WO2021047206A1

WO2021047206A1 - Preparation method for zirconium oxide-titanium oxide composite ultrafiltration membrane

Info

Publication number: WO2021047206A1
Application number: PCT/CN2020/092074
Authority: WO
Inventors: 陈云强; 洪昱斌; 方富林; 蓝伟光
Original assignee: 三达膜科技（厦门）有限公司
Priority date: 2019-09-12
Filing date: 2020-05-25
Publication date: 2021-03-18
Also published as: CN110743386A

Abstract

A preparation method for a zirconium oxide-titanium oxide composite ultrafiltration membrane. The method comprises: using a Ti-Zr composite sol prepared by means of a sol-gel method as a precursor, then performing processing by means of a hydrothermal method, using a two-step method to obtain a Ti-Zr composite nano solution having a uniform particle size, adding an appropriate amount of an additive to the Ti-Zr composite nano solution to directly prepare a coating solution, performing single coating, and then performing drying and calcining to obtain the Ti-Zr composite ultrafiltration membrane.

Description

Preparation method of zirconium oxide-titanium oxide composite ultrafiltration membrane

Technical field

The invention belongs to the technical field of ultrafiltration membrane preparation, and specifically relates to a method for preparing a zirconium oxide-titania composite ultrafiltration membrane.

Background technique

Membrane separation technology is a separation technology that emerged in the 1960s and has developed rapidly in decades. The application field of membrane separation technology has penetrated into all aspects of people's life and production, such as chemical industry, environmental protection, electronics, textiles, medicine, food and so on. Since the industrialization of membrane separation technology, organic polymer membranes have been dominant. Although organic membranes have many advantages, with the gradual expansion of membrane separation technology, some shortcomings of polymer separation membranes have gradually been exposed, such as inability to withstand high temperatures and Chemical resistance, easy pollution, swelling and shrinking in solvents, etc., make its application limited.

Compared with organic membranes, inorganic membranes, as emerging separation media, have many excellent characteristics, such as good chemical stability, high mechanical strength, high temperature resistance, anti-microbial corrosion and long service life, so they have become green and environmentally friendly materials. Using inorganic membrane media as the separation process is gradually developing into a large class of green and environmentally friendly high-tech. Inorganic separation membranes can be divided into two categories, dense membranes and porous membranes, from the surface structure. According to the materials, it can be divided into ceramic membranes, metal membranes, alloy membranes, zeolite membranes and glass membranes. Among them, ceramic membrane materials mainly include aluminum oxide, titanium oxide, zirconium oxide and silicon oxide, which are known for their thermal stability and are widely used.

The sol-gel method is the most important method for preparing ceramic ultrafiltration membranes. The sol-gel method is to hydrolyze and polycondensate alkoxides or non-alkoxides in a certain solvent to obtain a sol with a certain particle size distribution, and add appropriate additives to the sol to prepare a coating liquid with a certain viscosity and concentration; Then the coating liquid is applied to the porous support to form a gel membrane, which is dried and sintered to form an ultrafiltration membrane. The water content of the nanoparticles prepared by the sol-gel method is relatively high, and the film is easy to crack. The sol-gel method generally requires multiple coatings to ensure the integrity of the film; at the same time, the sol-gel method is used to prepare the nanoparticles. TiO2 and ZrO2 nanoparticles will appear anatase and tetragonal phases respectively at 300-400℃. When the sintering temperature rises to 500℃, TiO2 and ZrO2 particles will undergo a crystal transformation, accompanied by volume changes and crystal grains. The growth of the pore size will lead to the generation of defects and the increase of the pore size. In response to this problem, the current researchers are mainly doping crystalline stabilizers into TiO2 and ZrO2 to increase the crystalline transition temperature of TiO2 and ZrO2. However, since crystal stabilizers are expensive and are easy to react with acidic substances, the acid and alkali resistance of their products remains to be verified.

Summary of the invention

The purpose of the present invention is to overcome the defects of the prior art and provide a method for preparing a zirconium oxide-titanium oxide composite ultrafiltration membrane.

