WO2003092748A1 - Apparatus and process for decontaminating breathing air of toxic substances and pathogenic organisms - Google Patents

Abstract

A low temperature catalytic oxidation apparatus and process for decontaminating breathing air from organic toxins and pathogenic organisms, including a modular unit with at least one empty chamber (K) having heating elements (E, F) mounted at the air entry ports (C) followed by a heated chamber containing a porous adsorbent (G), preferably a hydrophobic molecular sieve, and at least one additional heated chamber containing an oxidation catalyst in a porous, refractory matrix (E). The chambers are interconnected with the inlet for contaminated air (C) opening into the empty chamber (K), the empty chamber opening into the adsorbent chamber (A), and the adsorbent and catalyst containing chambers (A, E, G) are heated to produce temperature gradients inside the layers in order to thermally destroy pathogenic organisms and simultaneously effect adsorption, desorption and catalytic oxidation of organic toxins. Continuous operation is achievable by connecting a second module in tandem and regenerating a used module while the other module is in use.

Description

APPARATUS AND PROCESS FOR DECONTAMINATING BREATHING AIR OF TOXIC SUBSTANCES AND PATHOGENIC ORGANISMS

BACKGROUND OF THE INVENTION

The present invention relates to a low temperature catalytic oxidation device for purifying preferably breathing air from harmful contaminants such as organic poisons and/or pathogenic bacteria, viruses, fungi and/or spores.

The air we all breathe is a mixture of gases. At sea level and under dry conditions, the average composition is 78.09 % nitrogen, 20.95 % oxygen, 0.93 % argon, 0.03 % carbon dioxide, trace amounts of rare gases and helium. The moisture content averages 50 g per cubic meter. Without air, life is impossible, and for this reason, its purity, constancy of composition and other parameters are of paramount importance. The process of respiration by all living organisms involves two gases, namely oxygen and carbon dioxide. Both form the basis of cellular metabolism and are absorbed or given up by a regulated osmosis across the semi-permeable membrane of cell walls.

Unintentional contamination of the air with poisonous substances produced as a result of fires or accidents of transport or industrial production are not uncommon and must be dealt with by firefighters, police and public health workers. In addition, the possibility of gas warfare or terrorist attack raises the prospect of a need for protection against intentional contamination of breathing air with toxic substances or pathogenic biological agents. Thus, there is an ongoing need for protective apparatus which can provide safe respiratory air to emergency personnel and ordinary citizens alike in the event of atmospheric contamination. Unintentional contamination of breathing air by dust, organic, or inorganic gaseous substances spilled accidentally or generated by combustion has been well studied in order to develop methods to enable on the spot personal investigation of the cause and needed remedial measures. The list of usual contaminants and methods for quantifying them are well known. Unintentional contaminants often are present in large concentrations. In cases of intentional or wanton contamination, the concentration of the poisons often is minute because their toxicity is very high. They also may be accompanied by bacteria, viruses, fungi or spores of highly pathogenic organisms.

The problem of chemical weapons is basically very complex and it can be said that a complete solution is far from being achieved. Poisonous gases embrace a huge number substances in gaseous form. Generally speaking, organic substances which have high toxicity are mostly aliphatic and aromatic in nature and to a large extent are derivatives of hydrocarbon ring compounds and nitrogenous polycyclic compounds. The substances are extremely toxic in very low concentrations, and whether they can be adsorbed, neutralized or oxidized is an open question. The predominant protective device heretofore available against such agents is an air purifying respirator, sometimes referred to as a gas mask. Air purifying respirators were conceived at the time of the first world war mainly as a temporary protection against attacks with toxic gases such as chlorine gas or mustard gas. They rely chiefly on an adsorbent such as activated carbon (e.g., coconut shell charcoal). Consequently, such devices can only be used until their adsorbing capacity is exhausted. Then a new adsorbent cartridge must be installed without any idea whether the old cartridge is active or not. An additional disadvantage of such gas masks is the problem of disposing of the used, at least partially saturated adsorbent cartridge, which typically must be handled as hazardous waste.

As far as deadly biological contaminants are concerned, potential bioweapons include pathogenic bacteria, viruses, fungi, spores of any of the foregoing, and bacterial adsorbates. In the case of biological weapons, the commonly used preventive is a microporous bacterial filter for the respiratory tract and fully impervious protective clothing. The availability and effectiveness of such devices is open to question. Moreover, the problem of disposing of such devices after use again presents difficulties because, due to their hazardous nature, they require special handling.

The possibility of industrial accidents, transport accidents, as well as terrorist attacks with chemical and/or biological weapons renders the need for widely available and efficient protection against such agents more imperative now than ever before.

Presently available devices and procedures for emergency self- protection in the event of exposure to toxic gases or airborne biological agents are essentially limited to conventional respirators of the air purifying type or of the atmosphere supplying type. Atmosphere supplying respirators use a cylinder of compressed clean air which is continuously fed in closed circuit to a protective mask. Air purifying respirators typically rely on the use of classical adsorption media. The usual adsorbent used is activated coconut charcoal in granular or tablet form, but other adsorbents are also mentioned in the technical literature. For bacteriological pollution the masks may contain a further filter whose pores are smaller than the average bacteria.

The most important disadvatages of conventional air purifying respirators or air supplying respirators are the following:

1) Whatever the adsorbent used is, the capacity and the adsorption isotherm follows the equation which was postulated long ago by Mittscherlich. Every adsorbent looses its power with increasing load up to a point which cannot be pre-determined unless there is a continuous monitoring of the poisons it adsorbs. The result is that it is advisable not to re-use a previously used air purifying mask .

2) Once an air purifying respirator has been fully saturated or has to be replaced, the adsorption cartridge containing the poison it has adsorbed necessarily must be disposed of as a hazardous waste. The same applies to bacterial filter masks. 3) In the case of air supplying respirators employing compressed clean air as source of breathing air, the disadvantage is that the compressability of air is low and hence the size and weight of a cylinder required to provide the volume of air needed by the user is quite large. Furthermore, the user has to plan exactly how quickly he can return to a safe area where replacement cylinders are available.

4) No single adsorbent can adsorb any amount of all types of organic substances. Some adsorbents adsorb totally aliphatic hydrocarbons, some others aromatic compounds, but not so well nitrogeneous ring substances and so on. Because no adsorbent is totally effective for all possible types of toxic gases, it is possible that in some cases an air purifying mask could be totally useless.

