# US 11,896,920 B2 · Fabrication of tragacanthin-PVA nanofibrous webs and applications thereof in water-absorbent filters

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- Number: US 11,896,920 B2
- Document ID: US11896920B2
- Status: Granted
- Kind: B2
- Application number: 16/942,052
- Filed: 2020-07-29
- Published: 2020-11-12
- Granted: 2024-02-13
- Earliest claimed: 2019-07-30
- Assignees: Isfahan University of Technology
- Applicants: Fatemeh Esmaelion; Hossein Tavanai; Ali Akbar Miran Beigi; Mehdi Bazarganipour; Mohammad Agha Morshed; Zhinoos Javadi
- Inventors: Fatemeh Esmaelion; Hossein Tavanai; Ali Akbar Miran Beigi; Mehdi Bazarganipour; Mohammad Agha Morshed; Zhinoos Javadi
- Web page: https://patentgrep.com/patent/US11896920B2

## CPC

- B01D 39/1615: {of natural origin}
- B01D 39/10: Filter screens essentially made of metal
- B29C 70/688: {the inserts being meshes or lattices (B29C70/82, B29C70/683 take precedence)}
- D01D 5/003: {the material being a polymer solution or dispersion (D01D5/0053 takes precedence)}
- D01D 5/0038: {the fibre formed by solvent evaporation, i.e. dry electro-spinning}
- D01D 5/0076: {characterised by the collecting device, e.g. drum, wheel, endless belt, plate or grid (D01D5/0046 takes precedence)}
- D01D 5/0084: {Coating by electro-spinning, i.e. the electro-spun fibres are not removed from the collecting device but remain integral with it, e.g. coating of prostheses}
- D01D 5/08: Melt spinning methods {(D01D5/0023 takes precedence)}
- D01F 1/00: General methods for the manufacture of artificial filaments or the like
- D01F 1/10: Other agents for modifying properties
- D01F 9/00: Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
- D01F 11/00: Chemical after-treatment of artificial filaments or the like during manufacture
- D04H 1/4266: Natural fibres not provided for in group D04H1/425
- D04H 1/43: Acrylonitrile series
- D04H 1/4309: Polyvinyl alcohol
- D04H 1/4374: using different kinds of webs, e.g. by layering webs
- D04H 1/728: by electro-spinning {(electro-spinning methods and apparatus D01D5/0007)}
- B01D 2201/0415: Details of supporting structures
- B01D 2239/025: comprising nanofibres
- B01D 2239/0428: Rendering the filter material hydrophobic
- B01D 2239/0478: on a layer of the filter
- B01D 2239/0631: Electro-spun
- B01D 2239/0654: Support layers
- B01D 2239/10: Filtering material manufacturing
- B29K 2005/00: Use of polysaccharides or derivatives as moulding material
- B29K 2029/04: {PVOH, i.e. polyvinyl alcohol (B29K2031/04 takes precedence)}
- B29K 2033/20: PAN, i.e. polyacrylonitrile
- B29L 2031/14: Filters {(optical filters B29L2011/0066, sieves or screens B29L2031/737)}
- B32B 5/265: {characterised by one fibrous or filamentary layer being a non-woven fabric layer}
- B32B 5/266: {next to one or more non-woven fabric layers}
- B82Y 30/00: Nanotechnology for materials or surface science, e.g. nanocomposites
- B82Y 40/00: Manufacture or treatment of nanostructures
- C08B 37/006: {Heteroglycans, i.e. polysaccharides having more than one sugar residue in the main chain in either alternating or less regular sequence; Gellans; Succinoglycans; Arabinogalactans; Tragacanth or gum tragacanth or traganth from Astragalus; Gum Karaya from Sterculia urens; Gum Ghatti from Anogeissus latifolia; Derivatives thereof}
- D01F 6/18: from polymers of unsaturated nitriles, e.g. polyacrylonitrile, polyvinylidene cyanide
- D10B 2505/04: Filters
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- D01D: MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01F: CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D04H: MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL (weaving D03; knitting D04B; braiding D04C; net-making D04G; sewing D05B; tufting D05C; finishing non-woven fabrics D06); FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING {; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION}(non-woven fabrics having an intermediate or external layer of a different kind, e.g. of woven fabric, B32B)
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- C08B: POLYSACCHARIDES; DERIVATIVES THEREOF (polysaccharides containing less than six saccharide radicals attached to each other by glycosidic linkages C07H; fermentation or enzyme-using processes C12P19/00; sugar industry C13; production of cellulose D21)
- D10B: INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES

## Abstract

A fabrication method for a filter containing tragacanthin-polyvinyl alcohol (PVA) nanofibers includes obtaining a homogenous tragacanthin-PVA solution by obtaining a PVA solution by dissolving PVA in distilled water, and adding tragacanthin to the PVA solution. The method may further include obtaining a support layer by coating a stainless steel mesh with a thin layer of a hydrophobic polymer, coating a stainless steel mesh with the thin layer of the hydrophobic polymer comprising electrospinning a hydrophobic polymer solution onto the stainless steel mesh, and forming a tragacanthin-PVA nanofibrous web on the support layer by electrospinning the homogenous tragacanthin-PVA solution onto the support layer.

## Claims

### Claim 1

A method for fabricating a filter containing tragacanthin-polyvinyl alcohol (PVA) nanofibers, the method comprising:
obtaining a homogenous tragacanthin-PVA solution by:
obtaining a PVA solution by dissolving PVA in distilled water; and
adding tragacanthin to the PVA solution, a concentration of tragacanthin in the homogenous tragacanthin-PVA solution being between 1 w/v % and 1.7 w/v %;
obtaining a support layer by coating a stainless steel mesh with a thin layer of a hydrophobic polymer; and
forming a tragacanthin-PVA nanofibrous web on the support layer by electrospinning the homogenous tragacanthin-PVA solution onto the support layer.

