CN113737395A - Flexible titanium dioxide nanofiber membrane and preparation method and application thereof - Google Patents

Abstract

The invention discloses a flexible titanium dioxide nanofiber membrane and a preparation method and application thereof. The flexible titanium dioxide nanofiber membrane is formed by interweaving nano titanium dioxide ceramic fibers, and the preparation method comprises the following steps: 1) preparing a ceramic precursor solution; 2) mixing the ceramic precursor solution and the organic polymer to obtain a spinning solution; 3) and adding the spinning solution into an electrostatic spinning machine, performing electrostatic spinning, and then performing curing, pyrolysis and sintering to obtain the flexible titanium dioxide nanofiber membrane. The flexible titanium dioxide nanofiber membrane has the advantages of good appearance and mechanical properties, high photocatalytic efficiency, high temperature resistance, oxidation resistance, acid and alkali corrosion resistance, good flexibility and the like, and is simple and reliable in preparation process, low in production cost and suitable for large-scale production and application.

Description

Flexible titanium dioxide nanofiber membrane and preparation method and application thereof

Technical Field

The invention relates to the technical field of membrane materials, in particular to a flexible titanium dioxide nanofiber membrane and a preparation method and application thereof.

Background

The titanium dioxide can efficiently absorb ultraviolet light, has the functions of photocatalysis, ultraviolet ray shielding, sterilization, bacteriostasis and the like, and has wide application range. When the titanium dioxide is used as the photocatalyst, the titanium dioxide is generally loaded on an inorganic porous matrix to prepare a loaded photocatalyst, so that a better photocatalytic effect is achieved, but the method has the problems of smaller specific surface area of the photocatalyst, lower photocatalytic efficiency, longer preparation process flow, higher cost and the like. In addition, researchers also prepare composite films of titanium dioxide and high polymer materials by mixing titanium alkoxide solutions or titanium dioxide sols with organic polymers and then performing electrostatic spinning, and the prepared composite films have excellent mechanical properties, but are poor in heat resistance, acid and alkali resistance, catalytic performance and the like, and thus cannot meet the requirements of practical application.

Disclosure of Invention

The invention aims to provide a flexible titanium dioxide nanofiber membrane and a preparation method and application thereof.

The technical scheme adopted by the invention is as follows:

a flexible titanium dioxide nanofiber membrane is formed by interweaving nano titanium dioxide ceramic fibers.

Preferably, the diameter of the nano titanium dioxide ceramic fiber is 30nm to 600 nm.

Preferably, the thickness of the flexible titanium dioxide nanofiber membrane is 10-800 μm.

Preferably, the nano titanium dioxide ceramic fiber is doped with at least one element of zirconium, aluminum, silicon, carbon, tungsten, yttrium, lanthanum and strontium.

The preparation method of the flexible titanium dioxide nanofiber membrane comprises the following steps:

1) dispersing a titanium-containing compound and an organic ligand in an organic solvent, and adding water for hydrolysis to obtain a ceramic precursor solution;

or dispersing a titanium-containing compound and an organic ligand in an organic solvent, adding at least one of zirconium n-propoxide, aluminum isopropoxide, tetraethyl silicate, tungsten chloride, yttrium chloride, lanthanum chloride and strontium chloride, and adding water for hydrolysis to obtain a ceramic precursor solution;

2) mixing the ceramic precursor solution and the organic polymer to obtain a spinning solution;

3) and adding the spinning solution into an electrostatic spinning machine, performing electrostatic spinning, and then performing curing, pyrolysis and sintering to obtain the flexible titanium dioxide nanofiber membrane.

Preferably, the molar ratio of the titanium-containing compound to the organic ligand in the step 1) is 1: 0.2-1: 10.

Preferably, the addition amount of zirconium n-propoxide, aluminum isopropoxide, tetraethyl silicate, tungsten chloride, yttrium chloride, lanthanum chloride or strontium chloride in step 1) is 0.5% to 20% of the total mass of the titanium-containing compound, the organic ligand, the organic solvent and water.

Preferably, the titanium-containing compound in step 1) is at least one of tetraethyl titanate, tetrabutyl titanate and isopropyl titanate.

