CN110193289A - The method that one pot a kind of, in-situ method prepares bielement nano material codope mixed substrate membrane containing nano-grade molecular sieve - Google Patents

Abstract

The invention provides a method for preparing a binary nanomaterial co-doped mixed matrix film by an in-situ method, comprising the following steps: (1) mixing a polymerizable oil phase medium, a polymerizable surfactant and water, Build a reverse micellar microemulsion; then add nanomaterial-I, stir and disperse, then add the precursor of nanomaterial-II, stir, and obtain a reverse micellar microemulsion containing nanomaterial-I and nanomaterial-II; (2) adding an initiator to carry out in-situ polymerization reaction to obtain co-doped polymer latex; (3) adjusting the viscosity to obtain a film-making liquid; (4) coating the film-making liquid evenly on the supporting film, and Heat treatment can be obtained. The "one pot", in-situ binary nanomaterial co-doped mixed matrix membrane preparation method of the invention is simple, economical and environmentally friendly. The gas separation performance or pervaporation performance of the mixed matrix membrane provided by the present invention is significantly improved due to the synergistic effect of nanomaterial-I and nanomaterial-II.

Description

A one-pot, in situ method for the preparation of binary nanomaterial co-doped mixed matrix membranes method

technical field

The invention relates to the technical field of membrane separation, in particular to the preparation and application of a binary nanomaterial co-doped mixed matrix membrane by a "one-pot" and in-situ method.

Background technique

Mixed matrix membrane is a hybrid membrane prepared by doping inorganic nanomaterials as a dispersed phase into a polymer continuous phase. This membrane combines the excellent properties of organic and inorganic materials, and is based on traditional polymer membranes. Inorganic nanomaterial structure and properties to enhance the performance of mixed matrix membranes. At present, the preparation methods of mixed matrix membrane mainly include physical blending method and in-situ polymerization method. Commonly used inorganic nanomaterials include metal nanoparticles (including metal element, metal oxide, metal halide, metal sulfide and other nanoparticles), low Dimensional carbon nanomaterials (graphene, carbon nanotubes), etc.

Chinese patent application CN201410301851.X discloses a sulfonated polyether ether ketone-amino acid modified graphene oxide hybrid membrane, which is composed of sulfonated polyether ether ketone and amino acid modified graphene oxide. The preparation process includes: first oxidizing graphite flakes to prepare graphene oxide, then adding graphene oxide into hydroxymethylaminomethane-HCl solution containing dopamine, and obtaining dopamine-modified graphene oxide through chelation reaction; Amino acid-modified graphene oxide was obtained by grafting reaction of graphene oxide into cysteine solution; then amino acid-modified graphene oxide was blended with sulfonated polyetheretherketone solution to obtain a casting solution, and the hetero film. The sulfonated polyether ether ketone/amino acid modified graphene oxide hybrid membrane of the invention is used for the separation of CO ₂ /CH ₄ mixed gas, and has high selectivity and permeability.

Chinese patent application CN201510726253.1 discloses a mixed matrix membrane containing trifluoromethyl polyimide/carboxyl multi-walled carbon nanotubes for gas separation and a preparation method thereof. The invention forms a mixed matrix membrane by adding trifluoromethyl-containing polyimide to carboxyl multi-walled carbon nanotubes, and utilizes the interaction of polar groups in the two to enable the carbon nanotubes to be uniformly distributed in the mixed matrix membrane. At the same time, the two-phase interface has good adhesion, so that the gas permeability and selectivity of the mixed matrix membrane are improved.

Chinese patent application CN201810589354.2 discloses a sulfonated polyether ether ketone mixed matrix membrane doped with carbon quantum dots in situ and its preparation method and application. Using polyvinyl alcohol and polyether ether ketone as raw materials, adding them to concentrated sulfuric acid, after the reaction, a sulfonated polyether ether ketone composite material doped with carbon quantum dots in situ is obtained; the composite material is dissolved in deionized water , prepared as a casting solution, and a functional layer is prepared on the surface of the microporous membrane by a coating method to form a sulfonated polyether ether ketone mixed matrix membrane doped with carbon quantum dots in situ. The prepared functional membrane can be applied to CO ₂ /N ₂ gas separation with high CO ₂ permeability and separation factor.

