Patent Application
20080173177
The present invention relates to a filter for removing dioxins in ambient air or harmful substances generated by smoking, specifically a filter comprising double stranded DNA and fibrous filter material for supporting the double stranded DNA and for efficiently removing the harmful substances by intercalating them between base pairs of the double stranded DNA.
For removing harmful substances contributing to environmental pollution from the air, filters have generally been used which comprise a honeycomb; a porous ceramic; regenerated cellulose supported by glass fiber, metal fiber, or carbon fiber; an activated carbon grain, powder or fiber material made from wood pulp, sawdust, coconut husk, coal, phenol, synthetic fiber or other raw materials; or zeolite. It has been known that these materials are useful to some extent. As another technique for removing harmful substances, Japanese Unexamined Patent Application Publication No. 2002-355299 has disclosed an air-cleaning filter using a photocatalyst in which functional powder (titanium oxide, zinc oxide, iron oxide, etc.) exhibiting photocatalysis is supported by activated carbon fiber. Furthermore, Japanese Unexamined Patent Application Publication No. 2001-95552 has disclosed a tobacco smoke filter including a porous glass containing at least CaO, B2O3, SiO2, and Al2O3.
As a filter used for cigarette, French patent No. 2798302 describes a filter containing nitrogen-containing cyclic compound such as DNA or RNA. French patent No. 2800299 describes a filter containing nucleic acid and a fuming product containing the filter. French patent No. 2828994 describes a method for producing a cigarette filter containing DNA.
There have recently been growing concerns about air pollution by dioxins and health impairment resulting from smoking, and accordingly, a method for removing dioxins in the air and harmful substances generated by smoking more efficiently than ever is increasingly desired. In use in air conditioners, fan heaters, air cleaners, electric vacuum cleaners, dryers, and other electrical or electronic appliances, the above-described filters have the effect of efficiently removing dust, but, disadvantageously, cannot remove dioxins effectively.
The filter described by French patent No. 2798302 utilizes a mechanism for trapping substances having electrophilic property, i.e., toxic products by nucleophilic nuclides, i.e., DNA or RNA. However, French patent No. 2798302 only describes in Tables 1 and 2 that benzo-(a)-pyrene can be obtained, but said patent does not show at all effects for removing other toxic products generated from cigarette. French patent No. 2800299 neither describes clearly a mechanism that the filter containing nucleic acid removes harmful substances such as pyrene, etc., nor discloses test data which support effects in removing harmful substances. Moreover, French patent No. 2828994 never describes that the cigarette filter containing DNA removes harmful substances such as pyrene, etc.
In view of these circumstances, the object of the present invention is to provide an effective method for removing dioxins in the air, pyrene generated by smoking and other chemical substances harmful to the human body; a filter for removing the harmful substances; and cigarette, a smoking utensil such as cigarette holder, a mask, and electrical and electronic apparatuses equipped with the filter.
A first invention of the present application relates to a filter for trapping and removing harmful substances from a gas containing said harmful substance, said filter comprising at least double stranded DNA and fibrous filter material for supporting the double stranded DNA, in which the double stranded DNA is supported in a free state, among the fibers at least in the region of the fibrous filter material which gas containing the harmful substance permeates.
In the above-mentioned filter for removing harmful substances, the double stranded DNA is preferably in a fiber form or a film form.
A second invention relates to a filter for trapping and removing harmful substance from a gas containing said harmful substance, said filter comprising at least double stranded DNA, another macromolecular compound and fibrous filter material for supporting the double stranded DNA and the another macromolecular compound, in which the double stranded DNA are supported in a form of a mixture with the another macromolecular compound, at least in the region of the fibrous filter material which a gas containing the harmful substances permeates to trap the harmful substances by intercalation.
A third invention relates to a filter for trapping and removing harmful substances from a gas containing said harmful substances, said filter comprising at least double stranded DNA and fibrous filter material for supporting the double stranded DNA, in which the double stranded DNA are fixed to the fibrous filter material to be supported at least in the region of the fibrous filter material which gas containing the harmful substance permeates to trap the harmful substances by intercalation.
