Ultrafine continuous fibrous ceramic filter and method of manufacturing same

• US 9,994,488 B2
• Filed: 05/04/2016
• Issued: 06/12/2018
• Est. Priority Date: 05/03/2010
• Status: Active Grant

• Current Assignee: Korea Advanced Institute of Science and Technology
• Original Assignee: Korea Advanced Institute of Science and Technology
• Inventors: Jo, Seong Mu, Kim, Dong Young, Jang, Sung-Yeon, Choo, Jeong Joo
• Primary Examiner(s): Gonzalez, Madeline
• Application Number:
  US15/146,204
• Publication Number:
  US 20160244373A1
• Time in Patent Office: 769 Days
• Field of Search: 210496, 210503-508, 2105101, 977777, 427458, 55523, 55527, 55528, 501 80, 501 82
• CPC Class Codes: B01D 2239/025 comprising nanofibres
• CPC Class Codes: B01D 2239/0258 comprising nanoparticles
• CPC Class Codes: B01D 2239/0478 on a layer of the filter
• CPC Class Codes: B01D 2239/086 Binders between particles or fibres
• CPC Class Codes: B01D 2239/1216 Pore size
• CPC Class Codes: B01D 2239/1225 Fibre length
• CPC Class Codes: B01D 2323/39 Electrospinning
• CPC Class Codes: B01D 39/2079 otherwise bonded, e.g. by resins
• CPC Class Codes: B01D 39/2082 the material being filamentary or fibrous
• CPC Class Codes: B01D 39/2089 otherwise bonded, e.g. by resins
• CPC Class Codes: B01D 67/00411 by sintering
• CPC Class Codes: B01D 69/108 Inorganic support material
• CPC Class Codes: B01D 69/14111 with nanoscale dispersed material, e.g. nanoparticles
• CPC Class Codes: B01D 71/025 Aluminium oxide
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C04B 2235/3218 Aluminium (oxy)hydroxides, e.g. boehmite, gibbsite, alumina sol
• CPC Class Codes: C04B 2235/441 Alkoxides, e.g. methoxide, tert-butoxide
• CPC Class Codes: C04B 2235/443 Nitrates or nitrites
• CPC Class Codes: C04B 2235/5228 Silica and alumina, including aluminosilicates, e.g. mullite
• CPC Class Codes: C04B 2235/5252 having a specific pre-form
• CPC Class Codes: C04B 2235/5264 : characterised by the diameter of the fibers
• CPC Class Codes: C04B 2235/5268 : Orientation of the fibers
• CPC Class Codes: C04B 2235/5296 : with a defined aspect ratio, e.g. indicating sphericity
• CPC Class Codes: C04B 35/62236 : Fibres based on aluminium oxide
• CPC Class Codes: C04B 35/6224 : Fibres based on silica
• CPC Class Codes: C04B 35/62245 : rich in aluminium oxide
• CPC Class Codes: C04B 35/624 : Sol-gel processing
• CPC Class Codes: C04B 35/6264 : Mixing media, e.g. organic solvents
• CPC Class Codes: C04B 35/62813 : Alumina or aluminates
• CPC Class Codes: C04B 35/62892 : with a coating layer consisting of particles
• CPC Class Codes: C04B 35/63444 : Nitrogen-containing polymers, e.g. polyacrylamides, polyacrylonitriles, polyvinylpyrrolidone [PVP], polyethylenimine [PEI]
• CPC Class Codes: C04B 35/76 : Fibres, filaments, whiskers, platelets, or the like
• CPC Class Codes: D01D 5/0007 : Electro-spinning non-woven fabrics produced by electro-spinning D04H1/728
• CPC Class Codes: D10B 2101/08 : Ceramic
• CPC Class Codes: D10B 2505/04 : Filters

Abstract

An ultrafine continuous fibrous ceramic filter, which comprises a filtering layer of a fibrous porous body, wherein the fibrous porous body comprises continuous ultrafine fibers of metal oxide which are randomly arranged and layered, and powdery nano-alumina incorporated into the ultrafine fibers or coated thereon, the ultrafine fibers being obtained by electrospinning a spinning solution comprising a metal oxide precursor sol-gel solution, and optionally, a polymer resin, and sintering the electrospun fibers, in which the ultrafine fibers have an average diameter of 10˜500 nm, and the fibrous porous body has a pore size of maximum frequency ranging from 0.05 to 2 μm, exhibits high filtration efficiency at a high flow rate, and can be regenerated.

Claims

1. A method for preparing a ceramic filter, which comprises the steps of:

(1) electrospinning a metal oxide precursor sol-gel solution or a mixture of a metal oxide precursor sol-gel solution and a polymer resin to make a layer of continuous ultrafine fibers randomly arranged, wherein the metal oxide precursor is selected from a group consisting of M(OR)_x, MR_x(OR)_y, MX_y, and M(NO₃)_y, wherein

M comprises Si (silicon) or Al (aluminum),

R comprises an alkyl group,

X is selected from the group consisting of F (fluorine), Cl (chlorine), Br (bromine) and I (iodine),

x and y are each independently an integer of 1 to 4; and

(2) sintering the electrospun ultrafine fibers at a temperature ranging from 250 to 1000°

C.,

wherein (A) in step (1), before the electrospinning, the metal oxide precursor sol-gel solution or the mixture of the metal oxide precursor sol-gel solution and the polymer resin is additionally mixed with one-dimensional powdery nano-alumina;

or (B) the sintered ultrafine fibers from step (2) are impregnated or coated with a suspension of one-dimensional powdery nano-alumina;

or (A) and (B) both are performed.