As previously noted, atmosphere supplying respirators can only be used for a relatively short period of time before it is necessary to connect them to a fresh supply of air. Similarly, filters can only be used for a limited period of time before they become fouled or clogged, and after use they require disposal as hazardous waste.

In view of these disadvantages of prior systems, there is a need for an apparatus and process for reliably decontaminating contaminated breathing air by removal and simultaneous destruction of even trace amounts of gaseous toxic organic substances and pathogenic bacteria, viruses, fungi and/or spores.

Catalytic oxidation with regenerable catalysts is widely used in industrial processes. By the use of catalytic agents which do not take part in the reaction, but which simply facilitate the reaction by their presence, it is possible to oxidize or destroy to the stage of carbon dioxide and water a very large number of gaseous organic substances. A particularly well known catalytic oxidation method is the one used in automobiles for cleaning the exhaust gases of the engine using noble metal catalysts. Automobile exhaust formed by internal combustion of fossil fuel in Otto engines is a huge mixture of aromatic, aliphatic and nitrogenous hydrocarbons. Almost 100% of these can be destroyed through oxidization to carbon dioxide and water by a noble metal catalyst which becomes heated by the heat of catalysis and combustion to temperatures of 600° C or more. A significant difficulty, however, is that car exhaust catalysts start working only at temperatures above about 300°C, and the degree of catalytic efficiency only increases to a respectable level at higher temperatures of, e.g., about 600°C or more. However, this temperature unsuitable for treating respiratory air because of the difficulty of cooling the treated air to acceptable breathing air temperatures, which should not exceed body temperature of about 37°C. For optimum comfort and effectiveness it is desirable that breathing air be cooled to a temperature of not more than about 30°C, preferably 25°C or less. Furthermore, the initiation of catalytic activity in the known methods is slow, and consequently a significant amount of unaffected organic compounds can pass through the catalyst bed before it becomes fully active.

German patent application no. DE 195 21 621.0 describes a two-stage process for cleaning automobile exhaust gases during the period of a so- called "Cold-Start". In the first stage the exhaust gases are conducted into a container provided with electrical heating and filled with an adsorbent. The cold engine exhaust after adsorption of major component gases is heated to a temperature above 170°C and then enters a second container also provided with electrical heating and filled with a noble metal catalyst in granular form similar to the one used in normal cars. The exhaust gases quickly attain a temperature of 600°C, and are thereby mostly oxidized to carbon dioxide and water vapor with traces of the originally present hydrocarbons remaining. This, however, is still unacceptable in systems intended for protection against toxic poisons in which it is necessary to completely prevent passage of such substances from the very beginning of use. Moreover, the temperatures to which the gas is heated are still too high for convenient cooling to suitable breathing temperatures. SUMMARY OF THE INVENTION

It was the object of the present invention to provide an improved apparatus and process for purifying breathing air.

It was also an object of the present invention to provide an apparatus and process for purifying breathing air which simultaneously removes a large number of gaseous organic poisons and kills potentially dangerous living organisms in contaminated air.

Another object of the present invention was to provide an apparatus and process which are self-regenerating so that user contact with hazardous used materials can be avoided.

A further object was to provide an apparatus and process which can be used continuously over an extended period of time without requirement for replacement of filter cartridges.

An additional object of the invention was to provide an apparatus and process which can be adapted to individual personal gas masks, to vehicles, to safety shelter rooms, or to entire building structures.

Another object of the invention was to provide a catalytic apparatus and process for decontaminating breathing air which operated at lower temperatures than prior catalytic air purification apparatus and processes.

Yet another object of the invention was to provide an apparatus and process for purifying breathing air which are effective at inlet temperatures below about 100°C, and particularly preferably at inlet temperatures as low as about 37°C.

Still another object of the invention was to provide an apparatus and method which would be effective to eliminate toxic gases and/or pathogenic organisms from the beginning of use.

A still further object of the invention was to provide an apparatus and process in which the temperature of the processed breathing air can be readily reduced to a maximum of 37°C; preferably to not more than about 30°C, and particularly preferably to not more than about 25°C.

These and other objects have been achieved in accordance with the present invention by providing an apparatus and method which effect a combination of thermal inactivation and catalytic oxidation to decompose and/or destroy both toxic chemical substances and pathogenic bacteria, viruses, fungi and/or spores.

The invention thus relates to a low temperature catalytic oxidation apparatus and process for purifying breathing air which is capable of simultaneously removing organic poisons and bacterial, viral, fungal and or spore contaminants from the air.

The basic system comprises a catalytic oxidation with special catalysts at a temperature below 100°C. In order to increase the efficiency to almost 100%, the system uses a pre-filter stage of special adsorbents which are capable of adsorbing and sequentially desorbing organic substances similar to procedures heretofore used in analytical gas chromatography. The invention provides an attractive alternative to the use of adsorbent cartridges and or bacterial filter cartridges in gas masks which are subject to the disadvantages described above.

The present invention makes use of catalyst materials which have the following properties:

1) They oxidize a very large number of organic substances to carbon dioxide and water at catalyst surface temperatures that would raise the temperature of the contaminated air flowing over its surface to at most about 100°C. This purified air leaving the catalyst surface can then be easily cooled down to body temperature of 37°C by a simple heat exchanger with outside ambient air circulation.

2) They permit formation of highly porous substrates of suitable geometrical shape.

3) They permit artificially heating the catalyst to the active surface temperature.

The catalyst may suitably be a noble metal oxidation catalyst selected from the group consisting of gold, silver, platinum, palladium, iridium, rhodium, mercury, ruthenium and/or osmium. Catalysts which contain gold, silver, platinum and/or palladium are preferred. Preferably, the catalyst metal is supported on an inert, porous support material, such as potassium aluminum silicate. Preferred supported catalysts may contain from about 1% to about 8% catalytic metal on from about 92% to about 99% of the porous support. Excellent results have been obtained with catalysts containing from about 1% to about 3% catalytic metal. If desired, the catalyst may include other catalytic metals such as copper and/or manganese, either in metallic form or in the form of their catalytically active oxides. An especially preferred catalyst comprises about 1.5% platinum, about 1% copper oxide, and about 0.5% manganese dioxide on a granular support comprised of porous potassium aluminum silicate.