Preferably, the organic ligand in step 1) is at least one of oxalic acid, acetic acid, formic acid, nitric acid, salicylic acid, citric acid, glycolic acid, acetylacetone, ethylenediamine, triethylamine and diethanolamine.

Preferably, the organic polymer in step 2) is at least one of polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, polyimide, polyurethane, phenolic resin, polyacrylonitrile and epoxy resin.

Preferably, the electrostatic spinning parameters in the step 3) are as follows: the spinning nozzle is connected with a voltage of 10kV to 20kV, the collecting device is connected with a voltage of-10 kV to 0kV, the specification of the needle is 14G to 25G, the distance between the spinning nozzle and the collecting device is 10cm to 15cm, and the supply speed of the spinning solution is 1mL/h to 3 mL/h.

Preferably, the electrostatic spinning in the step 3) is carried out at the ambient temperature of 20-30 ℃ and the relative humidity of 25-75%.

More preferably, the electrostatic spinning in step 3) is performed at an ambient temperature of 20 ℃ to 30 ℃ and a relative humidity of 30% to 40%.

Preferably, the curing manner in step 3) is high temperature air curing or moisture curing.

Preferably, the temperature of the high-temperature air curing is 100-300 ℃.

Further preferably, the temperature of the high-temperature air curing is 200 ℃ to 250 ℃.

Preferably, the temperature of the moisture curing is 100 ℃ to 200 ℃.

Further preferably, the temperature of the moisture curing is 110 ℃ to 150 ℃.

Preferably, the pyrolysis in the step 3) is carried out at 300-800 ℃, and the pyrolysis time is 1-24 h. The pyrolysis time is long, the pyrolysis is complete, no carbon is contained in the nano titanium dioxide ceramic fiber, the pyrolysis time is short, the pyrolysis is incomplete, and the carbon is contained in the nano titanium dioxide ceramic fiber.

Further preferably, the pyrolysis in the step 3) is carried out at 300-500 ℃, and the pyrolysis time is 1-4 h.

Preferably, the sintering in the step 3) is carried out at 400-800 ℃, and the sintering time is 10 min-12 h. Sintering helps to remove carbon residue.

Further preferably, the sintering in step 3) is carried out at 400-600 ℃, and the sintering time is 10 min-2 h.

The invention has the beneficial effects that: the flexible titanium dioxide nanofiber membrane has the advantages of good appearance and mechanical properties, high photocatalytic efficiency, high temperature resistance, oxidation resistance, acid and alkali corrosion resistance, good flexibility and the like, and is simple and reliable in preparation process, low in production cost and suitable for large-scale production and application.

Specifically, the method comprises the following steps:

1) the flexible titanium dioxide nanofiber membrane belongs to a nanofiber membrane consisting of pure inorganic materials, has the advantages of high temperature resistance, oxidation resistance, acid and alkali corrosion resistance, high catalytic efficiency and the like, maintains good flexibility, is convenient to use and separate, and can be repeatedly used;

2) the titanium dioxide nanofiber in the flexible titanium dioxide nanofiber membrane has smooth and flat surface, no local agglomeration and granular texture, uniform and fine appearance, no pulverization and fragmentation phenomena, and capability of being bent for more than hundred times, and is favorable for repeated utilization in practical application;

3) the flexible titanium dioxide nanofiber membrane is rapidly prepared through electrostatic spinning, the preparation method is simple and reliable, the thin film products can be prepared in batches in a short time, and the diameter, the thin film density, the thin film thickness and the like of the titanium dioxide nanofiber can be flexibly regulated and controlled through regulating and controlling electrostatic spinning parameters;

4) the invention rapidly prepares the flexible titanium dioxide nanofiber membrane through electrostatic spinning, can realize the doping modification at the molecular level, and is convenient for further improving the photocatalytic performance of the material.

Drawings

Fig. 1 is a photograph of a flexible titanium dioxide nanofiber membrane of example 1.

Fig. 2 is an SEM image of the flexible titania nanofiber membrane of example 1.

FIG. 3 is an XRD pattern of the flexible titanium dioxide nanofiber membranes of examples 1-3.

FIG. 4 is a graph showing the photocatalytic effects of the flexible titanium dioxide nanofiber membranes and the titanium dioxide nanopowders of examples 1 to 3.

