United States Patent (19) [11] Patent Number: 4,963,327 Russell 45) Date of Patent: Oct. 16, 1990

4,490,272 12/1984 Malafosse et al...... 422/20 (54 OXYGENGENERATING MODULE 4,534,775 8/1985 Frazier ...... 422/122 X

75 Inventor: Donald H. Russell, Cherry Hill, N.J. 4,582,054 4/1986 Ferrer...... 28/200.23 73 Assignee: Z-Gard, Inc., Kansas City, Mo. 4,717,549 1/1988 Malafosse et al...... 422/120 21 Appl. No.: 173,113 OTHER PUBLICATIONS Haigh, Frank; "A New Concept in Life Support Sys (22 Filed: Mar. 23, 1988 tem', Aircraft Engineering, 1982. 51 Int. Cl.5 ... A62B 7/08; A62B 21/00; Hogan, Brian J., Design News, pp. 58-59, Jan. 8, 1979. A62B 23/02 Gessner, David M., “New Developments in Ox 52 U.S. C...... 422/120; 422/122; ygen-Therapy Equipment for Home Use', Respiratory 422/305; 128/202.26; 128/203.21; 128/205.28 Therapy, Mar./Apr. 1978. 58) Field of Search ...... 422/120, 122; 128/202.26, 204.13, 203.21, 205.28, 206. 12, Primary Examiner-Robert J. Warden 206.17, 206.22 Assistant Examiner-Jeffrey R. Snay Attorney, Agent, or Firm-Hedman, Gibson, Costigan & (56) References Cited Hoare U.S. PATENT DOCUMENTS 57 ABSTRACT 1,111,055 9/1914 Carveth ...... 423/230 3,443,906 5/1969 McGoff et al...... 422/122 Apparatuses and methods for selectively absorbing 3,565,068 2/1971 Bickford ...... 28/2012.5 undesirable organic and inorganic vapors and gases 3,806,323 4/1974 Thompson ...... 422/122 from ambient air while providing level en 3,893,459 7/1975 Mausteller et al. ... 128/202.26 hancement of the treated air are disclosed. 3,992,317 11/1976 Brichard et al...... 252/186.32 4,112,048. 9/1978 Mascher ...... 423/20 4,168,706 9/1979 Lovell ...... 128/204.17X 14 Claims, 9 Drawing Sheets

U.S. Patent Oct. 16, 1990 Sheet 1 of 9 4,963,327

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U.S. Patent Oct. 16, 1990 Sheet 7 of 9 4,963,327 N

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4,963,327 1. 2 employed in many respiratory devices. However, sev OXYGEN GENERATING MODULE eral problems have prevented their full commercial development. One problem is a delay or start-up period BACKGROUND OF THE INVENTION which occurs before oxygen delivery begins. Also, the The present invention relates to an apparatus and 5 practical size and operating conditions of these devices method for use in respirator masks and/or place limitations on the quantities of functional chemi hoods for absorbing noxious gases and providing an cals and the design geometry in which they are used. adjustable oxygen output and consump Additionally, oxygen output efficiency declines signifi tion from an "at rest' level up to a high stress level, such cantly as the breathing rate increases. Therefore, at high as that which occurs during heavy work conditions. 10 stress levels, the moisture content of the respired air is Many devices, including respirators and , inadequate to generate the necessary oxygen levels. are well known in the art whose function is to provide The above problems have been addressed in several oxygen and absorb carbon dioxide for various uses, manners. For instance, a separate injectable water including health care applications, and to protect a user source has been tested, but not successfully. In addition, from airborne gaseous contaminants from fires, etc. 15 compacted briquettes of the are able to pro Such devices employ various strong chemical and vide extended oxygen delivery times, and the use of physical absorbants in order to remove contaminants large quantities of the same are able to over-ride the from gaseous or liquid streams. Chemically reactive efficiency loss. However, the resulting exothermic heat compounds such as soda line (ascarite) and anhydrous of reaction with water is sufficient to require external lithium hydroxide are carbon dioxide absorbers which 20 heat exchangers on the superoxide cannisters. Under are widely used. Chemical oxygen sources such as chlo these conditions, the rebreather must be physically sep rates, , and are also arated from the chemical source for obvious safety well known. Physical absorbents include for example, e2SOS. activated carbons, zeolites, silicas, aluminas and In addition to the above devices, synthetic and natu exchange resins. 25 ral zeolites of certain composition and porous sizes are Most devices are limited by the rate at which they used in pressure swing absorption devices to produce provide oxygen and the conditions under which they commerically high purity oxygen from air. Zeolites are can be used. In addition, these devices are not designed a family of crystalline hydrated alumino-silicate miner to protect the user against all types of airborne contami nants which the user may encounter. For instance, re 30 als, with the general formula MN2O-Al2O-nSiO2 cent publications show that there are long-lived free mH2O where M is calcium, strontium or barium and N radicals which are present in the smoke from burning is either sodium or . The ability of zeolites to organic materials. These free radicals can react with function as molecular sieves, separating complex gas lung surfaces if they are inspired and thereby cause mixtures into various components is derived primarily severe damage and even death. 35 from the highly uniform porous structure of the zeolite Respirators commonly use cartridge-type filters con crystal which is a 3-dimensional network of intercon taining selective absorbents for noxious gases and in necting cavities. Large polar molecules are retained on spired air. These devices are designed to remove unde the zeolite by Van der Waals forces rather than chemi sired chemicals and particulate matter from incoming cal bonding, while smaller and less polar molecules are air, enhance the oxygen level within the mask, and not. eliminate carbon dioxide, either directly or in conjunc Air pressure well above atmospheric is required for tion with mechanical check valves. Respirators are the efficient operation of the zeolite system. In addition, useful only when ambient oxygen levels are at least since zeolites are both powerful dessicants and selective 19.5%. For oxygen levels below this level, separate gas absorbants, the air must be pre-dried, or large ex mechanical supplies of air or oxygen are used, such as 45 cesses of zeolite must be used in order to compensate for tanks of compressed gases, or remote source air pump the moisture in ambient air. In its practical use as an ing. These devices are bulky and complicated, and the oxygen concentrator, the air is compressed and passed user must be trained in their proper use. through a column of zeolite material. The more polar Rebreathers are a separate class of