Method of preparing a sorbent material for use in an apparatus for releasing a gaseous material into the atmosphere

Abstract: An apparatus for releasing gaseous material into the atmosphere employs a sorbent material that is sorptively saturated with a predetermined quantity of the gaseous material at a predetermined pressure, preferably approximately equal to atmospheric pressure. The gaseous material to be released preferably has a vapor pressure lower than the predetermined pressure at which the sorbent material is sorptively saturated. The apparatus also includes means for selectively exposing the sorbent material to the atmosphere in order to allow the gaseous material to be desorptively released.

Description: The invention relates generally to a method of preparing a sorbent material for use in an apparatus for releasing a gaseous material into the atmosphere. More specifically, the invention relates to such a method wherein the gaseous material is sorptively stored on the sorbent material, which may then be selectively exposed to the atmosphere in order to cause such gas release. As used herein, the term "sorbent" or "sorptive", or the like, refer to the use of either the use of an adsorbent or an absorbent. Various devices have been provided for releasing a material, such as an odorant, an insect repellent or an antiseptic or other medicinal substance into the atmosphere in order to create a pleasant odour, an insect-free region or other beneficial atmospheric conditions. Typically, such previous devices have included wicks or other such media onto which the material has been placed and allowed to be released into the atmosphere by an evaporation process. In other instances, the released material has been discharged into the atmosphere by a technique in which a water vapour released into the atmosphere serves as a carrier for the material. Typically, however, such previous devices have only been capable of storing a relatively small amount of the material to be released into the atmosphere, and thus have been relatively short-lived, requiring frequent replacement, maintenance or recharging. In addition, such devices that use a released water vapour as a carrier for discharging the material into the atmosphere have required relatively expensive and complex vapour-producing mechanisms, which also require frequent maintenance and recharging with the material to be released. In light of the above-discussed state of the art, one of the objects of the present invention is to provide a method of preparing a sorbent material for releasing a gaseous material into the atmosphere in a predetermined, relatively controlled, concentration level, the sorbent material being capable of storing relatively large amounts of the released material in order significantly to lengthen the useful life of the apparatus. In addition, another object of the present invention is to provide such a method that does not require the use of relatively expensive, complex or high-maintenance mechanisms. The present invention prepares for use in an apparatus for releasing gaseous material into the atmosphere a sorbent material that is sorptively saturated with a predetermined quantity of the gaseous material at a predetermined pressure, equal to atmospheric pressure. The gaseous material to be released has a vapour pressure lower than the predetermined pressure at which the sorbent material is sorptively saturated. US-A-4 346 840, upon which the prior art portion of claim 1 is based, discloses a mechanism by which, using solid absorbent masses of different sizes, the relative proportions of different volatile constituents can be kept constant over their dispensing life. The present invention, as defined in claim 1, is specifically directed at providing the most advantageous conditions whereby maximum absorbency of the gas can be achieved for a relatively long dispensing life. This is achieved initially by heating and depressurising the sorbent material prior to supplying the gaseous material to the depressurised sorbent material, thereby increasing the sorptive storage/capability of the sorbent material. The heating of the sorbent material during depressurisation more effectively clears the sorbent material of undesirable sorbed contaminants or other substances, thereby increasing the sorptive storage capability of the sorbent material for the desired gaseous material to be released to the atmosphere. Additional objects, advantages, and features of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings. Brief Description of the Drawings Figure 1 is an overall perspective view of an apparatus for releasing a gaseous material into the atmosphere from sorbent material which has been charged using the method of the present invention. Figure 2 is a cross-sectional view taken generally along line 2-2 of Figure 1. Figure 3 is an overall perspective view of a sorbent material which has been sorptively saturated with the gaseous material to be released to the atmosphere and which has been moulded into a decorative shape. Figure 4 is a cross-sectional view of another application of the present invention in which the sorbent material is employed in an air supply system for controlled release of a gaseous material into an environmental space. Figure 5 is a diagrammatic representation of a preferred technique for loading the gaseous material onto the sorbent material. Figures 1 to 5 depict various exemplary embodiments of apparatus for purposes of illustration, with which the method of the present invention may be used. One skilled in the art will readily recognise from the following discussion that the sorbent material charged using the method of the invention is equally applicable in devices and applications other than those illustratively shown in the drawings. Referring to Figures 1 and 2, an air freshener 10 typically includes a base 12 and a top 14, with a number of tabs 16 protruding from the base 12 to slidably engage the top 14. When the top 14 is slidably moved away from the base 12, a number of openings 18 are provided therebetween in order to expose the interior of the air freshener 10 to the atmosphere. Within the interior of the air freshener 10, a number of prongs 20, or other similar suitable structures, are provided for retaining a sorbent material 22 within the interior of the air freshener 10. The sorbent material 22 can take many forms, including a mesh or fabric type of material onto which a sorbent material has been affixed, or alternatively, the sorbent material can be formed and shaped into the desired configuration. When the top 14 is moved away from the base 12 in order to form the openings 18, air from the atmosphere is free to flow through the interior of the air freshener 10, to contact the sorbent material 22. The sorbent material 22 has been previously sorptively saturated with a predetermined quantity of the gaseous material to be released into the atmosphere. Such gaseous material has been previously sorptively loaded, using the method of the invention, onto the sorbent material 22 at a pressure, equal to atmospheric pressure. Because of the low vapor pressure of the gaseous material to be released, small predetermined quantities of the gaseous material are released into the air flowing through the air freshener 10 in a controlled concentration and allowed to diffuse throughout the atmosphere. Because of the high storage capabilities of the sorbent material, which can be composed of an adsorbent material, such as activated carbon, ziolite, selica gel, or clay, for example, or which can alternatively be composed of an absorbent material, the useful life of the air freshener 10 is greatly increased over that of the previously-known air freshener devices described above. The gaseous material, which is sorptively saturated onto the sorbent material 22, can be an odorant material in order to provide a pleasant scent in the atmosphere, or alternatively the material to be released can be an insect repellant in order to provide a relatively insect-free environment, or even an antiseptic or other medicinal material in order to provide a germ-free environment or to aid in other medical treatments. In lieu of the air freshener apparatus 10 shown in Figures 1 and 2, the sorbent material can be shaped, molded, or otherwise formed into a solid shape such as the decorative sorbent material item 26 shown in Figure 3. Such decorative item 26 can then be placed on a convenient surface in the region into which the gaseous material is to be released, or otherwise affixed to any convenient object in the area in accordance with various mounting or fastening techniques well-known to those skilled in the art. Figure 4 illustrates another exemplary application, in which a building structure 30 includes a wall 32 having an opening 34 therein for receiving and housing an air supply grill or register 36. The air supply register 36 is connected in fluid communication with an air supply duct 38. Upstream of the air supply register 36, the supply duct 38 contains a sorbent material screen 40, or other suitable porous medium on to which the sorbent material is affixed, with the sorbent material screen 40 being placed in the air stream such that air from the air supply duct 38 flows through the sorbent material screen 40 and the air supply register 36 into the space 42. The sorbent material screen 40 has been previously sorptively saturated with the gaseous material to be released into the space 42, in a manner such as that described above in connection with Figures 1 and 2. Thus, the apparatus can be used to supply a pleasant scent to the space 42, for effecting a germ-free environment in the space 42, wherein the gaseous material to be released is an antiseptic, or alternatively, the gaseous material can be an insect repellant suitable for use in the space 42. Figure 5 diagrammatically illustrates a technique for preparing the sorbent material by the method of the present invention. Although the sorbent material 22 on Figures 1 and 2 is diagrammatically represented in Figure 5, the principles depicted in Figure 5 are equally applicable to other embodiments. First, the sorbent material 22 is subjected to a reduced pressure level substantially below atmospheric pressure, as diagrammatically represented by the vacuum arrow 46 shown in Figure 5. During such depressurization, heat is added as is diagrammatically represented by the heat arrow 48, in order to release as much as possible of any undesired contaminants or other substances that had previously been sorbed by the sorbent material 22. Next, the desired gaseous material to be released into the atmosphere is introduced onto the sorbent material as diagrammatically represented by gas arrow 50 in Figure 5, in order to sorptively saturate the sorbent material 22 with a desired gaseous material to be released. Preferably, such sorptive saturation is performed by introducing the gaseous material 50 under pressure in order to accomplish sorptive saturation at a predetermined pressure level, equal to atmospheric pressure. The sorptively saturated sorbent material 22 is then selectively placed in communication with air in the atmosphere, such as in the air freshener 10 illustrated in Figures 1 and 2, for example, in order to allow the previously sorptively stored gaseous material to be released into the atmosphere. Such release occurs primarily because of the low vapor pressure of the gaseous material to be released, but can also occur as a result of a displacement of the gaseous material on the sorbent material 22 by other substances or materials in the atmosphere which are preferentially sorbed by the sorbent material 22. Because of the high-capacity storage capabilities of the adsorbent or absorbent material 22, the air freshener 10 or other apparatuses are capable of providing an effective mechanism for releasing the gaseous material into the atmosphere in a simple, long-lived, and low-maintenance device.