A number of catalysts having the foregoing properties were prepared and tested verses adsorbents used in common gas masks. These preliminary tests showed promise, especially when the gas was admitted in pulsating volumes. It has been found that such pulsating volume flows can be attained by using an adsorbent pre-filter ahead of the catalytic oxidation which would adsorb the components of a gas mixture and then desorb them in sequence so that each component was oxidized in turn by the catalyst. Such auxiliary pretreatment improves the efficiency of overall oxidation to extremely high levels. The adsorption/desorption process is similar to that used in the analytical method of gas chromatography.

The system must be capable of being connected to a conventional filter of a half or full gas mask, and its aspiration pump must be capable of generating the needed air volume and pressure.

For gas masks, it is advantageous if the total weight of the complete device, including accumulator and belt straps, is not more than about one kilogram for 6 V DC supply.

In accordance with the present invention, it has been found that the objects of effective and long lasting protection against toxic gases and/or airborne pathogenic organisms could be achieved, if the adsorption and desorption process is very effective and if the catalytic oxidation of the unadsorbed components takes place completely to just carbon dioxide water vapor or nitrogen at a temperature of not more than about 100°C. A preferred apparatus of the invention comprises at least one empty chamber with electrical heating and air entry ports, followed by an adsorber chamber containing a suitable porous adsorber and another chamber containing a suitable oxidation catalyst distributed in a porous matrix together with means for heating each of the three chambers, for example, by means of electric heating coils.

Considering that a gaseous poison can be any organic, aliphatic or aromatic compound and a biological contaminant may contain bacteria, viruses, fungi and/or spores whose lethal temperature lies around 180°C, the basic embodiment of the present invention comprises using at least one heated air layer followed by a layer of a thermally stable porous adsorbent/adsorbent mixture preferably based on a zeolite type structure which acts as a molecular sieve in the same way as a gas chromatography column and effectively adsorbs a large number of organic compounds at room temperature but desorbs them completely at temperatures above 100°C. This adsorbent layer is followed by at least one further layer of a catalyst comprised of a noble metal, copper and/or manganese distributed in a heat stable porous matrix.

The adsorbents are preferentially made into a suitable granular form which enables quick heat transfer from an electrically heated coil to the granules so that the surface temperature of the granules reaches the desired lethal temperature of the living bacteria, viruses or spores while the adsorptive power for organics remains unaffected and the gas flow is not hindered. Furthermore, since the adsorbent layer is followed by catalyst layers also made into suitable granular form and also provided with suitable electrical heating, any spores and dust particles that might have escaped inactivation in the previous adsorbent layers impinge on even hotter granule surfaces, thereby ensuring complete sterilization. Simultaneously, the catalysts layers based on noble metals, copper and/or manganese generate heat of oxidation, thereby ensuring a completion of the oxidation process. The temperature of the heating element contacted by the incoming air stream within the heating chamber should be at least about 150° C to effectively sterilize entrained pathogenic organisms. Preferably the heating element temperature will lie in the range from about 180°C to about 200°C. Higher temperatures are effective, but make it more difficult to assure that the decontaminated breathing air is discharged from the apparatus at an acceptable breathing temperature. If desired, the heating element may be operated in a cyclic or so-called "spiked" manner to prevent the desired maximum temperature from being exceeded. Such cyclic operation may be effected, inter alia, by use of adjustable interval timers to control the heating cycles and thereby regulate the temperatures.

Because the air moving past the heating element is not all heated to the temperature of the heating element, the temperatures maintained in the subsequent adsorbent zone are somewhat cooler than the heating chamber heating element temperature. To increase the molecular sieve effect of the adsorbent, it is desirable to establish an increasing temperature gradient in the adsorbent chamber. Thus, the heating element in the adsorbent chamber should be designed to produce an increasing temperature gradient in the chamber. Beginning temperatures typically will be about 40 or 50°C, but may be as high as about 60°C or more due to heating of the gas as it passes through the heating chamber. End temperatures of about 80°C to about 100°C are suitable, but the end temperature may range up to 120°C or more for certain substances to provide suitable separation effects as toxins pass through the adsorbent bed. Optimum temperatures will vary depending on the toxins being treated, and can be readily determined by persons skilled in the art.

To prevent break-through of un-oxidized toxins upon start-up of the apparatus, the oxidation catalyst in the catalyst chamber must be heated very rapidly to so-called 'light off' temperature at which combustion of the toxins will commence. Thus, the catalyst chamber also is provided with a heating element. At the same time, the catalyst temperatures should be maintained as low as possible, while still achieving effective combustion of combustible materials released by the adsorbent, in order to minimize the cooling required to bring the decontaminated breathing air to breathable temperatures. Thus, it is important to use of oxidation catalysts which are effective at low temperatures. Although the oxidation of the toxic substances in the catalyst is exothermic, little heat is produced due to the fact that the toxins are almost always present in very dilute concentrations. Preferred catalyst exhaust temperatures lie in the range from about 40° C to about 80°C.

To cool the air discharged from the catalyst chamber to an acceptable breathing temperature, a heat exchanger is provided. The heat exchanger may be one designed to transfer excess heat to the ambient atmosphere, or it may be a counterflow heat exchanger which transfers excess heat to the incoming air stream before it enters the heating chamber. The decontaminated air is discharged from the heat exchanger at an acceptable breathing temperature, which preferably will not exceed normal body temperature of 37°C, although temperatures up to 40°C may be experienced for limited periods of time without serious consequences. It is preferred that the decontaminated air be cooled to a temperature of at most 30°C, and for reasons of comfort, to a temperature of at most 25°C.

As an extra measure of security, it is optionally possible to include a conventional adsorbent filter between the outlet of the heat exchanger and the breathing mask or the inlet to the safety chamber. For example a conventional active carbon filter could be used. The service life of such a filter should be extremely long, since all or virtually all of the toxins which might be adsorbed thereby are destroyed before the reach the filter.

If desired, a particle filter may also be interposed between the outlet of the heat exchanger and the breathing mask or inlet to the safety chamber to remove any dust or entrained particles.

Heating of the individual chambers may be effected by conventional electric heating elements operated with either DC or AC current. It is also possible to use heating elements which operate by induction. In additional microwave heating devices could be used, though they are most practical for larger units. Various types of heat exchange units can also be used as heating elements for the respective chambers of the apparatus of the invention. As used herein, the term heating element is intended to embrace all these alternatives, as well as others which might be used.

