CN114874488B

CN114874488B - Anti-pollution separation net and preparation method and application thereof

Info

Publication number: CN114874488B
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: 2023-05-23
Anticipated expiration: 2042-05-27
Also published as: CN114874488A

Abstract

The invention relates to an anti-pollution barrier net, a preparation method and application thereof, wherein the anti-pollution barrier net comprises a barrier net and an anti-pollution polymer brush arranged on the surface of the barrier 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 barrier web. The anti-pollution barrier provided by the invention has good anti-pollution capability for organic pollutants and biological pollutants, and self-cleaning capability of temperature response, and has a fluid drag reduction function. The anti-pollution separation net has simple preparation process and can be repeatedly used, and has great application prospect in the preparation of a coiled membrane assembly.

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 membrane materials with separation selectivity as cores. The separation membrane can realize the purposes of separating, concentrating, purifying and the like materials by taking pressure, concentration difference, vapor pressure difference and the like as driving forces. The membrane component is used as a core of membrane technology and mainly has a plate frame type, a tubular type, a hollow fiber type and a coiled type 4 structure. Industrial mass separation membranes often take the form of roll membranes assembled due to higher packing density and lower cost. The main components of the coiled membrane component comprise a interception side and a permeation side separation net, a separation membrane, a permeation side flow channel, a component shell, a sealing component and the like. As a green and efficient separation technology, membrane technology has been widely used in various fields such as drinking water purification, wastewater treatment, food and pharmaceutical processing, and the like.

However, the feed liquid processed by the membrane technology has complex components, and organic matters, thalli and fermentation metabolites contained in the feed liquid can be adsorbed on the surface of a feed side separation net or a membrane, so that serious membrane pollution is formed, and the membrane flux and separation selectivity are reduced. Taking a commercial polypropylene (PP) as an example, bacteria tend to adhere to their surfaces and form biofilms during long-term membrane separation. Wherein bacteria are highly susceptible to growth at the junction of the feed side spacer and the membrane, and severe bio-contamination is formed resulting in loss of feed side pressure (feed channel pressure drop, FCP) and transmembrane pressure differential (transmembrane pressure, TMP).

CN113041841a discloses a preparation method and application of an anti-pollution concentrated water screen, the disclosed method comprises the following steps: 1) Preparing a solution A: dissolving polyazacyclo 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 the solution as a solution B; 3) The solution A and the solution B are mixed according to the mass ratio of 1:1, mixing, regulating the pH value to 2-4, immersing the concentrated water screen into the mixed solution, and treating to obtain the anti-pollution concentrated water screen. The selected polyazacyclic polycarboxylic acid structure has reactive amino and carboxyl, hydrophilic and anti-fouling carboxyl groups can be introduced into the surface of the concentrated water isolation net through the fixation of the polyazacyclic polycarboxylic acid structure by a cross-linking agent, and a stable hydration layer is formed on the surface of the concentrated water isolation net through the unique three-dimensional cage-shaped structure of the polyazacyclic polycarboxylic acid, so that the anti-fouling property of the concentrated water isolation net is greatly improved. However, the disclosed method can only inhibit the adsorption of hydrophobic pollutants, and has poor anti-pollution performance on biological pollutants such as thalli and the like.

CN113549272a discloses a durable hydrophilic polypropylene separation net material and a preparation method, the disclosed method combines a magnesium sulfate whisker stiffening modification technology with a hydrophilic substance slow release traction technology, utilizes self-polymerization capability of dopamine to drag a hydrophilic agent to the surface of the material to form a uniform hydrophilic layer, and utilizes slow release and confinement effects of slow release agents such as EAA sodium salt and the like to lock the hydrophilic substance, so that the separation net material has good appearance, stiffness, solvent resistance, mechanical comprehensive performance, permanent hydrophilic performance and durable anti-pollution performance. The method is simple, excellent in performance and obvious in effect, has good industrial application prospect, and the prepared barrier material has the advantages of good supporting and shunting effects, corrosion resistance, high efficiency, lasting anti-pollution performance and easiness in cleaning, can greatly improve the adhesion problem of fine particles, greatly improves the service efficiency and service life of a fluid treatment component, and is suitable for the fluid treatment component which needs to be closely contacted with hydrophilic fluid and has the functions of isolating and supporting and shunting. However, the disclosed barrier net cannot inhibit the formation of biological pollution, and meanwhile, the acting force between the surface of the high-hydrophilicity barrier net and water molecules is strong, so that the pressure drop of the inlet and the outlet of the membrane assembly can be increased.

