CN114669204B - Composite separation membrane and preparation method and application thereof - Google Patents

Composite separation membrane and preparation method and application thereof Download PDF

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CN114669204B
CN114669204B CN202210182319.5A CN202210182319A CN114669204B CN 114669204 B CN114669204 B CN 114669204B CN 202210182319 A CN202210182319 A CN 202210182319A CN 114669204 B CN114669204 B CN 114669204B
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solution
ink
separation membrane
membrane
composite separation
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CN114669204A (en
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李仁杰
谢红丽
林红军
钟一可
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Zhejiang Normal University CJNU
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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
    • 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
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • 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
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/40—Devices for separating or removing fatty or oily substances or similar floating material
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/02—Hydrophilization
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/26—Spraying processes

Abstract

The invention relates to a preparation method of a composite separation membrane, which is characterized in that a metal salt solution, a polyphenol solution and an oxidant solution are matched for use, so that a complexing reaction and an oxidative polymerization reaction are carried out on a polymer substrate, a modified layer with stronger hydrophilicity is formed, and the flux, rejection rate and pollution resistance of the separation membrane are improved. The preparation method has the advantages of short time consumption, simple operation, mild reaction conditions, easy realization of large-scale industrial application and obvious popularization advantage. The preparation method can be carried out by ink-jet printing, has high utilization rate of raw materials, does not waste resources and is environment-friendly. The invention also relates to the composite separation membrane obtained by the preparation method, which has the advantages of strong hydrophilicity, high flux, rejection rate and pollution resistance, good separation effect and great significance in the separation of oil-water emulsion.

Description

Composite separation membrane and preparation method and application thereof
Technical Field
The invention relates to the field of preparation of polymer separation membranes, in particular to a composite separation membrane and a preparation method and application thereof.
Background
The membrane separation technology is to separate different components from a mixture by utilizing the selective permeability of a membrane under the action of external force, thereby achieving the purposes of separation, purification, concentration, classification and the like. The membrane separation technology has the advantages of high efficiency, low cost, small secondary pollution, simple operation, energy conservation and the like, and plays an increasingly important role in water and wastewater treatment.
However, the commonly used organic polymer membrane is easily polluted by oil drops due to low surface energy and strong hydrophobicity, so that the flux and the retention rate are seriously reduced, and the service life of the membrane is shortened. If the membrane surface is hydrophilic, a hydrated layer can be formed underwater, thereby maintaining high permeation flux and excellent antifouling performance. Therefore, the hydrophilic modification of the surface of the organic polymer membrane is an effective way for improving the anti-pollution performance of the membrane and expanding the application of the membrane separation technology in the field of oil-water separation. The commonly used hydrophilic modification method is to load a hydrophilic modification material on the surface of an organic polymer membrane. However, the existing organic polymer membrane loaded with the hydrophilic modification material still has the defect of weak hydrophilicity.
Therefore, it is required to develop a method for preparing a separation membrane having a high hydrophilicity.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a preparation method of a composite separation membrane, which is characterized in that a metal salt solution, a polyphenol solution and an oxidant solution are matched for use, so that a complexing reaction and an oxidative polymerization reaction are carried out on a polymer substrate, a modified layer with stronger hydrophilicity is formed, and the flux, the rejection rate and the pollution resistance of the separation membrane are improved.
Another object of the present invention is to provide a composite separation membrane obtained by the above preparation method, which has high flux, rejection rate and anti-pollution performance.
The invention also aims to provide application of the composite separation membrane in oily wastewater treatment.
In order to achieve the above object, the present invention provides the following technical solutions.
A method of making a composite separation membrane, comprising:
and (2) enabling the metal salt solution, the polyphenol solution and the oxidant solution to react on the surface of the polymer substrate, so as to form a modified layer on the surface of the polymer substrate, thereby obtaining the composite separation membrane.
In the present invention, the mechanism of formation of the modified layer is: and one part of phenolic hydroxyl of the polyphenol and metal ions in the metal salt solution can generate a complex reaction, and the other part of phenolic hydroxyl generates oxidative polymerization under the action of an oxidant, so that a modified layer is formed.
