CN115090132A - Self-cleaning composite membrane with catalytic separation function and preparation method thereof - Google Patents

Self-cleaning composite membrane with catalytic separation function and preparation method thereof Download PDF

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Publication number
CN115090132A
CN115090132A CN202210935594.XA CN202210935594A CN115090132A CN 115090132 A CN115090132 A CN 115090132A CN 202210935594 A CN202210935594 A CN 202210935594A CN 115090132 A CN115090132 A CN 115090132A
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membrane
pmaa
self
pvdf
catalytic
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陈熙
史鑫
王建祖
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Tianjin Polytechnic University
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Tianjin Polytechnic University
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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
    • B01D67/0079—Manufacture of membranes comprising organic and inorganic components
    • 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
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/02—Inorganic material
    • B01D71/022—Metals
    • 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
    • B01D71/02—Inorganic material
    • B01D71/024—Oxides
    • 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
    • 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
    • B01D71/58—Other polymers having nitrogen in the main chain, with or without oxygen or carbon only
    • B01D71/60—Polyamines
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • B01J21/063—Titanium; Oxides or hydroxides thereof
    • B01J35/39—
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2321/00—Details relating to membrane cleaning, regeneration, sterilization or to the prevention of fouling
    • B01D2321/34—Details relating to membrane cleaning, regeneration, sterilization or to the prevention of fouling by radiation
    • B01D2321/343—By UV radiation

Abstract

The invention relates to a self-cleaning composite membrane with a catalytic separation function and a preparation method thereof, wherein the preparation method comprises the following steps: (1) blending PMAA microspheres and PVDF powder and scraping the membrane, (2) utilizing an in-situ reduction method to carry out negative loading on the PMAA microspheres in membrane poresCarrying Pd metal nano particles to form a catalytic membrane, (3) coating a Polydopamine (PDA) layer on the surface of the catalytic membrane by utilizing the self-polymerization reaction of Dopamine (DA) under the alkaline condition, (4) carrying out liquid phase deposition on titanium dioxide (TiO) 2 ) The nanoparticles are deposited on the polydopamine. The prepared composite membrane has good hydrophilicity, anti-pollution performance and interception performance, can realize catalytic reaction and product separation coupling, has a self-cleaning function, and has good application prospects in the aspects of separation and degradation of multi-component mixtures, oil-water interface reaction and the like.

Description

Self-cleaning composite membrane with catalytic separation function and preparation method thereof
Technical Field
The invention relates to the field of membrane catalysis and separation, in particular to an organic-inorganic composite membrane with self-cleaning and catalytic separation functions and a preparation method thereof.
Background
PVDThe F film has excellent thermal stability, aging resistance, good chemical stability and high mechanical strength, and has been widely applied in the fields of gas separation, seawater desalination, ultrapure water preparation, sewage treatment and the like, but the PVDF film has lower surface energy, stronger hydrophobicity, more prominent pollution along with the increase of the use time, and rapid performance reduction. At present, methods for preparing a contamination-resistant membrane by means of membrane modification by introducing a hydrophilic polymer can be classified into physical methods and chemical methods. The blending method is the most basic method for physical modification, although the blending method is simple, the compatibility of the hydrophilic polymer and the hydrophobic PVDF membrane matrix is poor, the hydrophilic polymer is easy to diffuse into an aqueous solution in the phase inversion process, the hydrophilicity of the obtained blending membrane cannot achieve the expected effect, and the pollution resistance is not ideal. The chemical method is to connect related functional groups with membrane surface groups through chemical bonding, so that the functional groups cannot be lost, but the experimental conditions are harsh, the steps are complicated, and PVDF chains on the membrane surface can be broken. Therefore, the preparation of film materials with good stain resistance remains a challenge. Titanium dioxide (TiO) 2 ) As a novel nano material, the inorganic nano particles have good physical and chemical stability, thermal stability, nontoxicity, super-hydrophilicity, self-cleaning performance and the like, and are widely researched and applied in various fields. The titanium dioxide inorganic nanoparticles are used for modifying the membrane, so that the hydrophilicity and the pollution resistance of the membrane are expected to be improved, and the self-cleaning performance of the membrane is endowed.