emergency use components of air, i.e., water vapor, carbon dioxide, respirators, usually in hood form, which are designed to 50 and such pollutants as , sulfur dioxide, continuously absorb or remove respired carbon dioxide, nitrogen , and hydrocarbons are immediately. and excess moisture. Rebreathers obtain their air supply absorbed on to the uppermost layer of the zeolite, the from that which is trapped when the user puts on the nitrogen fraction is selectively removed, leaving oxy hood. Anhydrous lithium hydroxide is often used to gen, traces of inert gases and some residual nitrogen. absorb the respired carbon dioxide. However, rebreath 55 The zeolites are the active agents in many continuous ers have limited service life because oxygen levels are generators of oxygen-enriched air for health care appli not replenished. Compressed air devices are prone to cations, for example for use with patients having severe mechanical problems with release valves and the user is chronic obstructive pulmonary disease (COPD). required to operate them properly under life-threaten In accordance with the above, it is an object of the ing conditions. present invention to provide an apparatus and method Rebreathers using moisture activated alkali metal and for selectively absorbing undesirable organic and inor alkaline earth metal superoxides and the like as both an ganic gases and vapors from ambient air while provid oxygen source and a carbon dioxide absorber have been ing oxygen level enchancement of the treated air which tested extensively. Basically, these chemicals react is more efficient than prior are methods and devices. readily with moisture in respired air and evolve oxygen, 65 It is another object of the present invention to pro while at the same time providing a reaction product vide unique modifications of the chemical materials which will absorb carbon dioxide. Potassium superox commonly used in such systems to provide extended ide is especially useful for this purpose and has been and controlled oxygen production and utilization effi 4,963,327 3 4. ciencies that allow for major reductions in the sizes and unit is to provide oxygen generation and carbon dioxide weights of the components. absorption matched to a range of breathing rates, it is It is a further object of the present invention to pro also directed to selective gas absorption and free radical vide unique designs of component configurations and termination as secondary functions. The device is de arrays in order to make them compatible with estab signed to provide user protection against airborne gase lished breathing mask structures of both respirator and ous contaminents from fires in buildings, factories, air rebreather types and which can also be used in ventilat crafts, mines, etc. ing applications. The present invention is also related to a filter for It is another object of the present invention to pro generating oxygen and absorbing noxious and other vide an apparatus and method which allows the activa 10 undesired gases comprising a plurality of layers includ tion of an oxygen generating system on demand. ing an immobilized sorptive particulate material which It is yet another object of the present invention to is cationically exchanged with a heavy metalion, and at provide an oxygen enrichment system which is simple least one layer comprising an oxygen generating com and inexpensive to manufacture, safe and easily dis pound, said oxygen generating layer being in juxtaposi posed after use. 15 tion with said layers of immobilized sorptive material It has now been surprisingly discovered that by com layers. bining the use of the above-mentioned compounds in a The present invention is also related to a method for unique manner, the efficiency gain is much greater and generating oxygen gas comprising adding a strongly different from an additive effect of each of the compo basic compound and an oxygen generating material eats. which is substantially completely free of heavy metal SUMMARY OF THE INVENTION salts to a solution comprising aqueous hydrogen perox ide substantially completely free of heavy metal salts Thus, in accordance with the above-mentioned ob and thereafter contacting the solution with a composi jectives, one aspect of the present invention relates to a tion containing a heavy metal in elemental form togen multi-chamber permselective apparatus for providing 25 erate oxygen gas. The oxygen generating material dis oxygen-enriched filtered air matched to a range of solves in the solution, thereby raising the pH, and the breathing rates, comprising a first chamber containing aqueous hydrogen decomposes to water and microcapsules comprising an oxygen generating com oxygen upon contacting the heavy metal. This double pound as a core material and a coating which is mois decomposition procedure has advantages over prior art ture swellable but not soluble, wherein the coating 30 slowly exposes the core material to moisture when ex methods of generating oxygen through the use of either posed to respired air, thereby allowing the core material component alone because of an unexpectedly higher to react with the moisture and generate oxygen; a sec oxygen delivery capacity than an additive effect would ond chamber containing a solid carbon dioxide absorber dictate. for absorbing carbon dioxide from respired air; a third 35 In preferred embodiments, the oxygen generating chamber containing an aqueous solution of mildly compound comprises potassium superoxide, lithium acidic salt with a small amount of nonionic surfactant; superoxide, magnesium peroxide, calcium peroxide, and a fourth chamber containing aqueous hydrogen sodium peroxide calcium peroxide, lithium superoxide, peroxide and a small amount of nonionic surfactant. , or a mixture thereof and the immo The chambers are made from a semi-permeable fabric, bilized sorptive particulate material comprises a copper which prevents fluid penetration under normal pressure or iron exchanged clinoptilolite or mordenite. but allows fluid to pass through under moderate over The novel devices and unique modifications of the pressure. The invention also comprises a first pressure chemical materials used herein provide extended and means for forcing the aqueous solution from the third controlled oxygen production and utilization efficien chamber into said first chamber during faster breathing 45 cies which allow for major reductions in the sizes and rates, and a second pressure means for forcing the aque weights of the components. Other advantages occur in ous solution from the fourth chamber into the first manufacture, safety and disposal. In addition, the