As further preferable embodiment, a fourth invention relates to the filter for removing harmful substances of the third invention, wherein the double stranded DNA are fixed to the fibrous filter material by ultraviolet light exposure.
A fifth invention relates to the filter for removing harmful substances of the third invention, wherein the double stranded DNA are fixed to the fibrous filter material or glass beads contained in the fibrous filter material by chemical bonding resulting from the formation of a Schiff base, to be supported.
A sixth invention relates to the filter for removing harmful substances of the third invention, wherein the double stranded DNA are fixed to the fibrous filter material in a gel state or a porous form obtained by removing water from the gel, preferably an acrylamide gel, to be supported.
A seventh invention relates to the filter for removing harmful substances of the third invention, wherein the double stranded DNA are fixed to the fibrous filter material by intercalating psoralen between the double stranded DNA to be supported, the psoralen being bonded to the fibrous filter material with a spacer therebetween.
An eighth invention relates to the filter for removing harmful substances of the third invention, wherein the double stranded DNA are fixed to the fibrous filter material by a coupling agent to be supported.
Further, the present invention relates to a method for manufacturing a filter for removing harmful substances.
First one of the method invention relates to a method for manufacturing a filter for removing harmful substances, comprising the steps of: impregnating a fibrous filter material with an aqueous solution of double stranded DNA; and subsequently removing water from the fibrous filter material, whereby the double stranded DNA is supported in a free state, among the fibers of the fibrous filter material.
Second one of the method invention relates to a method for manufacturing a filter for removing harmful substances, comprising the steps of: impregnating a fibrous filter material with an aqueous solution containing a mixture of double stranded DNA and another macromolecular compound; and subsequently removing water from the fibrous filter material, whereby the double stranded DNA are supported by the fibrous filter material.
Third one of the method invention relates to a method for manufacturing a filter for removing harmful substances, comprising the steps of: impregnating a fibrous filter material with an aqueous solution of double stranded DNA; and subsequently exposing the fibrous filter material to ultraviolet light, whereby the double stranded DNA are fixed to the fibrous filter material to be supported.
Fourth one of the method invention relates to a method for manufacturing a filter for removing harmful substances, comprising the steps of: impregnating a fibrous filter material with an aqueous solution containing double stranded DNA and a mixture of double stranded DNA and another macromolecular compound; and subsequently exposing the fibrous filter material to ultraviolet light, whereby the double stranded DNA are fixed to the fibrous filter material to be supported.
Fifth one of the method invention relates to a method for manufacturing a filter for removing harmful substances, comprising the step of fixing double stranded DNA to a fibrous filter material or glass beads contained in a fibrous filter material by chemical bonding resulting from the formation of a Schiff base, to be supported.
Sixth one of the method invention relates to a method for manufacturing a filter for removing harmful substances, comprising the step of intercalating psoralen bonded to a fibrous filter material with a spacer therebetween, between the double strands of the double stranded DNA, thereby fixing the double stranded DNA to the fibrous filter material.
Seventh one of the method invention relates to a method for manufacturing a filter for removing harmful substances, comprising the steps of: impregnating a fibrous filter material with double stranded DNA in a sol state together with water and a gelling agent; and subsequently drying or freeze-drying the fibrous filter material to remove water, whereby the double stranded DNA is fixed to the fibrous filter material in a gel state or a porous form obtained by removing the water from gel state or the gel.
In each one, the harmful substances are dioxins.
Furthermore, the present invention relates to devices, utensils, supplies, etc. including a filter for removing harmful substances.
First one of the invention relates to a mask including any one of the filters for removing harmful substances of the first to eighth inventions.
Second one of the invention relates to a gas mask including any one of the filters for removing harmful substances of the first to eighth inventions.
Third one of the invention relates to a gas filter installed in a gas flow pass of an electrical or electronic apparatus using gas whose temperature or temperature and humidity are controlled, and the gas filter includes any one of the filters for removing harmful substances of the first to eighth inventions, and
Fourth one of the invention relates to an air filter installed in an air outlet, inlet, or flow pass of electrical or electronic apparatus from which, into which, or through which air or heated air flows, and the air filter includes any one of the filters for removing harmful substances of the first to eighth inventions.