On the other hand, although PVDF membranes are widely used in industry, they are limited to separation and purification, and the field is relatively single. In recent years, people load a nano catalyst on a membrane substrate to prepare a series of catalytic membranes, so that the activity of the nano catalyst is well exerted, the operation and the use are convenient, and the operation cost is greatly saved. However, most of the currently reported catalytic membranes are used as catalyst materials, and in use, reactants and products are in contact for a long time, so that side reactions are easy to occur and the reaction efficiency is reduced. Moreover, a large amount of reactants and products coexist, and the separation operation is complicated and high in cost. Therefore, research on preparing a composite membrane integrating catalytic reaction and separation is urgently needed.
Hair brushFirstly, preparing polymethacrylic acid (PMAA) microspheres with carboxyl functional groups by a distillation precipitation method, then blending the polymethacrylic acid microspheres and PVDF powder and scraping a membrane, and then preparing the catalytic membrane with palladium nano particles attached in membrane pores by palladium ion chelation and in-situ reduction in sequence. Then further adopting a dopamine coating to modify the surface of the catalytic membrane and adopting a liquid phase deposition method to remove TiO 2 The nano particles are deposited on Polydopamine (PDA) on the surface of the catalytic membrane to obtain the composite membrane. TiO 2 2 The nano particles are tightly combined with the surface of the membrane through the PDA, so that the membrane has good hydrophilicity and self-cleaning function. During the catalytic reaction, reactants do not react with titanium dioxide on the surface layer, enter the membrane and then contact with the metal catalyst on the lower layer to perform catalytic reaction, and then products are discharged from a reaction system through osmotic flow. The prepared composite membrane has the functions of catalysis and separation, and can realize the complete separation of reactants and products in an operation mode; in addition, TiO on the surface of the film 2 The nano particles can degrade organic pollutants under the irradiation of ultraviolet light, so that the film also has self-cleaning performance.
Disclosure of Invention
The invention relates to a PVDF composite membrane with self-cleaning and catalytic separation functions and a preparation method thereof. Firstly, preparing a blend membrane by a solution precipitation phase inversion method, uniformly distributing polymethacrylic acid (PMAA) microspheres in pores of a PVDF membrane, and then loading palladium nanoparticles by carboxylate radicals on the microspheres; then modifying the membrane surface by dopamine, and then further depositing TiO by liquid phase deposition method 2 The nano particles are deposited on the polydopamine on the surface of the membrane to prepare the organic-inorganic composite membrane. Because the hydrophilic titanium dioxide nano particles are arranged on the surface layer of the membrane, the membrane has better hydrophilicity and pollution resistance. Meanwhile, under the irradiation of ultraviolet light, the titanium dioxide nano particles on the surface layer have better catalytic degradation performance on surface pollutants, so that the film has a good self-cleaning function. By depositing titanium dioxide on the surface of the catalytic membrane, reactants can only react in a permeate flow in a cross flow mode, but do not react on the surface of the membrane, so that the automatic separation of the reactants and products in the cross flow mode is realized. The oil phase and the water phase can be catalyzed by placing the membrane at the oil-water interfaceReacting, gradually converting the oil-phase reactant into a product, and separating from the water phase. Therefore, the novel organic-inorganic composite membrane designed and prepared by the invention has self-cleaning function, and simultaneously has catalysis and separation functions, and has good application prospect in the aspects of reaction separation and the like.
The technical scheme for solving the technical problem of the preparation method of the product is as follows: palladium nano particles are loaded in membrane pores of the PVDF membrane, and then inorganic titanium dioxide with hydrophilicity and self-cleaning function is loaded on the surface of the membrane, so that the composite membrane with self-cleaning function, catalytic reaction and separation coupling function is designed and prepared. The preparation process comprises the following steps:
(1) preparing PMAA microspheres: dissolving monomer methacrylic acid, cross-linking agent ethylene glycol dimethacrylate and initiator azobisisobutyronitrile into acetonitrile, heating and polymerizing in a single-neck flask, and centrifuging, washing and drying to obtain PMAA microspheres;
(2) preparation of PVDF/PMAA membranes: dispersing PVDF powder, the PMAA microspheres prepared in the step 1 and a pore-forming agent in a solvent according to a ratio, magnetically stirring for 6 hours at 70 ℃, defoaming in vacuum for 30 minutes to prepare a membrane casting solution, scraping the membrane casting solution on a clean and flat glass plate to prepare a liquid membrane, and solidifying and forming in a solidifying bath at 25 ℃ to obtain a PVDF/PMAA membrane;
(3) preparation of PVDF/PMAA @ Pd membranes: the PVDF/PMAA membrane prepared in the step 2 is soaked in 100mL of 0.1mol/L aqueous solution of sodium hydroxide for 12 hours, washed by deionized water for 3 times, and then placed in 100mL of 0.11 mmol/L-0.44 mmol/L PdCl 2 Soaking in the solution for 12h, washing with deionized water for 3 times, and placing in NaBH with concentration of 1g/L 4 Soaking the solution in 100mL for 1h to obtain a PVDF/PMAA @ Pd membrane;
(4) preparation of TiO 2 PVDF/PMAA @ Pd catalytic separation composite membrane: adding 1.2g dopamine hydrochloride into Tris-HCl solution with pH value of 8.5 to prepare 2g/L dopamine solution, circulating the solution on the surface of the catalytic membrane prepared in the step 3 for 6h to form a polydopamine layer, and then using the polydopamine layer with the concentrations of 0.1mol/L and 0.4mol/L (NH4) 2 TiF 6 And H 3 BO 3 Soaking 200mL of the mixed solution for 60-180min to prepare the TiO 2 PVDF/PMAA @ Pd composite membrane.