The pressure in each of the chambers is preferably positive relative to ambient pressure. This will assure that in case of any leaks, that toxic or pathogenic agents from the ambient surroundings cannot be introduced the into the decontaminated air stream.

Suitable low temperature oxidation catalysts for use in the invention include the noble metals, e.g., platinum, palladium, rhodium, osmium, iridium, ruthenium, gold, silver, etc. or alloys thereof, as well as oxides of various other metals such as copper, manganese, rhenium, chromium, nickel, cobalt and berillium and or mixtures thereof. If a single catalyst is used, it is preferably a noble metal or copper oxide or manganese dioxide. Given an appropriate particle size distribution and surface area and the availability of sufficient oxygen, such catalysts are capable of effecting catalytic oxidation at temperatures as low as about 40°C to about 80°C. Such low temperature catalytic oxidation of toxic contaminants greatly facilitates subsequent cooling of the decontaminated air to acceptable breathing temperatures.

The catalyst utilized in the tests reported herein was a platinum and palladium alloy catalyst disposed on a porous refractory alumina support. The alloy comprised from 5 to 20 wt.-% palladium and from 95 to 80 wt.-% platinum. The amount of catalyst was selected such that the resulting catalyst particles comprised 3% by weight of catalytic metal. Oxidation catalysts of this type are commercially available, for example, from the firm DODUCO GmbH & Co. of Sinsheim, Germany.

For reasons of economics and efficiency, it is advantageous to disperse the catalyst in a porous matrix. Any matrix material which is porous, thermally and chemically stable, and non-friable may be used. Examples include various known refractory clays and ceramic materials, especially, for example, based on aluminates and/or silicates. A particularly preferred catalyst matrix is a fire resistant refractory cement composed of a cold setting double salt of calcium and magnesium aluminates. A material of this type is available commercially under the trade name "Feuerfest Zement" from the firm Dickerhof of Wiesbaden, Germany. From 2 to 10 wt.-%, preferably 3 to 5 wt.-%, of the catalyst is mixed with the refractory cement, and the resulting mixture is then granulated to the desired particle size to assure good contact with gases in the breathing air as it passes through the bed of catalyst particles. The non-friable nature of the particles prevents particle break-down which would reduce the porosity and volume of the catalyst bed and lead to clogging and dust formation.

Oxidation may also be facilitated by inclusion of reversible oxygen donor materials in the catalyst matrix. If a refractory cement is utilized as a matrix, they may simply be mixed in with the cement before granulation. Examples of such materials include cerium oxide and zirconium oxide. These substances release oxygen when heated which can then oxidize toxic substances. The effect is a reduction in the temperature at which oxidation commences, the so-called 'light off temperature". At cooler temperatures, the oxides regenerate with oxygen from atmospheric air and are then available once more to assist initiation of catalytic oxidation when the apparatus is started up again.

Additional means of increasing catalytic oxidation efficiency include the use of ozone generators upstream of or in the catalytic zone. Examples include UV radiators such as UV chips sold by the firm Osram which emit short wavelength UV light of 2090 Angstroms and produce highly reactive ozone.

The adsorbents utilized in the invention are typically molecular sieves such as hydrophobic zeolites. Materials of this type exhibit a good combination of adsorbent properties and thermal stability at the desired operating temperatures. Such materials are known in the art and are widely used in gas chromatography applications. These materials produce a certain retention time and sequential desorption which facilitates efficient oxidation in the subsequent catalytic zone. The zeolites may be either natural or synthetic zeolites. Also, either normal zeolites or Y-zeolites may be used. Good results have been obtained with a hydrophobic zeolite having an average pore diameter of 0.8 nm and a surface area of 700 meters²/gram. Treatment of the adsorber surface in a known manner with silicone oils, high molecular weight poly waxes, apiezon waxes, liquid paraffins or other materials which increase hydrophobicity, may be advantageous. Suitable materials are available commercially, for example, under the trade names "Wessalith DAZ-F20" and Wessalith DAY-F20" from the firm Degussa AG of Hanau, Germany.

The use of an adsorber upstream of the oxidation catalyst provides a braking or leveling effect on the introduction of toxic substances to the oxidation catalyst, thereby minimizing the chance of break-throughs and improving the efficiency and effectiveness of the catalytic oxidation of the combustible substances. The leveling effect is enhanced by the presence of a an increasing temperature gradient in the adsorbent, which modulates the release of molecules from the adsorbent.

The volume of supported oxidation catalyst required will necessarily vary depending on the amount of breathing air to be decontaminated. For a breathing unit for a single individual capable of producing 7 to 10 liters of decontaminated breathing air per minute, a minimum volume (expressed in terms of packing volume) of about 10 ml of supported catalyst should be provided. It is preferred to utilize at least about 20 ml of supported catalyst. Larger units should be scaled up appropriately depending on the volume of decontaminated breathing air to be provided.

The volume of adsorbent is generally greater than the volume of the catalyst. Typically, the volume of the adsorbent required is approximately twice that of the catalyst. Thus, for a breathing unit for a single individual, it is preferred to use about 20 ml of adsorbent (expressed in terms of packing volume), and it is particularly preferred to use approximately 40 ml of the adsorbent. Again, the adsorbent volume should be scaled up depending on the total volume of decontaminated breathing air to be provided.

The contents of the adsorbent and catalyst containing chambers may be in granular form or stable layers cast onto metal plates.

A particularly preferred embodiment of the apparatus and process of the invention is its adaptation for use in gas masks or protection of restricted areas from contamination.

According to one preferred embodiment of the present invention, the adsorbent layers and catalyst layers with the electrical heating are housed in the same container, thereby ensuring better utilization of heat energy.

According to another preferred embodiment of the invention a second, identical adsorber/catalyst module is provided which can be used in alternation with the first module so that one can be regenerated when the other is in use, and continuous operation can be maintained for an extended period of time. The regeneration process is carried out using higher temperatures so that the adsorbents and catalysts are reactivated and completely sterilized. The alternation of modules between gas purification and regeneration modes of operation is suitable for electronic automation.

In accordance with another preferred embodiment of the invention the processed breathing air, before it is inhaled, is passed through a cartridge filter unit comprised of a zeolite mixed with synthetic fibers.