Preferably, the preparation method of the metal salt solution comprises the following steps: dissolving a metal salt in a solvent, wherein the metal salt is ferric sulfate or ferric chloride, and the solvent is water, alcohol or a mixture thereof. Preferably, the alcohol is ethanol or propanol. Preferably, the solvent is a mixture of water and an alcohol. Preferably, the concentration of alcohol in the mixture is 10-30%. If the alcohol concentration is too low, the contact angle between the mixture and the surface of the film is larger, and the penetration of liquid drops is not facilitated, so that the coating is unevenly distributed. Too high concentration is not favorable for subsequent cleaning and causes reagent waste. Preferably, the concentration of the metal salt solution is below 23.5mmol/L, for example 4-23.5mmol/L. Excessive concentration may cause clogging of the ink cartridge, and excessive metal salt may be accumulated on the film surface when the metal salt, polyphenol and oxidizing agent react, resulting in insufficient uniform distribution of the coating. The concentration is too low, the spray printing effect is not obvious, the printing times are more, and the time cost is high.
Preferably, the preparation method of the polyphenol solution comprises: dissolving a polyphenol in a solvent, wherein the polyphenol is tannic acid and the solvent is water, an alcohol, or a mixture thereof. Preferably, the alcohol is ethanol or propanol. Preferably, the concentration of the polyphenol solution is 47mmol/L or less, for example, 7.8 to 47mmol/L. Excessive concentration may cause clogging of the ink cartridge, and excessive metal salt may be accumulated on the film surface when the metal salt, polyphenol and oxidizing agent react, resulting in insufficient uniform distribution of the coating. Preferably, the solvent used to dissolve the polyphenol does not contain dissolved oxygen, thereby preventing the polyphenol such as tannic acid from accumulating in the cartridge, clogging the cartridge. The concentration is too low, the spray printing effect is not obvious, the printing times are more, and the time cost is high.
Preferably, the method for preparing the oxidant solution comprises: dissolving an oxidizing agent in a solvent, wherein the oxidizing agent is at least one of sodium periodate, potassium permanganate, and potassium dichromate, and the solvent is water, an alcohol, or a mixture thereof. Preferably, the alcohol is ethanol or propanol. Preferably, the concentration of the oxidizing agent solution is 94mmol/L or less, for example, 15.7 to 94mmol/L. Excessive concentration can lead to clogging of the cartridge. The concentration is too low, the spray printing effect is not obvious, the printing times are more, and the time cost is high.
Preferably, the polymeric substrate is polyester, polypropylene, polyvinylidene fluoride, polysulfone or polyethylene. Preferably, the polymeric substrate is soaked in ethanol to remove surface stains prior to use, then ultrasonically cleaned, and then oven dried.
Preferably, the method for forming the modified layer includes: and sequentially printing a metal salt solution, a polyphenol solution and an oxidant solution on the surface of the polymer substrate by ink-jet printing, and reacting the metal salt solution, the polyphenol solution and the oxidant solution to form the modified layer. Preferably, the reaction time is 5-60min.
In the present invention, the modification layer may be formed on one or both surfaces of the polymer substrate.
In some embodiments, prior to printing, one surface of the polymeric substrate may be affixed to a substrate such as paper to form the modified layer on the other surface. The paper is convenient to print, cheap and easy to obtain, and can be repeatedly used when necessary.
Preferably, when the ratio of the concentrations of the metal salt solution, the polyphenol solution and the oxidant solution is 1 (1.8-2.2): 3.8-4.2, preferably 1. In some preferred embodiments, the metal salt solution is printed for 1 to 6 times, the polyphenol solution is printed for 1 to 3 times, and the oxidant solution is printed for 1 to 3 times.
Preferably, the metal salt solution, the polyphenol solution and the oxidizer solution are loaded into different cartridges, respectively, before printing, and then the cartridges loaded with the solutions are mounted on a printer for testing.
Preferably, after the reaction is completed, the resulting composite separation membrane is washed with water to remove unreacted raw materials.
Preferably, the preparation method further comprises: after the reaction is completed, washing and drying are performed. Preferably, the washing may be performed with water. Preferably, the drying comprises natural airing or oven drying. The drying temperature is 30-60 ℃.
The invention also provides a composite separation membrane obtained by the preparation method. The composite separation membrane has a water contact angle of 70 DEG or less. The composite separation membrane has an oil-containing emulsion retention rate of over 98% under the pressure of 0.4MPa, and flux of 4968.4 L.m -2 ·h -1 ·bar -1 The above. The flux recovery rate of the composite separation membrane reaches more than 89.1 percent. The composite separation membrane has lower water contact angle and stronger hydrophilicity, thereby having higher flux, rejection rate and pollution resistance.
The invention also provides application of the composite separation membrane in oily wastewater treatment.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention provides a preparation method of a composite separation membrane, which is characterized in that a metal salt solution, a polyphenol solution and an oxidant solution are matched for use, so that a complexing reaction and an oxidative polymerization reaction are carried out on a polymer substrate, a modified layer with stronger hydrophilicity is formed, and the flux, rejection rate and pollution resistance of the separation membrane are improved.