Fifth one of the invention relates to a filter apparatus for collecting or removing dust in an incinerator, and the filter apparatus includes any one of the filters for removing harmful substances of the first to eighth inventions.
Especially, the present invention relates to a cigarette and a cigarette holder containing a filter for removing harmful substances.
First one of the invention relates to a cigarette characterized in that in a cigarette provided with a filter portion at an end at the side of a mouth end, the inside of the filter portion is filled with a filter for removing harmful substances comprising at least double stranded DNA and a fibrous filter material for supporting the double stranded DNA, in which the double stranded DNA are supported in a free state, among the fibers at least in the region of the fibrous filter material which gas containing the harmful substance permeates to trap the harmful substances by intercalation.
Second one of the invention relates to a cigarette characterized in that in a cigarette provided with a filter portion at a mouth end of the cigarette, the inside of the filter portion is filled with a filter for removing harmful substances comprising at least double stranded DNA, sodium polyacrylate and a fibrous filter material for supporting the double stranded DNA and the sodium polyacrylate, the double stranded DNA is supported in a form of mixture with the another macromolecular compound, at least in the region of the fibrous filter material which gas containing the harmful substance permeates to trap dioxins by intercalation.
Third one of the invention relates to a cigarette holder characterized in that the inside of the cigarette holder is filled with a filter for removing harmful substances comprising at least double stranded DNA and a fibrous filter material for supporting the double stranded DNA, the double stranded DNA are in a free state, among the fibers at least in the region of the fibrous filter material which gas containing the harmful substance permeates to trap dioxins by intercalation.
a) is a perspective view of a cigarette equipped with a filter for removing harmful substances of the present invention, and
a) is a perspective view of a cigarette holder equipped with a filter for removing harmful substances of the present invention, and
a) is a fragmentary exploded view of a mask equipped with a filter for removing harmful substances of the present invention, and
a) is a perspective view of an air conditioner equipped with a filter for removing harmful substances of the present invention, and
DNA used in the present invention comprises two helical polynucleotide strands (double helices). Preferably, it is obtained from testes of fish, such as salmon, herring, or cod, or from thymus glands of mammals or birds, such as cow, pig, or chicken. In the double stranded DNA, pairs of planar bases with structural complementation protrude perpendicular to the axis of the helices from the sugar-phosphate skeletons of both the polynucleotide strands to the center of the helices, and each pair of bases are hydrogen-bonded. The double stranded DNA has spaces between the base pairs, and, in the case of B-form DNA, the spaces measure about 1.1 nm in width by 0.34 nm in height. Planar small molecules can be trapped in the spaces. This is referred to as intercalation. This phenomenon can be promoted due to the electric charge or hydrophobicity of the small molecules. Many substances harmful to the human body, such as dioxins, comprise a plurality of benzene rings and, thus, have a planar structure. Accordingly, the inventors of the present invention found that dioxins in ambient air or harmful substances generated by smoking tobacco can be removed more efficiently by utilizing DNA.
A method for removing harmful substances according to the present invention involves the use of the above-described characteristics of double stranded DNA and includes double stranded DNA and a fibrous filter material capable of supporting the double stranded DNA. Thus, when gas containing harmful substances such as dioxins brings into contact with the double stranded DNA, the harmful substances are trapped by intercalation to the double stranded DNA and removed. The fibrous filter material used in the present invention refers to an aggregation of fibers. However, it is not necessarily limited to fiber, and any material may be used as long as it is similar to fiber in form, and capable of supporting DNA and allowing gas containing harmful substances to permeate therethrough. Preferably, it may be cellulose fiber, such as paper; glass fiber; natural fiber; synthetic fiber, such as polyethylene, polypropylene, or nylon resin; or honeycomb.
The filter for removing harmful substances of the present invention can produce the effect of sufficiently removing harmful substance as long as DNA is supported among the fibers at least in the region of the fibrous filter material which gas containing the harmful substances permeates, in such a free state that the DNA can freely move among the fibers. However, the DNA may be supported over the entire fibrous filter material. In the present invention, the DNA supported by the fibrous filter material means that the DNA is present in such a state that the DNA does not fall off from the fibrous filter material. The form of the DNA is not particularly limited, but the DNA may be of powder, fiber, or film.