In a preferred embodiment, the invention relates to a modular respiration air purification apparatus which is adapted for mass production in any desired size and volume.

A suitable respiratory air protective apparatus must be able to provide a sufficient amount of breathable air. In the case of humans, the most important parameters of the respiration process are:

1. Lung volume (total capacity) 6 liters.

2. Vital capacity 4.8 liters.

3. Inspiration/Expiration volume 0.5 liters at a freqency of 14 per minute

4. Gas exchange value for inspired oxygen 0.28 liters per minute.

5. Gas exchange value for expired carbon dioxide 0.23 liters per minute. 6. Contact time with lung surface 0.3 seconds.

(See Thews et al., Anatomie Physiologie Pathophysiologie des Menschens; WVG Verlag, Stuttgart, 1980, Page 301). Based on these parameters, a person skilled in the art can readily design a system suitable to provide decontaminated breathing air for any number of people ranging from a single individual to a large group.

In accordance with a further aspect of the invention, the objects are achieved by providing a process for decontaminating contaminated breathing air comprising the steps of introducing contaminated air into a first chamber of a multi-chamber module electrically heated to a temperature sufficient to kill pathogenic organisms; conveying heated air from said first chamber to a second heated chamber of said module containing an adsorbent which adsorbs organic substances; and conveying air from said second chamber to a third heated chamber of said module containing a catalyst selected from the group consisting of noble metals, copper, manganese and mixtures thereof, which catalytically oxidizes organic substances at a temperature of at most about 100°C, whereby toxic substances and pathogenic organisms in the air are destroyed.

In a preferred aspect of the invention, a plurality of air decontamination modules are used, and the modules are cycled between decontamination and regeneration stages. Regeneration is effected by passing heated air at a temperature of at least 180°C, preferably about 200°C, for at least 15 minutes, preferably 20 minutes, and particularly preferably 30 minutes. Importantly, the air utilized for the regeneration is exhaled air from the individual respirator or safety chamber. Use of exhaled air for regeneration assures that the regeneration air is free of contamination by toxic substances and/or pathogenic organisms which may be present in the ambient air. The regeneration air may be heated by the same heating element used to heat the heating chamber, produce a temperature gradient in the adsorbent, and heat the catalyst to the light off temperature. Regeneration air may be passed through the apparatus in either the same direction as air to be decontaminated or in the reverse direction. It is preferable, however, to pass the regeneration air through the apparatus in the same direction as the air to be decontaminated as this simplifies the switching arrangements required to switch the modules between active use for decontaminating breathing air and regeneration.

The present invention further relates to processes for producing adsorbent and catalyst materials needed for the apparatus and process of the invention.

The apparatus and process of the invention, which use a combination of thermal inactivation and catalytic oxidation to simultaneously decompose both toxic substances and pathogenic organisms, have a number of advantages. They do not rely on adsorption or filtration, but instead actually destroy the contaminants in a reliable and highly efficient manner. They are capable of simultaneously destroying a wide range of contaminants including both toxic gases, volatile organic compounds, bacteria, viruses, fungi and spores. They are infinitely flexible and adaptable since the size and capacity can be adjusted to match the need, making them suitable for providing decontaminated breathing air for mobile units such as individual air purification respirators or vehicles such as automobiles or buses, or for stationary units such as ventilation devices for individual shelter rooms or entire buildings. They include an intrinsic self-cleaning mechanism which uses a self-contained, sequential adsorption/desorption system. They avoid worry about the need for replacement cartridges or canisters, since the regenerable modules can be re-used continuously without worry about the availability of replacement components. Thus, the apparatus and process can provide consistent, continual protection for significantly longer periods of time than conventional devices without compromising efficiency or increasing breathing resistance. They are highly cost-efficient, since the lack of need to replace cartridges or canisters also translates into significant cost savings for the user. Moreover, the apparatus and process are environmentally friendly because they decompose the contaminants so that toxic or pathogenic substances do not accumulate in any part of the apparatus as occurs in traditional filtration or adsorption systems. Consequently there is no need for concern about disposal of hazardous waste. Another advantage of the apparatus and process of the invention is that they enable simultaneous regeneration of used units without any need of disposal or additional disinfection or used units or procurement of new replacement units. A still further advantage of the apparatus and process of the invention is that they are capable of being electronically automated by suitable programs or carried out manually, if desired.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in further detail hereinafter with reference to illustrative preferred embodiments shown in the accompanying drawing figures, in which:

Figure 1 is a schematic representation of a first apparatus according to the invention for decontaminating breathing air from toxic substances and pathogenic organisms;

Figures 2a through 2d are schematic representations of alternative purification module arrangements;

Figure 3 is a schematic illustration of an arrangement of comprising a plurality of gas purification modules;

Figure 4 is a schematic illustration of a portable gas mask unit with dual treatment modules arranged to facilitate simultaneous gas treatment and module regeneration; and

Figure 5 is a schematic illustration of a treatment apparatus designed for use with a safety shelter.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Figure 1 shows the construction of a basic working unit or module which adsorbs, sequentially desorbs, and catalytically oxidizes a large number of organic compounds. This basic module comprises a lower empty chamber and two overlying chambers containing the adsorbent and catalyst placed one above the other in a single housing. Thus, as shown, the apparatus comprises three interconnected chambers. The means for electrically heating each of the chamber are also shown. The parts of the device are identified as follows:

(A) Container with adsorbent.

(B) Electrical heating coil.

(C) Air pump inlet tubes for contaminated air.

(D) Outlet tube from container with catalyst.

(E) Container with catalyst.

(F) Electrical heating coil.

(G) Metal sieve separator with supporting ring. (H) Insulating porcelain beads.

(I) Common negative ground connection to container wall. (J) Stainless steel wool plug. (K) Empty chamber.

The lowest chamber with two inlets ensures an impingement and hence combustion of any solid particles including microbiological contaminants by the red hot surface of the bare electrical heating coils. Furthermore, a dry heat sterilization of microbiological contaminants of the polluted air also takes place. As a result, after passage through the whole device, a complete sterilization is accomplished. The elevated combustion temperatures and accompanying exposure to dry heat lead to 100 % kill of living bacteria, spores or viruses. All the modules used contain identical electrically heated lower chambers.

The next chamber of the module contains a mixture of adsorbents which due to the heat gradient of the chamber produces a sequential chromatographic separation of classes of organic compounds which subsequently flow into the third chamber. The third chamber contains the electrically heated catalyst in highly porous form, which completes the oxidation of any heretofore un-oxidized organic substances.

