5. The method according to claim 4, wherein in the step (1), the grafting method comprises:

mixing a halogenated separation net with a solution containing metal halide salt and a ligand, a temperature-sensitive monomer and a reducing agent solution in sequence, and reacting in a closed space after deoxygenation to obtain a temperature-sensitive hydrogel polymer brush grafted on the surface of the separation net;

preferably, the mass ratio of the temperature-sensitive monomer to the separation net is 1: (0.5-5);

preferably, the halogenated barrier comprises a brominated barrier;

preferably, the metal halide salt comprises copper bromide;

preferably, the ligand comprises any one of hexamethyltriethylenetetramine, pentamethyldiethylenetriamine or tris (2-dimethylaminoethyl) amine or a combination of at least two of hexamethyltriethylenetetramine, pentamethyldiethylenetriamine or tris (2-dimethylaminoethyl) amine;

preferably, in the solution containing the metal halide salt and the ligand, the mass concentration of the metal halide salt is 1-10 mg/L;

preferably, the mass concentration ratio of the ligand to the metal halide salt is (1-5): 1;

preferably, the reducing agent comprises any one or a combination of at least two of ascorbic acid, glucose or stannous chloride;

preferably, the mass concentration of the ascorbic acid is 0.1-1.5 g/L;

preferably, the mixing of the halogenated barrier web with a solution of a reducing agent is carried out under a protective atmosphere;

preferably, the means for removing oxygen comprises passing a protective gas;

preferably, the time for introducing the protective gas is 5-15 min;

preferably, the temperature of the reaction is 60-90 ℃;

preferably, the reaction time is 0.5 to 5 hours.

6. The production method according to claim 4 or 5, wherein in the step (1), the halogenated partition net is produced by a method comprising: activating the screen to form a hydroxyl functional group on the surface, and then performing halogenation treatment on the surface of the hydroxylated screen to obtain a halogenated screen;

preferably, the activated solution comprises an ammonium sulfate solution;

preferably, the mass concentration of the activated solution is 5% -20%;

preferably, the activation is carried out under a protective atmosphere;

preferably, the temperature of the activation is 60-80 ℃;

preferably, the activation time is 1-2 h.

7. The method according to claim 6, wherein the halogenation treatment comprises: firstly, carrying out water removal treatment on an acid-binding agent and a halogen-containing compound, then mixing a hydroxylation separation net, the acid-binding agent and the halogen-containing compound in a protective atmosphere, and reacting to obtain the halogenated separation net;

preferably, the acid scavenger comprises triethylamine;

preferably, the halogen-containing compound comprises 2-bromoisobutyryl bromide;

preferably, the mixing comprises: firstly, mixing an acid-binding agent solution and a hydroxylation separation net for the first time, and then mixing the mixture with a halogen-containing compound for the second time;

preferably, the second mixing comprises: slowly dropwise adding a halogen-containing compound into an acid-binding agent solution containing a hydroxylation separation net in a protective atmosphere and an ice-water bath environment to obtain a mixed solution;

preferably, in the acid scavenger solution, the solvent comprises N, N-dimethylformamide;

preferably, the molar concentrations of the acid-binding agent and the halogen-containing compound in the mixed solution are respectively 100-450 mM;

preferably, the temperature of the reaction is 10-40 ℃;

preferably, the reaction time is 12-15 h.

8. The production method according to any one of claims 4 to 7, wherein in the step (2), the grafting comprises: mixing the modified separation net with the temperature-sensitive hydrogel polymer brush on the surface with a solution containing metal halide salt and ligand, a fluorine-containing monomer and a reducing agent solution in sequence, and reacting in a closed space after deoxygenation to obtain the temperature-sensitive hydrogel polymer brush grafted on the surface of the separation net;

preferably, the mass ratio of the fluorine-containing monomer to the screen is 1: (0.5-5);