pres chamber during prolonged faster breathing. ent invention may be used in ventilating applications or In preferred embodiments, the multi-chamber alternatively in breathing masks of both the respirator permselective apparatus further comprises a fifth cham 50 and rebreather type. ber also made from semipermeable fabric which con tains an immobolized sorptive particulate material for BRIEF DESCRIPTION OF THE DRAWINGS selective absorption of noxious and other undesired The following drawings in which like reference char gases which is cationically exchanged with a heavy acters indicate like parts are illustrative of embodiments metal ion. 55 of the invention are not meant to limit the scope of the In other preferred embodiments, the semi-permeable invention as encompassed by the Claims. fabric is coated with an antioxidant. Alternatively, a FIG. 1 is a cross-sectional view of a cartridge type sixth chamber may be included which includes an anti apparatus of the present invention; oxidant. Preferentially, the antioxidant comprises 2,6- FIG. 2 is a perspective view showing the cartridge tert-butyl-p-cresol, propyl gallate, t-butylhydroxy qui type apparatus of FIG. 1 a rebreather mask; none, a butylated hydroxyanisole or a mixture thereof. FIG. 3 is a cross-sectional view of a free standing This device is contemplated for use in respirator absorber apparatus of the present invention; masks and/orhoods of the rebreather type. Each cham FIG. 4 is a perspective view showing the free stand ber of the device carries a different chemical and has a ing apparatus of FIG. 3 within a rebreather unit; specific function. Overall, the device absorbs noxious 65 FIG. 5 is a schematic view of a test apparatus com gases and provides an adjustable oxygen output and prising a closed loop system for the present invention; carbon dioxide consumption matched to the oxygen FIG. 6 is a graphical representation of the oxygen demand of the user. Although the major function of the generation of microencapsulated potassium superoxide; 4,963,327 5 6 FIG. 7 is a graphical representation of a comparison polyurethane), and water resistant nylons and canvases of oxygen generation by lithium hydroxide alone available from various suppliers. against lithium hydroxide together with potassium su The chambers will vary is size and volume depending peroxide microcapsules; on the required level and duration of performance. The FIG. 8 is a graphical representation of a comparison largest chamber will be the peroxide holder, and it will of the effect of the presence of fumed colloidal silica on contain one or more microencapsulated solid oxygen oxygen transport in a molecular sieve. generating chemicals. FIG. 9 is a graphical representation of a comparison Various geometric shapes and designs are possible. of oxygen generation by a 5A mole seive coated with Two of these possible designs have been selected for 10 purposes of example. The first is a disc shape similar to hydrophobic colloidal silica against iron mordenite. the filter cartridge units commercially sold for respira DETAILED DESCRIPTION tor masks. It would be used in a face mask in which air The present invention provides O2 generation and is reversibly forced through the filter by breath action CO2 absorption matched to a range of breathing rates (Dynamic air flow). The second type is a free standing and also provides selective gas absorption and free radi 15 absorber pad for a hood type rebreather in which cal termination. This is accomplished by providing breathing causes air circulation. Device activation oc different chemical components, having specific func curs by permeation and diffusion (passive or semi-static tions. The chemical components include: a solid oxygen air flow). generating compound reactable with water to form Referring to FIG. 1, the cartridge type model 10 20 consists of 3 chambers arranged in sandwich fashion oxygen and which is microencapsulated in a wall mate and made of Goretex fabric. The layers may be separate rial that is moisture swellable but not soluble; a solid or mutually attached and housed for convenience and CO2 absorber; a cation exchanged zeolite; an aqueous handling in a rigid, open-grid container made of poly solution of a mildly acidic salt with a small amount of propylene, high impact polystyrene, or other impact nonionic surfactant; aqueous hydrogen peroxide prefer 25 resistant thermoplastic. -- entially of approximately 30 percent strength with a Attached to the circumference of the outside edge of small amount of nonionic surfactant; and one or more the microcapsule chamber 1 are either one or two elas antioxidants considered GRAS. tomeric chambers for reactive liquids. In the embodi In brief, oxygen is derived from both the oxygen ment herein depicted, chamber 2 contains a reservoir of generating compound and the hydrogen peroxide. Car 30 aqueous hydrogen peroxide, while chamber 3 eontains a bon dioxide is absorbed by both LiOH and the reaction reservoir of a mildly acidic salt such as aqueous MgCl2 product of the oxygen generating compound and water. solution, each with a small amount of nonionic surfac The zeolite is a selective absorbent for carbon monoxide tant. The liquid contents are kept separate from the and can also absorb other noxious gases such as SO2 and microcapsules by means of frangible discs 6, 7 made of NOX. In addition, as will be discussed in detail below, 35 brittle, impermeable plastic such as polystyrene. the combination of the microencapsulated oxygen gen Mounted onto and through the elastomeric walls are erating compound, such as potassium superoxide, and plungers 4, 5 which extends as studs or buttons outside zeolites cationically exchanged with heavy metal the chamber and terminates in a sharp point inside the provide surprisingly high levels of oxygen. The antioxi chamber and in proximity to the frangible discs 6, 7. dants are scavengers for free radicals present, for exam 40 The elastomeric material comprising the elastomeric ple, in the smoke from fires. Aqueous MgCl2 can be walls may be any oxidation resistant rubber or elasto used as a source of additional water to increase oxygen meric thermoplastic. A preferred material is neoprene. release from the oxygen generating microcapsules and Depressing either plunger 4, 5 ruptures the respective /or to decompose the alkaline reaction products from frangible disc 6, 7 and allows the contained liquids to the same. The specific actions and reactions of these 45 contact the outer wall of the microcapsule chamber 1. chemicals will be discussed below. Repeated depressions of the plunger 4, 5 pumps the The multi-chambered