The preparation method has the advantages of short time consumption, simple operation, mild reaction conditions, easy realization of large-scale industrial application and obvious popularization advantage.
2. The preparation method can be carried out by ink-jet printing, has high utilization rate of raw materials, does not waste resources and is environment-friendly. The existing method for preparing the modified layer is usually carried out by soaking the polymer substrate in a solution, so that the utilization rate of raw materials is low, most of the solution is not used, and serious resource waste and environmental pollution are caused.
3. The composite separation membrane has the advantages of strong hydrophilicity, high flux, rejection rate and pollution resistance, good separation effect and great significance in the separation of oil-water emulsion.
4. The invention has wide application range and can realize polyphenol coating on various polymer substrates.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a flow chart of the preparation of the composite separation membrane of the present invention.
FIG. 2 is SEM images of (a) a blank PVDF membrane, (b) an Fe-TA composite separation membrane, (c) a TA-SP composite separation membrane, and (d) an Fe-TA-SP composite separation membrane of example 1.
FIG. 3 is a graph showing the oil-water separation efficiency of the Fe-TA-SP composite separation membrane of example 1 against a blank PVDF membrane.
FIG. 4 is a graph of the flux recovery of the blank PVDF membrane and the Fe-TA-SP composite separation membrane of example 1 after 8 separation cycles of different oil-water emulsions.
Detailed Description
In order to facilitate understanding of the present invention, the technical solutions of the present invention are further described below with reference to specific embodiments, but the present invention is not limited thereto. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention. Unless otherwise indicated, the starting materials and reagents used in the examples are all commercially available products. Reagents, equipment, or procedures not described herein are routinely determinable by one of ordinary skill in the art.
Example 1: preparation of hydrophilic Fe-TA-SP composite separation membrane
(1) Treatment of blank films: firstly, soaking a polyvinylidene fluoride membrane in ethanol for 30min, removing stains on the surface of the membrane, then ultrasonically cleaning the membrane for 2-3 times by pure water, and finally drying at 60 ℃ to obtain a blank membrane;
(2) Preparing ink: preparing 17% n-propanol solution with boiled and cooled distilled water, and adding a certain amount of tannic acid to form 23.5mM tannic acid solution to obtain TA ink; preparing 17% n-propanol solution with distilled water, and preparing 11.75mM Fe from the above solution respectively 2 (SO 4 ) 3 Solution and 47mM NaIO 4 Obtaining Fe ink and SP ink by solution;
(3) Equipping an ink box: injecting the three inks prepared in the step (2) into three commercial HP ink boxes respectively by using injectors, and equipping an HP desk 1112 printer for testing;
(4) Ink-jet printing: and (3) sticking the blank film treated in the step (1) on A4 paper, firstly printing 4 times of Fe ink, then printing 2 times of TA ink, and finally printing 2 times of SP ink, and keeping the obtained film at room temperature for 15min to obtain the Fe-TA-SP composite separation film.
(5) Washing and drying: and (4) thoroughly cleaning the composite separation membrane prepared in the step (4) with pure water for 2-3 times, drying at 40 ℃, and then placing in a sealed bag for storage.
Example 2: preparation of hydrophilic Fe-TA-SP composite separation membrane
(1) Treatment of blank films: firstly, soaking a polyvinylidene fluoride membrane in ethanol for 30min, removing stains on the surface of the membrane, then ultrasonically cleaning the membrane for 2-3 times by pure water, and finally drying at 60 ℃ to obtain a blank membrane;
(2) Preparing ink: preparing 17% n-propanol solution with boiled and cooled distilled water, and adding a certain amount of tannic acid to form 23.5mM tannic acid solution to obtain TA ink; preparing 17% n-propanol solution with distilled water, and preparing 11.75mM Fe from the above solution respectively 2 (SO 4 ) 3 Solution and 47mM NaIO 4 Obtaining Fe ink and SP ink by solution;
(3) Equipping an ink box: injecting the three inks prepared in the step (2) into three commercial HP ink boxes respectively by using injectors, and equipping an HP desk 1112 printer for testing;
(4) Ink-jet printing: and (2) sticking the blank film treated in the step (1) on A4 paper, firstly printing 4 times of Fe ink, then printing 2 times of TA ink, finally printing 2 times of SP ink, and keeping the obtained film at room temperature for 5min to obtain the Fe-TA-SP composite separation film.
(5) Washing and drying: and (4) thoroughly cleaning the composite separation membrane prepared in the step (4) with pure water for 2-3 times, drying at 40 ℃, and then placing in a sealed bag for storage.