The technical scheme of the present invention is as follows:

A preparation method of zirconium oxide-titanium oxide composite ultrafiltration membrane includes the following steps:

(1) Add polyethylene glycol or nitric acid with a weight average molecular weight of 550-650 as a dispersant to the mixed solution of organic zirconium alkoxide and organic titanium alkoxide, and add ammonia water dropwise while stirring at 50-65°C Or sodium hydroxide to adjust the pH to 9-11, then keep the reaction for 2-3h, and then separate the solid and liquid to obtain a solid. After suction filtration, the solid is re-dissolved in water, and nitric acid is added for gelation and the gelatinized material The pH is 2-3 to prepare Ti-Zr composite sol; in the above mixed solution, the molar ratio of organic zirconium alkoxide and organic titanium alkoxide is 0.8-1.2:0.8-1.2, and the concentration is 0.1-1mol/L ；

(2) Put the above-mentioned Ti-Zr composite sol into a hydrothermal reaction kettle with a filling degree of 50-60%, keep the temperature at 200-250°C for 5-10 hours, and cool to prepare a Ti-Zr composite nano solution;

(3) Add polyethylene glycol with a weight average molecular weight of 350-450 as a plasticizer and a cellulose compound with a molecular weight of 6000-10000 as a binder to the above Ti-Zr composite nano solution to a final concentration of respectively 2-5wt% and 0.1-0.5wt%, after mixing uniformly, the coating liquid is prepared; the cellulose compound is hydroxymethyl cellulose, hydroxyethyl cellulose or hydroxypropyl cellulose;

(4) Apply the above coating liquid on the porous alumina ceramic membrane support, heat up to 100-120°C at a rate of 1-3°C/min, heat and dry for 2-5 hours, and then heat it at a temperature of 1-3°C/min The rate is increased to 600-700°C, the temperature is kept and calcined for 2-3 hours, and the zirconium oxide-titanium oxide composite ultrafiltration membrane is obtained after cooling.

In a preferred embodiment of the present invention, in the step (1), the added amount of the dispersant is 1-3 wt% of the mixed solution.

In a preferred embodiment of the present invention, in the step (1), the molar ratio of organic zirconium alkoxide and organic titanium alkoxide is 1:1.

In a preferred embodiment of the present invention, the organic zirconium alkoxide is zirconium n-butoxide or zirconium n-propoxide.

In a preferred embodiment of the present invention, the organic titanium alkoxide is titanium isopropoxide or titanium tert-butoxide.

In a preferred embodiment of the present invention, the step (3) is to add polyethylene glycol with a weight average molecular weight of 350-450 as a plasticizer and a binder as a plasticizer to the Ti-Zr composite nano solution. The final concentration of the cellulosic compound is 2-5wt% and 0.1-0.5wt%, respectively, and after being evenly mixed, the antifoaming agent is added to the final concentration of 0.01-0.1wt% to prepare the coating liquid.

Further preferably, the defoaming agent is a silicone defoaming agent.

In a preferred embodiment of the present invention, the average pore diameter of the porous alumina ceramic membrane support is 0.1 μm.

The beneficial effects of the present invention are: the present invention uses the Ti-Zr composite sol prepared by the sol-gel method as a precursor, and then is treated by a hydrothermal method, and a two-step method can be used to obtain a Ti-Zr composite nano solution with uniform particle size , Add appropriate amount of additives to directly make the coating liquid, apply the film once, then dry and calcine to make the Ti-Zr composite ultrafiltration membrane. Compared with the traditional preparation method, the method is simple and solves the problem of easy agglomeration of particles. In addition to the difficulty of multiple coatings and defects caused by the crystal transition temperature of the particles, the prepared nanoparticles have a uniform particle size, and the film has no shrinkage, cracks or cracks, and a defect-free Ti-Zr composite ceramic ultrafiltration membrane is realized. Preparation.

Description of the drawings

FIG. 1 is a scanning electron micrograph of the film layer of the zirconia ceramic ultrafiltration membrane prepared in Comparative Example 1.

2 is a scanning electron micrograph of the film layer of the titanium oxide ceramic ultrafiltration membrane prepared in Comparative Example 2.

FIG. 3 is a scanning electron micrograph of the film layer of the zirconia-titania ultrafiltration membrane prepared in Comparative Example 3. FIG.

