US20140165542A1

US20140165542A1 - Emission control devices for air intake systems

Info

Publication number: US20140165542A1
Application number: US14/127,177
Authority: US
Inventors: Caleb S. Loftin; Kyle Schumaker; Erik Versen
Original assignee: Meadwestvaco Corp
Current assignee: Ingevity South Carolina LLC
Priority date: 2011-07-01
Filing date: 2012-06-28
Publication date: 2014-06-19
Also published as: WO2013006359A1

Abstract

An emission control device for air intake system includes an extending conduit (400) and an adsorbing element (300) disposed about the conduit, wherein the adsorbing element comprises a substrate and an adsorbent material disposed substantially throughout the substrate. When the conduit includes an indentation portion (403) and an opening (404) located about the indentation portion, the adsorbing element may be disposed on at least a portion of the indention to cover at least a portion of the opening, and the closure element (105) may be used to secure the adsorbing element to the indentation portion. The air intake tube of the air intake system may be designed to include an indentation portion and an opening located about the indentation portion such that an adsorbent sheet with adsorbent material disposed substantially therethrough may wrap around at least a portion of the indentation and cover at least a portion of the opening.

Description

BACKGROUND OF THE DISCLOSURE

An increase in environmental concerns has continued to drive strict regulations of the hydrocarbon emissions from automotives into the environment, even when the vehicle is not operating. The great majority of internal combustion engines in use today are fuel-injected engines. When a fuel-injected engine is switched off after use, a small amount of residual fuel volatilizes and escapes from the injector tips. While a vehicle is sitting over time after use, this evaporated fuel may pass outwardly through the intake manifold, the intake air ducts and air filter, and may escape into an atmosphere contributing to air pollution. Therefore, it would be desirable to minimize this type of inadvertent evaporative emissions leakage.
One approach to abate the hydrocarbon emissions from the intake manifold after an engine shutdown is to use an air intake filter-like device having a hydrocarbon adsorbing., element, One drawback of these air intake emission control devices is that the devices may act as ail obstruction to the air flowing to the engine, thus causing a pressure drop in the airflow to the engine.
U.S. Pat. No. 6,692,551, issued on Feb. 17, 2004 to Wernholm et al., discloses an air cleaner assembly that includes: a housing having an inlet conduit and an outlet conduit; a retainer coupling to the housing and comprising a wall defining a first open end and a second open end; and an adsorber member disposed within the first open end of the retainer. The retainer wall further includes a cuffed portion about the second open end forming a recess facing the first open end, wherein a portion of the inlet conduit of the housing is seated in the recess so that the retainer is secured to the housing. The adsorber member is disposed inside the retainer with its outer perimeter sealingly abutting against the retainer wall so as to create an airtight seal between the adsorber member and the retainer wall, such that any gases accumulated within the device after engine shutdown would pass through the adsorber member before entering the atmosphere, The adsorber member comprises a substrate coated with adsorbent material.
U.S. Pat. No. 7,610,904, issued on Nov. 3, 2009 to Treier et al., discloses an inlet conduit for an engine air induction system, comprising: a plurality of openings located about the inlet conduit; a hydrocarbon vapor-adsorbent member disposed on an exterior surface of the inlet conduit covering the plurality of openings; and a covering member secured over the hydrocarbon vapor-adsorbent member. The adsorbent member comprises adsorbent materials, such as loose carbon materials, contained in a pouch or bag formed from non-woven cloth fabric, woven cloth fabric, fine mesh screens, or porous polymeric materials having a pore size/mesh size large enough to allow the hydrocarbons to pass through, yet small enough to prevent the loose adsorbents from passing through.
U.S. Pat. No. 7,918,912, issued on Apr. 5, 2011 to Tomlin et al., discloses a hydrocarbon adsorbing device comprising: an air intake tube; an internal structural element positioned within the air intake tube and including an outer shell and an inner cage; and a hydrocarbon adsorber disposed adjacent the internal structural element. The inner cage includes two rings which traverse the circumference of the air intake tube and a plurality of ribs coupled to the two rings, the ribs extending along the length of the outer shell between the two rings and adjacent to the hydrocarbon adsorber. The adsorber may be positioned between the inner cage and the outer shell.