Chinese patent application CN201710326631.6 discloses a carbon nanosphere-polyimide binary gas separation mixed matrix membrane and its preparation method, including the following steps: (1) under the action of ultrasound, uniformly disperse carbon nanospheres in N , N'-dimethylacetamide, then add 4,4'-diaminodiphenyl ether, after it is completely dissolved, slowly add 3,3',4,4'-biphenyltetracarboxylic dianhydride, add all Finally, seal and stir until the viscosity of the system reaches 100-300mPa·s to obtain the casting solution; (2) scrape the casting solution on the glass plate, heat-treat the glass plate loaded with the membrane, cool it to room temperature, and remove the film After that, the carbon nanosphere-polyimide binary gas separation mixed matrix membrane is obtained. The invention obtains a carbon nanosphere-polyimide binary gas separation mixed matrix membrane with excellent separation performance and stability.

Chinese patent application CN201710096026.4 discloses a visible light-catalyzed hollow fiber ultrafiltration membrane based on doped nano-Cu ₂ O and its preparation method. Add polysulfone or polyethersulfone, porogen, surfactant, doped nano-Cu ₂ O and solvent into the dissolution tank in a certain order, stir until completely dissolved, stand for defoaming, and make a casting solution; Visible light-catalyzed hollow fiber ultrafiltration membranes were prepared by traditional dry-wet spinning process. The ultrafiltration membrane prepared by the invention has good anti-pollution performance and visible light catalytic performance.

Contents of the invention

The invention provides a new preparation method of a binary nanomaterial co-doped mixed matrix membrane, which is prepared by a "one pot" and in-situ method.

A method for preparing a binary nanomaterial co-doped mixed matrix film, comprising the steps of:

(1) Mix the polymerizable oil phase medium and the polymerizable surfactant to construct reverse micellar microemulsion; add nanomaterial-I to the obtained reverse micellar microemulsion, stir and disperse, and then add nanomaterial- The precursor of II is stirred; the reverse micellar microemulsion containing nanomaterial-I and nanomaterial-II is obtained;

The nanomaterial-I is a low-dimensional carbon nanomaterial; the nanomaterial-II is a water-soluble transition metal salt;

(2) adding an initiator to the reverse micellar microemulsion containing nanomaterial-I and nanomaterial-II, and performing in-situ polymerization to obtain nanomaterial-I and nanomaterial-II co-doped polymer latex;

(3) adjusting the viscosity of the nanomaterial-I and nanomaterial-II co-doped polymer latex and leaving it to stand to obtain a binary nanomaterial co-doped polymer film-making solution;

(4) Uniformly coating the binary nanomaterial co-doped polymer film-making liquid on the support membrane, and heat-treating to obtain the binary nanomaterial co-doped mixed matrix membrane.

When using metal nanoparticles and low-dimensional carbon nanomaterials to prepare mixed matrix membranes, the structure of metal nanoparticles and low-dimensional carbon nanomaterials is one of the key factors that determine the performance of mixed matrix membranes. By growing metal nanoparticles in situ on low-dimensional carbon nanomaterials, metal nanoparticles/carbon nanomaterial composites with a three-dimensional structure can be obtained. This is a new type of inorganic nanocomposite material that has broad applications in the field of separation membranes. Application prospects.

The invention selects a polymerizable oil phase medium and a polymerizable surfactant to construct a reverse micellar microemulsion, and uses the reverse micellar microemulsion to in-situ grow nanomaterial-II on nanomaterial-I. Then, a binary nanomaterial co-doped polymer film-making liquid containing nanomaterial-I and nanomaterial-II is obtained through microemulsion polymerization. Finally, coating and heat treatment methods are used to obtain binary nanomaterial co-doped mixed matrix membranes, which are applied to the separation of gas mixtures such as CO ₂ /N ₂ , or aromatics/cycloalkanes such as benzene/cyclohexane, olefins/alkanes, etc. Pervaporation of organic mixtures.

The formation process of the film-forming liquid in steps (1) to (3) of the present invention is all carried out in the same reactor ("one pot"), and there is no separation and purification of products in the middle, and there is no generation and discharge of by-products, that is, The mixed matrix membrane film-making solution is formed in "one pot".

The mixed matrix membrane includes three materials: nanomaterial-I, nanomaterial-II and polymer. The nanomaterial-I is directly fed into the reactor, the nanomaterial-II is produced by in-situ synthesis of the precursor mixture fed into the reactor, and the polymer is produced by the in-situ polymerization of the oilable medium and the surfactant, namely The mixed matrix membrane material is formed in situ in a "one pot".

