CN108568221B - Negatively charged chlorine-containing polymer-based composite membrane based on interlayer covalent interaction enhancement and preparation method thereof - Google Patents

Negatively charged chlorine-containing polymer-based composite membrane based on interlayer covalent interaction enhancement and preparation method thereof Download PDF

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CN108568221B
CN108568221B CN201810191903.0A CN201810191903A CN108568221B CN 108568221 B CN108568221 B CN 108568221B CN 201810191903 A CN201810191903 A CN 201810191903A CN 108568221 B CN108568221 B CN 108568221B
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membrane
negatively charged
chlorine
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containing polymer
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CN108568221A (en
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朱宝库
赵斌
王纳川
肖玲
王俊
陈良刚
陈清
陈忱
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Hainan Lisheng Water Purification Technology Industrial Co ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/30—Polyalkenyl halides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/14—Ultrafiltration; Microfiltration
    • B01D61/145—Ultrafiltration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/14—Ultrafiltration; Microfiltration
    • B01D61/147—Microfiltration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D63/00—Apparatus in general for separation processes using semi-permeable membranes
    • B01D63/02—Hollow fibre modules
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D63/00—Apparatus in general for separation processes using semi-permeable membranes
    • B01D63/08—Flat membrane modules
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • B01D67/0006—Organic membrane manufacture by chemical reactions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12—Composite membranes; Ultra-thin membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/08—Polysaccharides
    • B01D71/10—Cellulose; Modified cellulose
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/30—Polyalkenyl halides
    • B01D71/32—Polyalkenyl halides containing fluorine atoms
    • B01D71/34—Polyvinylidene fluoride
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/40—Polymers of unsaturated acids or derivatives thereof, e.g. salts, amides, imides, nitriles, anhydrides, esters
    • B01D71/42—Polymers of nitriles, e.g. polyacrylonitrile
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/48—Polyesters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/56—Polyamides, e.g. polyester-amides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/14—Membrane materials having negatively charged functional groups

Abstract

The invention discloses a negatively charged chlorine-containing polymer matrix composite film enhanced based on interlayer covalent interaction and a preparation method thereof. The negatively charged chlorine-containing polymer matrix composite membrane consists of a support layer and a functional layer, wherein the support layer is a polyester fiber-containing reinforced layer, the functional layer consists of a chlorine-containing polymer and a negatively charged polymer, and the support layer and the functional layer are combined under the action of a covalent bond. The preparation method comprises the following steps: blending and dissolving a chlorine-containing polymer and a negatively charged polymer to prepare a membrane-making solution; taking a solution of an amine compound and a catalyst as a modifier to carry out heat treatment modification on the polymer fiber of the supporting layer; coating the membrane-making solution on the surface of the polymer fiber, and then, curing the membrane-making solution in a coagulating bath to form a membrane; and (3) carrying out heat treatment on the prepared composite membrane again, and cleaning to obtain the negative charge type chlorine-containing polymer matrix composite membrane enhanced based on the interlayer covalent interaction. The flux of the composite membrane reaches 660L/h.m 2 under 0.1MPa, the operation peel strength reaches 1MPa, and the composite membrane has good hydrophilicity and contamination resistance.

Description

Negatively charged chlorine-containing polymer-based composite membrane based on interlayer covalent interaction enhancement and preparation method thereof
Technical Field
The invention belongs to the technical field of membrane separation, and particularly relates to a negatively charged chlorine-containing polymer matrix composite membrane enhanced based on interlayer covalent interaction and a preparation method thereof.
Background
The membrane separation technology is a novel separation technology, and the separation membrane material can realize the functions of separating, grading, purifying or enriching bi-component or multi-component liquid or gas by taking external energy or chemical potential difference as a driving force, and has incomparable advantages compared with the traditional technology. The membrane separation technology is widely applied in the field of water treatment, and mainly comprises sewage purification, water purification, seawater desalination and the like.
Among a plurality of potential polymer membrane materials, the chlorine-containing polymer has the advantages of excellent acid and alkali resistance and chemical corrosion resistance, better comprehensive mechanical property and electrical insulation property, flame retardance, weather resistance and the like, and has great application potential in the field of normal-temperature membrane separation such as ultrafiltration, microfiltration and the like in China. Among them, polyvinyl chloride is inexpensive, about 1/20 of PVDF, and thus has received great attention, and a mature film product has been introduced into the market.
In order to solve the problem of low strength of a homogeneous membrane product of PVC, a composite supporting layer is usually adopted for reinforcement at present, so that the strength of the membrane can be obviously improved. Patents US 4061821 and US 5472607 disclose a method for preparing a PAN hollow fiber membrane and a PVDF hollow fiber membrane, respectively, having a braided tube as an inner layer, so that the mechanical properties of the membranes are significantly improved. Patent CN 103949166a also describes a preparation method of an internal pressure hollow fiber composite membrane, in which the outer layer is a braided tube, the inner layer is coated with membrane-making liquid, and the central pipeline is introduced with the inner core liquid for phase inversion membrane-forming. In addition, the technology of preparing a hollow fiber composite membrane (CN 102160967A) by double-layer coating, preparing the hollow fiber composite membrane (CN 101543731A) by synchronously coating membrane-making liquid after weaving fibers into a tube on a spinning die head, preparing the membrane-making liquid on the inner side and the outer side of the weaving tube, preparing a separation membrane layer (CN 1864828A) by a phase inversion method and the like is also provided. However, the technology of preparing the separation membrane layer by coating the surface of the braided tube inevitably causes the problems of poor bonding performance between the support layer and the separation membrane layer of the product, falling off, peeling off, poor backwashing resistance and the like in the use process.
Because of the characteristics of solvent resistance, high strength and the like of the polyester system, the polyester system is widely applied to a supporting layer of a film material at present. In order to solve the problem of poor bonding property of the supporting layer and the separation film layer, the common method at present is to pretreat the polyester supporting layer so as to improve the bonding property between the composite film supporting layer and the functional layer. CN 102553463A firstly soaks the braided tube in boiled alkali liquor to remove oil stains, and then the braided tube is soaked in a modified solution to be modified, so that a supporting layer and a coating layer of a product are not easy to separate, and the backwashing resistance of the membrane is obviously improved; CN102512990A uses normal pressure plasma to process the hollow braided rope when preparing polyvinylidene fluoride hollow fiber coating film, improving the interface wettability and hydrogen bond adhesive force between the braided rope and the polyvinylidene fluoride material of the skin layer; CN102784566A prepares a heterogeneous reinforced polyvinylidene fluoride hollow fiber membrane with high adhesive strength by the technologies of pretreatment of braided tubes, pre-coating of polyvinylidene fluoride solution and the like. In addition, CN2103691327A improves the penetration degree of the membrane-forming liquid in the supporting tube, and increases the contact area between the membrane-forming liquid and the supporting tube, so as to improve the bonding effect between the two.