CN113480805a discloses a preparation method of an antibacterial barrier net, and silver ions or quaternary ammonium salt antibacterial agents are added in the preparation process of the disclosed barrier net, so that the antibacterial performance of the barrier net can be effectively improved. However, the disclosed barrier net weakens the activity of the bacterial cells, is extremely unfavorable for processes such as separation of a biological fermentation coupling membrane, and meanwhile, silver ion leaching can cause the reduction of the antibacterial performance of the barrier net.

Therefore, the high-efficiency and stable feed side anti-pollution separation net is developed, is used for improving the anti-pollution performance of the separation net on organic and biological pollutants and reducing the pressure drop of inlet and outlet of the membrane component, and has important significance.

Disclosure of Invention

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

To achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides an anti-fouling screen comprising a screen and an anti-fouling polymer brush disposed on a 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 barrier web.

According to the invention, through the special design of surface grafting of the double polymer brushes, the anti-pollution barrier is endowed with excellent anti-adsorption capability 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 separator mesh has the performances of high-temperature structure shrinkage and low-temperature structure stretching, and the temperature-responsive structure change is beneficial to reducing pollutant adsorption and promoting the separation of a pollution layer from the separator mesh, so that the pollution resistance 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 pollution layer stripping effect of the temperature-sensitive hydrogel polymer brush can be improved. In addition, due to the excellent amphiphobic property 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 fluorinated polymer brush has higher interface sliding speed and lower fluid mass transfer resistance.

Preferably, the barrier comprises a membrane module rejection side polymeric porous barrier.

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

Preferably, the aperture shape of the spacer mesh comprises any one or a combination of at least two of a circle, triangle or quadrilateral, wherein typical but non-limiting combinations include: a combination of circles and triangles, a combination of triangles and quadrilaterals, a combination of circles, triangles and quadrilaterals, and the like.

Preferably, the surface of the partition net with the three-dimensional structure is provided with a wavy curved surface and/or a three-circumferential curved surface.

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

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

Preferably, the temperature-sensitive hydrogel polymer brush is prepared from a temperature-sensitive monomer.

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

Preferably, the fluoropolymer brush is prepared from a material comprising a fluoromonomer.

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

In a second aspect, the present invention provides a method for preparing the anti-pollution barrier according to the first aspect, the method comprising the steps of:

(1) Grafting a temperature-sensitive monomer on the halogenated screen surface to form a temperature-sensitive hydrogel polymer brush;

(2) And grafting fluorine-containing monomers at the tail end of the temperature-sensitive hydrogel polymer brush to form the fluorine-containing polymer brush, thereby obtaining the anti-pollution barrier net.

In the invention, the anti-pollution separation net has simple preparation process, can be reused and has huge application prospect.

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

and mixing the halogenated barrier net with a solution containing metal halogen salt and ligand, a temperature-sensitive monomer and a reducing agent solution in sequence, deoxidizing, and reacting in a closed space to obtain the temperature-sensitive hydrogel polymer brush grafted on the surface of the barrier 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 specific point values between the above point values, are limited in space and for brevity, the present invention is not intended to exhaustively list the specific point values included in the range.

In the invention, the mass ratio of the temperature-sensitive monomer to the separation net is controlled to be 1: (0.5-5) because: too high a mass ratio of the two results in a reduced monomer conversion; the mass ratio of the two is too low, so that the graft quantity of the polymer brush is insufficient, and the temperature sensitivity 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 or a combination of at least two of hexamethyltriethylenetetramine, pentamethyldiethylenetriamine or tris (2-dimethylaminoethyl) amine, wherein typical but non-limiting combinations include: a combination of hexamethyltriethylenetetramine and pentamethyldiethylenetriamine, a combination of pentamethyldiethylenetriamine and tris (2-dimethylaminoethyl) amine, a combination of hexamethyltriethyltriethylenetetramine, pentamethyldiethylenetriamine and tris (2-dimethylaminoethyl) amine, and the like.