Preferably, the polymerizable oil phase medium is styrene or a mixture of styrene and acrylate; the polymerizable surfactant is styrene lauryl dimethyl ammonium chloride, styrene deca Tetraalkyldimethylammonium chloride, styrene cetyldimethylammonium chloride, or styreneoctadecyldimethylammonium chloride. Both the oil phase medium and the polymerizable surfactant are commercially available.

Preferably, the mass ratio among the polymerizable surfactant, the polymerizable oil phase medium and water is 1g: 10-15g: 0.01-0.05g. More preferably, it is 1 g: 11.5-12.5 g: 0.02-0.03 g.

Preferably, the mass ratio of the dosage of the nanomaterial-I to the reverse micellar microemulsion is 1 mg: 6.0-8.5 g. More preferably, it is 1 mg: 7.0 to 7.5 g.

Preferably, the mass ratio of the dosage of the precursor of the nanomaterial-II to the reverse micellar microemulsion is 1mg: 1-6g. More preferably, it is 1 mg: 2.5 to 4.5 g.

Preferably, the low-dimensional carbon nanomaterial is graphene oxide, aminated graphene, acyl chlorided graphene, oxidized carbon nanotubes, aminated carbon nanotubes or acyl chlorided carbon nanotubes.

Preferably, the water-soluble transition metal salt is a water-soluble cobalt salt, zinc salt, copper salt, titanium salt, silver salt or manganese salt.

Preferably, the initiator is azobisisobutyronitrile. The dosage is 0.3% of the total mass of oil phase medium and surfactant.

Preferably, the in-situ polymerization reaction time is 2-4 hours.

Preferably, the viscosity of the nanomaterial-I and nanomaterial-II co-doped polymer latex is adjusted to be 250-350 mPa·s; the standing time is 4-6 hours.

Preferably, the support membrane is a polysulfone ultrafiltration membrane with a molecular weight cut-off of 20,000 to 40,000; the heat treatment temperature is 60-80° C., and the heat treatment time is 8-12 hours.

The invention also provides a binary nanomaterial co-doped mixed matrix membrane prepared by the preparation method.

The invention also provides an application of the binary nanomaterial co-doped mixed matrix film.

The invention prepares low-dimensional carbon nanomaterials and transition metal nanoparticle-doped mixed matrix membranes through a "one-pot" and in-situ method. The specific performance is that in a reactor ("one pot"), transition metal nanoparticles are grown in situ on low-dimensional carbon nanomaterials by using reverse micellar microemulsions, and then binary nanomaterials are co-doped by in situ polymerization of microemulsions. Heteropolymer film-making fluid. Finally, coating and heat treatment processes are adopted to obtain a mixed matrix film co-doped with low-dimensional carbon nanomaterials and transition metal nanoparticle binary nanomaterials.

Compared with the prior art, the present invention has the following advantages and characteristics:

Low-dimensional carbon nanomaterials, transition metal nanoparticles binary nanomaterials co-doped mixed matrix film "one pot" preparation method, the method is simple, economical and environmentally friendly.

The low-dimensional carbon nanomaterial and transition metal nanoparticle binary nanomaterial co-doped mixed matrix film provided by the present invention, due to the synergistic effect of the low-dimensional carbon nanomaterial and transition metal nanoparticle, the mixed matrix film can withstand CO ₂ /N ₂ etc. In the separation and purification of gas mixtures such as benzene/cyclohexane and other aromatics/cycloalkanes, olefins/alkanes and other organic mixtures, it shows excellent permeability and permeation selectivity.

Detailed ways

The following specific examples are used to further illustrate how to use the present invention to prepare low-dimensional carbon nanomaterials, transition metal nanoparticles binary nanomaterials co-doped mixed matrix membranes, and the CO ₂ , N ₂ permeation and permeation selectivity of the prepared membranes , or the pervaporation separation performance of benzene/cyclohexane mixtures.