In summary, none of the prior art modifications to the braided tube involve a chemical reaction between the support layer and the functional layer. In contrast, the specific surface area of polyester fibers is much smaller than that of polyester powder, and accordingly, it is difficult to improve the degree of modification of polyester fibers. In addition, in the composite film, the polyester fiber plays a role of a supporting layer, so that the supporting layer has strength requirements, the modification conditions are not well mastered, a large number of molecular chains of the polyester are easy to break, the required strength is lost, and the performance of the composite film is damaged. The polyester has good stability, so that the polyester cannot react with common raw materials of the functional layer. The modification of polyester fiber in the prior art basically realizes the purpose of improving the interlayer bonding force by improving the compatibility of the polyester surface and the functional layer, and the generated new functional groups have lower reactivity and can not generate chemical reaction with the common raw materials of the functional layer, so that the covalent bond is difficult to form between the supporting layer and the functional layer. Therefore, the composite film product prepared by the technology has an interface between the supporting layer and the functional layer which is only bonded by physical action, and the physical action is likely to gradually lose efficacy in long-term practical application. The problem of adhesion between the layers of the composite film cannot be fundamentally solved.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a negatively charged chlorine-containing polymer matrix composite film based on interlayer covalent interaction enhancement.
The technical scheme adopted by the invention is as follows:
a negatively charged chlorine-containing polymer matrix composite film based on interlayer covalent interaction enhancement is characterized in that: the composite membrane is composed of a supporting layer and a functional layer, wherein the supporting layer is a polyester fiber-containing reinforcing layer, the functional layer is composed of a chlorine-containing polymer and a negatively charged polymer, the mass percentage of the negatively charged polymer in the functional layer is 10-50%, the supporting layer and the functional layer are combined through a covalent bond, the surface of the composite membrane is provided with carboxyl or sulfonic acid groups, the composite membrane is negatively charged, the covalent bond is a C-O bond and a C-N bond, and the composite membrane is a negatively charged microfiltration membrane or an ultrafiltration membrane.
Further, the interlayer covalent interaction is realized by carrying out amination modification on the support layer to form an active group, and carrying out chemical reaction with the active group of the negatively charged polymer to form a C-O and C-N covalent bond, wherein the amination modification reaction degree is 1-5%. The amination modification degree refers to the proportion of the amination reaction of the polyester.
Further, the composite membrane is any one of a flat membrane and a hollow fiber membrane.
Further, the reinforced layer containing polyester fibers is selected from any one of polyester fibers, cotton/polyester blended fibers, polyester/cellulose blended fibers, polyester/polyamide blended fibers, polyester/polyurethane blended fibers and polyester/polyacrylonitrile blended fibers.
Further, the chlorine-containing polymer is selected from any one or more of polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), Chlorinated Polyethylene (CPE), chlorinated polyvinyl chloride (CPVC), vinyl chloride-vinylidene chloride copolymer (P (VC-VDC)), vinyl chloride-vinyl acetate copolymer (LC), polychloroprene (CR) and chlorinated polypropylene (CPP).
Further, the negatively charged polymer is a polymer containing carboxylic acid groups and sulfonic acid groups, preferably, the negatively charged polymer is selected from methyl methacrylate-methacrylic acid copolymer (P (MMA-MAA)), acrylic acid-acrylonitrile copolymer (P (AA-AN)), acrylic acid-hydroxypropyl acrylate copolymer (P (AA-HPA)), acrylic acid-acrylamide copolymer (P (AA-AM)), vinyl alcohol-acrylic acid copolymer (P (VA-AA)), sulfonic acid group modified polyvinyl alcohol (sulfonated PVA), acrylic acid-styrene sulfonic acid copolymer (P (AA-SSA)), maleic acid-styrene sulfonic acid copolymer (P (MA-SSA)), acrylic acid-sodium allylsulfonate copolymer (P (AA-SAS)), and the like, Any one or more of acrylic acid- (2-acrylamide-2-methyl propane sulfonic acid) copolymer (P (AA-AMPS)) and acrylic acid-methyl acrylate- (2-acrylamide-2-methyl propane sulfonic acid) terpolymer (P (AA-MA-AMPS)).
The invention also provides a preparation method of the negatively charged chlorine-containing polymer matrix composite film based on interlayer covalent interaction enhancement, which comprises the following steps:
(1) blending and dissolving a chlorine-containing polymer and a negatively charged polymer to prepare a membrane-making solution;
(2) preparing a supporting layer modifier;
(3) firstly, the supporting layer enters a modifier and is subjected to first heat treatment, so that the polyester fiber is subjected to amination reaction under the action of the modifier to generate polyester macromolecules with one end being hydroxyl or primary amino;
(4) coating a membrane-making liquid on the outer surface of the modified supporting layer obtained in the step (3), and performing phase inversion and solidification to form a membrane through immersion precipitation;
(5) and (3) placing the membrane obtained in the step (4) in a saturated water vapor environment for secondary heat treatment, enabling polyester macromolecules with one end of hydroxyl or primary amino in the supporting layer to react with carboxyl in the negatively charged polymer in the functional layer under the action of a modifier to form C-O and C-N covalent bonds, and then cleaning the membrane to obtain the supported chlorine-containing polymer matrix composite membrane with high adhesive force.
Further, the mass percentage of the negatively charged polymer in the membrane-forming solution is 1-10%.
Further, the modifier is a solution containing an amine compound and a catalyst, the solvent of the solution is water or a mixture of water and ethanol, the mass percentage of the amine compound is 5% -40%, the mass percentage of the catalyst is 0.01% -1%, the mass percentage of the solvent in the modifier is 59% -94.99%, and the mass percentage of the ethanol in the mixture of water and ethanol is 10% -30%.
Further, the amine compound is an amine monomer containing a primary amine group, and is selected from any one or any more of methylamine, ethylamine, ethanolamine, ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polyethylenepolyamine, p-phenylenediamine, and m-phenylenediamine.