4 is a scanning electron micrograph of the film layer of the zirconium oxide-titanium oxide composite ultrafiltration membrane prepared in Example 1.

detailed description

The technical solutions of the present invention will be further illustrated and described below through specific implementations in conjunction with the accompanying drawings.

Comparative example 1

(1) Add the dispersant polyethylene glycol PEG600 to the 0.5mol/L zirconium n-butoxide solution and make the final mass concentration 2%, and add 0.1moL sodium hydroxide dropwise at 60°C under stirring conditions Adjust the pH to 10; after reacting for 2.5 hours, separate the solid and liquid, re-dissolve in water, add 0.1M nitric acid for gelation, and make the pH of the gelatinized solution 2, to prepare zirconia sol;

(2) Put the zirconia sol obtained in step (1) into a hydrothermal reaction kettle with a filling degree of 60%, keep the reaction at 200°C for 8 hours, and cool to prepare a zirconia nano solution;

(3) Add PEG-400 and hydroxymethyl cellulose with a molecular weight of 6000-10000 to the zirconia nano solution obtained in step (2), and make the final mass concentrations of PEG-400 and hydroxymethyl cellulose be 3 %, 0.3%, and stir evenly, then add the silicone defoamer Dow Corning DC65 and make the final mass concentration 0.05%, and mix well to prepare a coating liquid;

(4) Apply the coating liquid on a porous alumina ceramic membrane support with an average pore diameter of 0.1μm, heat up to 120°C at a heating rate of 2°C/min, dry for 3 hours, and then follow a heating rate of 2°C/min The temperature is raised to 650°C, the temperature is kept and calcined for 2 hours, and then cooled to obtain the zirconia ceramic ultrafiltration membrane. The prepared zirconia ceramic ultrafiltration membrane has an average pore diameter of 15nm, and a rejection rate of 2g/L dextran (molecular weight of 150,000) exceeding 90%. After a bubble pressure test, the overall bubble pressure is greater than 0.5MPa. The film layer is shown in Figure 1.

Comparative example 2

(1) Add the dispersant polyethylene glycol PEG600 to the 0.5mol/L titanium isopropoxide solution and make the final mass concentration 2%, and add 0.1moL sodium hydroxide dropwise at 60°C under stirring conditions Adjust the pH to 10; after reacting for 2.5 hours, separate the solid and liquid, re-dissolve in water, add 0.1M nitric acid for gelation and make the pH of the gelatinized solution 2, to prepare a titanium oxide sol;

(2) Put the titanium oxide sol obtained in step (1) into a hydrothermal reaction kettle with a filling degree of 60%, keep the reaction at 200° C. for 8 hours, and cool to prepare a titanium oxide nano solution;

(3) Add PEG-400 and hydroxymethyl cellulose with a molecular weight of 6000-10000 to the titanium oxide nano solution obtained in step (2), and make the final mass concentrations of PEG-400 and hydroxymethyl cellulose be 3 %, 0.3%, and stir evenly, then add the silicone defoamer Dow Corning DC65 and make the final mass concentration 0.05%, and mix well to prepare a coating liquid;

(4) Apply the coating liquid on a porous alumina ceramic membrane support with an average pore diameter of 0.1μm, heat up to 120°C at a heating rate of 2°C/min, dry for 3 hours, and then follow a heating rate of 2°C/min Raise the temperature to 650°C, heat preservation and calcination for 2 hours, and cool to obtain the titanium oxide ceramic ultrafiltration membrane. The prepared titanium oxide ceramic ultrafiltration membrane has an average pore diameter of 12 nm, and a rejection rate of 2 g/L dextran (molecular weight 100,000) exceeding 90%. After a bubble pressure test, the overall bubble pressure is greater than 0.5 MPa. The film layer is shown in Figure 2.