Gas permeability evaluation of low-dimensional carbon nanomaterials, transition metal nanoparticles binary nanomaterials co-doped mixed matrix membrane: the mixed matrix membrane is placed in the percolation cell of the gas permeation test device, and the effective area of the membrane is 19.6cm ² , the gas (CO ₂ or N ₂ ) pressure on the upstream side of the membrane is 0.15Mpa, and the pressure on the downstream side of the membrane is 0.1Mpa. The flux of gas passing through the membrane is calculated and measured from the gas flow through the membrane. The gas permeation performance of low-dimensional carbon nanomaterials and transition metal nanoparticles co-doped mixed matrix membranes is evaluated by the gas permeation volume per unit membrane area per unit time (under standard conditions).

Evaluation of pervaporation performance of benzene/cyclohexane mixture system of low-dimensional carbon nanomaterials, transition metal nanoparticles binary nanomaterials co-doped mixed matrix membrane: the mixed matrix membrane was placed in the percolation tank of the pervaporation performance test device , the effective area of the membrane is 19.6cm ² , using a 30°C, 50wt% benzene/cyclohexane mixture system to evaluate the pervaporation performance of the mixed matrix membrane (permeation flux J, separation factor _{αbenzene/cyclohexane} ), the membrane downstream Side pressure is controlled at 100±10Pa.

Example 1

In a water bath at 30°C, mix 3g of styrene dodecyldimethylammonium chloride, 36.4g of styrene, and 0.08g of water, stir to dissolve, then add 5mg of graphene oxide, stir to disperse, and then slowly add 10mg The zinc chloride is stirred to form a reverse micellar microemulsion comprising graphene and zinc nanoparticles.

1.2 g of azobisisobutyronitrile was added to the formed reverse micellar microemulsion, and the polymerization reaction was carried out at normal temperature and pressure for 3 hours to obtain latex containing graphene and zinc nanoparticles. Adjust the viscosity of the obtained latex to about 250mPa.s, and coat it on the ultrafiltration support membrane after standing still, with a coating thickness of about 80μm, and then dry it for 12 hours at a temperature of 80°C to obtain graphene and zinc with a thickness of 17μm. Nanoparticle co-doped mixed matrix membranes.

The CO ₂ and N ₂ permeability properties of the graphene and zinc nanoparticles co-doped mixed matrix membrane prepared in this example are shown in Table 1.

Example 2

In a water bath at 30°C, mix 3g of styrene dodecyldimethylammonium chloride, 21.8g (40mL) of styrene, 15.1g (16mL) of methyl methacrylate, and 0.08g of water, stir to dissolve, and then add 5 mg of aminated carbon nanotubes were stirred and dispersed, and then 14.7 mg of copper acetate was slowly added and stirred to form a reverse micellar microemulsion containing carbon nanotubes and copper nanoparticles.

1.2 g of azobisisobutyronitrile was added to the formed reverse micellar microemulsion, and polymerization was carried out at normal temperature and pressure to obtain latex containing graphene and copper nanoparticle composites. The viscosity of the obtained latex was adjusted to about 250mPa.s, and after standing, it was coated on the ultrafiltration support membrane with a thickness of about 80 μm, and then dried at a temperature of 80°C for 12 hours to obtain carbon nanotubes with a thickness of 17 μm, Copper nanoparticles co-doped mixed matrix films.

The CO ₂ and N ₂ permeability of the carbon nanotube and copper nanoparticle co-doped mixed matrix membrane prepared in this example are shown in Table 1.

Example 3

In a water bath at 30°C, mix 3g of styrene tetradecyldimethylammonium chloride, 21.8g (24mL) of styrene, 15.1g (16mL) of methyl methacrylate, and 0.08g of water, stir to dissolve, and then add 5 mg of aminated graphene was stirred and dispersed, and then 12.4 mg of silver nitrate was slowly added and stirred to form a reverse micellar microemulsion containing graphene and silver nanoparticles.

Add 1.2 g of azobisisobutyronitrile to the formed reverse micellar microemulsion for polymerization to obtain latex containing graphene and silver nanoparticles. Adjust the viscosity of the obtained latex to about 250mPa.s, and coat it on the ultrafiltration support membrane after standing still. Nanoparticle co-doped mixed matrix membranes.

The pervaporation performance of the benzene/cyclohexane mixture of the graphene and silver nanoparticles co-doped mixed matrix membrane prepared in this example is shown in Table 2.