Further, the catalyst is selected from one or more of aluminum chloride, ferric chloride, titanium tetrachloride and boron trifluoride.
Further, the amination modification reaction degree is 1-5%.
Further, the temperature of the first heat treatment in the step (3) is 50-200 ℃, and the heat treatment time is 0.1-10 minutes.
Further, the temperature of the second heat treatment in the step (5) is 50-90 ℃, and the heat treatment time is 1-24 hours.
Different from the prior art, the negatively charged chlorine-containing polymer matrix composite membrane provided by the invention has the characteristics of high flux, good flux stability, excellent interception and anti-pollution performance, good mechanical property and the like without influencing the original characteristics of the composite membrane, and improves the stripping resistance and the anti-pollution performance of the membrane. The combination of all layers in the membrane is very stable, so that the membrane has stable comprehensive performance, long service life and backwashing resistance in the use process. Meanwhile, the membrane is charged negatively, and based on the charge repulsion effect, the composite membrane has better selectivity on certain charged pollutants, thereby widening the application range of membrane products.
In the existing reinforced composite membrane technology, methods for improving the binding capacity between a fiber support layer and a functional coating generally include: 1. carrying out chemical treatment on the supporting layer by normal pressure plasma, alkali liquor and the like, so that the interface performance of the supporting layer is similar to that of the coating, and the bonding performance of the supporting layer is improved; 2. the surface of the support layer is pre-coated with dilute coating solution or a substance with better compatibility with the film material so as to improve the similarity of the support layer and the coating and further improve the caking property; 3. the adhesion is improved by improving the mutual interpenetration between the support layer and the coating. In the above method, an interface based on physical adhesion, either physical coating or physical entanglement, inevitably occurs between the support layer and the coating layer, and the stability is not as good as that of establishing a strong covalent bond between the support layer and the coating layer. Through the supporting layer and the coating layer which are combined by covalent bonds, the cohesive force between the supporting layer and the coating layer can be effectively improved, so that the membrane has higher bursting strength and stronger backwashing resistance, and the service life is greatly prolonged.
The improvement of the adhesive force among the layers of the chlorine-containing polymer-based reinforced composite membrane is mainly based on the enhancement of the chemical action among the layers, namely strong molecular-level covalent bond combination is established between the support layer and the functional coating layer. Firstly, the chemical structure of the polyester fiber is changed by pretreating the polymer fiber supporting layer, and active groups such as hydroxyl groups and amino groups are introduced on the surface. The invention strictly limits the mass percentage of amine compounds, the mass percentage of catalysts, and the temperature and time of the first heat treatment in the modifier, so as to control the amination modification reaction degree to 1-5%. Meanwhile, negative charge type polymers with active groups are mixed in the membrane preparation liquid. Therefore, in the process of film formation and post treatment of the composite film, active groups introduced on the supporting layer react with active groups of the negatively charged polymer to form covalent bonds, so that the interlayer adhesive force is improved. Meanwhile, in order to further improve the interlayer adhesive force, a certain cross-linking agent can be added into the membrane-making solution, so that an intermolecular interpenetrating network can be formed between the layers while ensuring and promoting the interlayer chemical reaction, thereby further improving the adhesive force.
The chlorine-containing polymer-based composite membrane consists of a supporting layer and a functional layer, wherein the functional layer consists of a chlorine-containing polymer and a negatively charged polymer. The negatively charged polymer is a polymer which has good compatibility with chlorine-containing polymers and has certain hydrophilicity. The negatively charged polymer has reactive active groups and simultaneously has carboxylic acid or sulfonic acid groups, and can endow a film with negative charge after the film is formed. Therefore, the chlorine-containing polymer matrix composite membrane has charge repulsion besides a pore size sieve in the separation process, so that the composite membrane has some special adsorption and separation characteristics, has better interception performance on certain charged pollutants, has obvious removal effect on protein, humic acid and the like in water, and the pollution resistance of the membrane is obviously improved.
The performance of each functional layer of the composite membrane is realized and stabilized, and the C-O and C-N covalent bonds are formed mainly on the basis of the reaction of active groups of a fiber supporting layer and active groups of a negatively charged polymer (figure 1), so that on one hand, the bonding strength between the supporting layer and the functional layers can be effectively improved, and simultaneously, the stability of the negatively charged polymer in the membrane is promoted, and the membrane is endowed with full charge. Specifically, the method comprises the following steps:
(1) studies have shown that polyester fibers (PET) can undergo amination reactions with primary amines under heated conditions. Based on the reaction, the invention takes the solution of amine monomer containing primary amine group as modifier, and can make the fiber generate amination reaction to generate PET containing active groups such as terminal hydroxyl, amino and the like in the first heat treatment process of the polyester fiber of the supporting layer under the action of catalyst. (FIG. 1-1)
The technical key point of the invention is to strictly control the amination reaction degree of PET. The invention realizes the control of the PET reaction degree by strictly limiting the mass percentage of the amine compound in the modifier to be 5-40%, the mass percentage of the catalyst to be 0.01-1%, the first heat treatment temperature to be 50-200 ℃, and the heat treatment time to be 0.1-10 minutes, and realizes the amination reaction degree of the PET to be 1-5%.
Because the amination reaction of the PET fibers is accompanied by the cleavage of the molecular chain. If the reaction degree is too high, the broken PET molecular chains are too much, so that the strength of the supporting layer is greatly reduced, and the functional layer cannot be supported; if the reaction degree is too low, the generated active groups such as terminal hydroxyl, amino and the like are less, the support layer can not provide enough active groups to react with the negative charge polymer in the functional layer to generate covalent bonds, the binding force is not enhanced, and the stripping resistance of the film can not be improved.
(2) The negatively charged polymer adopted by the invention has carboxylic acid and sulfonic acid groups besides reactive active groups. The presence of carboxyl and sulfonic acid groups imparts a negative charge to the membrane. And carboxyl and the like have reactive groups, so that the negatively charged polymer in the membrane making liquid can react with the modified PET, and a strong covalent bond connection is established between the support layer and the functional layer. For example, hydroxyl in the modified PET and carboxyl of P (MMA-MAA) in the film-forming solution undergo esterification reaction during film formation and the second heat treatment to form C-O bond connection (FIG. 1-2); the amino group in the modified PET and the carboxyl group of P (MMA-MAA) in the film-forming liquid undergo amidation reaction during film formation and the second heat treatment process to form a C-N bond connection (figure 1-3).