Claims: A method of preparing a sorbent material for use in an apparatus for releasing a gaseous material into the atmosphere, characterised in that prior to supplying the gaseous material, which has a vapour pressure lower than atmospheric pressure, to the sorbent material, the sorbent material is heated and depressurised to a pressure lower than atmospheric pressure, and in that the gaseous material is provided to said depressurised sorbent material in a quantity to saturate the sorbent material at atmospheric pressure. A method according to claim 1, wherein said sorbent material is an adsorbent or absorbent material. A method according to claim 2, wherein said adsorbent material comprises activated carbon. A method according to claim 1, 2 or 3, wherein the gaseous material is an odorant, an insect repellant, and/or an antiseptic material. A method according to any one of claims 1 to 4, wherein the gaseous material is introduced onto said sorbent material in a gaseous state and sorptively saturated thereby. A method according to any one of claims 1 to 4, wherein the gaseous material is introduced onto said sorbent material in a liquid state, said vapour pressure being sufficiently low to allow at least a portion of said predetermined quantity of the gaseous material to be sorbed by the sorbent material in a gaseous state.

Inventors: CZERWINSKI KENNETH STEVE, TURKO JOHN WALTER, CZERWINSKI, KENNETH STEVE, TURKO, JOHN WALTER
Applicants: FUEL CONCEPTS INC, FUEL CONCEPTS INC.
Application year: 1988
Main classification: A61L9
IPC codes: A01M13, A61L9, A01M1, A01N25, C09K3, B01D53