The manner for supporting the DNA in a free state among the fibers of the filter material is not particularly limited, and various forms may be applied. For example, as shown in
In the filter for removing harmful substance, preferably, the DNA is supported in a form of mixture with another macromolecular compound, at least in the region of the fibrous filter material which gas containing the harmful substances permeates. By combination with another macromolecular compound, the DNA can be more firmly supported by the fibrous filter material after removing water, in comparison with being used alone. Consequently, the possibility that the DNA falls off from the fibrous filter material is reduced and, thus, the filter for removing harmful substances exhibits a stable effect of removing harmful substances even in long-term use. Any macromolecular compound may be used, as long as it does not affect the effect of removing harmful substances and is capable of being mixed with the DNA and of adhering to the fibrous filter material by one or both of a physical force, such as intermolecular force or electrostatic force, and a chemical bonding, such as covalent binding, ionic bonding, or coordination bonding. Exemplary macromolecular compounds include: acrylates, such as sodium polyacrylate and sodium polymethacrylate; and celluloses, such as methylcellulose, carboxymethylcellulose, and their salts.
It is also preferable that, in the filter for removing harmful substances of the present invention, the DNA be fixed to the fibrous filter material to be supported, at least in the region of the fibrous filter material which gas containing the harmful substances permeates. Since the DNA is more firmly secured to the fibrous filter material in this structure, the DNA does not easily fall from the fibrous filter material. Consequently, the filter for removing harmful substances of the present invention hardly reduces the effect of removing harmful substances due to the falling of the DNA, even if the filter is used for a long time.
For one of the variations of the filter for removing harmful substances in which the DNA is fixed to the fibrous filter material, the DNA is fixed to the fibrous filter material by ultraviolet light exposure. In this variation, preferably, the ultraviolet light radiated to the DNA has a wavelength in the range of 250 to 270 nm.
Alternatively, in the filter for removing harmful substances, the DNA may be fixed to the fibrous filter material by chemical bonding resulting from the formation of a Schiff base. For example, the DNA is fixed to a cellulose fiber being the fibrous filter material to obtain the filter for removing harmful substances, as shown in
For another variation of the filter for removing harmful substances in which the DNA is fixed to the fibrous filter material, the DNA is fixed to the fibrous filter material, in a gel state or a porous form obtained by removing water from the gel. For preparing the filter, the fibrous filter material is immersed in a DNA aqueous solution, and a dispersant such as sodium polyacrylate is added to the solution to form a gel. Then, the fibrous filter material is drawn up, or after drawing up, water is removed from the gel adhered to the fibrous filter material to obtain a porous form. Alternatively, the DNA may be compounded with water and a gelling agent, such as acrylamide or silica gel, to form a sol, and the fibrous filter material is immersed in, or coated or sprayed with the sol. The sol is dried or freeze-dried to obtain a gel, or, furthermore, water is removed from the resulting gel to obtain a porous form. Gelatin, agar-agar, and the like may be used as the gelling agent.
In a more preferred variation of the filter for removing harmful substances in which the DNA is fixed to the fibrous filter material, the DNA is fixed to the fibrous filter material by intercalating psoralen bonded to the fibrous filter material between the double strands of the DNA. For example, as shown in
In the filter for removing harmful substances of the present invention, the DNA may be fixed to the fibrous filter material by a coupling agent. For this type of filter for removing harmful substances, the DNA is mixed with silica gel, a silane coupling agent, and, if necessary, another additive to prepare an aqueous solution or a suspension. A supporter is immersed in the aqueous solution or the suspension or the fibrous filter material is coated or sprayed with the aqueous solution or the suspension so as to be impregnated with the aqueous solution or the suspension, and then water is removed. This form of variation is particularly advantageous for cases in which the DNA, being an organic material, is more firmly fixed to an inorganic fibrous filter material. A preferred coupling agent is, for example, a silane coupling agent.