Preferably, the mass concentration of the metal halide salt in the solution containing the metal halide salt and the ligand is 1-10mg/L, for example, 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 point values between the above point values are limited in length and for the sake of brevity, the present invention does not exhaustively list the specific point 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 or a combination of at least two of ascorbic acid, glucose or stannous chloride, wherein typical but non-limiting combinations include: 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, further preferably ascorbic acid.

Preferably, the ascorbic acid is present in 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 point values between the above point values, are limited to a spread and for brevity, the invention is not intended to be exhaustive of the specific point values comprised in the range.

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

In the present invention, the protective atmosphere comprises nitrogen.

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

In the present invention, the protective gas includes nitrogen.

Preferably, the time for passing the protective gas is 5-15min, such as 6min, 7min, 8min, 9min, 10min, 11min, 12min, 13min, 14min, etc., and specific point values among the above point values, which are limited in space and for brevity, the present invention is not exhaustive.

Preferably, the temperature of the reaction is 60-90 ℃, such as 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, etc., and specific point values between the above point values, are limited in space and for the sake of brevity, the present invention is not exhaustive of the specific point values included in the range.

Preferably, the reaction is carried out for a period of time ranging from 0.5 to 5 hours, such as 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, etc., and specific point values between the above point values, are limited in space and for the sake of brevity, the present invention is not exhaustive of the specific point values included in the range.

Preferably, in step (1), the method for preparing the halogenated spacer comprises: activating the barrier net to form hydroxyl functional groups on the surface, and then carrying out halogenation treatment on the surface of the hydroxylation barrier net to obtain the halogenated barrier net.

Preferably, the activated solution comprises an ammonium sulfate solution.

Preferably, the activated solution has a mass concentration of 5% -20%, such as 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% and specific point values between the above point values, for the sake of brevity and for the sake of brevity, the invention is not intended to be exhaustive of the specific point values comprised in the range.

Preferably, the activation is performed under a protective atmosphere.

Preferably, the activation temperature is 60-80 ℃, such as 62 ℃, 64 ℃, 66 ℃, 68 ℃, 70 ℃, 72 ℃, 74 ℃, 76 ℃, 78 ℃, 80 ℃, and specific point values between the above, the present invention is not exhaustive of the specific point values included in the range for reasons of space and for reasons of simplicity.

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 specific point values between the above point values, are limited in length and for brevity, the invention is not intended to be exhaustive of the specific point values included in the range.

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

Preferably, the acid binding agent comprises triethylamine.

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

Preferably, the mixing comprises: the acid binding agent solution and the hydroxylated spacer are mixed for the first time and then mixed with the halogen-containing compound for the second time.

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

Preferably, the solvent in the solution of the acid-binding agent comprises N, N-dimethylformamide.

Preferably, the molar concentrations of the acid-binding agent and the halogen-containing compound in the mixture are each independently from 100 to 450mM, e.g., 150mM, 200mM, 250mM, 300mM, 350mM, 400mM, etc., and specific point values between the above point values, are limited in space and for the sake of brevity, the present invention is not exhaustive of the specific point values included in the ranges, and more preferably the molar concentrations of both are the same.

Preferably, the temperature of the reaction is 10-40 ℃, such as 15 ℃, 20 ℃, 25 ℃, 30 ℃, 35 ℃, etc., and specific point values between the above point values, are limited in space and for the sake of brevity, the present invention is not exhaustive of the specific point values included in the range.

Preferably, the reaction is carried out for a period of time ranging from 12 to 15 hours, such as 12.5 hours, 13 hours, 13.5 hours, 14 hours, 14.5 hours, etc., and specific point values between the above point values, are limited in space and for the sake of brevity, the present invention is not exhaustive of the specific point values encompassed by the range.

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

Preferably, the mass ratio of the fluorine-containing monomer to the barrier 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 specific point values between the above point values, are limited in space and for brevity, the present invention is not intended to exhaustively list the specific point values included in the range.

In the invention, the mass ratio of the fluorine-containing monomer to the barrier net is controlled to be 1: (0.5-5) because: too high a mass ratio of the two results in a reduced monomer conversion; the quality ratio of the two is too low, so that the graft quantity 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 barrier net is controlled simultaneously, 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% (for example, 1.72%, 1.74%, 1.76%, 1.78%, and the like), so that the comprehensive performance of the anti-pollution barrier net is further improved.