Example 3: preparation of hydrophilic Fe-TA-SP composite separation membrane
(1) Treatment of blank films: firstly, soaking a polyvinylidene fluoride membrane in ethanol for 30min, removing stains on the surface of the membrane, then ultrasonically cleaning the membrane for 2-3 times by pure water, and finally drying at 60 ℃ to obtain a blank membrane;
(2) Preparing ink: after boilingPreparing 17% n-propanol solution with cooled distilled water, and adding a certain amount of tannic acid to form 23.5mM tannic acid solution to obtain TA ink; preparing 17% n-propanol solution with distilled water, and preparing 11.75mM Fe from the above solution respectively 2 (SO 4 ) 3 Solution and 47mM NaIO 4 Obtaining Fe ink and SP ink by solution;
(3) Equipping an ink box: injecting the three inks prepared in the step (2) into three commercial HP ink boxes respectively by using injectors, and equipping an HP desk 1112 printer for testing;
(4) Ink-jet printing: and (3) sticking the blank film treated in the step (1) on A4 paper, firstly printing 4 times of Fe ink, then printing 2 times of TA ink, and finally printing 2 times of SP ink, and keeping the obtained film at room temperature for 10min to obtain the Fe-TA-SP composite separation film.
(5) Washing and drying: and (4) thoroughly cleaning the composite separation membrane prepared in the step (4) with pure water for 2-3 times, drying at 40 ℃, and then placing in a sealed bag for storage.
Example 4: preparation of hydrophilic Fe-TA-SP composite separation membrane
(1) Treatment of blank films: firstly, soaking a polyvinylidene fluoride membrane in ethanol for 30min, removing stains on the surface of the membrane, then ultrasonically cleaning the membrane for 2-3 times by pure water, and finally drying at 60 ℃ to obtain a blank membrane;
(2) Preparing ink: preparing 17% n-propanol solution with boiled and cooled distilled water, and adding a certain amount of tannic acid to form 23.5mM tannic acid solution to obtain TA ink; preparing 17% n-propanol solution with distilled water, and preparing 11.75mM Fe from the above solution respectively 2 (SO 4 ) 3 Solution and 47mM NaIO 4 Obtaining Fe ink and SP ink by solution;
(3) Equipping an ink box: injecting the three inks prepared in the step (2) into three commercial HP ink boxes respectively by using injectors, and equipping an HP desk 1112 printer for testing;
(4) Ink-jet printing: and (2) sticking the blank film treated in the step (1) on A4 paper, firstly printing 4 times of Fe ink, then printing 2 times of TA ink, finally printing 2 times of SP ink, and keeping the obtained film at room temperature for 30min to obtain the Fe-TA-SP composite separation film.
(5) Washing and drying: and (4) thoroughly cleaning the composite separation membrane prepared in the step (4) with pure water for 2-3 times, drying at 40 ℃, and then placing in a sealed bag for storage.
Example 5: preparation of hydrophilic Fe-TA-SP composite separation membrane
(1) Treatment of blank films: firstly, soaking a polyvinylidene fluoride membrane in ethanol for 30min, removing stains on the surface of the membrane, then ultrasonically cleaning the membrane for 2-3 times by pure water, and finally drying at 60 ℃ to obtain a blank membrane;
(2) Preparing ink: preparing 17% n-propanol solution with boiled and cooled distilled water, and adding a certain amount of tannic acid to form 23.5mM tannic acid solution to obtain TA ink; preparing 17% n-propanol solution with distilled water, and preparing 11.75mM Fe from the above solution respectively 2 (SO 4 ) 3 Solution and 47mM NaIO 4 Obtaining Fe ink and SP ink by solution;
(3) Equipping an ink box: injecting the three inks prepared in the step (2) into three commercial HP ink boxes respectively by using injectors, and equipping an HP desk 1112 printer for testing;
(4) Ink-jet printing: and (3) adhering the blank film treated in the step (1) to A4 paper, firstly printing 1 time of Fe ink, then printing 1 time of TA ink, and finally printing 1 time of SP ink, and keeping the obtained film at room temperature for 15min to obtain the Fe-TA-SP composite separation film.
(5) Washing and drying: and (4) thoroughly cleaning the composite separation membrane prepared in the step (4) with pure water for 2-3 times, drying at 40 ℃, and then placing in a sealed bag for storage.