unit to which the present in liquid through the wall by the overpressure technique vention is directed is made of a semi-permeable fabric. previously described. Alternatively, the frangible discs Each chamber carries a different chemical and each has 6, 7 can be backed by and a porous conduit 8. Porous a specific function. The term semi-permeable fabric is 50 conduit 8 is made of a porous material. In the present defined herein as a broad group of woven and non example, a porous plastic is molded into the walls of the woven materials whose physical structure is controlled microcapsule chamber 1 and extends transversely to give breathability; that is, to allow passage of air but through the diameter of microcapsule chamber 1. In not liquids. Needle punching, leaching of dispersed this embodiment, frangible discs 6, 7 are preferentially soluble salts, fibrillation, and biaxial orientation are 55 located at either end of porous conduit 8. FIG. 2 is a some of the well known methods for producing con perspective view showing the cartridge module in place trolled porosity. There are many water repellent fin in a rebreather mask. ishes for conventional porous fabrics that will render FIG. 3 shows a free standing absorber module 20 for them semi-permeable. These finishes will prevent water passive flow use for a hood type rebreather in which penetration under normal pressure, but water can be 60 activation occurs by permeation and diffusion. The forced through under moderate over-pressure. In this outer structure comprises a module holder which holds fashion the fabric can function as a pressure activated the multi-chambered unit. The module 20 comprises the valve to admit liquids on demand. One material of microcapsule chamber 24 which contains one or more choice is a widely used fabric called Goretex available micro-encapsulated solid oxygen generating chemicals from W. L. Gore Co., which is an oriented, micropo 65 26. Attached to the microcapsule chamber 24 at either rous teflon composite. Other acceptable semi-permable end are either one or two chambers for reactive liquids. fabrics include CT breathable film, available from Con In the module herein depicted, reactive chambers 28 solidated Thermoplastics Co. (an oriented, microporous and 30 are arranged at either end and contain aqueous 4,963,327 7 8 hydrogen peroxide and aqueous MgCl2 respectively, in proportion to the number of capsules "opened' by each with a small amount of nonionic surfactant. incoming moisture. Mounted onto and through module holder 22 are plung The microencapsulated oxygen generating material ers 31, 32 which terminate in a sharp point inside cham generally comprises a core material comprising an oxy bers 28 and 30, respectively, and in proximity to frangi gen generating compound and a coating comprising an ble discs 33, 34, frangible discs 33, 34 are located at acceptable wall-forming water swellable polymer, and either end of porous conduit 36. Alongside microcap are disclosed in U.S. Pat. No. 4,867,902, filed on, 1988, sule chamber 1 are two additional chambers. Chamber the assignee of record, and incorporated herein by ref. 38 contains a solid carbon dioxide absorber such as solid erence in the interest of brevity. anhydrous LiOH particles 40, although any of the well 10 Preferably, the core material comprises one or more known solid carbon dioxide absorbers may be substi of the alkali and alkaline earth peroxides, superoxides, tuted in its place. trioxides, percarbonates or permanganates. Most prefer Chamber 42 contains a copper or iron exchanged ably, the core material is comprised of potassium super clinoptilolite or mordenite. FIG. 4 is a perspective view . showing the free standing absorber module placed 15 The water swellable coating preferentially comprises within a rebreather hood, for passive or static use with a copolymer of an olefin such as ethylene, propylene, an alternate module. isobutylene, or styrene and a vinyl compound such as Additionally, in preferred embodiments the present vinyl acetate, vinyl alcohol, the alkyl, hydroxyalkyl and invention also includes antioxidants as scavengers for amino alkyl acrylic and methacrylic esters, maleic anhy the free radicals either as a separate layer in the unit, or dride, maleate esters, maleate salts, vinyl alkyl ethers, preferably as a coating on the semi-permeable fabric of vinyl pryidive, vinyl pyrollidone, and vinyl sulfonic acid, esters and salts; homopolymers of the above-men the unit. The antioxidants are non-volatile under these tioned vinyl monomers, acrylics and maleic anhydrides; use conditions and are not transferred to the air stream. anhydrous polymeric alkylene oxide polyols and alkoxy Food grade antioxidants are used for safety. These anti 25 derivatives having a molecular weight greater than 500; oxidants are used for safety. These antioxidants are gelatins; starches; gums; polyamides; polyurethanes commonly referred to in the art as GRAS antioxidants, modified for high hydroplilicity; and mixtures of any of and include 2,6-di-tertbutyl-p-cresol, propyl gallate, the foregoing. t-butyl hydroxy quinone, butylated hydroxyanisole, The microcapsule coating may also comprise one of combinations of any of the foregoing, and the like. 30 the combustion resistent coatings disclosed in previ The above devices have been designed in component ously mentioned U.S. Pat. No. 4,867,902. configurations and arranged in order to make them At slow breathing rates, respired moisture causes the compatible with established breathing mask structures. microcapsule coating to swell and peel back in the pre However, these configurations may be changed in man viously mentioned exfoliating manner, thus allowing ners apparent to those skilled in the art in order to make 35 water to react with the oxygen generating compound. them compatible with new structures which may arise. Although the reaction between the oxygen generating Although mechanisms have been provided herein for compound and water differs slightly depending upon activating the system on demand, the chemicals and the whether the oxygen generating compound is in the multi-chambered unit as a whole function differently peroxide, superoxide, trioxide, etc., form, the end result depending upon the breathing rate and the work level 40 is substantially the same in that oxygen is generated and of the user. However, for the purposes of this disclo the resultant alkali or alkaline earth hydroxide thus sure, their function can be categorized into three breath formed absorbs carbon dioxide. The various reactions ing rate levels; namely, (1) slow or at rest, (2) fast breathing, and (3) high stress rate breathing. At condi are set forth in Table 1. tion, (1) typical oxygen demand is about 0.3 liter/min 45 TABLE 1. and CO2 generation is 0.25 liter/min. As breathing and Reactions of the Oxygen Generating Compounds work rate increases, oxygen need greatly increases and Compounds: Peroxides - M2O2 CO2 production rate increases faster than that of O2 Superoxides - MO2 demand. At high stress rates, CO2/O2, are in balance, Trioxides - M2O3 with both at a level of 2.5 liters/min or about 8.3 times Reaction with H2O (O2 evolution) 50 2M2O2 + 2H2O -> 4MOH -- O2 the at-rest requirements. 