The invention relates to a preparation method of a PVDF composite membrane with self-cleaning and catalytic separation functions, which is characterized in that PVDF powder and PMAA microspheres are dispersed in a solvent to form a membrane casting solution, then the membrane casting solution is scraped to form a membrane, metal palladium nanoparticles are attached to the PMAA microspheres by an in-situ reduction method, then dopamine reacts on the surface of the membrane to form a polydopamine coating, and inorganic titanium dioxide nanoparticles are further attached to the polydopamine coating, so that the PVDF composite membrane with self-cleaning, catalytic reaction and separation functions is prepared. The advantages are that: (1) the polymethacrylic acid microspheres provide attachment sites for the catalyst, avoid the agglomeration and loss of the metal nano catalyst, and overcome the defects of the lack of functional groups of PVDF (polyvinylidene fluoride) or the degradation of chain segments in the modification process, the complex modification process and the like. (2) The polydopamine coating on the surface of the membrane ensures that titanium dioxide nano particles are well distributed on the surface of the membrane, improves the hydrophilicity of the composite membrane, enhances the pollution resistance of the composite membrane, and endows the composite membrane with a better self-cleaning function. (3) The titanium dioxide nano particles isolate metal catalyst nano particles on the surface of the membrane, so that the catalytic reaction of the composite membrane only occurs on a PVDF/PMAA @ Pd layer, and the reactant can be separated from the catalytic reaction product in time under the cross-flow catalytic operation mode or under the oil-water interface reaction condition.
The solvent of the invention is a solvent capable of dissolving PVDF and obtaining a uniform solution, and is a solvent such as N, N '-Dimethylformamide (DMF), N' -dimethylacetamide (DMAc) or N-methylpyrrolidone.
The pore-forming agent in the invention is understood to be a substance capable of forming pores in the casting solution during the curing process, and includes polyoxyethylene-b-polyoxypropylene-b-polyoxyethylene (F127), polyvinylpyrrolidone (PVP), polyethylene glycol (PEG) and the like.
The coagulating bath is non-solvent substances such as deionized water or ethanol.
The PVDF/PMAA membrane is prepared by a solution precipitation phase inversion method through a membrane casting solution consisting of 3.0-5.0g of PVDF powder, 1.0g of PMAA microspheres, 0.0235g-1.0g of pore-foaming agent and 19.5g-44.0g of solvent; the catalytic reaction separation composite membrane is prepared by allowing a PVDF/PMAA membrane to pass through palladium chloride with the concentration of 0.11-0.44mmoL/LPalladium is loaded on the aqueous solution, 1.2g of dopamine hydrochloride is added into a dopamine solution (2g/L) prepared from Tris-HCl (pH 8.5) solution to treat the surface of the membrane for 6h, and then 200mL of 0.1mol/L (NH) 4 ) 2 TiF 6 And 0.4mol/LH 3 BO 3 The mixed solution is soaked on the surface of the film for 60-180min and then loaded with TiO 2 And then the compound is prepared. Under the cross-flow catalysis or oil-water interface reaction mode, reactants and catalytic products are separated in time, and the longer the titanium dioxide loading time is, the higher the concentration of the palladium chloride aqueous solution is, and the better the catalytic separation effect is.