Preferably, the halogenated barrier comprises a brominated barrier.

Preferably, the metal halide salt comprises copper bromide.

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

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

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

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

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

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

In the present invention, the solvent in each solution comprises 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, N-dimethylformamide is further preferred.

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

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

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

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

(4') mixing a modified barrier net with a poly N-isopropyl acrylamide temperature-sensitive polymer brush on the surface with an N, N-dimethylformamide solution containing 1-10 mg/L copper bromide and 1-5 times pentamethyl diethylenetriamine, and adding the mixture into the solution according to the mass ratio of 1: (0.5-5) of 2- (perfluorooctyl) ethyl methacrylate, adding 0.1-1.5 g/L of ascorbic acid N, N-dimethylformamide solution under nitrogen atmosphere, deoxidizing the reactor, sealing the container, and reacting for 0.5-5 h at 60-90 ℃ to obtain the anti-pollution barrier with the temperature-sensitive polymer brush and the fluorinated polymer brush on the surface.

In a third aspect, the present invention provides a liquid separation roll membrane assembly comprising the anti-fouling barrier of the first aspect.

In the present invention, specific types of the liquid separation roll-type 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 reduced to below a critical temperature, the structure is unfolded, the stripping of pollutants is promoted, the anti-pollution separation net has stronger self-cleaning capability, meanwhile, after 12h pollution experiments, the pressure difference of the interception side outlet is relatively low, and in addition, the cross-flow membrane filtration by adopting the anti-pollution separation net has lower pressure drop of the feeding side.

(2) In a preferred range, the anti-pollution separation net has the bovine serum albumin pollution desorption efficiency of more than 41.05 percent at 25 ℃ and the bovine serum albumin pollution desorption efficiency of more than 33.85 percent at 40 ℃; the anti-pollution separation net has the saccharomycete pollution desorption efficiency of above 56.79 percent at 25 ℃ and the saccharomycete pollution desorption efficiency of above 45.35 percent at 40 ℃; the pressure difference of the cross-flow pollution of the saccharomycete 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 cross-flow membrane filtration by adopting the anti-pollution separation net is more than 14 percent.

Drawings

FIG. 1 is a schematic view of the anti-fouling screen according to embodiment 1;

wherein, 1-polypropylene screen; 2-poly N-isopropyl acrylamide temperature-sensitive polymer brush; 3-poly 2- (perfluorooctyl) ethyl methacrylate polymer brush;

FIG. 2a is a graph of drag reduction performance evaluation of an anti-fouling barrier prepared in comparative example 1;

FIG. 2b is a graph of drag reduction performance evaluation of the anti-fouling barrier prepared in comparative example 2;

FIG. 2c is a graph of drag reduction performance evaluation of the anti-fouling barrier prepared in comparative example 3;

FIG. 2d is a graph of drag reduction performance evaluation of the anti-fouling barrier prepared in comparative example 4;

FIG. 2e is a graph of drag reduction performance evaluation of the anti-fouling barrier prepared in comparative example 5;

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

Detailed Description

To facilitate understanding of the present invention, examples are set forth below. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.

Example 1

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

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 at the tail end of the poly N-isopropyl acrylamide temperature-sensitive polymer brush;

the poly N-isopropyl acrylamide temperature-sensitive polymer brush is in direct contact with the separation net.

The anti-pollution barrier is prepared by a method comprising the steps of:

(1) 7g of ammonium persulfate is dissolved in 30mL of deionized water to prepare 18.9% ammonium persulfate solution;

placing 0.2g of polypropylene separation net (from brand new roll membrane component, purchased from Andeyia membrane separation technology engineering (Beijing)) into 30mL of ammonium persulfate solution, and reacting for 1h at 60 ℃ to obtain the separation net with hydroxyl functional groups on the surface;

deionized water was used to shake at 200rpm for 30min to elute the ammonium persulfate solution at the screen surface.

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

mixing the hydroxylation barrier net with the solution under the nitrogen atmosphere; slowly dropwise adding 2-bromo-isobutyryl bromide with an equimolar amount into the solution in a nitrogen atmosphere and an ice-water bath environment to obtain a solution containing triethylamine and 2-bromo-isobutyryl bromide;

The reaction was carried out at 25℃for 15h, followed by washing the spacer with acetone and deionized water in sequence to give a surface brominated spacer.