2MO2 + H2O - 2MOH + 3/2O2 The oxygen generating compound such as potassium M2O3 + H2O - 2MOH -- O2 superoxide and the like is a demand source of chemical Reaction of CO2 with Hydroxide (MOH) oxygen. When this compound reacts with water, it MOH + CO2- MHCO3 forms which absorbs carbon diox 55 2MOH + CO2- M2CO3 ide. In the present invention, it is used in a microcapsule form having a very small particle size (approximately Since the oxygen generating particles emerge on a 250-1000 microns), since the bulk form of this com gradual or timed basis, there initially are not enough pound is not adaptable to compact cartridge design. In available particles to absorb all of the carbon dioxide bulk form, the compaction density of the potassium present. Accordingly, an additional chamber containing superoxide is relied upon to control permeation and solid anhydrous lithium hydroxide is provided as a sup diffusion of moist air and give extended release times. plementary carbon dioxide absorber. As the breathing The small particle size provides a very reactive and rate increases (thereby increasing the moisture present), large surface area when the capsules open. As these the microcapsules open more rapidly, and the lithium microcapsules are exposed to moisture, the coating 65 hydroxide serves a secondary role. slowly peels back in an exfoliating manner, exposing For fast breathing rates, hereafter referred to as a first increasing amounts of the core material. Thus, unlike breathing rate, it is necessary to provide more moisture the bulk form, the active core material is available only to the microcapsules than the amount obtained from 4,963,327 9 10 respiration. In this case, an aqueous solution of MgCl2, peroxide, since metal salt impurities are sufficient to with a small amount of surfactant is pumped into the cause decomposition. microcapsule chamber from an attached reservoir. Oxy Microfine silver and samarium catalysts are used to gen evolution and gas flow become very rapid and promote the violent and instantaneous decomposition of diffusion of carbon dioxide to the oxygen generating concentrated hydrogen peroxide into oxygen and sites is inhibited. Lithium hydroxide is the primary car steam. It has use for propulsion of rocket sleds and bon dioxide absorber. The contained surfactant aids in related devices, but is not suited for controlled release wetting the organic capsule surfaces. The MgCl2 serves systems. It has been found that solid forms (rods, wires, two functions; namely, as an anti-freeze and as a decom screens) made of any of stainless steel, copper, iron, position agent for the alkaline salts from the oxygen 10 carbon steel, silver, nickel, or chromium initiate oxygen generating compound/water/carbon dioxide reaction release from metastable aqueous hydrogen peroxide. An insoluble gel of magnesium hydroxide/carbonate is Removal of metal source stops the oxygen release, and formed together with pH neutral salt, such as potassium it can be re-started repeatedly by replacing the metal chloride when potassium oxides are used. catalyst. Instead of MgCl2, other well known salts in the art 15 Once again, the gas flow rates which occur during which provide significant freezing point depressions in this prolonged high stress rate operation are such that aqueous solutions and which form substantially insolu the lithium hydroxide becomes the primary carbon ble compounds when reacted with alkali hydroxides dioxide absorber. Optionally, the MgCl2 solution can be and/or carbonates may be used. Examples include used to neutralize the alkaline reaction products when CaCl2, FeCl3 and ZnCl2. 20 the oxygen release is completed and the unit is to be For high stress breathing rates, hereafter referred to disposed of. as a second breathing rate, the oxygen requirements are In adgiition to the advantages provided by the multi supplied by both the microencapsulated oxygen gener chambered unit in regard to the increased oxygen re ating compound and hydrogen peroxide. In this situa 25 lease provided by the double decomposition reaction tion, aqueous hydrogen peroxide (30 percent strength, discussed above, the present invention has a further for example) containing surfactant is pumped from its novel feature in that it has been found that the selective reservoir to the microcapsule chamber. A double de absorption of noxious and/or undesired gases and the composition reaction occurs which comprises the reac extended controlled production and delivery of oxygen tion of the oxygen generating compound (i.e., potassium 30 through the utilization of both physical means, i.e. zeo superoxide) with aqueous hydrogen peroxide, and sub lites cationically exchanged with heavy metal ions, and sequent metal catalyzed decomposition of the resulting chemical means, i.e. superoxide/water reaction, in the metastable alkaline aqueous hydrogen peroxide. For unique compact form herein disclosed provides an effi purpose of the present disclosure, metastable means ciency gain which is much greater and different from an chemically unstable, but not liable to spontaneous rapid 35 additive effect of these components. This result occurs decomposition. with or without added anhydrous lithium hydroxide. The double decomposition procedure has the advan This result is totally unexpected given the fact that tage of higher oxygen delivery capacity than either superoxides function only by reacting with water, while system alone. The individual chemical reactions are as zeolites absorption capacity is deactivated by water. In follows: addition, superoxides work well at atmospheric pres sure whereas zeolites do not. One possible explanation for this phenomenon is that there is a complex interac tion of absorption dynamics with small particle size and high specific absorbency chemicals. It may also include Overall, the simplified reaction is: 45 effects due to reduced competition for absorbency chemicals. It may also include effects due to reduced competition for absorption sites and gas transfer pro Ko; + 2aq.H.O. metal