Detailed Description
The invention relates to a self-cleaning and catalytic separation functional composite membrane and a preparation method thereof. The composite membrane selects polymethacrylic acid (PMAA) microspheres as a palladium metal nanoparticle carrier, is blended with PVDF powder, is formed into a membrane by a solution precipitation phase inversion method, is treated by an alkali solution, is soaked by a palladium chloride solution, is reduced by sodium borohydride, is further subjected to loading of a surface polydopamine coating and generation of inorganic titanium dioxide particles on the surface of the membrane, and is finally prepared to obtain the self-cleaning and catalytic separation functional composite membrane.
The self-cleaning and catalytic separation functional composite membrane and the preparation method thereof according to the present invention will be further described by examples.
Example 1
(1) Adding 0.12g of initiator AIBN, 3g of cross-linking agent EGDMA, 3g of MAA monomer and 160mL of acetonitrile into a clean single-neck flask, and carrying out reflux reaction for 2 hours at 80 ℃ under the condition of magnetic stirring; then the reaction solution cooled to room temperature is centrifugally precipitated, washed by acetonitrile and water and repeated for 3 times; and (3) drying the obtained product in a vacuum drying oven at 60 ℃ to constant weight to obtain the PMAA microspheres.
(2) Adding 3.0g of PVDF powder and 1.0g of PMAA microspheres obtained in the step (1) into 19.5g of DMF (dimethyl formamide), N' -dimethylacetamide (DMAc) or N-methylpyrrolidone (NMP), adding 0.0235g to 0.235g of pore-forming agent F127 or PVP or PEG, magnetically stirring for 6 hours at 70 ℃, carrying out vacuum defoamation for 30 minutes to form a casting solution, pouring the casting solution on a clean glass plate, scraping the casting solution into a liquid film by a film scraper, and solidifying the casting solution into a film in water or ethanol at 25 ℃.
(3) Soaking the membrane prepared in the step (2) in 100mL of 0.1mol/L sodium hydroxide aqueous solution for 12h, and then repeatedly washing with deionized water for 3 times to remove residual NaOH on the membrane; placing the membrane after alkali treatment in 100mL of PdCl with the concentration of 0.11mmol/L 2 Soaking in the solution for 12h, and washing with deionized water for 3 times to remove PdCl remaining on the surface of the membrane 2 Then put into NaBH of 1g/L 4 Soaking the solution in 100mL for 1h to obtain the PVDF/PMAA @ Pd catalytic membrane.
(4) Adding 1.2g of dopamine hydrochloride into a Tris-HCl solution with the pH value of 8.5 at room temperature to prepare a 2g/L dopamine solution, circulating the solution on the surface of the catalytic membrane prepared in the step (3) for 6h to form a polydopamine layer, and then using the polydopamine layer with the concentrations of 0.1mol/L and 0.4mol/L (NH4) 2 TiF 6 And H 3 BO 3 Soaking 200mL of the mixed solution for 60min to ensure that TiO 2 Inorganic nano particles are loaded on the surface of the membrane to prepare the TiO 2 PVDF/PMAA @ Pd composite membrane.
Example 2
(1) Same as example 1
(2) Same as example 1
(3) Soaking the membrane prepared in the step (2) in 100mL of 0.1mol/L aqueous solution of sodium hydroxide for 12h, then washing with deionized water for 3 times, and removing residual NaOH on the membrane; the membrane after the alkali treatment is placed in 100mL of PdCl with the concentration of 0.22mmol/L 2 Soaking in the solution for 12h, and washing with deionized water for 3 times to remove PdCl residue on the surface of the membrane 2 Then put into NaBH of 1g/L 4 Soaking the solution in 100mL for 1h to obtain the PVDF/PMAA @ Pd catalytic membrane.
(4) Same as example 1
Example 3
(1) Same as example 1
(2) Same as example 1
(3) Soaking the membrane prepared in the step (2) in 100mL of 0.1mol/L sodium hydroxide aqueous solution for 12h, then washing with deionized water for 3 times, and removing residual NaOH on the membrane; placing the membrane after alkali treatment in 100mL of PdCl with the concentration of 0.44mmol/L 2 Soaking in the solution for 12h, and washing with deionized water for 3 times to remove PdCl residue on the surface of the membrane 2 Then placed in a container of 1gNaBH of/L 4 Soaking the solution in 100mL for 1h to obtain the PVDF/PMAA @ Pd catalytic membrane.