Example 6: preparation of hydrophilic Fe-TA-SP composite separation membrane
(1) Treatment of blank films: firstly, soaking a polyvinylidene fluoride membrane in ethanol for 30min, removing stains on the surface of the membrane, then ultrasonically cleaning the membrane for 2-3 times by pure water, and finally drying at 60 ℃ to obtain a blank membrane;
(2) Preparing ink: preparing 17% n-propanol solution with boiled and cooled distilled water, and adding a certain amount of tannic acid to form 23.5mM tannic acid solution to obtain TA ink; preparing 17% n-propanol solution with distilled water, and preparing 11.75mM Fe from the above solution respectively 2 (SO 4 ) 3 Solution and 47mM NaIO 4 Obtaining Fe ink and SP ink by solution;
(3) Equipping an ink box: injecting the three inks prepared in the step (2) into three commercial HP ink boxes respectively by using injectors, and equipping an HP desk 1112 printer for testing;
(4) Ink-jet printing: and (3) adhering the blank film treated in the step (1) to A4 paper, firstly printing 2 times of Fe ink, then printing 1 time of TA ink, and finally printing 1 time of SP ink, and keeping the obtained film at room temperature for 15min to obtain the Fe-TA-SP composite separation film.
(5) Washing and drying: and (4) thoroughly cleaning the composite separation membrane prepared in the step (4) with pure water for 2-3 times, drying at 40 ℃, and then placing in a sealed bag for storage.
Example 7: preparation of hydrophilic Fe-TA-SP composite separation membrane
(1) Treatment of blank films: firstly, soaking a polyvinylidene fluoride membrane in ethanol for 30min, removing stains on the surface of the membrane, then ultrasonically cleaning the membrane for 2-3 times by pure water, and finally drying at 60 ℃ to obtain a blank membrane;
(2) Preparing ink: preparing 17% n-propanol solution with boiled and cooled distilled water, and adding a certain amount of tannic acid to form 23.5mM tannic acid solution to obtain TA ink; preparing 17% n-propanol solution with distilled water, and preparing 11.75mM Fe from the above solution respectively 2 (SO 4 ) 3 Solution and 47mM NaIO 4 Obtaining Fe ink and SP ink by solution;
(3) Equipping an ink box: injecting the three inks prepared in the step (2) into three commercial HP ink boxes respectively by using injectors, and equipping an HP desk 1112 printer for testing;
(4) Ink-jet printing: and (3) adhering the blank film treated in the step (1) to A4 paper, firstly printing 3 times of Fe ink, then printing 1 time of TA ink, and finally printing 1 time of SP ink, and keeping the obtained film at room temperature for 15min to obtain the Fe-TA-SP composite separation film.
(5) Washing and drying: and (4) thoroughly cleaning the composite separation membrane prepared in the step (4) with pure water for 2-3 times, drying at 40 ℃, and then placing in a sealed bag for storage.
Example 8: preparation of hydrophilic Fe-TA-SP composite separation membrane
(1) Treatment of blank films: firstly, soaking a polyvinylidene fluoride membrane in ethanol for 30min, removing stains on the surface of the membrane, then ultrasonically cleaning the membrane for 2-3 times by pure water, and finally drying at 60 ℃ to obtain a blank membrane;
(2) Preparing ink: preparing 17% n-propanol solution with boiled and cooled distilled water, and adding a certain amount of tannic acid to form 23.5mM tannic acid solution to obtain TA ink; preparing 17% n-propanol solution with distilled water, and preparing 11.75mM Fe from the above solution respectively 2 (SO 4 ) 3 Solution and 47mM NaIO 4 Obtaining Fe ink and SP ink by solution;
(3) Equipping an ink box: injecting the three inks prepared in the step (2) into three commercial HP ink boxes respectively by using injectors, and equipping an HP desk 1112 printer for testing;
(4) Ink-jet printing: and (3) adhering the blank film treated in the step (1) to A4 paper, firstly printing 5 times of Fe ink, then printing 1 time of TA ink, and finally printing 1 time of SP ink, and keeping the obtained film at room temperature for 15min to obtain the Fe-TA-SP composite separation film.
(5) Washing and drying: and (5) thoroughly washing the composite separation membrane prepared in the step (4) by pure water for 2-3 times, drying at 40 ℃, and placing in a sealed bag for storage.
Example 9: preparation of hydrophilic Fe-TA-SP composite separation membrane
(1) Treatment of blank films: firstly, soaking a polyvinylidene fluoride membrane in ethanol for 30min, removing stains on the surface of the membrane, then ultrasonically cleaning the membrane for 2-3 times by pure water, and finally drying at 60 ℃ to obtain a blank membrane;
(2) Preparing ink: preparing 17% n-propanol solution with boiled and cooled distilled water, and adding a certain amount of tannic acid to form 23.5mM tannic acid solution to obtain TA ink; preparing 17% n-propanol solution with distilled water, and preparing 11.75mM Fe from the above solution respectively 2 (SO 4 ) 3 Solution and 47mM NaIO 4 Obtaining Fe ink and SP ink by solution;
(3) Equipping an ink box: injecting the three inks prepared in the step (2) into three commercial HP ink boxes respectively by using injectors, and equipping an HP desk 1112 printer for testing;
(4) Ink-jet printing: and (3) adhering the blank film treated in the step (1) to A4 paper, firstly printing 4 times of Fe ink, then printing 1 time of TA ink, and finally printing 2 times of SP ink, and keeping the obtained film at room temperature for 15min to obtain the Fe-TA-SP composite separation film.