seaq KOH + 24 O, CSS. More particularly, one possible explanation for this Specifically, the double decomposition reaction com 50 phenomenon could be a combination of the following: prises the in situ formation of potassium hydroxide sub the increased surface area of the small oxygen generat stantially free of heavy metal salts which dissolves in ing particles can compensate for short gas/solid contact the aqueous hydrogen peroxide as the oxygen is being times required for efficient permeation and diffusion, liberated, thereby raising the pH of the aqueous hydro thus effectively achieving a longer pathway; the hydro gen peroxide from its normal range of pH 3-5 to its 55 phobic zeolites function as selective gas absorbents metastable range of pH 9-12. Gradual decomposition of rather than as dessicants; the lithium hydroxide in the the metastable hydrogen peroxide to oxygen and water unit functions exclusively as a carbon dioxide absorber then occurs, thus providing a secondary source of oxy and thereby decreases competition for carbon dioxide gen. The decomposition to water and oxygen has been 60 absorption sites in the zeolites; oxygen generation and found to be controllable by contacting the solution with carbon dioxide and the like is enhanced by the microen solid metal surfaces. capsulated form (shorter diffusion pathways); and con As previously mentioned, the alkaline aqueous hy tinuous generation of oxygen from the microcapsules in drogen peroxide is metastable. It is known in the art that juxtaposition to hydrophobic zeolite surfaces causes a metastable aqueous hydrogen peroxide decomposes 65 gas transfer phenomenon in which absorbed gases, i.e., rapidly and uncontrollably in the presence of soluble nitrogen and carbon dioxide, are constantly displaced heavy metal salts. However, only chemically pure alka from the zeolites by oxygen, and then more effectively lis can be used to make metastable aqueous hydrogen reabsorbed upon cycling through filter. 4,963,327 11 12 DESCRIPTION OF THE PREFERRED TABLE 4 EMBODIMENTS DISKTYPE MODULE CHAMBER DIMENSIONS The following examples illustrate various aspects of Volume Contained Diameter Height 5 (CC) Wit. (GMS) (In.) (In.) the invention. They are not to be construed to limit the KO2 Microcapsules 163 86.2 4. 0.8 claims in any manner whatsoever. Anhydrous Lithium 82 36 4 0.4 Hydroxide EXAMPLES 1-6 Cationic Zeolite 15 10 4 0.08 30% H2O2 30 30 (a) (a) Microcapsules comprising various oxygen generating 10 10% aq. MgCl2 30 --- (a) (a) core materials and a wall-forming water swellable coat (a)Attached to the circumferential edge of the KO microcapsules chamber. Length ing were prepared in accordance to methods well -3" of circumference, width 0.8", Height - 0.75". known in the art (particle size 250-1000 microns), and Upon activation, the oxygen delivery capacity was their oxygen generating properties were tested. The determined to be approximately 24 liters at 25 C. The results are shown in Table 2. 15 useful working life depended upon the breathing rate of TABLE 2 the user. At low stress (rest) breathing rates, the useful Properties of KO2 and Alternate Inorganic Oxides working life of the module was greater than 80 minutes. Core At high stress breathing rates, the useful working life Compound % contained lbs O2/1b lbs CO2/1b 20 was determined to be approximately 9-10 minutes. (formula) (MW) oxygen (generation) (absorption) EXAMPLES 12-14 KO2 7 45 0.34 0.31 K2O3 126 38 0.25 0.3S Examples 12-14 are directed to the effect of the inclu Li2O2 46 69.5 0.35 0.96 sion of solid metals in the double decomposition reac Na2O2 78 41 0.21 0.56 25 tion and the effect of different forms of potassium super NaO2 55 58 0.43 0.40 oxide. Ca(O2)2 104 61.5 0.46 0.42 In Example 12, powdered potassium superoxide was 'calculated as carbonate added to FMC 35% superD hydrogen peroxide (pH 3-5) and oxygen production was essentially immediate. 30 The resulting alkaline mestable aqueous hydrogen per EXAMPLES 7-10 oxide (pH 9-12) showed no evidence of spontaneous The properties of MgCl2 and alternate salts used in oxygen release. Loops of 0.0625" diameter copper wire the present invention as a source of additional water to immersed in the liquid caused slow, steady gas evolu increase oxygen release from the microcapsules and/or tion from the immediate wire surface. The test was to decompose the alkaline reaction products from the 35 repeated successfully with wires made from each of same were tested at different weight percentage. The silver, iron, carbon steel, stainless steel, nickel, and chromium. The same metal wires placed in regular 35% results are shown in Table 3. hydrogen peroxide did not cause oxygen release. TABLE 3 In Example 13, microencapsulated potassium super Properties of MgCl2 and Alternate Salts 40 oxide was used instead of potassium superoxide powder Aq. solution in a repeat of the tests from Example 1. The major (Percentage by difference observed was that oxygen release from potas weight of dissolved Freezing Point Depression (C) sium superoxide occured over an extended time period salt) CaCl2 MgCl2 FeCl3 ZnCl2 and the pH increase also occured gradually over the 1. 0.44 0.55 0.38 0.45 45 period of oxygen release. The various metals behaved as 3 1.33 1.62 1.13 1.25 in Example 1. 5 2.36 2.97 1.90 2.19 In Example 14, Example 13 was repeated but with 7.5 3.93 5.14 3.6 3.78 10 5.85 7.91 4.77 5.52 metal wires in place prior to introduction of the potas 15 11.0 15.64 9.33 9.83 50 sium superoxide microcapsules. As the pH gradually Solubility in increased, there was an onset of gas evolution concur water 20 C. rently with the release from the reaction. The concur (g/100g H2O) rent oxygen production started at about pH 8 and the Hydroxide 0.10 0.009 0.001 0.001 aqueous hydrogen peroxide oxygen production rate Carbonate 0.0014 0.01.06 0001 0.001 55 increased continuously up to pH 12. An approximately overall uniform gas delivery resulted since the aqueous hydrogen peroxide rate accelerated as the potassium EXAMPLE 11 superoxide rate decreased. Although potassium superoxide was used in these A cartridge type module similar to that shown in tests, other sources of alkali substantially completely FIG. 1 having chambers containing potassium superox- 60 free of metal salts can be used. It is preferred to use ide microcapsules, anhydrous lithium hydroxide, cati water reactive peroxides and superoxides since they onic zeolite, a reservoir of aqueous of 30% strength liberate desired oxygen. The corresponding salts of hydrogen peroxide, and a reservoir of aqueous MgCl2 potassium, sodium, and lithium are particularly useful was tested in order to determine its oxygen delivery 65 because their hydroxides are strong bases and extremely capacity and its useful working life. water soluble. The dimensions of the individual chambers and their The list of metals that catalyze the peroxide decom contents are provided in Table 4. position is not complete, and is not meant to be limiting. 