The filter for removing harmful substances may be prepared by impregnating a fibrous filter material with a DNA aqueous solution, and subsequently removing water from the fibrous filter material. Thus, the DNA is supported in a free state, among the fibers of the fibrous filter material. For example, the fibrous filter material is coated with a DNA aqueous solution with a brush or the like and subsequently dried in hot air or with a heater, preferably at 60° C. or less to yield the filter for removing harmful substances. Alternatively, as shown in
In addition, for the filter for removing harmful substances, after being impregnated with the DNA aqueous solution, or after being impregnated with a solution containing DNA and a mixture of the DNA and another macromolecular compound, the fibrous filter material may be exposed to ultraviolet light so that the DNA is fixed to the fibrous filter material.
Various types of harmful substances can be involved in the present invention. However, since the present invention utilizes intercalation into DNA, the present invention can particularly advantageously treat organic compounds having a planer structure, such as those having an aromatic ring. In particular, it is extremely advantageous for the present invention to treat dioxins, such as dibenzo-p-dioxin (DD), dibenzofuran (DF), biphenyl (BP), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and coplannar PCB.
The filter for removing harmful substances of the present invention can preferably be incorporated in or with various products including: smoking utensils, such as cigarettes and cigarette filters; masks; gas masks; filter apparatuses for collecting or removing dust in an incinerator; funnels; car mufflers; and minus ion generators. In addition, it can be preferably used for a gas filter installed in a flow pass of an electrical or electronic apparatus using gas whose temperature or temperature and humidity are controlled. Exemplary electrical or electronic apparatuses using gas whose temperature or temperature and humidity are controlled include air conditioners, fan heaters, and humidifiers. The gas filter installed in such an electrical or electronic apparatus is disposed between the position where the temperature or the temperature and humidity of the gas taken in the apparatus are controlled and the position from which the gas is discharged. For example, for an air conditioner, the gas filter is disposed in a position from which the gas whose temperature is set at a predetermined point in the inside of the air conditioner is discharged. The gas filter includes a filter, so that dust contained in the gas passing through the gas filter is removed and, thus, clean gas is discharged from the apparatus to the outside. The filter for removing harmful substances of the present invention may also be used for an air filter installed in an air outlet, inlet, or flow pass of an electrical or electronic apparatus from which, into which, or through which air or heated air flows. Coolers, air cooling, and such electrical or electronic apparatuses include air cleaners, electric vacuum cleaners, driers, and coolers for car engines. The air filter installed in these apparatuses includes a filter. Air or heated air taken in the apparatus is filtered during passing through the air filter to remove dust and foreign particles. For example, in an electric vacuum cleaner, the air filter is disposed between the position into which air is drawn with dust and foreign particles and the position from which the air is discharged. Thus, the dust and foreign particles contained in air are removed by the filter during passing through the air filter.
As described above, the filter for removing harmful substances of the present invention includes DNA supported by a fibrous filter material. The amount of the supported DNA is appropriately determined according to the concentration of existing harmful substances. For example, dioxins are present on the order of 10−12 g/m3 in ambient air. Accordingly, for sufficient removal of dioxins, the DNA is supported by the fibrous filter material in an amount of the order of at least 10−9 grams per volume (m3) of the region which air containing harmful substances permeates.
The filter for removing harmful substance of the present invention may contain various additives, such as a colorant and a deodorant, if necessary, in addition to the DNA and fibrous filter material.
The present invention will be further illustrated in detail using the following embodiments. However, these embodiments do not limit the invention.
a) and 9(b) show a cigarette using the filter for removing harmful substances of the present invention.
a) and 10(b) show a cigarette holder using the filter for removing harmful substances of the present invention.
a) and 11(b) show a mask using the filter for removing harmful substances of the present invention as gauze.
a) shows an air conditioner using the filter for removing harmful substances of the present invention as the air filter.
In order to examine how efficiently the harmful substance-removing filer removes harmful substances, the following tests were conducted.
An experiment was performed on cigarettes having the harmful substance-removing filter of the present invention and a known filter to examine their effects of removing harmful substances generated by smoking.