Comparative example 3

(1) Add the dispersant polyethylene glycol PEG600 to the 0.5 mol/L zirconium n-butoxide and titanium isopropoxide solution (molar ratio 1:1) and make the final mass concentration 2%, and stir at 60°C. Under conditions, 0.1moL sodium hydroxide was added dropwise to adjust the pH to 10; after the reaction for 2.5 hours, the solid-liquid was separated and re-dissolved in water, and 0.1M nitric acid was added for gelation and the pH of the gelled solution was 2. Prepare Ti-Zr composite sol;

(2) Add PEG-400 and hydroxymethyl cellulose with a molecular weight of 6000-10000 to the Ti-Zr composite nano solution obtained in step (1), and make the final mass concentrations of PEG-400 and hydroxymethyl cellulose respectively 3%, 0.3%, after stirring evenly, then add the silicone defoamer Dow Corning DC65 and make the final mass concentration of 0.05%, mix well to prepare the coating liquid;

(3) Apply the coating liquid on a porous alumina ceramic membrane support with an average pore diameter of 0.1μm, heat up to 120°C at a heating rate of 2°C/min, dry for 3 hours, and then follow a heating rate of 2°C/min The temperature is raised to 650° C., the temperature is kept and calcined for 2 hours, and then cooled to obtain the zirconium oxide-titanium oxide composite ultrafiltration membrane. The prepared zirconium oxide-titanium oxide composite ultrafiltration membrane showed cracking in the membrane layer and could not be made into a complete membrane layer, as shown in Figure 3.

Example 1

(2) Put the Ti-Zr composite sol obtained in step (1) into a hydrothermal reaction kettle with a filling degree of 60%, keep the reaction at 200°C for 8 hours, and cool to prepare a Ti-Zr composite nano solution;

(3) Add PEG-400 and hydroxymethyl cellulose with a molecular weight of 6000-10000 to the Ti-Zr composite nano solution obtained in step (2), and make the final mass concentrations of PEG-400 and hydroxymethyl cellulose respectively 3%, 0.3%, after stirring evenly, then add the silicone defoamer Dow Corning DC65 and make the final mass concentration of 0.05%, mix well to prepare the coating liquid;

(4) Apply the coating liquid on a porous alumina ceramic membrane support with an average pore diameter of 0.1μm, heat up to 120°C at a heating rate of 2°C/min, dry for 3 hours, and then follow a heating rate of 2°C/min The temperature is raised to 650° C., the temperature is kept and calcined for 2 hours, and then cooled to obtain the zirconium oxide-titanium oxide composite ultrafiltration membrane. The prepared zirconium oxide-titanium oxide composite ultrafiltration membrane has an average pore diameter of 8 nm, a rejection rate of 2 g/L dextran (molecular weight 40,000) exceeding 90%, and the bubble pressure test shows that there are no defective pore bubbles. The film layer is shown in Figure 4.

Example 2

(1) Add the dispersant polyethylene glycol PEG600 to the 0.1 mol/L zirconium n-butoxide and titanium isopropoxide solution (molar ratio 1:1) and make the final mass concentration 2%, and stir at 60°C. Under the conditions, 0.1moL sodium hydroxide was added dropwise to adjust the pH to 9; after the reaction for 2h, the solid-liquid was separated and re-dissolved in water, and 0.1M nitric acid was added for gelation and the pH of the gelled solution was 3 , The Ti-Zr composite sol is prepared;

(2) Put the Ti-Zr composite sol obtained in step (1) into a hydrothermal reaction kettle with a filling degree of 50%, keep the reaction at 200°C for 10 hours, and cool to prepare a Ti-Zr composite nano solution;

(3) Add PEG-400 and hydroxymethyl cellulose to the Ti-Zr composite nano solution obtained in step (2), and make the final mass concentrations of PEG-400 and hydroxymethyl cellulose be 2% and 0.1%, respectively , After stirring uniformly, add the silicone defoamer Dow Corning DC65 and make the final mass concentration 0.01%, and mix well to prepare a coating liquid;

(4) Apply the coating liquid on the porous alumina ceramic membrane support with an average pore diameter of 0.1μm, raise the temperature to 100°C at a heating rate of 1°C/min, dry for 3 hours, and then follow the heating rate of 2°C/min Raise the temperature to 600°C, heat and calcine for 2h, and cool to obtain the zirconium oxide-titanium oxide composite ultrafiltration membrane. The rejection rate of 2g/L dextran (molecular weight 40,000) exceeds 90%, and the bubble pressure test shows that there is no Defective hole bubbles appear.