4,963,327 13 14 As can be seen from the graphs provided in FIG. 8, EXAMPLES 15-35 coating the 5A mole sieve with hydrophobic colloidal The present invention of a modular unit having multi silica raises its performance to near that of the iron chambers by which the combined ingredients provide a mordenite. more efficient and compact system than previously 5 In Example 18, a test material comprising iron ex possible is not readily treatable in quantitative terms changed mordenite was compared to a test material since gas absorption dynamics in an environment of comprising both iron exchanged mordenite and potas continuously changing conditions involves complex sium superoxide microcapsules. The results are shown permeation and diffusion controlled parameters, in ad in FIG. 9. - dition to other variable factors such as breathing rates, 10 A comparison of the two sets of curves shows that contact times with filter surfaces, atmospheric operat the combination of iron mordenite and microencapsu ing pressures, humidity, and changing gas compositions lated potassium superoxide gives lesser loss in immedi and temperatures. ate oxygen level on respired air injection and faster Accordingly, a review of available standard tests recovery to ambient conditions. Additive results from showed that existing procedures were inadequate. 15 this combination of materials would be expected to Therefore, a special test device and method were devel yield curves similar to that for microencapsulated supe oped to measure the performance of the materials in a roxides alone. These findings are novel and not pre simulated rebreather mode. dicted. The test apparatus is shown schematically in FIG. 5 These results were confirmed by the further test re and consists of a closed loop system into which mea 20 sults provided by Examples 19-27 which provide the sured air samples can be introduced and recycled relative recovery rates for the above-mentioned test through a test filter by means of a pump and in contact materials for raising the oxygen level from 18.2 percent with an oxygen level detector. (corresponding to the oxygen level in respired air) to The test method comprises (1) introduction of a fixed 19.5 percent. The results are shown in Table 5. Exam amount of respired air to a reservoir 2 through an inlet 25 ples 28-35, provide the amount of respired air necessary valve 8, (2) starting recycle pump 1 after shutting inlet to achieve 19.5 percent, 20 percent and 21 percent oxy valve 8 and recording immediate change in O2 level, (3) gen levels for certain of the above-mentioned test mate measuring the time and rate of O2 recovery to ambient rials. The results are shown in Table 6. In addition, levels at a given pump rate. After quasiequilibrium is these results indicate that there is no essential differ attained, the air sample is released and a new sample of 30 ences by this test procedure between copper and iron as respired air is injected and recycled as before. A total of the heavy metal cation exchanged into mordenite. This 10 respired air injections were used for each filter as result conflicts with literature references which suggest sembly. that the iron zeolites provide better selective gas ab Test chemicals were sandwiched between layers of sorption than the copper zeolites. Also, the microencap fiberglass mat, and held in the simulator device by an 35 sulated potassium superoxide results in Table 6 show open grid rigid support. Respired air (18.2% O2) at that there were lower total gas transport requirements room temperature was the test gas. The rate of recovery for the gradual oxygen release to reach 21 percent (am of O2 to ambient level (20.8%) was used as an indicator bient air) oxygen levels than the other tested materials. offilter performance, and changes in the recovery char acteristics were used as capacity measures. 40 Recovery rate data are presented in graph form, and TABLE 5 other data are given numerically as relative recovery RELATIVE TIME TO RAISE, O2 FROM 18.2% TO 19.5% times and total gas transport to achieve target O2 con EXAMPLE MATERIAL SECONDS centrations. - 19 5A Mole Sieve 300 In Example 15, the oxygen generation of uncoated 45 20 5A Mole Sieve w/1.5% TS-720 150 21 Fe Mordenite 150 and microencapsulated potassium superoxide over a 22 Cu Mordenie 150 twenty second span was calculated on the basis of the 23 Anhydr. LiOH 100 percentage of oxygen in the air. The data for air injec 24 KO2 Microcapsules 100 tion 1, 3 and 10 are shown in the graphs provided in 25 Fe Mordenite/KO2 Microcaps 20 26 Fe Mordenite/KO2 Microcaps/Anh. 20 FIG. 6. From these graphs, it is readily apparent that 50 LiOH extended controlled release of oxygen by the microen 27 Anh. LiOH/KO2 Microcaps' 80 capulation is achieved even after 10 cycles. Cabot Hydrophobic Colloidal Silica In Example 16, anhydrous lithium hydroxide alone Cation Exchanged with Fe(NO3)3 cation Exchanged with Cu(NO), (carbon dioxide absorber only) was compared to a sys 1/1 Weight Ratio tem containing anhydrous lithium hydroxide and potas 55 1/1/1 Weight Ratio sium superoxide microcapsules in a one-to-one weight 1/1 Weight Ratio ratio. The results are shown in FIG. 7. Pump Rate = 8 Secs/Cycle The anhydrous lithium hydroxide alone showed de Union Carbide 5AMG (Calcium Zeolite) creased oxygen generating capacity on repeated air injections, while the potassium superoxide microcap TABLE 6 sules and anhydrous lithium hydroxide together RESPIRED AIR (LITERS) showed increased capacity due to sustained oxygen CYCLED THROUGH FILTER TO REACH release. OR EXCEED 19.5%, 20% and 21% OXYGEN LEVELS In Example 17, a test material comprising cationic EXAMPLE MATERIAL 19.5% O2 20% O2, 21% O2 65 28 5A Mole Sieve 5-7.5 10 10 exchanged zeolite (iron mordenite) was compared 29 5A Mole Sieve 2.5 3.75 7.5 against a 5A mole sieve (ued in pressure swing oxygen w/1.5%TS-720 generation), and a 5A mole sieve which is coated with 30 Fe Mordenite 25 2.5 7.5 hydrophobic colloidal silica. 