(i) Preparation of Cigarettes
Preparation 1: A fibrous filter layer of the known cigarette was immersed in a 10% by weight solution of DNA and sodium polyacrylate for 10 seconds, and, after being drawn up, the filter layer was dried at 40° C. The resulting harmful substance-removing filter was used as the filter of a cigarette to yield Research Cigarette 2R4F (trade name, Kentucky Unv., U.S.) cigarette A.
Preparation 2: A fibrous filter layer of the known cigarette was immersed in a 10% by weight solution of DNA and sodium polyacrylate for 10 seconds, and, after being drawn up, the filter layer was dried at 40° C. The resulting harmful substance-removing filter was used as the filter of a cigarette in combination with activated carbon to yield Research Cigarette 2R4F (trade name, Kentucky Unv., U.S.) cigarette B.
Preparation 3: Only a fibrous filter layer of a known cigarette was used as the filter for a cigarette to yield Research Cigarette 2R4F (trade name, Kentucky Unv., U.S.) C.
Preparation 4: A fibrous filter layer of a known cigarette and activated carbon were used for the filter of a cigarette to yield Research Cigarette 2R4F (trade name, Kentucky Unv., U.S.) D.
(ii) Smoking Manner
A puff of 35 mL of the mainstream smoke from each of cigarettes A, B, C, and D obtained in above preparations was taken for 2 seconds, and this puff was performed on 20 cigarettes per day, 10 times in total. The masses of chemical substances contained in the entirety of the discharged gas were measured. The results are shown in Table 1.
Table 1 shows that cigarette A using the harmful substance-removing filter of the present invention exhibited an effect of removing chemical substances superior to that of cigarettes C and D using the known cigarette fibrous filter layer, for all the chemical substances listed in Table 1. In addition, it has been shown that cigarette B using the harmful substance-removing filter in combination with activated carbon exhibits an effect of removing chemical substances still superior to that of cigarette A.
In this test example, an experiment was performed on the filter for removing harmful substances of the present invention to examine the effect of removing dioxins, specifically polychlorinated dibenzo-p-dioxin (PCDDs), polychlorinated dibenzofuran (PCDF5), and coplannar PCB, in ambient air.
(i) Preparation of Air Filters
Over the entire area of a commercially available air filter (20 cm in length by 30 cm in width), 1000 mg of powder DNA was uniformly sprayed. Then the air filter was exposed to ultraviolet light with a wavelength of 260 nm to support the DNA by the air filter. Thus a harmful substance-removing filter of the present invention was prepared.
(ii) Measuring Process
In a city T, an air cleaner equipped with the harmful substance-removing filter obtained in (i) was operated to collect air discharged from the air cleaner. The concentrations of dioxins contained in the discharged air were measured. The measurement of dioxins was performed in accordance with “Manual on Determination of Dioxins in Ambient Air” (June 2000, by Air Quality Management Division, Environmental Management Bureau, Environment Agency, Japan). Table 2 shows the toxicity equivalency quantities of dioxins in ambient air before and after passing through the air cleaner, that is, through the filter of the present invention installed in the air cleaner.
Table 2 shows that the toxicity equivalency quantity of dioxins in ambient air after passing through the harmful substance-removing filter of the present invention is reduced to one-tenth that before passing through the filter, and that the harmful substance-removing filter of the present invention has an extremely excellent effect of trapping and removing dioxins.
A method and a filter for efficiently removing harmful substances in ambient air or generated from tobacco, such as dioxins, using DNA are provided. The filter is advantageously used in, for example, cigarettes, smoking utensils such as cigarette holder; masks; gas masks; gas filters installed in electrical or electronic apparatuses using gas whose temperature or temperature and humidity are controlled, such as air conditioners, fan heaters, and humidifiers; air filters installed in electrical or electronic apparatuses from which, into which, or through which air flows, such as electric vacuum cleaners, driers, and air cleaners; minus ion generators; filter apparatuses for collecting or removing dust in an incinerator; funnels; car mufflers; and so on.
The present application is a divisional application of application Ser. No. 10/479,462 filed Dec. 2, 2003, which in turn is a U.S. National Stage of PCT/JP03/04817 filed Apr. 16, 2003. The disclosure of each prior application is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10479462 | Dec 2003 | US |
| Child | 12055558 | US |