(4) Same as example 1
Example 4
(1) Same as example 1
(2) Same as example 1
(3) Same as example 2
(4) Adding 1.2g dopamine hydrochloride into Tris-HCl solution with pH value of 8.5 at room temperature to prepare 2g/L dopamine solution, circulating the dopamine solution on the surface of the catalytic membrane prepared in the step (3) for 6h to form a polydopamine layer, and then using (NH4) with the concentration of 0.1mol/L and 0.4mol/L respectively 2 TiF 6 And H 3 BO 3 Soaking 200mL of the mixed solution for 90min to ensure that TiO 2 Inorganic nano particles are loaded on the surface of the membrane to prepare the TiO 2 PVDF/PMAA @ Pd composite membrane.
Example 5
(1) Same as example 1
(2) Same as example 1
(3) Same as example 2
(4) Adding 1.2g dopamine hydrochloride into Tris-HCl solution with pH value of 8.5 at room temperature to prepare 2g/L dopamine solution, circulating the dopamine solution on the surface of the catalytic membrane prepared in the step (3) for 6h to form a polydopamine layer, and then using (NH4) with the concentration of 0.1mol/L and 0.4mol/L respectively 2 TiF 6 And H 3 BO 3 Soaking 200mL of the mixed solution for 120min to ensure that TiO 2 Inorganic nano particles are loaded on the surface of the membrane to prepare the TiO 2 PVDF/PMAA @ Pd composite membrane.
Example 6
(1) Same as example 1
(2) Same as example 1
(3) Same as example 2
(4) Adding 1.2g dopamine hydrochloride into Tris-HCl solution with pH value of 8.5 at room temperature to prepare 2g/L dopamine solution, circulating the dopamine solution on the surface of the catalytic membrane prepared in the step (3) for 6h to form a polydopamine layer, and then using (NH4) with the concentration of 0.1mol/L and 0.4mol/L respectively 2 TiF 6 And H 3 BO 3 Soaking 200mL of the mixed solution for 150min to ensure that TiO 2 Inorganic nano particles are loaded on the surface of the membrane to prepare the TiO 2 PVDF/PMAA @ Pd composite membrane.
Example 7
(1) Same as example 1
(2) Same as example 1
(3) Same as example 2
(4) Adding 1.2g dopamine hydrochloride into Tris-HCl solution with pH value of 8.5 at room temperature to prepare 2g/L dopamine solution, circulating the dopamine solution on the surface of the catalytic membrane prepared in the step (3) for 6h to form a polydopamine layer, and then using (NH4) with the concentration of 0.1mol/L and 0.4mol/L respectively 2 TiF 6 And H 3 BO 3 Soaking 200mL of the mixed solution for 180min to ensure that TiO 2 Inorganic nano particles are loaded on the surface of the membrane to prepare the TiO 2 PVDF/PMAA @ Pd composite membrane.
Example 8
(1) Same as example 1
(2) Adding 4.0g of PVDF powder and 1.0g of PMAA microspheres obtained in the step (1) into 24.4g of DMF (dimethyl formamide), N' -dimethylacetamide (DMAc) or N-methylpyrrolidone (NMP), adding 0.0294g to 0.294g of pore-forming agent F127 or PVP or PEG, magnetically stirring at 70 ℃ for 6 hours, carrying out vacuum defoaming for 30 minutes to form a casting solution, pouring the casting solution on a clean glass plate, scraping the casting solution into a liquid film by a film scraper, and solidifying the liquid film in water or ethanol at 25 ℃ to form the film.
(3) The same as example 1 or example 2 or example 3
(4) The same as example 1 or example 4 or example 5 or example 6 or example 7
Example 9
(1) Same as example 1
(2) Adding 5.0g of PVDF powder and 1.0g of PMAA microspheres obtained in the step (1) into 29.3g of DMF (dimethyl formamide), N' -dimethylacetamide (DMAc) or N-methylpyrrolidone (NMP), adding 0.0353g-0.353g of pore-forming agent F127 or PVP or PEG, magnetically stirring at 70 ℃ for 6h, carrying out vacuum defoaming for 30min to form a casting solution, pouring the casting solution on a clean glass plate, scraping with a film scraper to form a liquid film, and solidifying in water or ethanol at 25 ℃ to form the film.
