Ultrafine continuous fibrous ceramic filter and method of manufacturing same

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.

1 . A ceramic filter comprising 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.   
     
     
         2 . The ceramic filter of  claim 1 , wherein the electrospun fibers are sintered at a temperature ranging from 250 to 1000° C. 
     
     
         3 . The ceramic filter of  claim 2 , wherein, before sintered, the ultrafine fibers are subjected to heat compression at a temperature ranging from room temperature to 250° C. 
     
     
         4 . The ceramic filter of  claim 1 , wherein the fibrous porous body comprises 1˜90 wt % of nano-alumina based on the total weight of the porous body. 
     
     
         5 . The ceramic filter of  claim 1 , wherein the nano-alumina is a nanoparticle selected from the group consisting of boehmite (AlOOH), aluminum hydroxide (Al(OH) 3 ), gamma-alumina (γ-Al 2 O 3 ) 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. 
     
     
         6 . The ceramic filter of  claim 1 , wherein the ultrafine fibers are made of an metal oxide selected from the group consisting of silica (SiO 2 ), gamma-alumina (γ-Al 2 O 3 ), and a mixture thereof. 
     
     
         7 . The ceramic filter of  claim 1 , wherein the polymer resin is selected from the group consisting of polyvinylpyrrolidone, polyvinylalcohol, polyvinylacetate, polyethylene oxide, and a mixture thereof. 
     
     
         8 . The ceramic filter of  claim 1 , wherein the polymer resin is polyacrylonitrile or its copolymer. 
     
     
         9 . The ceramic filter of  claim 1 , wherein said electrospinning is melt-blowing, flash spinning, or electro-blowing. 
     
     
         10 . A method for preparing the ceramic filter of  claim 1 , 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; 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; (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. 
     
     
         11 . The method of  claim 10 , 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.