31 Cu Mordenite 12S 2.5 7.5 4,963,327 15 16 a first level of oxygen generation being activated TABLE 6-continued by depressing said first plunger to rupture said first RESPIRED AIR (LITERS) CYCLED THROUGH FILTER TO REACH frangible disc, wherein subsequent to said rupture OR EXCEED 19.5%, 20% and 21% OXYGEN LEVELS of said first frangible disc a repeated depression of EXAMPLE MATERIAL 19.5% O2 20% O2 21% O2 5 said first plunger resulting from a first breathing 32 KO2 Microcaps 1-1.25 2.0 5.0 rate causes an increase of pressure, thereby increas 33 Anh. LiOH 1-1.25 3.75 7.5 ing a flow of said aqueous solution of mildly acidic 34 KO2 Microcaps/ 2-2.5 S.0 salt through said porous wall and into said first Anh. LiOH 35 Fe Mordenite/ 0.25 0.25-0.50 1.75-2.0 10 chamber KO2 Microcaps a second pressure means comprising a second plunger Pump Rate = 8 Secs/Cycle and a second frangible disc, said second plunger 18.2% O2 being attached to said fourth chamber and said second frangible disc separating said aqueous hy Although the primary focus of the present invention drogen peroxide from said porous wall of said first has been directed to respirator applications, it is con 15 chamber, a second level of oxygen generation templated that various aspects of the present invention, being activated by depressing said second plunger taken both individually and together, may be applied to to rupture said second frangible disc, wherein sub many other applications. For example, the controlled sequent to said rupture of said second frangible disc gas absorption/release mechanisms of the present in a repeated depression of said second plunger result. vention may be used for removal of toxic gases such as ing from a second breathing rate causes an increase ammonia, carbon monoxide, sulfur dioxide and chlorine of pressure, thereby increasing a flow of said aque gas, and for removal of corrosive vapors such as hydro ous hydrogen peroxide to pass through said porous gen fluoride, hydrogen chloride, and sulfur trioxide. It may also be used for fruit ripening (release of ethylene) wall and into said first chamber. and water purification. In addition, it is contemplated 25 2. An apparatus as defined in claim 1, further com this aspect of the present invention is suitable for use in prising a fifth chamber containing an immobilized sorp fire extinguishers (for carbon dioxide, halon, etc.) tive particular material for selective absorption of nox The controlled hydrophobicity aspects of the present ious and other undesired gases which is cationically invention may be used for inorganic cements, mortars exchanged with a heavy metal ion, said fifth chamber and plastics, and for moisture reactives such as carbides, being made from a semipermeable fabric. hydroxides and the like. It may also be used for gas 3. An apparatus as defined in claim 2, wherein said absorption from aqueous or high humidity sources. semipermeable fabric of said fifth chamber is coated Finally, the moisture activated microcapsules of the with an antioxidant. present invention may also be used for other exo- and 4. An apparatus as defined in claim 3, wherein said endothermic devices as well as for insecticides, fungi-35 antioxidant is selected from the group consisting of cides, and the like. 2,6-di-tert-butyl-p-cresol, propyl gallate, t-butylhy The examples provided above are not meant to be droxy quinone, a butylated hydroxyanisole, and mix exclusive. Many other variations of the present inven tures thereof. tion would be obvious to those skilled in the art, and are 5. An apparatus as defined in claim 2, further com contemplated to be within the scope of the appended prising a sixth chamber containing an antioxidant. claims. 6. An apparatus as defined in claim 2, wherein said I claim: immobilized sorptive particulate material comprises a 1. A multi-chamber permselective apparatus for pro zeolite. viding oxygen enriched filtered air matched to a range 7. An apparatus as defined in claim 2, wherein said of breathing rates, comprising 45 immobilized sorptive particulate material comprises a a first chamber containing microcapsules comprising copper or iron exchanged clinoptilolite or copper or an oxygen generating compound as a core material iron exchanged mordenite. and a coating which is moisture swellable but not 8. An apparatus as defined in claim 2, wherein said soluble, said coating slowly exposing said core semi-permeable fabric of said fifth chamber is selected material to moisture in respired air, said core mate 50 from the group consisting of an oriented, microporous rial reacting with the moisture and generating oxy teflon composite, an oriented, microporous polyolefin, gen; a polyurethane, a water resistant nylon, and water resis a second chamber containing a solid carbon dioxide tant canvas. absorber for absorbing carbon dioxide from re 9. An apparatus as defined in claim 2, wherein said spired air; 55 oxygen generating compound is selected from the a third chamber containing an aqueous solution of a group consisting of alkali metal and alkaline earth metal mildly acidic salt and a nonionic surfactant; peroxides, superoxides, trioxides, percarbonates, per a fourth chamber containing aqueous hydrogen per manganates and mixtures thereof. oxide and a nonionic surfactant, 10. An apparatus as defined in claim 9, wherein said said chambers being made from a semi-permeable solid carbon dioxide absorber is lithium hydroxide. fabric, said fabric preventing fluid penetration 11. An apparatus as defined in claim 9, wherein said under normal pressure but allowing fluid to pass oxygen generating compound is selected from the through under moderate over-pressure, group consisting of potassium superoxide, lithium su a first pressure means comprising a first plunger and peroxide, calcium superoxide, sodium peroxide, potas a first frangible disc, said first plunger being at 65 sium peroxide, lithium peroxide and mixtures thereof. tached to said third chamber and said first frangible 12. An apparatus as defined in claim 11, wherein said disc separating said aqueous solution of mildly coating is selected from the group consisting of olefin acidic salt from a porous wall of said first chamber, copolymers with vinyl compounds, homopolymers of 4,963,327 17 18 vinyl monomers, the alkyl, hydroxyalkyl and amino mildly acidic salt is selected from the group consisting alkyl acrylics and methacrylics, maleic anhydrides, of magnesium chloride, calcium chloride, iron chloride, anhydrous polymeric alkylene oxide polyols and alkoxy or zinc chloride. derivatives having a molecular weight greater than 500, gelatins, starches, gums, polyamides, polyurethanes 5 14. An apparatus as defined in claim 13, wherein said modified for high hydrophilicity, and mixtures of any of microcapsules are from about 250 to about 1000 microns the foregoing. in diameter. 13. An apparatus as defined in claim 11, wherein said st se k : 10

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