Selective filtration of cigarette smoke using chitosan derivatives

Inactive Publication Date: 2005-11-10
R J REYNOLDS TOBACCO COMPANY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0008] It has been discovered that chitosan can be chemically modified to have the physical attributes of a filter medium and have a chemical

Problems solved by technology

Many of these filter materials, however, are only effective in the removal of particulates, tars and condensable components from tobacco smoke.
Among the problems encountered with prior filters has been the plugging or clogging with use and the consumption or rendering ineffective of reactive filtering surfaces and materials.
However, they have little or no effect in removing certain gaseous components in the vapor phase of the tobacco smoke such as hydrogen cyanide, aldehydes, carbonyls, metals and sulphides.
Ion-exchange resins of porous structure have been found to be somewhat effective, but their efficiency diminishes during smoking, as does that of carbon and porous minerals.
This may be due to the material becoming saturated and, therefore, increasingly in

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Example

Example I

[0021] Porous chitosan resin was synthesized according to a phase inversion technique. This was accomplished by preparing a 7% chitosan solution by dissolving approximately 20 grams of chitosan flakes (practical grade) in 3.5% acetic acid. The mixture increased in viscosity and gelled upon the completion of the chitosan addition. Further dilution with acetic acid resulted in a solution having approximately 3% chitosan flake. This provided for a chitosan solution having a more manageable viscosity. The total amount of acetic acid used to dissolve the chitosan flake was approximately 665 milliliters. The solution was then filtered to separate any undissolved materials. This chitosan solution was then added dropwise to a precipitation bath of 2 molar sodium hydroxide to yield water swollen gel beads. The gel beads were then filtered and washed with deionized water until neutral, pH of the wash water being approximately 7.

[0022] Heterogeneous cross-linking of the chitosan bea...

Example

Example II

[0023] Porous chitosan resin was synthesized according to the phase inversion technique in Example 1. In this example the heterogeneous cross-linking of the chitosan beads was accomplished by suspending the beads for several hours in a 2.5% aqueous solution of glyoxal. After cross-linking, the beads were filtered and washed with warm deionized water to remove any excess glyoxal. The beads were then freeze dried which resulted in porous glyoxal cross-linked chitosan resin beads.

Example

Example III

[0024] Porous chitosan resin was prepared according to a thermally induced phase separation procedure. A 4% chitosan solution was prepared by dissolution of chitosan powder (Vansen Chemical; 92% deacetylation) in 3.5% acetic acid. A precipitation bath of sodium hydroxide (2 molar) in 20:80 methanol / water solution was prepared and cooled to 0° C. The chitosan solution was then added dropwise to the precipitation bath with moderate stirring. Precipitation of chitosan occurred shortly after addition of the solution to the precipitation bath. The precipitation bath having the chitosan precipitate was then allowed to return to room temperature. The resulting beads were filtered and washed with deionized water until the wash water became neutral, having a pH of approximately 7.

[0025] Heterogeneous cross-linking of the chitosan beads was then accomplished by suspending approximately 396 grams of wet beads in approximately 1980 milliliters of 2.5% aqueous glutaraldehyde solutio...

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PUM

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Abstract

A smoking article filter having a porous resin with a high surface area to mass ratio comprised of a chitosan derivative. Preferred embodiments include chitosan cross-linked with glutaraldehyde and chitosan cross-linked with glyoxal. The chitosan derivative provides for the selective filtration of cigarette smoke, particularly for the removal of aldehydes, hydrogen cyanide, heavy metals and carbonyls.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] Not applicable. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] Not applicable. FIELD OF INVENTION [0003] This invention concerns improvements relating to tobacco smoke filters. More particularly, the invention relates to a cigarette filter that can selectively remove undesirable constituents from tobacco smoke. BACKGROUND OF THE INVENTION [0004] A wide variety of materials have been suggested in the prior art as filters for tobacco smoke. Examples of such filter materials include cotton, paper, cellulose acetate, and certain synthetics. Many of these filter materials, however, are only effective in the removal of particulates, tars and condensable components from tobacco smoke. The art is replete with a myriad of filtration techniques and materials for removing undesirable components in smoke and for causing other reactions as the smoke passes through filtration beds or other reactive media. Among the problems en...

Claims

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Application Information

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IPC IPC(8): A24D3/08
CPCA24D3/08
Inventor CARAWAY, JOHN W. JR.
Owner R J REYNOLDS TOBACCO COMPANY
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