Example 3

(1) Add the dispersant polyethylene glycol PEG600 to the 1mol/L zirconium n-butoxide and titanium isopropoxide solution (molar ratio 1:1) and make the final mass concentration 2%, at 65 ℃, stirring conditions Then, 0.1moL sodium hydroxide was added dropwise to adjust the pH to 11; after 2 hours of reaction, the solid-liquid was separated and re-dissolved in water, and 0.1M nitric acid was added for gelation and the pH of the gelatinized solution was 3. Prepared Ti-Zr composite sol;

(2) Put the Ti-Zr composite sol obtained in step (1) into a hydrothermal reaction kettle with a filling degree of 60%, heat and react at 200°C for 10 hours, and cool to prepare a Ti-Zr composite nano solution;

(3) Add PEG-400 and hydroxymethyl cellulose with a molecular weight of 6000-10000 to the Ti-Zr composite nano solution obtained in step (2), and make the final mass concentrations of PEG-400 and hydroxymethyl cellulose respectively It is 5% and 1%. After stirring evenly, add the silicone defoamer Dow Corning DC65 and make the final mass concentration of 0.1%, and mix well to prepare the coating liquid;

(4) Apply the coating liquid on the porous alumina ceramic membrane support with an average pore diameter of 0.1μm, heat up to 120°C at a heating rate of 1°C/min, dry for 3 hours, and then follow a heating rate of 2°C/min Raise the temperature to 700℃, heat and calcine for 2h, and cool to obtain the zirconium oxide-titanium oxide composite ultrafiltration membrane. The rejection rate of 2g/L dextran (molecular weight 40,000) exceeds 90%, and after bubble pressure test, there is no Defective hole bubbles appear.

The hydroxymethyl cellulose in the above embodiments can also be replaced with hydroxyethyl cellulose or hydroxypropyl cellulose.

Table 1

It can be seen from Table 1 that in the present invention, the method of doping crystalline stabilizers into TiO ₂ and ZrO ₂ can reduce the particle size and prepare a ceramic ultrafiltration membrane with a smaller pore size.

The above are only the preferred embodiments of the present invention, so the scope of implementation of the present invention cannot be limited accordingly. That is, equivalent changes and modifications made according to the scope of the patent of the present invention and the contents of the specification should still be covered by the present invention. In the range.

Industrial applicability

The invention discloses a method for preparing a zirconium oxide-titanium oxide composite ultrafiltration membrane. The present invention uses the Ti-Zr composite sol prepared by the sol-gel method as the precursor, and then is treated by the hydrothermal method. A two-step method can be used to obtain a Ti-Zr composite nano solution with uniform particle size, and an appropriate amount of additives are added to it It is directly made into the coating liquid, the film is coated once, and then dried and calcined to make the Ti-Zr composite ultrafiltration membrane. Compared with the traditional preparation method, the method is simple and solves the problem of easy agglomeration of particles and the need for multiple coatings. Difficulties and defects caused by the crystal transition temperature of the particles. The prepared nanoparticles have uniform particle size and no shrinkage, cracks or cracks in the film. The preparation of defect-free Ti-Zr composite ceramic ultrafiltration membranes is realized, which has industrial practicability. .

Claims

A preparation method of zirconium oxide-titanium oxide composite ultrafiltration membrane, which is characterized in that it comprises the following steps:

(1) Add polyethylene glycol or nitric acid with a weight average molecular weight of 550-650 as a dispersant to the mixed solution of organic zirconium alkoxide and organic titanium alkoxide, and the added amount of the dispersant is the amount of the mixed solution. 1-3wt%, while stirring at 50-65℃, add ammonia water or sodium hydroxide dropwise to adjust the pH to 9-11, then keep the reaction for 2-3h, and then separate the solid from the liquid to obtain the solid, which is re-dissolved in water and added The nitric acid gelled and the pH of the gelled material was 2-3 to prepare Ti-Zr composite sol; in the above mixed solution, the molar ratio of organic zirconium alkoxide and organic titanium alkoxide was 0.8-1.2:0.8- 1.2, and the concentration is 0.1-1mol/L;