SUMMARY OF THE DISCLOSURE

An embodiment of an emission control device for an air intake system includes an extending conduit and an adsorbing element disposed about the conduit, wherein the adsorbing element comprises a substrate and an adsorbent material disposed substantially throughout the substrate. When the conduit includes an indentation portion and an opening located about the indentation portion, the adsorbing element may be disposed on at least a portion of the indention to cover at least a portion of the opening, and the closure element may be used to secure the adsorbing element to the indentation portion. The air intake tube of the air intake system may be designed to include an indentation portion and an opening located about the indentation portion such that an adsorbent sheet with adsorbent material disposed substantially therethrough may wrap around at least a portion of the indentation and cover at least a portion of the opening.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a known air intake emission control device;

FIG. 2A shows one embodiment of the disclosed air intake emission control device, wherein an extending conduit is a one-piece structure connecting to an air intake tube;

FIG. 2B shows one embodiment of the disclosed emission control device, wherein an extending conduit includes an outer conduit and an inner conduit located within the outer conduit;

FIG. 3A shows one embodiment of the disclosed emission control device wherein an adsorbing element adheres to an interior surface of the extending conduit;

FIGS. 3B and 3C are cross-section views of the extending conduit of FIG. 3A, showing an interior surface of the extending conduit and the adsorbing element positioned on the interior surface;

FIG. 4A shows one embodiment of the disclosed emission control device wherein an extending conduit is positioned between air intake ductwork and air outlet ductwork;

FIG. 4B shows one embodiment of the extending conduit of FIG. 4A wherein the conduit includes an indentation portion and openings located about the indentation portion;

FIG. 4C is an exploded assembly view of the disclosed emission control device showing: the extending conduit of FIG. 4A; an adsorbing element positioning about the indentation portion and covering the openings; and a closure component securing the adsorbing element to the extending conduit;

FIG. 5A shows one embodiment of the disclosed emission control device, wherein an air intake tube includes an indentation portion and openings located about the indentation portion;

FIG. 5B shows one embodiment of the disclosed emission control device with an adsorbent sheet wrapping around the indentation portion and covering the openings of the air intake duct of FIG. 5A; and

FIG. 5C is an exploded assembly view of the disclosed emission control device showing: the air intake duct of FIG. 5A, an adsorbent sheet around the indentation portion of the air intake duct, and a two-piece closure element positioned over the adsorbent sheet.