Fig. 5 is an SEM image of the flexible titania nanofiber membrane of example 2.

Fig. 6 is an SEM image of the flexible titania nanofiber membrane of example 3.

Detailed Description

The invention will be further explained and illustrated with reference to specific examples.

Example 1:

a flexible titanium dioxide nanofiber membrane is prepared by the following steps:

1) dispersing 30g of isopropyl titanate in 70g of isopropanol, adding 6g of acetic acid while stirring, dropwise adding 3g of deionized water, reacting at room temperature for 8 hours, and concentrating the solution to 40g to obtain a ceramic precursor solution;

2) 10g of polyacrylonitrile (number average molecular weight 150000g/mol) was dispersed in 30g of N, N-dimethylformamide to obtain a polyacrylonitrile solution;

3) mixing the ceramic precursor solution and the polyacrylonitrile solution to obtain a spinning solution;

4) adding the spinning solution into an electrostatic spinning machine, carrying out electrostatic spinning through a 14G needle, connecting a spinning nozzle with 15kV voltage, connecting a collecting device with-3 kV voltage, enabling the distance between the spinning nozzle and the collecting device to be 12cm, enabling the spinning solution supply speed to be 1.5mL/h, enabling the spinning environment temperature to be 25 ℃ and the relative humidity to be 40%, and obtaining a fiber membrane;

5) and (3) curing the fiber membrane in an oven at 250 ℃ for 2h, then putting the fiber membrane in a tubular furnace filled with nitrogen for protection, pyrolyzing the fiber membrane at 600 ℃ for 6h, and then putting the fiber membrane in a muffle furnace for sintering at 400 ℃ for 2h to obtain the flexible titanium dioxide nanofiber membrane (the thickness is about 100 mu m).

And (3) performance testing:

1) the physical photograph of the flexible titanium dioxide nanofiber membrane of the present example is shown in fig. 1, the Scanning Electron Microscope (SEM) image is shown in fig. 2, and the X-ray powder diffraction (XRD) image is shown in fig. 3.

As can be seen from fig. 1 and 2: the flexible titanium dioxide nanofiber membrane of the embodiment has a smooth surface, the titanium dioxide nanofibers in the flexible titanium dioxide nanofiber membrane have a smooth and flat surface and do not have local agglomeration or particle texture, and the diameter of the titanium dioxide nanofibers is 300 nm-400 nm.

As can be seen from fig. 3: the crystal structure of the flexible titanium dioxide nanofiber membrane of the present example is dominated by the anatase phase, with a small amount of rutile structure present.

2) The photocatalytic effect of the flexible titanium dioxide nanofiber membrane and the titanium dioxide nanopowder (P25) of the present embodiment was tested, and the test method was: an LED ultraviolet lamp (with the wavelength of 365nm) with the power of 100W is used as a light source, methylene blue is used as a degradation substrate, the flexible titanium dioxide nanofiber membrane or the titanium dioxide nano powder is soaked in a watch glass containing methylene blue aqueous solution, the distance between the watch glass and the light source is 15cm, and the test result is shown in figure 4.

As can be seen from fig. 4: the photocatalytic efficiency of the flexible titanium dioxide nanofiber membrane of the embodiment is close to that of titanium dioxide nano powder, and the photocatalytic performance is excellent.

Example 2:

a flexible titanium dioxide nanofiber membrane is prepared by the following steps:

1) dispersing 30g of tetraethyl titanate in 70g of ethanol, adding 10g of acetylacetone while stirring, dropwise adding 2g of deionized water, reacting at room temperature for 6 hours, and concentrating the solution to 40g to obtain a ceramic precursor solution;

2) 10g of polyimide (number average molecular weight 2300g/mol) was dispersed in 30g of N, N-dimethylformamide to obtain a polyimide solution;

3) mixing the ceramic precursor solution and the polyimide solution to obtain a spinning solution;

4) adding the spinning solution into an electrostatic spinning machine, carrying out electrostatic spinning through a 17G needle, connecting 12kV voltage to a spinning nozzle, connecting-3 kV voltage to a collecting device, wherein the distance between the spinning nozzle and the collecting device is 15cm, the supply speed of the spinning solution is 1mL/h, the spinning environment temperature is 25 ℃, and the relative humidity is 40%, so as to obtain a fiber membrane;

5) and (3) curing the fiber membrane in an oven at 250 ℃ for 2h, then putting the fiber membrane in a tubular furnace filled with nitrogen for protection at 800 ℃ for pyrolysis for 4h, and then putting the fiber membrane in a muffle furnace at 400 ℃ for sintering for 30min to obtain the flexible titanium dioxide nanofiber membrane (the thickness is about 180 mu m, and carbon is doped in the titanium dioxide nanofiber).