(2) Put the above-mentioned Ti-Zr composite sol into a hydrothermal reaction kettle with a filling degree of 50-60%, keep the temperature at 200-250°C for 5-10 hours, and cool to prepare a Ti-Zr composite nano solution;

(3) Add polyethylene glycol with a weight average molecular weight of 350-450 as a plasticizer and a cellulose compound with a molecular weight of 6000-10000 as a binder to the above Ti-Zr composite nano solution to a final concentration of respectively 2-5wt% and 0.1-0.5wt%, after mixing uniformly, the coating liquid is prepared; the cellulose compound is hydroxymethyl cellulose, hydroxyethyl cellulose or hydroxypropyl cellulose;

(4) Apply the above coating liquid on the porous alumina ceramic membrane support, heat up to 100-120°C at a rate of 1-3°C/min, heat and dry for 2-5 hours, and then heat it at a temperature of 1-3°C/min The rate is increased to 600-700°C, the temperature is kept and calcined for 2-3 hours, and the zirconium oxide-titanium oxide composite ultrafiltration membrane is obtained after cooling.
The preparation method according to claim 1, wherein the organic zirconium alkoxide is zirconium n-butoxide or zirconium n-propoxide.
The preparation method according to claim 1, wherein the organic titanium alkoxide is titanium isopropoxide or titanium tert-butoxide.
The preparation method according to claim 1, wherein the step (3) is to add polyethylene glycol with a weight average molecular weight of 350-450 as a plasticizer to the Ti-Zr composite nano solution and as a plasticizer. The final concentration of the cellulose compound of the binder is 2-5wt% and 0.1-0.5wt% respectively, and after uniform mixing, the defoamer is added to the final concentration of 0.01-0.1wt% to prepare a coating liquid.
A preparation method of zirconium oxide-titanium oxide composite ultrafiltration membrane, which is characterized in that it comprises the following steps:

(1) Add as dispersant or nitric acid to the mixed solution of organic zirconium alkoxide and organic titanium alkoxide, and make the final mass concentration of 2%; add ammonia or sodium hydroxide to adjust the pH to 9-11, and keep it warm for reaction 2-3h, then solid-liquid separation to obtain a solid, redissolve it in water, add nitric acid to peptize and make the pH of the gelatinized material be 2-3 to prepare Ti-Zr composite sol; in the above mixed solution, organic zirconium The molar ratio of alkoxide and organic titanium alkoxide is 0.8-1.2:0.8-1.2, and the concentration is 0.1-1mol/L;

(2) Put the above-mentioned Ti-Zr composite sol into a hydrothermal reaction kettle with a filling degree of 50-60%, keep the temperature at 200-250°C for 5-10 hours, and cool to prepare a Ti-Zr composite nano solution;

(3) Add a plasticizer and a binder to the above Ti-Zr composite nano solution, and mix them evenly to prepare a coating liquid;

(4) Apply the above coating liquid on the porous alumina ceramic membrane support, heat up to 100-120°C at a rate of 1-3°C/min, heat and dry for 2-5 hours, and then heat it at a temperature of 1-3°C/min The rate is increased to 600-700°C, the temperature is kept and calcined for 2-3 hours, and the zirconium oxide-titanium oxide composite ultrafiltration membrane is obtained after cooling.
The method for preparing a zirconium oxide-titanium oxide composite ultrafiltration membrane according to claim 5, wherein the plasticizer in the step (3) is polyethylene glycol with a weight average molecular weight of 350-450. The concentration is 2-5wt%; the binder is a cellulose compound with a molecular weight of 6000-10000, and the final concentration is 0.1-0.5wt%.
The method for preparing a zirconium oxide-titanium oxide composite ultrafiltration membrane according to claim 6, wherein the step (3) is: adding a weight-average plasticizer as a plasticizer to the Ti-Zr composite nano-solution Polyethylene glycol with a molecular weight of 350-450 and a cellulose compound as a binder to a final concentration of 2-5wt% and 0.1-0.5wt%, respectively. After mixing uniformly, add defoamer to the final concentration of 0.01 -0.1wt% to prepare a coating liquid.