DESCRIPTION OF THE DISCLOSURE

The present disclosures now will be described more fully hereinafter, but not all embodiments of the disclosure are shown. While the disclosure has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof,
FIG. 1 shows a known air intake emission control system comprising an air intake plate 101, an air intake tube 102 connecting to the air intake plate 101, and an adsorbing element 300 positioned inside the air intake tube.
A particular embodiment of the disclosed emission control device may include: an extending conduit connecting to an air intake tube and an adsorbing element positioned adjacent to the extending conduit, wherein the adsorbing element comprises a substrate and an adsorbent material disposed substantially throughout the substrate.
By placing the adsorbing element adjacent to the extending conduit rather than inside the air intake tube, an adsorption capacity of the emission control device may be enhanced. With the extending conduit, a distance and time which the intake air communicates with the adsorbing element may be increased, resulting in an enhanced adsorption of the hydrocarbon vapors without a substantial increase in pressure drop.
The extending conduit may be a one-piece component, a two-piece component or a multiple-piece component.
FIG. 2A shows one embodiment of the disclosed emission control device wherein the extending conduit is a one-piece component. The device includes an air intake plate 101, an air intake tube 102 having one end connecting to the air intake plate 101, an extending conduit 200 connecting to the other end of the air intake tube 102, and an adsorbing element 300 positioned inside the extending conduit 200.
FIG. 2B shows one embodiment of the disclosed emission control device wherein the extending device is a two-piece component, The device includes an air intake plate 101, an air intake tube 102 having one end connecting to the air intake plate 101, an extending conduit 200 connecting to the other end of the air intake tube 102, and an adsorbing element 300 positioned adjacent to the extending conduit 200, wherein the extending conduit 200 comprises an outer conduit 201 and an inner conduit 202 located within the outer conduit 201. The adsorbing element 300 may be positioned inside the inner conduit, between the outer and inner conduits, on an exterior of the outer conduit, or combinations thereof. As shown in the embodiment of FIG. 2B, the adsorbing element 300 may be placed inside the inner conduit 202 of the extending conduit.
Various materials may be used for the extending conduit including, but not limbed to, plastic such as polyolefin, polystyrene, polyurethane, and nylon; rubber; metallic; aluminum; stainless steel; galvanized steel; composite; powder coated metal; or the like. In one embodiment, the extending conduit may comprise polypropylene.
Although the illustrated figures show the extending conduit in a circular cylindrical shape, one of ordinary skill in the art understands that the disclosure is readily applicable to the extending conduit of other structures, shapes, or sizes. Different designs of the extending conduit may be chosen for the intended applications to provide a predetermined air flow resistance and sufficient communication between the adsorbing element and the intake airflow.
In one embodiment of the present disclosure, the adsorbing element may be disposed on the interior surface of the extending conduct. Alternatively and additionally, the adsorbing element may be disposed about the exterior surface of the extending conduct.
When desired, the adsorbing element may be disposed on substantially entire interior surface of the extending conduct. FIG. 3 shows a non-limiting example of such embodiment, wherein the adsorbing element 300 is disposed on substantially entire interior surface of the extending conduct 200.
The adsorbing element may be permanently disposed on the interior surface of the extending conduit such that the adsorbing element becomes a unitary part of the extending conduit. The extending conduit may be removed from the emission control device after the adsorbing element is spent (i.e., the adsorbing element reaches its full adsorption capacity). The extending conduit may be reused after desorbing the hydrocarbons from the spent adsorbing element.
Alternatively, the adsorbing element may be removably disposed on the interior surface of the extending conduit. Once the adsorbing element reaches its full adsorption capacity, the extending conduit may be disconnected from the device, and then the spent adsorbing element may be removed from the extending conduit and replaced with a fresh adsorbing element prior to reassembling the extending conduit to the device. The spent absorbing element may be regenerated and reused after desorbing the hydrocarbons from the spent adsorbing element.
When the adsorbing element is removably disposed on the exterior surface of the extending conduit, the spent adsorbing element may be replaced with a fresh adsorbing element without the need for removing the extending conduit from the disclosed device. This may enhance the ease of replacing the adsorbing element in the air intake emission control device throughout the engine's lifetime. Non-limiting examples of such embodiments are illustrated in FIGS. 4 and 5.
In one embodiment, the disclosed air intake emission control device may include: an extending conduit comprising an indentation portion and an opening located about the indentation portion; an adsorbing element disposed about at least a portion of the indentation portion and covers at least a portion of the opening; and a closure element securing the adsorbing element to the extending conduit. As shown in the embodiment of FIGS. 4A and 4B, the device includes an extending conduit 400 connecting to an air intake tube 102. The extending conduit 400 may comprise an indentation portion 403 and openings 404 located about the indentation portion 403. The device further includes an absorbing element 300 disposed about the indentation portion 403 and covered the openings 404; and a closure element 405 securing the adsorbing element 300 to the indentation portion 403 of the extending conduit 400. As shown in the embodiment of FIG. 4C, the adsorbing element 300 may wrap around substantially entire indentation portion 403 and cover substantially entire openings 404 of the extending conduit.