(5) Washing and drying: and (4) thoroughly cleaning the composite separation membrane prepared in the step (4) with pure water for 2-3 times, drying at 40 ℃, and then placing in a sealed bag for storage.
Example 10: preparation of hydrophilic Fe-TA-SP composite separation membrane
(1) Treatment of blank films: firstly, soaking a polyvinylidene fluoride membrane in ethanol for 30min, removing stains on the surface of the membrane, then ultrasonically cleaning the membrane for 2-3 times by pure water, and finally drying at 60 ℃ to obtain a blank membrane;
(2) Preparing ink: preparing 17% n-propanol solution with boiled and cooled distilled water, and adding a certain amount of tannic acid to form 23.5mM tannic acid solution to obtain TA ink; preparing 17% n-propanol solution with distilled water, and preparing 11.75mM Fe from the above solution respectively 2 (SO 4 ) 3 Solution and 47mM NaIO 4 Obtaining Fe ink and SP ink by solution;
(3) Equipping an ink box: injecting the three inks prepared in the step (2) into three commercial HP ink boxes respectively by using injectors, and equipping an HP desk 1112 printer for testing;
(4) Ink-jet printing: and (3) adhering the blank film treated in the step (1) to A4 paper, firstly printing 6 times of Fe ink, then printing 1 time of TA ink, and finally printing 3 times of SP ink, and keeping the obtained film at room temperature for 15min to obtain the Fe-TA-SP composite separation film.
(5) Washing and drying: and (4) thoroughly cleaning the composite separation membrane prepared in the step (4) with pure water for 2-3 times, drying at 40 ℃, and then placing in a sealed bag for storage.
Example 11: preparation of hydrophilic Fe-TA-SP composite separation membrane
(1) Treatment of blank films: firstly, soaking a polyvinylidene fluoride membrane in ethanol for 30min, removing stains on the surface of the membrane, then ultrasonically cleaning the membrane for 2-3 times by pure water, and finally drying at 60 ℃ to obtain a blank membrane;
(2) Preparing ink: preparing 17% n-propanol solution with boiled and cooled distilled water, and adding a certain amount of tannic acid to form 23.5mM tannic acid solution to obtain TA ink; preparing 17% n-propanol solution with distilled water, and preparing 11.75mM Fe from the above solution respectively 2 (SO 4 ) 3 Solution and 47mM NaIO 4 Obtaining Fe ink and SP ink by using the solution;
(3) Equipping an ink box: injecting the three inks prepared in the step (2) into three commercial HP ink boxes respectively by using injectors, and equipping an HP desk 1112 printer for testing;
(4) Ink-jet printing: and (2) sticking the blank film treated in the step (1) on A4 paper, firstly printing 6 times of Fe ink, then printing 3 times of TA ink, finally printing 3 times of SP ink, and keeping the obtained film at room temperature for 15min to obtain the Fe-TA-SP composite separation film.
(5) Washing and drying: and (4) thoroughly cleaning the composite separation membrane prepared in the step (4) with pure water for 2-3 times, drying at 40 ℃, and then placing in a sealed bag for storage.
Comparative example 1: preparation of Fe-TA composite separation membrane
(1) Treatment of blank films: firstly, soaking a polyvinylidene fluoride membrane in ethanol for 30min, removing stains on the surface of the membrane, then ultrasonically cleaning the membrane for 2-3 times by pure water, and finally drying at 60 ℃ to obtain a blank membrane;
(2) Preparing ink: preparing 17% n-propanol solution with boiled and cooled distilled water, and adding a certain amount of tannic acid to form 23.5mM tannic acid solution to obtain TA ink; a17% n-propanol solution was prepared using distilled water, and 11.75mM Fe was prepared using the above solution 2 (SO 4 ) 3 Obtaining Fe ink by the solution;
(3) Equipping an ink box: injecting the two kinds of ink prepared in the step (2) into two commercial HP ink cartridges respectively by using injectors, and equipping an HP desk top 1112 printer for testing;
(4) Ink-jet printing: and (3) adhering the blank film treated in the step (1) to A4 paper, firstly printing 4 times of Fe ink, then printing 2 times of TA ink, and keeping the obtained film at room temperature for 15min to obtain the Fe-TA composite separation film.