2. The method of claim 1, wherein, before the sintering of step (2), the ultrafine fibers are subjected to heat compression at a temperature ranging from room temperature to 250°

C.

3. The method of claim 1, wherein the ultrafine fibers have an average diameter of 10˜

500 nm.

4. The method of claim 1, wherein the one-dimensional powdery nano-alumina is a nanoparticle selected from the group consisting of boehmite (AlOOH), aluminum hydroxide (Al(OH)₃), gamma-alumina (γ

-Al₂O₃) and a mixture thereof, which are provided in the form of nanorods, nanotubes or nanofibers, having a diameter of 1 nm or more and a diameter to length ratio (an aspect ratio) of 5 or more.

5. The method of claim 1, wherein the ultrafine fibers are made of a metal oxide selected from the group consisting of silica (SiO₂), gamma-alumina (γ

-Al₂O₃), and a mixture thereof.

6. The method of claim 1, wherein the polymer resin is selected from the group consisting of polyvinylpyrrolidone, polyvinylalcohol, polyvinylacetate, polyethylene oxide, and a mixture thereof.

7. The method of claim 1, wherein the polymer resin is polyacrylonitrile or its copolymer.

8. The method of claim 1, wherein the electrospinning in step (1) is melt-blowing, flash spinning, or electro-blowing.

9. A method for preparing a ceramic filter, which comprises the steps of:

(1) electrospinning a metal oxide precursor sol-gel solution or a mixture of a metal oxide precursor sol-gel solution and a polymer resin to make a layer of continuous ultrafine fibers randomly arranged, wherein the metal oxide precursor is selected from a group consisting of M(OR)_x, MR_x(OR)_y, MX_y, and M(NO₃)_y, wherein

M comprises Al (aluminum),

R comprises an alkyl group,

X is selected from the group consisting of F (fluorine), Cl (chlorine), Br (bromine) and I (iodine),

x and y are each independently an integer of 1 to 4; and

(2) sintering the electrospun ultrafine fibers at a temperature ranging from 250 to 1000°

C.,

wherein (A) in step (1), before the electro pinning, the metal oxide precursor sol-gel solution or the mixture of the metal oxide precursor sol-gel solution and the polymer resin is additionally mixed with one-dimensional powdery nano-alumina;

or (B) the sintered ultrafine fibers from step (2) are impregnated or coated with a suspension of one-dimensional powdery nano-alumina;

or (A) and (B) both are performed.

10. The method of claim 9, wherein, before the sintering of step (2), the ultrafine fibers are subjected to heat compression at a temperature ranging from room temperature to 250°

C.

11. The method of claim 9, wherein the ultrafine fibers have an average diameter of 10˜

500 nm.

12. The method of claim 9, wherein the one-dimensional powdery nano-alumina is a nanoparticle selected from the group consisting of boehmite (AlOOH), aluminum hydroxide (Al(OH)₃), gamma-alumina (γ

-Al₂O₃) and a mixture thereof, which are provided in the form of nanorods, nanotubes or nanofibers, having a diameter of 1 nm or more and a diameter to length ratio (an aspect ratio) of 5 or more.

13. The method of claim 9, wherein the ultrafine fibers are made of a metal oxide selected from the group consisting of gamma-alumina (γ

-Al₂O₃) and a mixture of gamma-alumina (γ

-Al₂O₃) and silica (SiO₂).

14. The method of claim 9, wherein the polymer resin is selected from the group consisting of polyvinylpyrrolidone, polyvinylalcohol, polyvinylacetate, polyethylene oxide, and a mixture thereof.

15. The method of claim 9, wherein the polymer resin is polyacrylonitrile or its copolymer.

16. The method of claim 9, wherein the electrospinning in step (1) is melt-blowing, flash spinning, or electro-blowing.

17. A method for preparing a ceramic filter, which comprises the steps of:

(1) electrospinning a metal oxide precursor sol-gel solution or a mixture of a metal oxide precursor sol-gel solution and a polymer resin to make a layer of continuous ultrafine fibers randomly arranged, wherein the metal oxide precursor is selected from a group consisting of M(OR)_x, MR_x(OR)_y, MX_y, and M(NO₃)_y, wherein

M comprises Si (silicon) or Al (aluminum),

R comprises an alkyl group,

X is selected from the group consisting of F (fluorine), Cl (chlorine), Br (bromine) and I (iodine),

x and y are each independently an integer of 1 to 4; and

(2) sintering the electrospun ultrafine fibers at a temperature ranging from 250 to 1000°

C.,

wherein (A) in step (1), before the electrospinning, the metal oxide precursor sol-gel solution or the mixture of the metal oxide precursor sol-gel solution and the polymer resin is additionally mixed with one-dimensional powdery nano-alumina; and

(B) the sintered ultrafine fibers from step (2) are impregnated or coated with a suspension of one-dimensional powdery nano-alumina.