The extending conduit may include more than one indentation portion. Moreover, the extending conduit may include more than one opening located about the indentation portion. For example as shown in FIG. 4B, the extending conduit 400 may include a plurality of openings 404 located about the indentation portion 403.
The shapes, sizes, and numbers of the indentation portions and of the openings on the extending conduit may be modified such that the adsorbing element has sufficient communication with the intake airflow to ensure adequate adsorption of hydrocarbon vapors onto the adsorbing element during engine shutdown. The shapes, sizes, and numbers of the indentation portions and of the openings may also be varied according to the internal engine types to achieve enhanced adsorption efficiency without imparting a substantial airflow resistance.
Additionally, the extent which the indentation portion is wrapped and the openings are covered with the adsorbing element may be varied depending upon the desired adsorption efficiency and the airflow resistance.
The absorbing element may be permanently or removably disposed about the indentation portion of the extending conduit. When being removably disposed about the extending conduit, the spent adsorbing element may be removed and replaced with a fresh adsorbing element without the need for disconnecting the extending conduit from the emission control device.
The closure element may be positioned on the adsorbing element and secure the absorbing element to the extending conduit after the absorbing element is disposed about a predetermined portion of the indentation and opening on the extending conduit. A non-limiting example of such closure element may be adhesive strip or tab.
Alternatively, the closure element may be a separated element from the adsorbing element. The closure element may be positioned over the adsorbing element after the absorbing element is disposed about a predetermined portion of the indentation and opening on the extending conduit. The closure element may be positioned over a portion of the adsorbing element, or alternatively over substantially entire adsorbing element. As shown in the embodiment of FIG. 4C, the closure element may comprise two components secured together and positioned over substantially entire adsorbing element.
The closure element may be a one-piece component, a two-piece component, or a multiple-piece component. When the closure element comprises more than one component, each component may be secured together by various coupling tools to retain the adsorbing element on the extending conduit. Non-limiting examples of such coupling tools may include hinges, bolts, clamping devices such as a screw and threaded band type hose clamp, complementary structures, or other means for securing the closure components together.
In one embodiment, the closure element may include a first component and a second component configured and adapted to permanently or releasably engage the first component and secure the adsorbing element to the extending conduit. When the second component releasably engages the first component, the spent adsorbing element may be removed and replaced with a fresh adsorbing element without the need for disconnecting the extending conduit from the emission control device.
For the disclosed emission control device, the adsorbing element may comprise a substrate and an adsorbent material disposed substantially throughout the substrate.
The substrate may be derived from a variety of materials having appropriated porosity as not to substantially interfere with the airflow, while exhibiting suitable structural integrity and flexibility for wrapping or shaping about the extending conduit. Non-limiting examples of suitable substrates may include paper, plastic, foam, composite, membrane, woven fabric, non-woven fabric, or combinations thereof.
Many known adsorbents may be used in the present disclosure including, but not limited to, activated carbon, charcoal, zeolite, kaolin, titanic, ceria, or combinations thereof. Examples of the carbon forms suitable for use in the present disclosure may include, but are not limited to, fibers, particulates, or combinations thereof. Activated carbon suitable for use in the present disclosure may be derived from various carbon sources including, but not limited to, wood, wood dust, wood flour, cotton linters, peat, coal, coconut, lignite, carbohydrates, petroleum pitch, petroleum coke, coal tar pitch, fruit pits, fruit stones, nut shells, nut pits, sawdust, palm, vegetables such as rice hull or straw, synthetic polymer, natural polymer, lignocellulosic material, or combinations thereof. Furthermore, the activated carbon may be produced using a variety of processes including, but not limited to, chemical activation, thermal activation, or combinations thereof.
In one embodiment, the adsorbing element lay comprise an activated carbon sheet.
In one particular embodiment of the present disclosure, the air intake emission control device may comprise: a conduit including an indentation portion and an opening located about the indentation portion; an adsorbent sheet wrapping around at least a portion of the indentation portion and covering at least a portion of the opening, the adsorbent sheet comprising a substrate and an adsorbent material disposed substantially throughout the substrate; and a closure element securing the adsorbent sheet to the conduit. Such conduit may function as an extending conduit as previously discussed and illustrated in the exemplary embodiment of FIG. 4. Furthermore, such conduit may be an air intake tube of the air intake system and FIG. 5 shows a non-limiting example of such conduit.
As shown in the embodiment of FIGS. 5A-5C, the device may comprise: an air intake plate 101; and an air intake tube 102 connecting to the air intake plate 101 and comprising an indentation portion 103 and openings 104 located about the indentation portion 103. The device further includes an adsorbent sheet 500 wrapping around an exterior peripheral of the indentation portion 103 and covering the openings 104, and a closure element 105 securing the adsorbent sheet 500 to the indentation portion 103 of the air intake tube. As shown in the embodiment of FIG. 5B, the adsorbent sheet 500 may wrap around substantially entire indentation portion 103 and cover substantially entire openings 104 of the air intake tube, The air intake tube 102 may include more than one indentation portion. The air intake tube 102 may include more than one opening located about the indentation portion. For example as shown in the embodiment of FIG. 5A, the air intake tube 102 may include a plurality of openings 104 located about the indentation portion 103.