The resulting purified gas stream, which has a temperature of about 100°C as it leaves the catalyst bed, is diverted to the lower part of the device thereby loosing to a large extent its temperature. By using a suitable heat exchanger the air stream temperature can be brought to below 37° C, preferably below 30°C, and particularly preferably below 25°C, before it is conducted to the breathing mask connection. Each module can be built in any size and volume to suit stationary or mobile use.

Figures 2a through 2d depict examples of alternative breathing air purifying module arrangements according to the invention in which a plurality of chambers containing different types of adsorber granules and/or different catalyst granules are connected to ensure higher efficiency for total oxidation of contaminants. The parts are identified as follows:

(A) Catalyst based on noble metals (Platinum group metal, etc).

(B) Hydrophobic zeolite adsorber

(C) Zeolite adsorber with molecular sieve effect coated with silicone oil.

(D) Catalyst composed of copper and/or manganese.

Each layer is provided with separate electrical heating elements. The heating element at the inlet in all cases is meant to destroy the majority of spores and bacteria which would be completely removed after passage through other layers. Figure 2a shows a device in which the initial air heating chamber (empty chamber) is followed by a second chamber containing a noble metal catalyst on a granular substrate, a third chamber containing zeolite adsorber granules with a molecular sieve effect coated with silicone oil, and a fourth chamber containing a further noble metal oxidation catalyst on a granular catalyst substrate. Figure 2b shows an alternative arrangement in which the air heating chamber is followed by a second chamber containing a granular zeolite molecular sieve adsorbent, a third chamber containing a noble metal oxidization catalyst, and a fourth chamber containing a further molecular sieve adsorbent. Figure 2c shows a further alternative arrangement in which the air heating chamber is followed by a second chamber containing a granular zeolite molecular sieve adsorbent, a third chamber containing a further zeolite adsorbent, and a fourth chamber containing the noble metal oxidization catalyst. Figure 2d shows a five chamber arrangement in which the empty first chamber is followed in succession by a second chamber containing the granular zeolite molecular sieve adsorbent, a third chamber containing a further zeolite adsorbent, a fourth chamber containing an oxidation catalyst of copper and manganese, and a fifth chamber containing the noble metal oxidation catalyst. The five chamber arrangement with two adsorber beds and two oxidation catalyst beds provides additional security against breakthrough of toxic substances.

The apparatus configuration shown in Figure 2a provides an initial catalyst chamber A in which a large portion of any toxic substances are oxidized before they pass to the adsorbent chamber B. This prevents overloading of the adsorbent in the event there is a relatively high concentration of toxic substances in the air to be treated. This also helps to assure that the second catalyst zone A will be able to completely destroy any remaining toxins.

The apparatus configuration shown in Figure 2b includes a second adsorber zone B following the catalyst zone A. This configuration of device is particularly suitable as a pre-treatment stage before a further catalytic oxidation module, as illustrated, for example, by module 1 in Figure 3.

The apparatus configuration shown in Figure 2c includes plural catalyst zones to assure complete oxidative destruction of toxins. The first catalyst zone C, following adsorber zone B, contains a mixture of adsorbent zeolite particles and catalyst particles containing, for example, a copper oxide oxidation catalyst, which effects an initial oxidation. Any toxins which escape the catalyst zone C, are eliminated by the, for example, noble metal catalyst in the subsequent second catalyst zone A.

The apparatus configuration depicted in Figure 2d is similar to that in Figure 2c, except that a further catalyst zone D containing, for example, a copper oxide or manganese dioxide oxidation catalyst is provided between the mixed adsorbent and oxidation catalyst zone C and the final or polish catalyst zone A in order to provide a further assurance that all toxic substances present in the initial air stream are completely destroyed by oxidation. Figure 3 is a schematic representation of an air decontamination unit with full regeneration and sterilization for continuous use. A particularly preferred embodiment incorporates a minimum of three modules. Figure 3 schematically depicts a system using three modules for mobile use as a personal protection mask. This arrangement has the capacity for full regeneration and sterilization for continuous use. At the outset of operation, the pump 1 and the electrical heating of all modules are switched on, and modules 1 and 2 are connected to each other in series by appropriate switching of the valves identified by numerals 1 to 9. The first module 1 is in permanently in working mode as it performs the function of a pre-filter to protect the aspiration diaphragm pump from contamination as well as achieve quite a sizeable cleaning of the polluted air. The partially cleaned air passes next to the second module through suitable manually or electromagnetically operated gas valves.

The outlet of module 2 is connected to the air inlet of illustrated full gas mask. The second module is similar to the first and completely eliminates all remaining contaminants of the breathing air. The air is thereafter cooled to body temperature or below in a heat exchanger and then conveyed to the inlet of a suitable half or full gas mask or to the inlet vent of a shelter room.

At the same time, pump 2 and the heaters for module 3 are started, and module 3 is connected for separate regeneration by switching the valves so that exhaled air from the gas mask can be heated and used to flush out the module. The use of exhaled air from the mask solves the problem of obtaining a contaminant free gas stream for the regeneration step. As module 2 approaches the predetermined time limit of safe and effective operation, the valves are switched to connect the now fully regenerated and sterilized module 3 to the gas mask inlet and to subject the used module 2 to regeneration.

All aspects of the regeneration process, including the heating temperature, the duration of heating and the operation of the valves, can be controlled by an electronic circuit that follows a definite sequence to open and close electromagnetically actuated gas valves to switch the gas flows and intermittently heat the modules containing catalysts and adsorbers in order to regenerate them. The sequence can be simplified when manual operation is required.

The apparatus delivers a greater volume of cleaned air than is required for respiration by the users so that excess clean air is provided. This excess of clean air plus expired air exhaled by the users leaves the mask or room through a suitable valve and is conveyed by another membrane pump as a decontaminated flush gas to a previously used third module which is being fully regenerated and disinfected. When the regeneration of the third module is complete, it can be substituted for one of the other modules by appropriate switching of the valves on the connecting lines and re-used while the module it replaced is regenerated. The regeneration is always carried out using clean air to flush out any contaminants trapped in the module being regenerated. Since the amounts of poisonous organic substances present in intentionally contaminated air are generally quite small, the amount of carbon dioxide formed by catalytic oxidation is negligible. Further since the adsorption and catalytic oxidation take place in two identical modules connected in series, a virtually 100% effective oxidation can be achieved, the more so because the amount of contaminants is much less than that in the exhaust gases from an automobile.