And (3) performance testing:

1) the XRD pattern of the flexible titania nanofiber membrane of this example is shown in fig. 3.

As can be seen from fig. 3: the crystal structure of the flexible titanium dioxide nanofiber membrane of the embodiment is not obvious, which shows that carbon doping can effectively inhibit the growth of titanium dioxide crystals.

2) The photocatalytic effects of the flexible titanium dioxide nanofiber membrane and the titanium dioxide nanopowder (P25) of this example were tested in the same manner as in example 1, and the test results are shown in fig. 4.

As can be seen from fig. 4: the photocatalytic efficiency of the flexible titanium dioxide nanofiber membrane of the embodiment is close to that of titanium dioxide nano powder, and the photocatalytic performance is excellent.

3) An SEM image of the flexible titania nanofiber membrane of this example is shown in fig. 5.

As can be seen from fig. 5: the titanium dioxide nanofiber in the flexible titanium dioxide nanofiber membrane of the embodiment has a smooth and flat surface, and does not have local agglomeration or particle texture, and the diameter of the titanium dioxide nanofiber is 200 nm-300 nm.

Example 3:

a flexible titanium dioxide nanofiber membrane is prepared by the following steps:

1) dispersing 27g of isopropyl titanate and 3g of zirconium n-propoxide in 70g of isopropanol, adding 5g of ethylamine while stirring, dropwise adding 2g of deionized water, reacting at room temperature for 5 hours, and concentrating the solution to 40g to obtain a ceramic precursor solution;

2) 10g of a phenol novolac resin (number average molecular weight 800g/mol) was dispersed in 30g of N, N-dimethylformamide to obtain a phenol novolac resin solution;

3) mixing the ceramic precursor solution and the phenolic resin solution to obtain a spinning solution;

4) adding the spinning solution into an electrostatic spinning machine, carrying out electrostatic spinning through a 20G needle, connecting a spinning nozzle with 15kV voltage, connecting a collecting device with-3 kV voltage, enabling the distance between the spinning nozzle and the collecting device to be 12cm, enabling the spinning solution supply speed to be 1.5mL/h, enabling the spinning environment temperature to be 25 ℃ and the relative humidity to be 40%, and obtaining a fiber membrane;

5) and (3) curing the fiber membrane in an oven at 250 ℃ for 2h, then putting the fiber membrane in a tubular furnace filled with nitrogen for protection at 800 ℃ for pyrolysis for 6h, and then putting the fiber membrane in a muffle furnace at 400 ℃ for sintering for 2h to obtain the flexible titanium dioxide nanofiber membrane (the thickness is about 150 mu m, and the titanium dioxide nanofibers are doped with zirconium dioxide).

And (3) performance testing:

1) the XRD pattern of the flexible titania nanofiber membrane of this example is shown in fig. 3.

As can be seen from fig. 3: the crystal structure of the flexible titanium dioxide nanofiber membrane of the present example is dominated by the rutile phase.

2) The photocatalytic effects of the flexible titanium dioxide nanofiber membrane and the titanium dioxide nanopowder (P25) of this example were tested in the same manner as in example 1, and the test results are shown in fig. 4.

As can be seen from fig. 4: the photocatalytic efficiency of the flexible titanium dioxide nanofiber membrane of the embodiment is close to that of titanium dioxide nano powder, and the photocatalytic performance is excellent.

3) An SEM image of the flexible titania nanofiber membrane of this example is shown in fig. 6.

As can be seen from fig. 6: the titanium dioxide nanofiber in the flexible titanium dioxide nanofiber membrane of the embodiment has a smooth and flat surface, and does not have local agglomeration or particle texture, and the diameter of the titanium dioxide nanofiber is 100 nm-200 nm.