(3) The support layer and the functional layer of the composite membrane are combined under the action of a covalent bond, and when different negatively charged polymers are blended in the chlorine-containing polymer base membrane solution, the support layer and the functional layer can form one or more covalent bonds of C-O bonds and C-N bonds for connection; meanwhile, the surface of the charged membrane contains one or more of carboxyl and sulfonic acid groups which are negatively charged. Therefore, blending different charged polymers will result in films exhibiting different interlayer adhesion and charge characteristics, and the composite films will have different microstructures (FIG. 2).
The technical key point of the invention is to strictly control the content of the negative-charge polymer in the functional layer. The invention realizes the control of the content of the negative-charged polymer in the functional layer by strictly limiting the mass percentage of the negative-charged polymer in the membrane-making solution to be 1-10%.
Because if the content of the negative charge polymer is too low, enough negative charge groups cannot be provided, enough active groups cannot be provided, and the negative charge groups and the modified supporting layer react to generate C-O bonds and C-N bonds, the prepared film does not show obvious negative charge characteristics, flux, hydrophilicity, pollution resistance and the like, and does not have strong stripping resistance; if the content of the negatively charged polymer is too high, the structure of the functional layer film having a chlorine-containing polymer as a skeleton is changed, and the overall properties of the film are unexpectedly changed.
The technical key point of the invention is to strictly control the reaction degree of the active group of the supporting layer and the negative-charged polymer in the functional layer. The content of the negative-charge polymer in the functional layer is strictly limited, the temperature of the second heat treatment is 50-90 ℃, and the time of the heat treatment is 1-24 hours, so that the control of the reaction degree of the active group of the supporting layer and the negative-charge polymer in the functional layer is realized. The invention realizes the control of the content of the negative-charge polymer in the functional layer by strictly limiting the mass percentage of the negative-charge polymer in the membrane-making solution to be 1-10%.
If the reaction degree is too high, the negative charge groups such as carboxyl or sulfonic acid groups of the negative charge polymers in the functional layer can be greatly consumed, and the composite membrane can not show negative charge characteristics, flux, hydrophilicity, pollution resistance and the like can not be improved; if the degree of reaction is too low, sufficient covalent bonds of C-O and C-N cannot be formed, the bonding force is not enhanced, and the peeling resistance of the film cannot be improved. The reaction degree of the active group of the supporting layer and the negative charge polymer in the functional layer is strictly controlled, and the purpose is to realize the balance of the negative charge property and the stripping resistance of the film.
The invention also provides a membrane module comprising a composite membrane according to any one of the forms of the invention.
The invention has the beneficial effects that:
(1) the invention discloses a negative charge type chlorine-containing polymer matrix composite membrane enhanced based on interlayer covalent action, which consists of a supporting layer and a functional layer, wherein the supporting layer and the functional layer are combined by the covalent bond action, so that the interlayer adhesive force is strong, the problem of peeling off between layers in the membrane during use is solved while the mechanical property of the membrane is improved by adopting a fiber supporting layer, the stability and the service life of the membrane are improved, and the backwashing resistance of the membrane is enhanced;
(2) the functional layer of the invention consists of chlorine-containing polymer and negatively charged polymer. The introduction of the negatively charged polymer ensures that the composite membrane has certain negatively charged property, improves the membrane flux, simultaneously ensures that the composite membrane has special adsorption and separation characteristics, has better removal performance on certain charged pollutants, and obviously improves the anti-pollution performance of the membrane.
(3) The invention adopts the membrane preparation technology which synchronously realizes the modification of the supporting layer and the phase inversion membrane formation, and the production process is simple. And when different support layer structures and membrane making processes are adopted, the membrane making technology is simultaneously suitable for preparing flat membranes and hollow fiber membranes.
Drawings
FIG. 1 is a schematic diagram of the chemical reactions involved in the present invention
Wherein 1-1 is a schematic diagram of amination reaction of PET; 1-2 is a schematic diagram of the esterification reaction between the hydroxyl of PET and the carboxyl of P (MMA-MAA); 1-3 is a schematic diagram of amidation reaction between the amino group of PET and the carboxyl group of P (MMA-MAA).
FIG. 2 is a schematic view of the microstructure of the filtration membrane of the present invention.
The support layer is a non-woven fabric or a braided tube composed of polymer fibers, the functional layer is formed by phase inversion after blending chlorine-containing polymers and negatively charged polymers, the support layer and the functional layer are connected through a plurality of covalent bonds such as C-O bonds and C-N single bonds, and the surface of the functional layer is provided with one or more of negatively charged carboxyl groups and sulfonic groups.
The specific implementation mode is as follows:
the present invention will be described in detail below with reference to the accompanying drawings and examples. The following examples are intended to illustrate the invention only and are not intended to limit the scope of the invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.
The invention provides a negative charge type chlorine-containing polymer matrix composite membrane enhanced based on interlayer covalent interaction, which comprises a supporting layer and a functional layer, wherein the supporting layer is a polyester fiber-containing reinforcing layer, the functional layer is composed of a chlorine-containing polymer and a negative charge type polymer, the supporting layer and the functional layer are combined under the action of the covalent bond, and the composite membrane is negatively charged.
The invention discloses a specific implementation method for preparing a negatively charged chlorine-containing polymer matrix composite film enhanced based on interlayer covalent interaction, which comprises the following steps:
(1) preparing membrane-forming liquid containing chlorine-containing polymer and negatively charged polymer. Wherein, the membrane-forming liquid comprises a chlorine-containing polymer, a negatively charged polymer, a pore-forming agent and a solvent. Specifically, the chlorine-containing polymer is selected from one or more of polyvinyl chloride, polyvinylidene chloride, chlorinated polyethylene, chlorinated polyvinyl chloride, a vinyl chloride-vinylidene chloride copolymer, a vinyl chloride-olefin copolymer, polychloroprene and chlorinated polypropylene, and the mass percentage of the chlorine-containing polymer is 10-25%; the negative electric polymer is a polymer containing carboxylic acid groups and sulfonic acid groups, and is selected from one or more of methyl methacrylate-methacrylic acid copolymer, acrylic acid-acrylonitrile copolymer, acrylic acid-hydroxypropyl acrylate copolymer, acrylic acid-acrylamide copolymer, vinyl alcohol-acrylic acid copolymer, acrylic acid-styrene sulfonic acid copolymer, maleic acid-styrene sulfonic acid copolymer, acrylic acid-sodium allylsulfonate copolymer, acrylic acid- (2-acrylamido-2-methylpropanesulfonic acid) copolymer and acrylic acid-methyl acrylate- (2-acrylamido-2-methylpropanesulfonic acid) terpolymer, and the mass percentage of the negative electric polymer is 1-10%; the pore-forming agent is selected from one or more of water, ethanol, glycerol, glycol and polyethylene glycol (PEG) with the molecular weight of 200-8000, and the mass percentage of the pore-forming agent is 0.1-10%; the solvent is selected from one or a mixture of N, N-Dimethylformamide (DMF), N-Dimethylacetamide (DMAC), N-methylpyrrolidone (NMP) and dimethyl sulfoxide (DMSO), and the total mass percentage of the solvent is 55-88.9%; the preparation and standing temperature of the membrane preparation liquid is 25-90 ℃.