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

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

2mL of a solution containing copper bromide and pentamethyldiethylenetriamine was added to 23mL of an N, N-dimethylformamide solution, and a brominated spacer and 0.1g of N-isopropylacrylamide were added to the solution;

under the nitrogen atmosphere, 5mL of ascorbic acid solution is added into the solution, the reactor is subjected to nitrogen introducing treatment for 15min, and the reaction is carried out for 1h at 90 ℃ to obtain the modified barrier net with the poly N-isopropyl acrylamide temperature-sensitive polymer brush on the surface.

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

2mL of a solution containing copper bromide and pentamethyldiethylenetriamine was added to 23mL of an N, N-dimethylformamide solution, and a brominated spacer and 0.1g of 2- (perfluorooctyl) ethyl methacrylate were added to the solution;

under the nitrogen atmosphere, 5mL of ascorbic acid solution is added into the solution, the reactor is subjected to nitrogen introducing treatment for 15min, and the reaction is carried out for 3h at 90 ℃ to obtain the anti-pollution barrier with the temperature-sensitive polymer brush and the fluorinated polymer brush on the surface.

Example 2

The present example provides an anti-pollution barrier, which is different from example 1 in that the poly N-isopropyl acrylamide temperature-sensitive polymer brush is a poly dimethylaminoethyl methacrylate brush; the process differs from example 1 in that the N-isopropylacrylamide in step (3) is replaced with an equimolar amount of dimethylaminoethyl methacrylate.

Example 3

The embodiment provides an anti-pollution barrier, which is different from embodiment 1 in that the poly N-isopropyl acrylamide temperature-sensitive polymer brush is a polyethylene glycol monomethyl ether methacrylate brush; the process differs from example 1 in that the N-isopropylacrylamide in step (3) is replaced with an equimolar amount of ethylene glycol monomethyl ether methacrylate.

Example 4

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

Example 6

The difference between this example and example 1 is that in step (3), the amount of N-isopropylacrylamide added was 0.02g, the mass ratio of the N-isopropylacrylamide to the polypropylene separator was 1:10, and the remainder was the same as in example 1.

Example 7

This example differs from example 1 in that in step (4), the amount of 2- (perfluorooctyl) ethyl methacrylate added was 0.02g, the mass ratio to the polypropylene separator was 1:10, respectively, and the remainder was the same as in example 1.

Example 8

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

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 at the tail end of the poly N-isopropyl acrylamide temperature-sensitive polymer brush;

The anti-pollution barrier is prepared by a method comprising the steps of:

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

the reaction was carried out at 10℃for 15h, after which the screen was washed with acetone and deionized water in sequence to give a surface brominated screen.

Example 9

The anti-pollution barrier is prepared by a method comprising the steps of:

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

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

the reaction was carried out at 20℃for 15h, after which the screen was washed with acetone and deionized water in sequence to give a surface brominated screen.

Comparative example 1

This comparative example provides an anti-fouling barrier that is an untreated polypropylene barrier.

Comparative example 2

The comparative example provides an anti-pollution barrier, the preparation method of which is different from that of the example 1 in that the operation of the step (2) is not performed, and the step (3) is directly performed after the step (1) is finished; as the surface of the barrier net is free of bromine, no polymer brush is generated on the surface of the barrier net finally.

Comparative example 3

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

Comparative example 4

The present comparative example provides an anti-pollution barrier, the manufacturing method of which is different from example 1 in that the operation of step (4) is not performed; the resulting antipollution spacer surface was free of fluorinated polymer brushes.

Comparative example 5

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

Performance testing

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

(1) Pollution desorption efficiency: an adsorption amount of 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 barrier.

(2) Pressure difference change of the intercepting side and the intercepting side of the membrane component: after testing each anti-pollution barrier net cross-flow filtration for 30g/L saccharomycete fermentation liquor for 12 hours, the pressure difference of the interception side and the outlet of the membrane component changes.

(3) Drag reduction performance: deionized water is used as a feed liquid, and the drag reduction performance of the anti-pollution barrier is tested in a cross-flow mode.