Example 4:

a flexible titanium dioxide nanofiber membrane is prepared by the following steps:

1) dispersing 30g of tetrabutyl titanate and 0.5g of lanthanum chloride in 70g of isopropanol, adding 6g of acetic acid while stirring, dropwise adding 3g of deionized water, reacting at room temperature for 8 hours, and concentrating the solution to 40g to obtain a ceramic precursor solution;

2) 10g of polyvinylpyrrolidone (number average molecular weight of 100000g/mol) was dispersed in 30g of N, N-dimethylformamide to obtain a polyvinylpyrrolidone solution;

3) mixing the ceramic precursor solution and the polyvinylpyrrolidone solution to obtain a spinning solution;

4) adding the spinning solution into an electrostatic spinning machine, carrying out electrostatic spinning through a 16G needle, connecting a spinning nozzle with 15kV voltage, connecting a collecting device with-3 kV voltage, enabling the distance between the spinning nozzle and the collecting device to be 12cm, enabling the spinning solution supply speed to be 2mL/h, enabling the spinning environment temperature to be 25 ℃ and the relative humidity to be 30%, and obtaining a fiber membrane;

5) and (3) curing the fiber membrane in an oven at 250 ℃ for 2h, then putting the fiber membrane in a tubular furnace filled with nitrogen for protection at 600 ℃ for pyrolysis for 6h, and then putting the fiber membrane in a muffle furnace for sintering at 400 ℃ for 2h to obtain the flexible titanium dioxide nanofiber membrane (the thickness is about 150 mu m, and the titanium dioxide nanofiber is doped with lanthanum).

And (3) performance testing:

1) the micro-morphology and the crystal structure of the flexible titanium dioxide nanofiber membrane of the present example were tested with reference to the method of example 1.

Tests show that the surface of the titanium dioxide nanofiber in the flexible titanium dioxide nanofiber membrane of the embodiment is smooth and flat, no local agglomeration and no particle texture are generated, the diameter of the titanium dioxide nanofiber is 200 nm-300 nm, and the crystal structure of the flexible titanium dioxide nanofiber membrane of the embodiment is mainly in an anatase phase.

2) The photocatalytic effect of the flexible titania nanofiber membrane of the present example was tested with reference to the method of example 1.

Tests show that the photocatalytic efficiency of the flexible titanium dioxide nanofiber membrane is close to that of titanium dioxide nanopowder, and the photocatalytic performance is excellent.

Example 5:

a flexible titanium dioxide nanofiber membrane is prepared by the following steps:

1) dispersing 30g of tetraethyl titanate, 0.5g of tungsten chloride and 0.5g of lanthanum chloride in 70g of ethanol, adding 6g of acetic acid while stirring, dropwise adding 3g of deionized water, reacting at room temperature for 8 hours, and concentrating the solution to 40g to obtain a ceramic precursor solution;

2) 10g of polyacrylonitrile (number average molecular weight 150000g/mol) was dispersed in 30g of N, N-dimethylformamide to obtain a polyacrylonitrile solution;

3) mixing the ceramic precursor solution and the polyacrylonitrile solution to obtain a spinning solution;

4) adding the spinning solution into an electrostatic spinning machine, carrying out electrostatic spinning through a 17G needle, connecting 10kV voltage to a spinning nozzle, connecting-1 kV voltage to a collecting device, wherein the distance between the spinning nozzle and the collecting device is 12cm, the supply speed of the spinning solution is 1mL/h, the spinning environment temperature is 25 ℃, and the relative humidity is 30%, so as to obtain a fiber membrane;

5) and (3) curing the fiber membrane in an oven at 250 ℃ for 2h, then putting the fiber membrane in a tubular furnace filled with nitrogen for protection at 800 ℃ for pyrolysis for 4h, and then putting the fiber membrane in a muffle furnace at 400 ℃ for sintering for 2h to obtain the flexible titanium dioxide nanofiber membrane (the thickness is about 200 mu m, and the titanium dioxide nanofiber is doped with elements of tungsten and lanthanum).

And (3) performance testing:

1) the micro-morphology and the crystal structure of the flexible titanium dioxide nanofiber membrane of the present example were tested with reference to the method of example 1.