(5) Washing and drying: and (4) thoroughly cleaning the composite separation membrane prepared in the step (4) with pure water for 2-3 times, drying at 40 ℃, and then placing in a sealed bag for storage.
Comparative example 2: preparation of TA-SP composite separation membrane
(1) Treatment of blank films: firstly, soaking a polyvinylidene fluoride membrane in ethanol for 30min, removing stains on the surface of the membrane, then ultrasonically cleaning the membrane for 2-3 times by pure water, and finally drying at 60 ℃ to obtain a blank membrane;
(2) Preparing ink: preparing 17% n-propanol solution with boiled and cooled distilled water, and adding a certain amount of tannic acid to form 23.5mM tannic acid solution to obtain TA ink; a17% n-propanol solution was prepared using distilled water, and 47mM NaIO was prepared using the above solution 4 Obtaining SP ink;
(3) Equipping an ink box: injecting the two kinds of ink prepared in the step (2) into two commercial HP ink cartridges respectively by using injectors, and equipping an HP desk top 1112 printer for testing;
(4) Ink-jet printing: and (3) adhering the blank membrane treated in the step (1) to A4 paper, firstly printing 2 times of TA ink, then printing 2 times of SP ink, and keeping the obtained membrane at room temperature for 15min to obtain the TA-SP composite separation membrane.
(5) Washing and drying: and (4) thoroughly cleaning the composite separation membrane prepared in the step (4) with pure water for 2-3 times, drying at 40 ℃, and then placing in a sealed bag for storage.
To further illustrate the excellent effects of the composite separation membrane prepared by the present invention, the inventors also conducted the following tests:
measurement of Water contact Angle of Fe-TA-SP composite separation Membrane
Table 1 shows the results of measuring the water contact angles of the Fe-TA-SP composite separation membranes obtained in examples 1 to 11
TABLE 1
Figure BDA0003521841100000161
Figure BDA0003521841100000171
As can be seen from Table 1, the method of the invention can successfully coat the tannin coating on the surface of the polymer substrate, so that the hydrophilicity of the modified membrane is obviously improved compared with that of a blank PVDF membrane (the contact angles of the blank PVDF membrane are respectively 87.8 degrees), and the requirement on oil-water separation application is fully met.
In addition, as can be seen from table 1, the hydrophilicity of the modified film is greatly affected by the number of printing passes of the trivalent ferric salt, the tannic acid and the sodium periodate, and the optimal parameters are 4 times for the trivalent ferric salt, 2 times for the tannic acid and 2 times for the sodium periodate.
(II) morphology study of separation Membrane
The morphology of the Fe-TA-SP composite separation membrane prepared in example 1 was studied using Scanning Electron Microscopes (SEM) of different magnifications, and compared with the morphologies of a blank PVDF membrane, a separation membrane without printed sodium periodate (i.e., the Fe-TA composite separation membrane of comparative example 1), and a separation membrane without printed ferric salt (i.e., the TA-SP composite separation membrane of comparative example 2), as shown in fig. 2.
As can be seen from FIG. 2, the surface of the blank PVDF membrane is a porous and interconnected fiber network structure; the other three composite separation membranes exhibited a uniform and distinct coating color in appearance compared to the blank PVDF membrane. The surface of the Fe-TA composite separation membrane of comparative example 1 appeared purple, the surface of the TA-SP composite separation membrane of comparative example 2 appeared light yellow, and the surface of the Fe-TA-SP composite separation membrane prepared in example 1 appeared brown, indicating that the coating of the tannic acid polymer on the PVDF membrane could be successfully applied by the inkjet printing method. As can be seen from the SEM images, the deposits on the surface of the Fe-TA-SP composite separation membrane printed with Fe, TA and SP at the same time were significantly more than those of the Fe-TA composite separation membrane and the TA-SP composite separation membrane, the membrane pores thereof were the smallest among the three kinds of membranes, and the deposits on the surface of the membrane were uniformly distributed, closely bonded to the matrix of the membrane, and no aggregation of large particles was observed. The above results indicate that the combined action of Fe and SP can increase the deposition amount of TA.
(III) oil-water separation application
10ml of oil-red-dyed oil was added to 990ml of ultrapure water, and 20mg of Twen 80 as an emulsifier was added, followed by stirring at 10000rpm for 2 hours to obtain a diesel/water emulsion.