(2) Preparing a modifier. The modifier is a solution containing an amine compound and a catalyst, and the solvent of the solution is water or a mixture of water and ethanol. The amine compound is an amine monomer containing a primary amine group, and is selected from any one or more of methylamine, ethylamine, ethanolamine, ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polyethylenepolyamine, p-phenylenediamine and m-phenylenediamine, and the mass percentage of the amine compound is 5-40%; the catalyst is selected from one or more of aluminum chloride, ferric chloride, titanium tetrachloride and boron trifluoride, and the mass percentage of the catalyst is 0.01-1%; if the solvent is a mixture of water and ethanol, the mass percentage of the ethanol in the solvent is 10-30%.
(3) The support layer is first treated with a modifier and subjected to a first heat treatment. The supporting layer is a polyester fiber-containing reinforcing layer containing a polyester material, and is selected from any one of polyester fiber, cotton/polyester blended fiber, polyester/cellulose blended fiber, polyester/polyamide blended fiber, polyester/polyurethane blended fiber and polyester/polyacrylonitrile blended fiber. The support layer is first treated with a modifier and subjected to a first heat treatment. Immediately immersing the fiber supporting layer into a pretreatment tank with a modifier after the fiber supporting layer is unwound, and then entering a heating drying tunnel for carrying out first heat treatment, so that the surface moisture of the fiber supporting layer is dried while the fiber supporting layer is subjected to amination reaction to introduce active groups. The temperature of the heating drying tunnel is 50-200 ℃, and the residence time of the supporting layer is 0.1-10 minutes.
(4) And (4) coating a membrane-making solution on the outer surface of the modified supporting layer obtained in the step (3), and performing immersion precipitation phase inversion curing to form a membrane. Wherein the solidification liquid is water, and the temperature is 20-60 ℃. The fiber supporting layer is uncoiled, the modifier is pretreated, the drying channel is subjected to first heat treatment, the supporting layer enters a film head, and the film is solidified and formed into a continuous process, namely the movement speed of the fiber supporting layer is always consistent with the spinning speed, and a film preparation technology synchronously realized by supporting layer modification and phase conversion film formation is adopted.
(5) And (4) placing the membrane obtained in the step (4) in a saturated steam environment for second heat treatment, and then placing the membrane in water for soaking and cleaning to obtain the support type negatively charged chlorine-containing polymer matrix composite membrane with high adhesive force. The temperature of the second heat treatment is 50-90 ℃, and the heat treatment time is 1-24 hours; the membrane cleaning time is 10-24 hours, and water is changed at least 3 times in the process.
The performance characterization of the negatively charged chlorine-containing polymer matrix composite membrane based on the interlayer covalent interaction enhancement is as follows:
the pure water flux was measured using a home-made flux measuring device. Namely, the pure water permeability of a unit membrane area in a unit time under the pressure of 0.1MPa and the temperature of 25 ℃ is measured;
and calculating the amination modification reaction degree of the polyester fiber supporting layer by adopting a surface infrared spectrum measurement result. As shown in FIG. 1-1, in the amination reaction of the polyester fiber, a polyester molecule reacts with an amine substance to generate an amino-terminated molecule and a hydroxyl-terminated molecule, and therefore, the amination modification reaction degree of the polyester fiber support layer can be calculated by measuring the ratio of the amino-terminated molecule to the ester group on the surface of the modified polyester fiber through surface infrared spectroscopy.
The peel strength of the reinforced composite membrane is determined by a self-made testing device. And packaging the membrane filaments into small assemblies, and testing a pressure-flux curve by adopting an internal pressure water inlet mode. The operation pressure is slowly increased, the internal pressure flux of the membrane is monitored, when the flux is suddenly changed, the conditions of membrane yarn breakage, skin layer peeling and the like are explained, and the operation pressure at the moment can be used for describing the peeling strength of the membrane. When covalent bond connection exists between the support layer and the functional layer of the composite membrane, the peeling strength of the membrane can be obviously increased;
the charge negative electricity property is measured by a zeta potential meter to determine the isoelectric point of the membrane, and the isoelectric point is the pH value when the surface charge of the membrane is 0. Generally, the isoelectric point of an uncharged polymer film is about 6, when the isoelectric point is less than 6, the film shows the negative charge characteristic under the conventional condition, and the smaller the isoelectric point is, the stronger the negative charge characteristic of the film is;
hydrophilicity the initial contact angle of pure water in contact with the membrane surface was determined by a contact angle determinator, the lower the degree of the contact angle, the easier water spreading on the surface and the better hydrophilicity;
the contamination resistance was measured by a static adsorption test using Bovine Serum Albumin (BSA). BSA was dissolved in 0.01M phosphate buffer (PBS, pH 7.4) to prepare a 10mg/mL protein solution. The membrane filaments are packaged into a module with certain effective membrane area and size, and are repeatedly and fully cleaned by water and ethanol. Protein solution is fully injected into the assembly cavity, and then the assembly cavity is adsorbed for 24 hours at 37 ℃ in oscillating water bath. After adsorption was complete, the membrane was removed and rinsed thoroughly with PBS and deionized water. The membrane was then immersed in a 1 wt% Sodium Dodecyl Sulfate (SDS) solution and desorbed with shaking for 2 h. The protein concentration in the SDS solution was determined by absorbance at 280nm using a UV spectrophotometer. The protein solution concentration-absorbance standard curve is determined by measuring the absorbance of 0.1-2 mg/mL protein in SDS solution. The amount of BSA adsorbed per membrane area was calculated. The lower the adsorption amount of bovine serum albumin, the better the contamination resistance of the membrane.