(3) The same as example 1 or example 2 or example 3
(4) The same as example 1 or example 4 or example 5 or example 6 or example 7
Example 10
(1) Same as example 1
(2) Adding 3.0g of PVDF powder and 1.0g of PMAA microspheres obtained in the step (1) into 29.3g of DMF (dimethyl formamide), N' -dimethylacetamide (DMAc) or N-methylpyrrolidone (PVP) solvent, adding 0.0333g to 0.333g of pore-forming agent F127 or PVP or PEG, magnetically stirring at 70 ℃ for 6 hours, carrying out vacuum defoaming for 30 minutes to form a casting solution, pouring the casting solution on a clean glass plate, scraping the casting solution into a liquid film by a film scraper, and solidifying the liquid film in water or ethanol at 25 ℃ to form the film.
(3) The same as example 1 or example 2 or example 3
(4) Same as example 1 or example 4 or example 5 or example 6 or example 7
Example 11
(1) Same as example 1
(2) Adding 4.0g of PVDF powder and 1.0g of PMAA microspheres obtained in the step (1) into 36.7g of DMF (dimethyl formamide), N' -dimethylacetamide (DMAc) or N-methylpyrrolidone (NMDA) solvent, adding 0.0417g to 0.417g of pore-forming agent F127 or PVP or PEG, magnetically stirring for 6 hours at 70 ℃, defoaming in vacuum for 30 minutes to form a casting solution, pouring the casting solution on a clean glass plate, scraping with a doctor blade to form a liquid film, and solidifying in water or ethanol at 25 ℃ to form the film.
(3) The same as example 1 or example 2 or example 3
(4) Same as example 1 or example 4 or example 5 or example 6 or example 7
Example 12
(1) Same as example 1
(2) Adding 5.0g of PVDF powder and 1.0g of PMAA microspheres obtained in the step (1) into 44.0g of DMF (dimethyl formamide), N' -dimethylacetamide (DMAc) or N-methylpyrrolidone (NMDA) solvent, adding 0.05g to 1.0g of pore-forming agent F127, PVP or PEG, magnetically stirring for 6 hours at 70 ℃, carrying out vacuum defoaming for 30 minutes to form a casting solution, pouring the casting solution on a clean glass plate, scraping the casting solution into a liquid film by a doctor blade, and solidifying the liquid film in water or ethanol at 25 ℃ to form a film.
(3) Same as example 1 or example 2 or example 3
(4) The same as example 1 or example 4 or example 5 or example 6 or example 7
The test and the characterization prove that the prepared composite membrane consists of polyvinylidene fluoride, inorganic titanium dioxide, polymethacrylic acid microspheres loaded with metal palladium nano particles and polydopamine, the average thickness of the membrane is 0.17mm, the average pore diameter is 11.84nm, and the pure water flux is 50-80L/m under the pressure of 0.1MPa at normal temperature 2 H; the membrane section is divided into two layers of a PVDF/PMAA @ Pd catalytic layer and a polydopamine-titanium dioxide nanoparticle layer.
The experimental verification result proves that the organic-inorganic composite membrane prepared by the invention has good catalytic separation performance and self-cleaning performance on organic matters such as nitrophenol, methylene blue, Congo red, methyl orange and the like in an aqueous solution in a cross-flow operation mode. In addition, the composite membrane prepared by the invention is directly placed in benzyl alcohol liquid, and then hydrogen peroxide (hydrogen peroxide) is added, so that the benzyl alcohol can be directly catalytically oxidized into benzaldehyde. When the composite membrane prepared by the invention is placed in the interface of benzyl alcohol and hydrogen peroxide, one surface of titanium dioxide faces hydrogen peroxide, and the other surface faces benzyl alcohol, the benzyl alcohol on one side of the membrane can be gradually catalyzed and oxidized into benzaldehyde, and the benzaldehyde is automatically separated from a water phase.
The preparation method of the self-cleaning, catalytic separation and coupling composite membrane provided by the invention has been described by way of example, and the invention can be realized by modifying or properly changing and combining the contents described herein without departing from the content, spirit and scope of the invention. It is expressly intended that all such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and content of the invention.