Figure 4 and Figure 5 show block diagrams of the elements of respiration air purifying systems for gas masks and/or safety shelters, respectively. Figure 4 is a schematic illustration of an apparatus and connections for a continuously usable gas mask. The parts of this device are identified as follows:

(A) Unit in use with electric heating of chambers for adsorbent and catalyst.

(B) Unit in reserve identical to (A).

(C) Electronic control unit for temperature regulation of adsorber chamber and catalyst chamber, automatic valve control for connection to reserve unit, automatic pre-set switching to higher temperature needed for re activation of used unit after a definite time period of use. (D) Main inlet air pump for contaminated air feed to unit in use (A) or reserve unit (B) and also to heat exchanger (E) which cools processed clean air before entry into conventional gas mask (F) with charcoal filter (G). (H) Separate air pump for regeneration.

The apparatus of Figure 4 operates as follows. The main pump (D) for contaminated air is connected to unit (A) and the electronic control (C) regulates the process so that cleaned air is fed to the mask in slight excess. After a predetermined time the unit (B) is connected instead of unit (A) by means of the automatic program of control unit (C) which actuates the required magnetic valves. The unit (A) is also automatically connected to regeneration pump (H) which pumps not the contaminated air but the exhaled pure air leaving the mask to the unit (A). The regeneration temperature is automatically set to 250°C. At this temperature the adsorbent desorbs all organic substances held by it, and becomes reactivated. Simultaneously, any viable bacteria, viruses, fungi or spores are killed, and the effluent gas leaving the unit (A) into the atmosphere after re-activation does not contain any contaminants.

While the apparatus of the invention has been described above in terms of an individually wearable system for personal protection, a similar, somewhat larger scale system is suitable to provide decontaminated respiration air for safety shelters, or so-called bomb shelters. The apparatus according to the invention could also be used to provide decontaminated breathing air to individuals traveling in passenger compartments of cars, buses, trains, boats, aircraft or other vehicles. Figure 5 depicts an apparatus according to the invention designed for continuous use in a small safety shelter compartment. Depending on the size of the unit any volume of contaminated air can be purified. The electronic control (A) for heating unit in use (B) and also the necessary sequence of valve action for unit to be regenerated (C) is essentially the same as that described in Figure 4. The capacity of the air pump should be selected to be sufficient to ensure a positive pressure inside the chamber at all times. A positive pressure will prevent infiltration in case there is a leak in the chamber.

Further details of the invention will become apparent from a consideration of the following examples, which are intended to be illustrative in nature and not limiting on the scope of the invention:

Example 1

A prototype apparatus corresponding to the embodiment of Figure 1 was constructed suitable for mobile use with a gas mask and capable of supplying 10 liters of breathing air per minute was constructed according to the following specifications:

1) Diameter of copper housing for chamber with catalyst granules (E), chamber with adsorber granules (A), and chamber (K): 2.5 cm.

2) Length of catalyst chamber (E): 3.5 cm

3) Length of adsorber chamber (A): 6 cm

4) Length of air chamber (K) with electrical heating coil (B): 2 cm.

5) Total length of combined chambers: 11.5 cm

6) Internal diameter of copper tubing of inlet and outlet: 0.3 cm

7) Wall thickness of chamber and tubing: 0.15 cm

8) Power supply: rechargeable 12 Volt DC accumulator

9) Electric resistance of heating coil for adsorber chamber (A): 1.3 Ohm

10) Electric resistance of heating coil for chamber (K): 1.0 Ohm

11) Insulation beads (H) of porcelain, diameter: 0.4 cm

12) Pump maximum capacity: 12 liters/minute

13) Voltage of electric motor: 12 V DC

14) Metal sieve and separator with support ring (G)

15) Steel wool filter plugs (J) for inlet and outlet ports.

As can be seen from Example 5 below, based on the values for normal inhaled air volume (vital capacity), this example unit proved to be effective in purifying artificial samples of air contaminated with definite amounts of mixtures of several types of aliphatic, aromatic and nitrogenous organic compounds, and definite volumes of Aspergillus niger spores. Example 2

A test was carried out to determine the effectiveness of the apparatus of the invention to destroy organic molecules. A 50 liter gas vessel was filled with a synthetic air mixture and 50 μl aliquots of methylethylketone, methylcyclohexane, toluene and cyclohexanol were injected through a septum into the air mixture with 100 μl hypodermic needles. The resulting composition was allowed to equilibrate, and then the concentrations of the organic compounds in the resulting gas mixture were determined by withdrawing samples through the septum and also at the outlet valve.

For Test 1, the gas pump of the test apparatus was switched on, and the volume flow was set to 30 liters per hour. The outlet of the gas vessel containing the test mixture was connected to the inlet of the test apparatus, and the apparatus was flushed with the doped test air for one minute. Then a one liter gas collecting vessel was connected to the outlet of the apparatus and filled completely with the air stream discharged by the apparatus.

Test 2 was carried out in the same way as Test 1, except that the catalyst was electrically heated to a temperature of 37°C before the commencement of the test.

Test 3 was carried out in an analogous manner except that the catalyst was electrically heated to a temperature of 50°C before commencement of the test.

Test 4 was also carried out in an analogous manner, except that the catalyst was heated to a temperature of 80°C.

As a control, the laboratory air also was tested.

Each collected sample was analyzed as follows. An aliquot of each gas sample was introduced into a 20 ml septum glass and equilibrated in the head space auto sampler for 45 minutes at 75° C. An aliquot of the resulting gas mixture was subsequently analyzed by gas chromatography under the following measurement conditions: the capillary column was an Rtx-volatile(EPA624) having a length of 30 meters, an inside diameter of 0.32 mm and an FD of 1.5 μm. The carrier gas was helium 5.0 at a pressure of 0.5 bar. Injections were effected automatically 3mL, split 1:50 at 250°C. The temperature program was three minutes at 40° C, then increased at a rate of 10°C per minute up to 90°C, where the temperature was maintained for two minutes. Afterward, the temperature was increased at 20°C per minute up to 260°C, where it was maintained for 30 minutes. The mass selective detector was an HP 5970 and the mass range was SIN. The concentrations of methylethylketone, methylcyclohexane, toluene and cyclohexanol were determined by external calibration via injection of standard mixtures.