Example 1:
preparing a fiber-reinforced negatively-charged chlorine-containing polymer-based hollow fiber membrane body:
(1) preparing a membrane preparation liquid: polyvinyl chloride (PVC, 18 wt%), methyl methacrylate-methacrylic acid copolymer (P (MMA-MAA), 3 wt%), polyethylene glycol (PEG400, 7 wt%), H2O (0.6 wt%) and DMAC (71.4 wt%) were stirred at 70 ℃ for 24 hours, filtered, defoamed at 70 ℃ and allowed to stand for further use.
(2) Preparing a supporting layer modifier: dissolving 50 wt% of diethylenetriamine and 0.1 wt% of aluminum chloride in water to prepare a modified solution at room temperature.
(3) The supporting layer is a polyester braided tube. The braided tube is immerged into a pretreatment tank with modifier after decoiling, and then passes through a heating drying tunnel with the temperature of 90 ℃ and the retention time of 5min for the first heat treatment.
(4) And (4) coating the film-making liquid on the outer surface of the modified polyester braided tube obtained in the step (3), and then soaking the polyester braided tube into water at 40 ℃ for curing and film-forming.
(5) And (3) placing the membrane obtained in the step (4) in a saturated water vapor environment for secondary heat treatment at 70 ℃ for 12 hours, and then placing the membrane in water for soaking and cleaning for 24 hours to obtain the support type negatively charged chlorine-containing polymer-based hollow fiber membrane with high adhesive force.
The specific film-making parameters are as follows:
Figure BDA0001591949140000111
as a result of the test, the pure water flux at 0.1MPa was 660L/h.m2The amination modification reaction degree of the polyester fiber supporting layer is 4%, and the stripping phenomenon occurs when the operation pressure reaches 1 MPa. The isoelectric point of the membrane is 3.5, the initial contact angle of the membrane surface is 65 degrees, and the adsorption quantity of bovine serum albumin is 8.4 mu g/cm2。
Comparative example 1:
the specific steps are the same as example 1, and the specific film-making parameters are as follows:
Figure BDA0001591949140000112
Figure BDA0001591949140000121
description of the drawings: in comparison with example 1, comparative example 1 did not perform the first heat treatment, i.e., the support layer was not subjected to the modification treatment.
As a result of the test, the pure water flux at 0.1MPa was 630L/h.m2The amination modification reaction degree of the polyester fiber supporting layer is 0%, and the stripping phenomenon occurs when the operation pressure reaches 0.44 MPa. The isoelectric point of the membrane is 3.7, the initial contact angle of the membrane surface is 73 degrees, and the adsorption quantity of bovine serum albumin is 15.9 mu g/cm2。
Comparative example 2:
the specific steps are the same as example 1, and the specific film-making parameters are as follows:
Figure BDA0001591949140000122
description of the drawings: in comparison with example 1, comparative example 2 uses a modifier having a lower concentration of amine compound than the present invention in the first heat treatment, i.e., the conditions are not strictly controlled in the modification treatment of the support layer.
As a result of the test, the pure water flux at 0.1MPa was 600L/h.m2The amination modification reaction degree of the polyester fiber supporting layer is 0.2%, and the stripping phenomenon occurs when the operation pressure reaches 0.48 MPa. The isoelectric point of the membrane is 4.3, the initial contact angle of the membrane surface is 76 degrees, and the adsorption quantity of bovine serum albumin is 17.1 mu g/cm2。
Comparative example 3:
the specific steps are the same as example 1, and the specific film-making parameters are as follows:
Figure BDA0001591949140000123
Figure BDA0001591949140000131
description of the drawings: in comparison with example 1, comparative example 2 uses a modifier having a lower concentration of amine compound than the present invention in the first heat treatment, i.e., the conditions are not strictly controlled in the modification treatment of the support layer.
As a result of the test, the pure water flux at 0.1MPa was 640L/h.m2The amination modification reaction degree of the polyester fiber supporting layer is 0.6%, and the stripping phenomenon occurs when the operation pressure reaches 0.49 MPa. The isoelectric point of the membrane is 4.4, the initial contact angle of the membrane surface is 78 degrees, and the adsorption quantity of bovine serum albumin is 18.3 mu g/cm2。
Comparative example 4:
the specific steps are the same as example 1, and the specific film-making parameters are as follows:
Figure BDA0001591949140000132
description of the drawings: in comparison with example 1, comparative example 3 has a lower temperature at the first heat treatment than the present invention, i.e., the conditions are not strictly controlled when the support layer is subjected to the modification treatment.
As a result of the test, the pure water flux at 0.1MPa was 620L/h.m2The amination modification reaction degree of the polyester fiber supporting layer is 0.1%, and the stripping phenomenon occurs when the operation pressure reaches 0.45 MPa. The isoelectric point of the membrane is 3.8, the initial contact angle of the membrane surface is 74 degrees, and the adsorption quantity of bovine serum albumin is 16.2 mu g/cm2。
Compared with example 1, the support layer is not modified in comparative example 1, and the conditions are not strictly controlled in comparative examples 2 to 4. The amination modification reaction degree of the polyester fiber support layer is very low, the support layer cannot provide enough active groups to react with the negative charge polymer in the functional layer to generate covalent bonds, the binding force is not enhanced, and the stripping resistance of the membrane is obviously weaker than that of the example 1.
Comparative example 5:
the specific steps are the same as example 1, and the specific film-making parameters are as follows:
Figure BDA0001591949140000141
description of the drawings: in contrast to example 1, comparative example 4 did not have negatively charged polymer blended in the dope solution.
As a result of the test, the pure water flux at 0.1MPa was 430L/h.m2The amination modification reaction degree of the polyester fiber supporting layer is 3.8%, and the stripping phenomenon occurs when the operation pressure reaches 0.52 MPa. The isoelectric point of the membrane is 6.2, the initial contact angle of the membrane surface is 105 degrees, and the adsorption quantity of bovine serum albumin is 41.5 mu g/cm2。
Compared with example 1, the negative-charge polymer is not blended in the membrane-forming liquid of comparative example 5, no substance capable of reacting with the modified supporting layer exists in the functional layer, the binding force is not enhanced, and the stripping resistance of the membrane is obviously weaker than that of example 1. Meanwhile, the isoelectric point of the membrane is about 6, and the membrane also has the characteristics of negative charge, flux, hydrophilicity and pollution resistance which are obviously weaker than those of the membrane in the example 1.