Claims (8)

1. A self-cleaning composite membrane with catalytic separation function and a preparation method thereof are characterized by comprising the following steps:
step 1, preparing polymethacrylic acid (PMAA) microspheres: dissolving monomer methacrylic acid (MAA), cross-linking agent Ethylene Glycol Dimethacrylate (EGDMA) and initiator Azobisisobutyronitrile (AIBN) in acetonitrile, heating and polymerizing in a single-neck flask, centrifuging, washing and drying to obtain PMAA microspheres;
step 2, preparing a PVDF/PMAA membrane: dispersing polyvinylidene fluoride (PVDF) powder, the PMAA microspheres prepared in the step 1 and a pore-forming agent in a solvent according to a ratio, magnetically stirring for 6 hours at 70 ℃, defoaming for 30 minutes in vacuum to prepare a membrane casting solution, scraping the membrane casting solution on a clean and flat glass plate to prepare a liquid membrane, and solidifying and forming in a solidification bath at 25 ℃ to obtain a PVDF/PMAA membrane;
step 3, preparing a PVDF/PMAA @ Pd membrane: soaking the PVDF/PMAA membrane prepared in the step 2 in 100mL of 0.1mol/L sodium hydroxide aqueous solution for 12h, washing with deionized water for 3 times, and then placing in 100mL of 0.11-0.44mmol/L PdCl 2 Soaking in the solution for 12h, washing with deionized water for 3 times, and placing in NaBH with concentration of 1g/L 4 Obtaining a PVDF/PMAA @ Pd membrane in 100mL of the solution for 1 h;
step 4, preparing TiO 2 PVDF/PMAA @ Pd composite membrane: adding 1.2g dopamine hydrochloride into Tris-HCl solution with pH value of 8.5 to prepare 2g/L dopamine solution, circulating the solution on the surface of the catalytic membrane prepared in the step 3 for 6h to form a polydopamine layer, and then using (NH) with the concentration of 0.1 and 0.4mol/L respectively 4 ) 2 TiF 6 And H 3 BO 3 Soaking the mixed solution for 60-180min in 200mL to prepare the TiO 2 PVDF/PMAA @ Pd composite membrane.
2. The self-cleaning composite membrane with catalytic separation function as claimed in claim 1, wherein the initiator azobisisobutyronitrile in step 1 is 0.12g, the cross-linking agent ethylene glycol dimethacrylate is 3g, the monomer methacrylic acid has a mass of 3g, the volume of acetonitrile is 160mL, the reaction temperature is 80 ℃, and the reaction time is 2 h.
3. The self-cleaning composite membrane with catalytic separation function as claimed in claim 1, wherein in step 2, the PVDF powder is 3.0-5.0g, the PMAA microspheres are 1.0g, the porogen is 0.0235-1.0g, and the solvent is 19.5-44.0 g.
4. The self-cleaning composite membrane with catalytic separation function as claimed in claim 1, wherein the coagulating bath in step 2 is non-solvent material such as deionized water or ethanol, the pore-forming agent is material capable of forming pores in the casting solution during the curing process, such as polyoxyethylene-b-polyoxypropylene-b-polyoxyethylene (F127), polyethylene glycol (PEG) or polyvinylpyrrolidone (PVP), and the solvent is N, N '-Dimethylformamide (DMF) or N, N' -dimethylacetamide (DMAc) or N-methylpyrrolidone (PVP).
5. The self-cleaning composite membrane with catalytic separation function as claimed in claim 1, wherein said membrane is composed of polyvinylidene fluoride, inorganic titanium dioxide, polymethacrylic acid microsphere loaded with metal palladium nano-particle and polydopamine, the average thickness of said membrane is 0.17mm, the average pore diameter is 11.84nm, and the pure water flux is 50-80L/m under the pressure of 0.1MPa at normal temperature 2 ·h。
6. A self-cleaning composite membrane with catalytic separation function as claimed in claim 1, wherein the cross section of the membrane is composed of two layers of PVDF/PMAA @ Pd layer and poly dopamine-titanium dioxide nanoparticle layer.
7. The self-cleaning composite membrane with catalytic separation function as claimed in claim 6, wherein the PVDF/PMAA @ Pd layer has catalytic function, and the polydopamine-titanium dioxide nanoparticle layer has good hydrophilicity and self-cleaning function.
8. The self-cleaning composite membrane with catalytic separation function and its preparation method as claimed in claim 1, wherein said membrane has catalytic and separation function, self-cleaning function and good anti-pollution performance in organic matter degradation reaction and oil-water interface reaction.
CN202210935594.XA 2022-08-05 2022-08-05 Self-cleaning composite membrane with catalytic separation function and preparation method thereof Pending CN115090132A (en)

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