The shapes, sizes, and numbers of the indentation portions and of the openings on the disclosed air intake tube may be modified to achieve enhanced adsorption efficiency of the emission control device without a substantial increase of airflow resistance. Furthermore, the extent which the indentation portion is wrapped and the openings are covered with the adsorbent sheet may be varied depending upon the desired adsorption efficiency and the airflow resistance.
The adsorbent sheet may be permanently or removably disposed about the indentation portion of the disclosed air intake tube. When being removably disposed about the indentation, the spent adsorbent sheet may be removed and replaced with a fresh adsorbent sheet without the need for disconnecting the air intake tube from the emission control device.
The closure element may be positioned on the adsorbent sheet and secure the wound absorbent sheet to the air intake tube. Alternatively, the closure element may be a separated element from the adsorbent sheet. The closure element may be positioned over a portion of the wound adsorbent sheet, or alternatively over substantially entire adsorbent sheet. As shown in the embodiment of FIG. 5C, the closure element may comprise two components secured together and positioned over substantially entire exterior peripheral of the wound adsorbent sheet.
The closure element y be a one-piece component, a two-piece component, or a multiple-piece component. In one embodiment, the closure element may include a first component and a second component configured and adapted to permanently or releasably engage the first component and secure the wound adsorbent sheet to the air intake tube. When the second component releasably engages the first component, the spent adsorbent sheet may be removed and replaced with a fresh adsorbent sheet without the need for disconnecting the air intake tube from the engine's air intake system.
The adsorbent sheet suitable for the disclosed air intake tube may comprise a substrate and an adsorbent material disposed substantially throughout the substrate. The substrate may be derived from a variety of materials having appropriated porosity as not to substantially interfere with the airflow, while exhibiting suitable structural integrity and flexibility for wrapping or shaping about the extending conduit. The substrates may include, but are not limited to paper, plastic, foam, composite, membrane, woven fabric, non-woven fabric, or combinations thereof. Many known adsorbents may be used in the present disclosure including, but not limited to, activated carbon, charcoal, zeolite, kaolin, titania, ceria, or combinations thereof. Examples of the carbon forms suitable for use in the present disclosure may include, but are not limited to, fibers, particulates, or combinations thereof. Activated carbon suitable for use in the present disclosure may be derived from various carbon sources including, but not limited to, wood, wood dust, wood flour, cotton linters, peat, coal, coconut, lignite, carbohydrates, petroleum pitch, petroleum coke, coal tar pitch, fruit pits, fruit stones, nut shells, nut pits, sawdust, palm, vegetables such as rice hull or straw, synthetic polymer, natural polymer, lignocellulosic material, or combinations thereof. Furthermore, the activated carbon may be produced using a variety of processes including, but not limited to, chemical activation, thermal activation, or combinations thereof. In one embodiment, the adsorbent sheet may comprise an activated carbon sheet.
When desired, the disclosed emission control device may further include a filter for removing particulate matters from a fluid stream during an operation of the internal combustion engine.
During engine operation, the fluid stream flows through the disclosed emission control device that is in communication with an engine combustion chamber or chambers through a carburetor or intake manifold. In this manner, the intake air flows through the disclosed device prior to being introduced to a combustion chamber. After the engine shutdown, the contaminant-laden air stream from the combustion chamber may backflow through into the disclosed device. Any hydrocarbons vapor accumulating in the disclosed device or migrating from the intake manifold will pass through the adsorbing element of the device, and the hydrocarbon vapors in the contaminant-laden air are adsorbed onto the adsorbing element before the treated air is discharged to the atmosphere. Once the engine is turned on, fresh air from the external environment flows into the disclosed device, &sorbs some of the previously adsorbed hydrocarbons on the adsorbing element, and carries these hydrocarbon vapors through to the combustion chamber, wherein the fluid will be combusted along with the fuel.
The contaminants in the laden fluid stream may include, but are not limited to, saturated and unsaturated hydrocarbons utilized in fuels and byproducts caused by combustion; certain carbon oxides such as carbon monoxide, nitrates, sulfides, ozone, and the like; or combinations thereof.
The emission control device of the present disclosure may be for use in removing residual fuel vapor, after the engine has been turned off, from within an engine's intake system or downstream of a throttle body.
When desired, the disclosed emission control device may be used in combination with other known air intake emission control devices. Examples of the supplemental air intake emission control devices suitable for use with the disclosed device include, but not limited to, a flow-by air intake emission control device with an adsorbing element locating in an air duct, a flow-through air intake emission control device having an adsorbing element locating in an air duct, and combinations thereof.
The disclosed emission control device may have enhanced adsorption efficiency for hydrocarbons emitted from an engine's intake manifold into an atmosphere during engine shutdown without substantially imparting airflow resistance to the air induction system, while exhibiting an improved structural integrity.
While the disclosure has been described by reference to various specific embodiments, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiments, but will have full scope defined by the language of the following claims.