Comparative example 6:
the specific steps are the same as example 1, and the specific film-making parameters are as follows:
Figure BDA0001591949140000142
description of the drawings: in comparison with example 1, in comparative example 5, the second heat treatment was not performed, i.e., the reaction of the modified PET with the negatively charged polymer in the film-forming solution was not promoted to form C-O bonds and C-N bonds.
As a result of the test, the pure water flux at 0.1MPa was 650L/h.m2The amination modification reaction degree of the polyester fiber supporting layer is 3.9%, and the stripping phenomenon occurs when the operation pressure reaches 0.54 MPa. The isoelectric point of the membrane is 4.7, the initial contact angle of the membrane surface is 84 degrees, and the adsorption quantity of bovine serum albumin is 21.7 mu g/cm2。
Comparative example 7:
the specific steps are the same as example 1, and the specific film-making parameters are as follows:
Figure BDA0001591949140000151
description of the drawings: in comparison with example 1, the temperature for the second heat treatment in comparative example 6 was much lower than that in claim 11, i.e., the conditions were not strictly controlled to promote the reaction of the modified PET with the negatively charged polymer in the casting solution to form C-O bonds and C-N bonds.
As a result of the test, the pure water flux at 0.1MPa was 640L/h.m2The amination modification reaction degree of the polyester fiber supporting layer is 3.9%, and the stripping phenomenon occurs when the operation pressure reaches 0.5 MPa. The isoelectric point of the membrane is 5.1, the initial contact angle of the membrane surface is 82 degrees, and the adsorption quantity of bovine serum albumin is 22.5 mu g/cm2。
In comparison with example 1, the second heat treatment was not performed in comparative example 6, and the conditions were not strictly controlled when the second heat treatment was performed in comparative example 7. The active group provided by the modified support layer can not fully react with the negative charge polymer in the functional layer to generate a covalent bond, the binding force is not obviously enhanced, and the stripping resistance of the membrane is weaker than that of the membrane in example 1.
Example 2:
the specific steps are the same as example 1, and the specific film-making parameters are as follows:
Figure BDA0001591949140000152
Figure BDA0001591949140000161
as a result of the test, the pure water flux at 0.1MPa was 620L/h.m2The amination modification reaction degree of the polyester fiber supporting layer is 5.0%, and the stripping phenomenon occurs when the operation pressure reaches 1.23 MPa. The isoelectric point of the membrane is 4.3, the initial contact angle of the membrane surface is 63 degrees, and the bovine serum albuminThe adsorption capacity was 18.5. mu.g/cm2。
Example 3:
the specific steps are the same as example 1, and the specific film-making parameters are as follows:
Figure BDA0001591949140000162
as a result of the test, the pure water flux at 0.1MPa was 690L/h.m2The amination modification reaction degree of the polyester fiber supporting layer is 4.2%, and the stripping phenomenon occurs when the operation pressure reaches 0.9 MPa. The isoelectric point of the membrane is 3.9, the initial contact angle of the membrane surface is 67 degrees, and the adsorption quantity of bovine serum albumin is 19.2 mu g/cm2。
Example 4:
the specific steps are the same as example 1, and the specific film-making parameters are as follows:
Figure BDA0001591949140000163
as a result of the test, the pure water flux at 0.1MPa was 600L/h.m2The amination modification reaction degree of the polyester fiber supporting layer is 1.0%, and the stripping phenomenon occurs when the operation pressure reaches 0.88 MPa. The isoelectric point of the membrane is 3.5, the initial contact angle of the membrane surface is 81 degrees, and the adsorption quantity of bovine serum albumin is 12.6 mu g/cm2。
Example 5:
the specific steps are the same as example 1, and the specific film-making parameters are as follows:
Figure BDA0001591949140000171
as a result of the test, the pure water flux at 0.1MPa was 630L/h.m2The amination modification reaction degree of the polyester fiber supporting layer is 1.5%, and the stripping phenomenon occurs when the operation pressure reaches 0.75 MPa. The isoelectric point of the membrane is 2.8, the initial contact angle of the membrane surface is 79 degrees, and the adsorption quantity of bovine serum albumin is 9.7 mu g/cm2。
Example 6:
the specific steps are the same as example 1, and the specific film-making parameters are as follows:
Figure BDA0001591949140000172
as a result of the test, the pure water flux at 0.1MPa was 480L/h.m2The amination modification reaction degree of the polyester fiber supporting layer is 2.8%, and the stripping phenomenon occurs when the operation pressure reaches 0.83 MPa. The isoelectric point of the membrane is 3.7, the initial contact angle of the membrane surface is 89 degrees, and the adsorption quantity of bovine serum albumin is 20.6 mu g/cm2。
Example 7:
the specific steps are the same as example 1, and the specific film-making parameters are as follows:
Figure BDA0001591949140000181
as a result of the test, the pure water flux at 0.1MPa was 510L/h.m2The amination modification reaction degree of the polyester fiber supporting layer is 3.6%, and the stripping phenomenon occurs when the operation pressure reaches 0.77 MPa. The isoelectric point of the membrane is 3.2, the initial contact angle of the membrane surface is 80 degrees, and the adsorption quantity of bovine serum albumin is 14.2 mu g/cm2。
Example 8:
the specific steps are the same as example 1, and the specific film-making parameters are as follows:
Figure BDA0001591949140000182
as a result of the test, the pure water flux at 0.1MPa was 390L/h.m2The amination modification reaction degree of the polyester fiber supporting layer is 4.0%, and the stripping phenomenon occurs when the operation pressure reaches 0.8 MPa. The isoelectric point of the membrane is 3.7, the initial contact angle of the membrane surface is 66 degrees, and the adsorption quantity of bovine serum albumin is 19.5 mu g/cm2。
Example 9:
the specific steps are the same as example 1, and the specific film-making parameters are as follows:
Figure BDA0001591949140000191
as a result of the test, the pure water flux at 0.1MPa was 420L/h.m2The amination modification reaction degree of the polyester fiber supporting layer is 4.3%, and the stripping phenomenon occurs when the operation pressure reaches 0.79 MPa. The isoelectric point of the membrane is 3.6, the initial contact angle of the membrane surface is 74 degrees, and the adsorption quantity of bovine serum albumin is 23.5 mu g/cm2。
Example 10:
the specific steps are the same as example 1, and the specific film-making parameters are as follows:
Figure BDA0001591949140000192
as a result of the test, the pure water flux at 0.1MPa was 350L/h.m2The amination modification reaction degree of the polyester fiber supporting layer is 3.1%, and the stripping phenomenon occurs when the operation pressure reaches 0.76 MPa. The isoelectric point of the membrane is 2.5, the initial contact angle of the membrane surface is 95 degrees, and the adsorption quantity of bovine serum albumin is 29.5 mu g/cm2。
Example 11:
the specific steps are the same as example 1, and the specific film-making parameters are as follows:
Figure BDA0001591949140000193
Figure BDA0001591949140000201
as a result of the test, the pure water flux at 0.1MPa was 390L/h.m2The amination modification reaction degree of the polyester fiber supporting layer is 1.8%, and the stripping phenomenon occurs when the operation pressure reaches 0.76 MPa. The isoelectric point of the film was 3.2, and the initial contact angle of the film surface was 91 °The adsorption amount of bovine serum albumin was 26.3. mu.g/cm2。

Claims (14)

1. A negatively charged chlorine-containing polymer matrix composite film based on interlayer covalent interaction enhancement is characterized in that: the composite membrane comprises a supporting layer and a functional layer, wherein the supporting layer is a polyester fiber-containing reinforcing layer, the functional layer is composed of a chlorine-containing polymer and a negatively charged polymer, the mass percentage of the negatively charged polymer in the functional layer is 10-50%, the supporting layer and the functional layer are combined under the action of a covalent bond, the surface of the composite membrane is provided with carboxyl or sulfonic acid groups, the composite membrane is negatively charged, the covalent bond is a C-O bond and a C-N bond, and the composite membrane is a negatively charged microfiltration membrane or an ultrafiltration membrane; the interlayer covalent effect is realized by carrying out amination modification on the support layer to form an active group and carrying out chemical reaction with the active group of the negatively charged polymer to form a C-O and C-N covalent bond, wherein the reaction degree of the amination modification is 1-5%.