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

TABLE 1

As can be seen from the analysis of the data in Table 1, the anti-pollution separation net has the bovine serum albumin pollution desorption efficiency of more than 15.11% at 25 ℃ and more than 13.59% at 40 ℃; the anti-pollution separation net has the saccharomycete pollution desorption efficiency of more than 14.24 percent at 25 ℃ and the saccharomycete pollution desorption efficiency of more than 11.64 percent at 40 ℃; the pressure difference of the cross-flow pollution of the saccharomycete 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 reduced to below a critical temperature, the structure is stretched, the stripping of pollutants is promoted, the anti-pollution separation net has stronger self-cleaning capability, and meanwhile, after 12h pollution experiments, the pressure difference of the interception side inlet and the interception side outlet is relatively low.

Further preferred embodiments 1 to 5 are those wherein the anti-pollution barrier has a bovine serum albumin pollution desorption efficiency of 41.05% or more at 25 ℃ and 33.85% or more at 40 ℃; the anti-pollution separation net has the saccharomycete pollution desorption efficiency of above 56.79 percent at 25 ℃ and the saccharomycete pollution desorption efficiency of above 45.35 percent at 40 ℃; the pressure difference of the cross-flow pollution of the saccharomycete liquid of the anti-pollution separation net is between 0.49 and 0.55 bar. The temperature-sensitive polymer brush in the anti-pollution separation net is reduced to below a critical temperature, the structure is stretched, the stripping of pollutants is promoted, the anti-pollution separation net has stronger self-cleaning capability, and meanwhile, after 12h pollution experiments, the pressure difference of the interception side inlet and the interception side outlet is relatively low.

Examples 6-7 have lower organic and biological contamination resistance than examples 1-5 due to the lower concentration of the reactive monomer. The temperature-sensitive polymer brush of the anti-pollution barrier in the embodiment 6 has low grafting amount, so that the temperature-sensitive polymer brush structure is not remarkably changed when the temperature is reduced below the critical temperature, and the pollutant stripping cannot be effectively promoted. The fluorinated polymer of the anti-fouling barrier of example 7 has a lower brush graft and thus has poor anti-fouling and drag reducing properties.

Example 8 the aqueous ammonium persulfate solution used in step (1) was of lower concentration, i.e., the mass fraction of the activated solution was lower, resulting in a decrease in the degree of hydroxylation of the polypropylene screen surface, resulting in a decrease in both the subsequent screen bromination and polymer brush grafting. The anti-organic, biological contamination barrier is lower than in examples 1-5.

Example 9 the acid binding agent triethylamine used in step (2) has a low concentration, so that the acidic byproduct hydrogen bromide generated by the reaction of 2-bromo isobutyryl bromide and hydroxyl cannot be removed in time, and the product inhibition is formed, so that the bromination degree of the barrier net is inhibited. The anti-organic, biological contamination barrier is lower than in examples 1-5.

Compared with the polypropylene separation net in the comparative example 1, the anti-pollution separation nets prepared in the examples 1 to 5 have stronger organic and biological pollution resistance, higher pollutant desorption efficiency and smaller pressure difference. The polypropylene separating net has weaker anti-pollution performance and self-cleaning performance, while the anti-pollution separating nets prepared in the examples 1 to 5 have stronger self-cleaning performance, and have lower pressure drop because of less pollutant adsorption in the filtering process. The adsorption capacity of organic and biological pollutants can be reduced by more than 85%, the desorption efficiency is obviously increased, and for example, the saccharomycete pollution desorption efficiency of the embodiment 1 is increased from 1.38% of the comparative example 1 to 65.21%.

Compared with the anti-pollution barrier of comparative examples 2-3, the anti-pollution barrier prepared in example 1 has stronger organic and biological pollution resistance, higher pollutant desorption efficiency and smaller pressure difference. The method shows that the subsequent reaction can not be carried out due to the fact that halogenation (bromination) is not carried out or the reducing agent ascorbic acid is not added, and polymer brush grafting is not carried out on the surface of the barrier net, so that the anti-pollution and self-cleaning performances of the barrier net are not remarkably improved.

The anti-fouling barrier prepared in example 1 has a more pronounced improvement in contaminant desorption efficiency and a smaller pressure differential than comparative example 4, indicating that the fluorinated polymer brush is a major factor in improving the barrier's anti-fouling and self-cleaning properties compared to the temperature sensitive polymer brush.