Claims

We claim:

1. An emission control device for an air intake system, comprising:

an extending conduit connecting to an air intake tube, the extending conduit having an interior surface and an exterior surface; and

an adsorbing element positioned adjacent to the extending conduit, the adsorbing element comprising a substrate and an adsorbent material disposed substantially throughout the substrate.

2. The device of claim 1, wherein the adsorbing element is disposed on substantially entire interior surface of the extending conduit.

3. The device of claim 1, wherein the adsorbing element is disposed on the exterior surface of the extending conduit.

4. The device of claim 3, wherein the adsorbing element is removably disposed on the exterior surface of the extending conduit.

5. The device of claim 1, wherein:

the extending conduit comprises an indentation portion and an opening located about the indentation portion;

the adsorbing element positions about at least a portion of the indentation portion and covers at least a portion of the opening; and

the device further comprises a closure element securing the adsorbing element to the extending conduit.

6. The device of claim 5, wherein the adsorbing element wraps around substantial indentation portion and covers substantially entire opening.

7. The device of claim 5, wherein the adsorbing element is removably disposed about the indentation portion.

8. The device of claim 5, wherein the closure element is positioned on the adsorbing element.

9. The device of claim 5, wherein the closure element is positioned over substantially entire adsorbing element.

10. The device of claim 5, wherein the closure element includes a first component and a second component configured and adapted to engage the first component and secure the adsorbing element to the extending conduit.

11. The device of claim 10, wherein the first component is configured and adapted to releasably engage the second component.

12. The device of claim 1, wherein the substrate includes a member selected from the group consisting of paper, plastic, foam, composite, membrane, woven fabric, non-woven fabric, and combinations thereof.

13. The device of claim 1, wherein the absorbent includes a member selected from the group consisting of activated carbon, charcoal, zeolite, kaolin, titania, ceria, and combinations thereof.

14. The device of claim 1, wherein the adsorbing element comprises an activated carbon sheet.

15. The device of claim 1, wherein the extending conduit comprises a material selected from the group consisting of plastic, rubber, metallic, galvanized steel, stainless steel, aluminum, composite, powder coated metal, and combinations thereof.

16. An emission control device for an air intake system, comprising:

a conduit including an indentation portion and an opening located about the indentation portion;

an adsorbent sheet wrapping around at least a portion of the indentation portion and covering at least a portion of the opening, the adsorbent sheet comprising a substrate and an adsorbent material disposed substantially throughout the substrate; and

a closure element securing the adsorbent sheet to the conduit.

17. The device of claim 16, wherein the conduit is an extending conduit connecting to the air intake ductwork.

18. The device of claim 16, wherein the conduit is an air intake tube.

19. The device of claim 16, wherein the conduit comprises a material selected from the group consisting of plastic, rubber, metallic, galvanized steel, stainless steel, aluminum, composite, powder coated metal, and combinations thereof.

20. The device of claim 16, wherein the adsorbent sheet removably wraps about the indentation portion.

21. The device of claim 16, wherein the closure element includes a first component and a second component configured and adapted to engage the first component and secure the adsorbent sheet to the extending conduit.

22. The device of claim 21, wherein the second component is configured and adapted to releasably engage the first component.

23. The device of claim 16, wherein the adsorbent sheet includes a substrate selected from the group consisting of paper, plastic, foam, composite, membrane, woven fabric, non-woven fabric, and combinations thereof.

24. The device of claim 16, wherein the absorbent sheet includes an adsorbent selected from the group consisting of activated carbon, charcoal, zeolite, kaolin, titania, ceria, and combinations thereof.

25. The device of claim 16, wherein the adsorbent sheet comprises an activated carbon sheet.