2. The negatively charged chlorine-containing polymer matrix composite film based on interlayer covalent interaction enhancement as claimed in claim 1, wherein: the composite membrane is any one of a flat membrane and a hollow fiber membrane.
3. The negatively charged chlorine-containing polymer matrix composite film based on interlayer covalent interaction enhancement as claimed in claim 1, wherein: the polyester fiber-containing reinforced layer is selected from any one of polyester fiber, cotton/polyester blended fiber, polyester/cellulose blended fiber, polyester/polyamide blended fiber, polyester/polyurethane blended fiber and polyester/polyacrylonitrile blended fiber.
4. The negatively charged chlorine-containing polymer matrix composite film based on interlayer covalent interaction enhancement as claimed in claim 1, wherein: the chlorine-containing polymer is selected from any one or more of polyvinyl chloride, polyvinylidene chloride, chlorinated polyethylene, chlorinated polyvinyl chloride, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-vinyl acetate copolymer, polychloroprene and chlorinated polypropylene.
5. The negatively charged chlorine-containing polymer matrix composite film based on enhancement of interlayer covalent interaction as claimed in any one of claims 1 to 4, wherein: the negatively charged polymer is a polymer containing carboxylic acid groups and sulfonic acid groups.
6. The negatively charged chlorine-containing polymer matrix composite film based on interlayer covalent interaction enhancement as claimed in claim 5, wherein: the negatively charged polymer is selected from any one or more of methyl methacrylate-methacrylic acid copolymer, acrylic acid-acrylonitrile copolymer, acrylic acid-hydroxypropyl acrylate copolymer, acrylic acid-acrylamide copolymer, vinyl alcohol-acrylic acid copolymer, acrylic acid-styrene sulfonic acid copolymer, maleic acid-styrene sulfonic acid copolymer, acrylic acid-sodium allylsulfonate copolymer, acrylic acid- (2-acrylamide-2-methyl propane sulfonic acid) copolymer and acrylic acid-methyl acrylate- (2-acrylamide-2-methyl propane sulfonic acid) terpolymer.
7. The method for preparing the negatively charged chlorine-containing polymer matrix composite film based on interlayer covalent interaction enhancement according to claim 1, characterized by comprising the following steps:
(1) blending and dissolving a chlorine-containing polymer and a negatively charged polymer to prepare a membrane-making solution;
(2) preparing a supporting layer modifier;
(3) the support layer firstly enters a modifier, and is subjected to primary heat treatment, so that the polyester fiber is subjected to amination reaction under the action of the modifier to generate a polyester macromolecule with one end being a hydroxyl group or a primary amino group, wherein the amination modification reaction degree is 1-5%;
(4) coating a membrane-making liquid on the outer surface of the modified supporting layer obtained in the step (3), and performing phase inversion and solidification to form a membrane through immersion precipitation;
(5) placing the membrane obtained in the step (4) in a saturated water vapor environment for secondary heat treatment, enabling polyester macromolecules with one end of hydroxyl or primary amino in the supporting layer to react with carboxyl in the negatively charged polymer in the functional layer under the action of a modifier to form C-O and C-N covalent bonds, and then cleaning the membrane to obtain the negatively charged chlorine-containing polymer matrix composite membrane enhanced based on interlayer covalent interaction;
wherein the mass percentage of the negatively charged polymer in the membrane-forming solution in the step (1) is 1-10%.
8. The method of claim 7, wherein: the modifier in the step (3) and the step (5) is a solution containing an amine compound and a catalyst, the solvent of the solution is water or a mixture of water and ethanol, the mass percent of the amine compound is 5-40%, the mass percent of the catalyst is 0.01-1%, the mass percent of the solvent in the modifier is 59-94.99%, and the mass percent of the ethanol in the mixture of water and ethanol is 10-30%.
9. The method of claim 8, wherein: the amine compound is an amine monomer containing a primary amine group, and is selected from any one or more of methylamine, ethylamine, ethanolamine, ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, p-phenylenediamine and m-phenylenediamine.
10. The method of claim 8, wherein: the amine compound is polyethylene polyamine.
11. The method of claim 8, wherein: the catalyst is selected from one or more of aluminum chloride, ferric chloride, titanium tetrachloride and boron trifluoride.
12. The method of claim 7, wherein: the first heat treatment temperature in the step (3) is 50-200 ℃, and the heat treatment time is 0.1-10 minutes.
13. The method of claim 7, wherein: and (5) performing secondary heat treatment at 50-90 ℃ for 1-24 hours.
14. A membrane module, characterized by: the membrane module comprises a composite membrane according to any one of claims 1 to 6.
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