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

The anti-fouling barrier prepared in example 1 and comparative examples 1-5 were tested for drag reduction in cross-flow mode using deionized water as the feed solution, and the results are shown in fig. 2 a-2 f. Since none of comparative examples 1 to 4 was grafted with the fluorinated polymer brush, the pressure drop on the feed side was not changed much. While comparative example 5 and example 1 each had a fluorinated polymer brush, and thus the transmembrane pressure differential was reduced compared to comparative examples 1-4, with the lowest reduction in transmembrane pressure differential of example 1 being 14%.

The applicant states that the detailed method of the present invention is illustrated by the above examples, but the present invention is not limited to the detailed method described above, i.e. it does not mean that the present invention must be practiced in dependence upon the detailed method described above. It should be apparent to those skilled in the art that any modification of the present invention, equivalent substitution of raw materials for the product of the present invention, addition of auxiliary components, selection of specific modes, etc., falls within the scope of the present invention and the scope of disclosure.

Claims

1. An anti-pollution barrier, characterized in that the anti-pollution barrier comprises a barrier and an anti-pollution polymer brush arranged on the surface of the barrier;

2. The anti-fouling barrier of claim 1, wherein the barrier comprises a membrane module rejection side polymeric porous barrier.

3. The anti-fouling screen of claim 1, wherein the screen comprises any one or a combination of at least two of a planar screen, a woven screen, or a screen with a three-dimensional structure.

4. The anti-fouling barrier of claim 1, wherein the pore shape of the barrier comprises any one or a combination of at least two of a circle, triangle, or quadrilateral.

5. The anti-fouling screen of claim 3, wherein the surface of the screen having a three-dimensional structure is provided with a wavy curved surface and/or a three-week curved surface.

6. The anti-fouling barrier of claim 1, wherein the barrier material comprises any one or a combination of at least two of polyethylene, polypropylene, or polyester.

7. The anti-fouling barrier of claim 1, wherein the temperature sensitive hydrogel polymer brush is prepared from a material comprising a temperature sensitive monomer.

8. The anti-fouling barrier of claim 7, wherein the temperature sensitive monomer comprises any one or a combination of at least two of N-isopropyl acrylamide, dimethylaminoethyl methacrylate, or ethylene glycol monomethyl ether methacrylate.

9. The anti-fouling barrier of claim 1, wherein the fluoropolymer brush is prepared from a feedstock comprising a fluoromonomer.

10. The anti-fouling barrier of claim 9, wherein the fluoromonomer comprises any one or a combination of at least two of 2- (perfluorooctyl) ethyl methacrylate, dodecafluoroheptyl methacrylate, or perfluoroalkyl ethyl methacrylate.

11. A method of making an anti-fouling barrier according to any one of claims 1 to 10, comprising the steps of:

12. The method of claim 11, wherein in step (1), the method of grafting comprises:

13. The method of claim 12, wherein the mass ratio of the temperature-sensitive monomer to the spacer is 1: (0.5-5).

14. The method of making according to claim 12, wherein the halogenated barrier comprises a brominated barrier.

15. The method of claim 12, wherein the metal halide salt comprises copper bromide.

16. The method of claim 12, wherein the ligand comprises any one or a combination of at least two of hexamethyltriethylenetetramine, pentamethyldiethylenetriamine, or tris (2-dimethylaminoethyl) amine.

17. The method of claim 12, wherein the mass concentration of the metal halide salt in the solution containing the metal halide salt and the ligand is 1-10mg/L.

18. The method according to claim 17, wherein the mass concentration ratio of the ligand to the metal halide salt is (1-5): 1.

19. The method of claim 12, wherein the reducing agent comprises any one or a combination of at least two of ascorbic acid, glucose, or stannous chloride.

20. The method according to claim 19, wherein the ascorbic acid has a mass concentration of 0.1 to 1.5g/L.

21. The method of claim 12, wherein the mixing of the halogenated spacer with the reducing agent solution is performed under a protective atmosphere.