Tests show that the surface of the titanium dioxide nanofiber in the flexible titanium dioxide nanofiber membrane of the embodiment is smooth and flat, no local agglomeration and no particle texture are generated, the diameter of the titanium dioxide nanofiber is 100 nm-200 nm, and the crystal structure of the flexible titanium dioxide nanofiber membrane of the embodiment is mainly in an anatase phase.

2) The photocatalytic effect of the flexible titania nanofiber membrane of the present example was tested with reference to the method of example 1.

Tests show that the photocatalytic efficiency of the flexible titanium dioxide nanofiber membrane is close to that of titanium dioxide nanopowder, and the photocatalytic performance is excellent.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims (10)

1. A flexible titanium dioxide nanofiber membrane is characterized by being formed by interweaving nano titanium dioxide ceramic fibers.

2. The flexible titanium dioxide nanofiber membrane of claim 1, wherein: the diameter of the nano titanium dioxide ceramic fiber is 30 nm-600 nm.

3. The flexible titanium dioxide nanofiber membrane of claim 1 or 2, wherein: the nano titanium dioxide ceramic fiber is doped with at least one element of zirconium, aluminum, silicon, carbon, tungsten, yttrium, lanthanum and strontium.

4. The method for preparing a flexible titanium dioxide nanofiber membrane as claimed in claim 1 or 2, characterized by comprising the steps of:

1) dispersing a titanium-containing compound and an organic ligand in an organic solvent, and adding water for hydrolysis to obtain a ceramic precursor solution;

2) mixing the ceramic precursor solution and the organic polymer to obtain a spinning solution;

3) and adding the spinning solution into an electrostatic spinning machine, performing electrostatic spinning, and then performing curing, pyrolysis and sintering to obtain the flexible titanium dioxide nanofiber membrane.

5. The method for preparing a flexible titanium dioxide nanofiber membrane according to claim 4, characterized in that: step 1) the titanium-containing compound is at least one of tetraethyl titanate, tetrabutyl titanate and isopropyl titanate; the organic ligand in the step 1) is at least one of oxalic acid, acetic acid, formic acid, nitric acid, salicylic acid, citric acid, glycolic acid, acetylacetone, ethylenediamine, triethylamine and diethanolamine.

6. The method for preparing a flexible titanium dioxide nanofiber membrane according to claim 4 or 5, characterized in that: and 2) the organic polymer is at least one of polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, polyimide, polyurethane, phenolic resin, polyacrylonitrile and epoxy resin.

7. The method for preparing a flexible titanium dioxide nanofiber membrane according to claim 4 or 5, characterized in that: and step 3), the electrostatic spinning parameters are as follows: the spinning nozzle is connected with a voltage of 10kV to 20kV, the collecting device is connected with a voltage of-10 kV to 0kV, the specification of the needle is 14G to 25G, the distance between the spinning nozzle and the collecting device is 10cm to 15cm, and the supply speed of the spinning solution is 1mL/h to 3 mL/h.

8. The method for preparing a flexible titanium dioxide nanofiber membrane according to claim 4 or 5, characterized in that: the pyrolysis in the step 3) is carried out at the temperature of 300-800 ℃, and the pyrolysis time is 1-24 h; and 3) sintering at 400-800 ℃ for 10 min-12 h.

9. The method for preparing the flexible titanium dioxide nanofiber membrane as claimed in claim 3, characterized by comprising the steps of:

1) dispersing a titanium-containing compound and an organic ligand in an organic solvent, adding at least one of zirconium n-propoxide, aluminum isopropoxide, tetraethyl silicate, tungsten chloride, yttrium chloride, lanthanum chloride and strontium chloride, and adding water for hydrolysis to obtain a ceramic precursor solution;

2) mixing the ceramic precursor solution and the organic polymer to obtain a spinning solution;

3) and adding the spinning solution into an electrostatic spinning machine, performing electrostatic spinning, and then performing curing, pyrolysis and sintering to obtain the flexible titanium dioxide nanofiber membrane.

10. Use of the flexible titanium dioxide nanofiber membrane of any one of claims 1 to 3 in the preparation of a photocatalyst, a catalyst support or an antibacterial material.

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