Example 4

In a water bath at 30°C, mix 3g of styrene tetradecyl dimethyl ammonium chloride, 21.8g of styrene, 15.1g of methyl methacrylate, and 0.08g of water, stir to dissolve, and then add 5mg of carbonyl chloride tube, stirred and dispersed, then slowly added 13.4 mg of cobalt nitrate, stirred, and formed a reverse micellar microemulsion containing carbon nanotubes and cobalt nanoparticles.

Add 1.2 g of azobisisobutyronitrile to the formed reverse micellar microemulsion for polymerization to obtain latex containing graphene and cobalt nanoparticles. The viscosity of the obtained latex was adjusted to about 250mPa.s, and after standing still, it was coated on the ultrafiltration support membrane with a thickness of about 80 μm, and then dried at a temperature of 80°C for 12 hours to obtain carbon nanotubes with a thickness of 17 μm, Co-doped mixed matrix films with cobalt nanoparticles.

The pervaporation performance of the benzene/cyclohexane mixture of the carbon nanotubes and cobalt nanoparticles co-doped mixed matrix membrane prepared in this example is shown in Table 2.

Table 1. CO ₂ and N ₂ permeability of low-dimensional carbon nanomaterials and transition metal nanoparticles co-doped mixed matrix membranes prepared in the examples of the present invention.

Table 2. Benzene/cyclohexane mixture pervaporation performance of low-dimensional carbon nanomaterials and transition metal nanoparticles co-doped mixed matrix membranes prepared in the examples of the present invention

The above is only a specific implementation case of the patent of the present invention, but the technical characteristics of the patent of the present invention are not limited thereto. Any changes or modifications made by those skilled in the relevant field within the scope of the present invention are covered by the patent of the present invention. within the scope of the patent.

Claims (9)

1. A method for preparing a binary nanomaterial co-doped mixed matrix film, characterized in that, comprising the steps: (1) Mix a polymerizable oil phase medium, a polymerizable surfactant and water to construct a reverse micellar microemulsion; add nanomaterial-I to the obtained reverse micellar microemulsion, stir and disperse, and then add nanometer The precursor of material-II is stirred; the reverse micellar microemulsion containing nanomaterial-I and nanomaterial-II is obtained; The nanomaterial-I is a low-dimensional carbon nanomaterial; the nanomaterial-II is a water-soluble transition metal salt; (2) adding an initiator to the reverse micellar microemulsion containing nanomaterial-I and nanomaterial-II, and performing in-situ polymerization to obtain nanomaterial-I and nanomaterial-II co-doped polymer latex; (3) adjusting the viscosity of the nanomaterial-I and nanomaterial-II co-doped polymer latex and leaving it to stand to obtain a binary nanomaterial co-doped polymer film-making solution; (4) Uniformly coating the binary nanomaterial co-doped polymer film-making liquid on the support membrane, and heat-treating to obtain the binary nanomaterial co-doped mixed matrix membrane. 2. The preparation method according to claim 1, wherein the mass ratio of the polymerizable surfactant, the polymerizable oil phase medium, and water is 1g: 10-15g: 0.01-0.05g. 3. The preparation method according to claim 1, characterized in that the mass ratio of the dosage of the nanomaterial-I to the reverse micellar microemulsion is 1 mg: 6.0-8.5 g. 4. The preparation method according to claim 1, characterized in that the mass ratio of the dosage of the precursor of the nanomaterial-II to the reverse micellar microemulsion is 1mg: 1-6g. 5. The preparation method according to claim 1, wherein the low-dimensional carbon nanomaterial is graphene oxide, aminated graphene, acyl chloride graphene, carbon oxide nanotubes, aminated carbon nanotubes or acyl chloride carbon nanotubes. 6. The preparation method according to claim 1, wherein the water-soluble transition metal salt is water-soluble cobalt salt, zinc salt, copper salt, titanium salt, silver salt or manganese salt. 7. The preparation method according to claim 1, characterized in that the viscosity of the nanomaterial-I and nanomaterial-II co-doped polymer latex is adjusted to be 250-350 mPa·s; the standing time is 4-6 hours. 8 . The preparation method according to claim 1 , wherein the support membrane is a polysulfone ultrafiltration membrane with a molecular weight cut-off of 20,000 to 40,000; the heat treatment temperature is 60-80° C., and the heat treatment time is 8-12 hours. 9. A binary nanomaterial co-doped mixed matrix film prepared by the preparation method according to any one of claims 1 to 8.