The Fe-TA-SP composite separation membrane prepared in the example 1 is arranged in a filtering device, the separation test of oil-water emulsion is carried out under the pressure of 0.4Mpa, and the membrane flux and the retention rate of the composite separation membrane to different oil-water emulsion are examined, wherein the examined conditions comprise that:
(1) filtering the gasoline emulsion, (2) filtering the diesel oil emulsion; (3) filtering the soy oil emulsion; (4) flux recovery test after 8 cycles of filtration in (1), (2) and (3) above.
The membrane flux (J), rejection (R) and flux recovery (FRR) were calculated using the formulas (1) to (3), respectively:
J＝V/(A×Δt) (1)
R＝(1-C 1 /C 0 )×100％ (2)
FRR＝(J p2 /J p1 )×100％ (3)
wherein V is the volume of filtrate (L) and A is the effective area of the membrane (m) 2 ) Δ t is the sampling time interval (h), C 1 And C 0 The oil concentrations in the filtrate and the stock solution (mg. ML) were measured -1 )，J p1 And J p2 Respectively the initial water flux and the recovery water flux (L.m) -2 ·h -1 ·bar -1 )。
As shown in FIG. 3, the retention rate of the Fe-TA-SP composite separation membrane prepared in example 1 on gasoline or diesel emulsion can reach 98%, and the flux can reach 7340.4 L.m -2 ·h -1 ·bar -1 And 4968.4L · m -2 ·h -1 ·bar -1 The retention rate of the soybean oil emulsion can reach 99.3 percent, and the flux can reach 5501.8 L.m -2 ·h -1 ·bar -1 Compared with a blank PVDF film, the composite film has obvious improvement. Therefore, the Fe-TA-SP composite separation membrane prepared by the invention shows excellent performance on the separation of oily wastewater.
As shown in fig. 4, the final FRR of the Fe-TA-SP composite separation membrane prepared in example 1 for eight filtrations of gasoline, diesel and soybean oil emulsions reached 98.0%, 89.1% and 93.4%, respectively, which were much higher than the FRR of the blank PVDF membrane for three emulsions, 51.3% (gasoline), 43.2% (diesel) and 36.0% (soybean oil), respectively. Therefore, the Fe-TA-SP composite separation membrane prepared by the method shows excellent anti-pollution performance on oily wastewater.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims (8)

1. A method of making a composite separation membrane, comprising:
sequentially printing a metal salt solution, a polyphenol solution and an oxidant solution on the surface of a polymer substrate by ink-jet printing, and reacting the metal salt solution, the polyphenol solution and the oxidant solution to form a modified layer on the surface of the polymer substrate to obtain a composite separation membrane;
the concentration ratio of the metal salt solution, the polyphenol solution and the oxidant solution is 1 (1.8-2.2) to 3.8-4.2, and the printing frequency ratio of the metal salt solution, the polyphenol solution and the oxidant solution is 1-10 to 1-5;
the metal salt used in the metal salt solution is ferric sulfate or ferric chloride.
2. The production method according to claim 1, wherein the concentration of the metal salt solution is 23.5mmol/L or less; the concentration of the polyphenol solution is below 47 mmol/L; the concentration of the oxidant solution is less than 94mmol/L.
3. The manufacturing method according to claim 1, wherein the number of printing of the metal salt solution is 1 to 6 passes, the number of printing of the polyphenol solution is 1 to 3 passes, and the number of printing of the oxidant solution is 1 to 3 passes.
4. The production method according to claim 1,
the preparation method of the metal salt solution comprises the following steps: dissolving the metal salt in a solvent, the solvent being water, an alcohol or a mixture thereof;
the preparation method of the polyphenol solution comprises the following steps: dissolving a polyphenol in a solvent, wherein the polyphenol is tannic acid and the solvent is water, alcohol or a mixture thereof;
the preparation method of the oxidant solution comprises the following steps: an oxidizing agent is dissolved in a solvent, the oxidizing agent is at least one of sodium periodate, potassium permanganate and potassium dichromate, and the solvent is water, alcohol or a mixture thereof.
5. The production method according to claim 1,
the polymer substrate is polyester, polypropylene, polyvinylidene fluoride, polysulfone or polyethylene;
the reaction time is 5-60min.
6. The method of claim 1, further comprising: after the reaction is completed, washing and drying are performed.
7. The composite separation membrane obtained by the production method according to any one of claims 1 to 6, characterized in that a water contact angle is 70 ° or less; the retention rate of the oil-containing emulsion under the pressure of 0.4Mpa reaches more than 98 percent, and the flux reaches 4968.4 L.m -2 ·h -1 ·bar -1 The above; the flux recovery rate reaches more than 89.1 percent.
8. Use of the composite separation membrane of claim 7 in the treatment of oily wastewater.
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