### Claim 2 (depends on 1)

The method of claim 1, further comprising cross-linking the tragacanthin-PVA nanofibrous web by exposing the tragacanthin-PVA nanofibrous web to a saturated vapor of a cross-linking agent.

### Claim 3 (depends on 2)

The method of claim 2, wherein coating the stainless steel mesh with the thin layer of the hydrophobic polymer comprises electrospinning a polyacrylonitrile (PAN) solution onto the stainless steel mesh.

### Claim 4 (depends on 3)

The method of claim 3, wherein electrospinning the PAN solution onto the stainless steel mesh comprises electrospinning the PAN solution with a mass concertation of 16 w/v % onto the stainless steel mesh.

### Claim 5 (depends on 2)

The method of claim 2, wherein adding tragacanthin to the PVA solution comprises mixing tragacanthin powder with the PVA solution such that a mass ratio of tragacanthin to PVA between 10 to 90 (mass of tragacanthin to mass of PVA) and 90 to 10.

### Claim 6 (depends on 2)

The method of claim 2, wherein adding tragacanthin to the PVA solution comprises adding tragacanthin to the PVA solution with a mass ratio of tragacanthin to PVA between 10 to 90 and 60 to 40.

### Claim 7 (depends on 2)

The method of claim 2, wherein adding tragacanthin to the PVA solution comprises adding tragacanthin to the PVA solution with a mass ratio of tragacanthin to PVA between 70 to 30 and 90 to 10.

### Claim 8 (depends on 7)

The method of claim 7, wherein obtaining the PVA solution further comprises adding formic acid to the distilled water.

### Claim 9 (depends on 2)

The method of claim 2, wherein electrospinning the PAN solution onto the stainless steel mesh comprises electrospinning the PAN solution from an electrospinning nozzle with a flow rate between 0.025 mLhr−1 and 0.25 mLhr−1 onto the stainless steel mesh, the stainless steel mesh positioned at a distance between 5 cm and 15 cm from a tip of the electrospinning nozzle, a voltage between 10 kV and 15 kV applied between the electrospinning nozzle and the stainless steel mesh.

### Claim 10 (depends on 2)

The method of claim 2, wherein electrospinning the homogenized homogenous tragacanthin-PVA solution onto the support layer comprises electrospinning the homogenous tragacanthin-PVA solution from an electrospinning nozzle with a flow rate between 0.025 mLhr−1 and 0.125 mLhr−1 onto the support layer, the support layer positioned at a distance between 7 and 17 cm from a tip of the electrospinning nozzle, a voltage between 10 and 20 kV applied between the electrospinning nozzle and the support layer.

### Claim 11 (depends on 2)

The method of claim 2, wherein exposing the tragacanthin-PVA nanofibrous web to the saturated vapor of a cross-linking agent comprises putting the tragacanthin-PVA nanofibrous web in contact with the saturated vapor of the cross-linking agent, the cross-linking agent comprising glutaraldehyde.

### Claim 12

A method for fabricating a filter containing tragacanthin-polyvinyl alcohol (PVA) nanofibers, the method comprising:
obtaining a homogenous tragacanthin-PVA solution by:
obtaining a PVA solution by dissolving PVA in distilled water; and
adding tragacanthin to the PVA solution, a concentration of tragacanthin in the homogenous tragacanthin-PVA solution being between 1 w/v % and 1.7 w/v %;
obtaining a support layer by coating a stainless steel mesh with a thin layer of a hydrophobic polymer, the coating a stainless steel mesh with the thin layer of the hydrophobic polymer comprising electrospinning a hydrophobic polymer solution onto the stainless steel mesh;
forming a tragacanthin-PVA nanofibrous web on the support layer by electrospinning the homogenous tragacanthin-PVA solution onto the support layer; and
cross-linking the tragacanthin-PVA nanofibrous web by exposing the tragacanthin-PVA nanofibrous web to a saturated vapor of a cross-linking agent.

### Claim 13

A method for fabricating a filter containing tragacanthin-polyvinyl alcohol (PVA) nanofibers, the method comprising:
obtaining a homogenous tragacanthin-PVA solution by adding tragacanthin to a PVA solution, a concentration of tragacanthin in the homogenous tragacanthin-PVA solution being between 1 w/v % and 1.7 w/v %;
forming a tragacanthin-PVA nanofibrous web on a support layer; and
cross-linking the tragacanthin-PVA nanofibrous web by exposing the tragacanthin-PVA nanofibrous web to a saturated vapor of a cross-linking agent.

### Claim 14 (depends on 13)

The method of claim 13, wherein the support layer comprises a stainless steel mesh with a thin layer of a hydrophobic polymer coated onto the stainless steel mesh.

### Claim 15 (depends on 14)

The method of claim 14, wherein forming a tragacanthin-PVA nanofibrous web on a support layer comprises electrospinning the homogenous tragacanthin-PVA solution onto the support layer.

### Claim 16 (depends on 15)

The method of claim 15, wherein obtaining a homogenous tragacanthin-PVA solution by adding tragacanthin to a PVA solution comprises:
obtaining a PVA solution by dissolving PVA in a solvent; and
adding tragacanthin to the PVA solution.

### Claim 17 (depends on 16)

The method of claim 16, wherein the solvent comprises distilled water, ethyl acetate, acetic acid, and formic acid.