22. The method of claim 12, wherein the means for scavenging oxygen comprises passing a protective gas.

23. The method of claim 22, wherein the protective gas is passed for a period of 5 to 15 minutes.

24. The method of claim 12, wherein the temperature of the reaction is 60-90 ℃.

25. The method of claim 12, wherein the reaction time is 0.5 to 5 hours.

26. The method of claim 11, wherein in step (1), the halogenated spacer is prepared by a method comprising: activating the barrier net to form hydroxyl functional groups on the surface, and then carrying out halogenation treatment on the surface of the hydroxylation barrier net to obtain the halogenated barrier net.

27. The method of preparing according to claim 26, wherein the activated solution comprises an ammonium sulfate solution.

28. The method of claim 26, wherein the activated solution has a mass concentration of 5% to 20%.

29. The method of claim 26, wherein the activating is performed under a protective atmosphere.

30. The method of claim 26, wherein the activation temperature is 60-80 ℃.

31. The method of claim 26, wherein the time of activation is 1-2 hours.

32. The method of claim 26, wherein the halogenating treatment comprises: firstly, carrying out water removal treatment on an acid binding agent and a halogen-containing compound, and then, mixing and reacting the hydroxylation barrier net, the acid binding agent and the halogen-containing compound in a protective atmosphere to obtain the halogenated barrier net.

33. The method of claim 32, wherein the acid-binding agent comprises triethylamine.

34. The method of preparing as claimed in claim 32, wherein the halogen-containing compound comprises 2-bromoisobutyryl bromide.

35. The method of preparing according to claim 32, wherein the mixing comprises: the acid binding agent solution and the hydroxylated spacer are mixed for the first time and then mixed with the halogen-containing compound for the second time.

36. The method of preparing according to claim 35, wherein the second mixing comprises: slowly dropwise adding a halogen-containing compound into an acid binding agent solution containing a hydroxylation barrier net in a protective atmosphere and an ice water bath environment to obtain a mixed solution.

37. The method of claim 36, wherein the solvent comprises N, N-dimethylformamide in the solution of the acid-binding agent.

38. The method according to claim 36, wherein the molar concentrations of the acid-binding agent and the halogen-containing compound in the mixed solution are each independently 100 to 450mM.

39. The method of claim 32, wherein the temperature of the reaction is 10-40 ℃.

40. The method of claim 32, wherein the reaction time is 12-15 hours.

41. The method of claim 11, wherein in step (2), the grafting comprises: and mixing the modified barrier net with the temperature-sensitive hydrogel polymer brush on the surface with a solution containing metal halogen salt and ligand, a fluorine-containing monomer and a reducing agent solution in sequence, deoxidizing, and reacting in a closed space to obtain the temperature-sensitive hydrogel polymer brush grafted on the surface of the barrier net.

42. The method of claim 40, wherein the mass ratio of fluoromonomer to spacer is 1: (0.5-5).

43. The method of making according to claim 11, wherein the halogenated barrier comprises a brominated barrier.

44. The method of claim 41, wherein the metal halide salt comprises copper bromide.

45. The method of claim 41, wherein the ligand comprises any one or a combination of at least two of hexamethyltriethylenetetramine, pentamethyldiethylenetriamine or tris (2-dimethylaminoethyl) amine.

46. The process of claim 41, wherein the mass concentration of the metal halide salt in the solution containing the metal halide salt and the ligand is 1-10mg/L.

47. The process of claim 46, wherein the mass concentration ratio of ligand to metal halide salt is (1-5): 1.

48. The method of claim 47, wherein the reducing agent comprises any one or a combination of at least two of ascorbic acid, glucose, or stannous chloride.

49. The process according to claim 48, wherein the ascorbic acid has a mass concentration of 0.1 to 1.5g/L.

50. The process of claim 41 wherein the mixing of the halogenated spacer with the reducing agent solution is performed under a protective atmosphere.

51. The method of claim 50, wherein the means for scavenging oxygen comprises passing a protective gas.

52. The method of claim 51, wherein the time for passing the protective gas is 5-15 minutes.

53. The process of claim 40 wherein the temperature of the reaction is 60-90 ℃.

54. The process of claim 40 wherein the reaction time is from 0.5 to 5 hours.

55. The preparation method according to claim 11, characterized in that the preparation method comprises the steps of:

56. A liquid separation roll-to-roll membrane assembly comprising the anti-fouling barrier of any one of claims 1-10.