Column retention times for the four tested organic substances were as follows:

Methylethylketone 4.11 minutes

Methylcyclohexanol 7.29 minutes

Toluene 9.16 minutes

Cyclohexanol 12.92 minutes.

Results of the tests are shown in the following table.

The results showed that the concentrations of the test compounds in the air samples were reduced by factors ranging from about 50 to about 3,000, thereby establishing that the apparatus of the invention destroyed the organic compounds in the test air sample almost completely and was effective to reduce the concentration of the test substances to tolerable breathing levels. Moreover, it is apparent that the effectiveness of the apparatus increases with increasing catalyst temperature.

Example 3

Granular adsorbents were prepared by mixing a commercially available powdered alumina substrate material sold under the trade name Wessalyth DAY (Degussa, Hanau, Germany) with different percentages of powdered molecular sieve zeolites. The resulting mixture was then mixed with a cold setting double salt of calcium and magnesium aluminate, and after addition of water, the mass was granulated. The granules were dried and conditioned in moist atmosphere till fully set.

Example 4

Catalysts based on noble metals, copper and/or manganese, were manufactured by mixing a commercially available product containing about 3 percent metal dispersed in aluminum oxide with a cold setting double salt of calcium and magnesium aluminate and then granulating the resulting mixture by known techniques.

As an alternative to granulation, the mixtures of zeolite or metal powder and cold setting double salt may be applied to the surfaces of respective metal supports, such as metal grids, and then dried to form coated layers on the metal support surfaces.

Example 5

The prototype of example 1 was subjected to a simple preliminary effectiveness test under simulated conditions using as sample a container containing one cubic meter of air contaminated with the following:

1) Pyridine (lmg )

2) Aliphatic C2 to CIO straight chain hydrocarbon mixture (5 mg)

3) Aromatic C6 to C14 hydrocarbon mixture (5 mg)

4) Spore suspension of Aspergillus niger sufficient to give an agar plate count of 1000 spores per liter of air.

After passage through the apparatus, the air was analyzed by gas chromatography and found to be totally free of organic substances, thereby indicating that aliphatic, aromatic and nitrogen-containing compounds were totally destroyed by the apparatus. The air stream was also impinged against a suitable microorganism culture medium, which after subsequent incubation for 72 hours showed no evidence of microorganism growth, thereby indicating that the air stream was completely sterilized. These test results demonstrate the effectiveness of the apparatus of the invention in personal protection devices which provide a high margin of safety in case of sudden exposure to toxic gases and/or pathogens.

The foregoing description and examples have been set forth merely to illustrate the invention and are not intended to be limiting. Since modifications of the described embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed broadly to include all variations within the scope of the appended claims and equivalents thereof.

Claims

WHAT IS CLAIMED IS:

1. An apparatus for simultaneously decontaminating breathing air from organic contaminants and microbial contamination, said apparatus comprising:

- an air heating chamber having an air heating means and at least one air inlet port;

- at least one adsorbent layer of porous material with adsorbent capacity for organic substances and a molecular sieve effect, and means for heating said adsorbent layer; and

- at least one layer of oxidizing catalyst capable of oxidizing aliphatic and aromatic organic compounds and nitrogenous aliphatic or aromatic organic compounds, and means for heating said oxidizing catalyst; wherein the adsorbent material comprises a low aluminum content, hydrophobic zeolite having a molecular sieve effect with high adsorption at normal operating temperatures and short retention times at higher temperatures, and the oxidizing catalyst is selected from the group consisting of noble metals, copper, manganese and mixtures thereof.

2. An apparatus according to claim 1, wherein the air heating chamber has at least two air inlet ports.

3. An apparatus according to claim 1, wherein the air heating means comprises an electrical heating means.

4. An apparatus according to claim 1, wherein the means for heating the adsorbent and the oxidizing catalyst each comprise an electrical heating element.

5. An apparatus according to claim 1, wherein the oxidizing catalyst comprises a first oxidizing catalyst for oxidizing aliphatic and aromatic organic compounds and a second oxidizing catalyst for oxidizing sulfurous or nitrogenous aliphatic or aromatic organic compounds.

6. An apparatus according to claim 5, wherein the first oxidizing catalyst comprises a noble metal catalyst and the second oxidizing catalyst comprises a copper or manganese catalyst.

7. An apparatus according to claim 3, wherein contaminated air introduced into said first chamber impinges directly onto a heating element of said electrical heating means, whereby any pathogenic organisms are killed by incineration.

8. An apparatus according to claim 1, wherein the means for heating the oxidizing catalyst heats the catalyst to a temperature at which organic compounds contacting the catalyst are immediately oxidized.

9. An apparatus according to claim 1, wherein the adsorbent layer comprises a mixture of adsorbents, and the catalyst layer comprises a mixture of catalysts.

10. An apparatus according to claim 1, wherein the air stream is made to pass first through an adsorbent layer containing a mixture of adsorbents and thereafter through a catalyst layer containing heated mixed catalysts.

11. An apparatus according to claim 1, wherein the air stream is made to pass first through an initial oxidation catalyst layer, then through an adsorbent layer, and thereafter through a further catalyst layer.

12. An apparatus according to claim 1, wherein said apparatus is constructed as an exchangeable modular unit comprising at least three chambers, with a first chamber being the air heating chamber, a subsequent chamber containing the adsorbent, and another subsequent chamber containing the catalyst.

13. An apparatus according to claim 12, wherein after a predetermined period of use, a second modular unit is substituted for the used one, and the used modular unit is purged with a clean stream of exhaled air at high temperature to regenerate and sterilize the adsorbent and reactivate the catalyst.

14. An apparatus according to claim 1, wherein the adsorbent material is a granulate comprising hydrophobic synthetic or natural zeolite having a minimum surface area of 0.1 square centimeter.

15. An apparatus according to claim 14, wherein the zeolite is coated with silicone oil.

16. An apparatus according to claim 14, wherein the granulate is obtained by mixing the zeolite in powder form with a cold setting double salt of calcium and magnesium aluminate and thereafter granulating the mixture.

17. An apparatus according to claim 1, wherein the catalyst is a granular catalyst obtained by mixing a finely powdered noble metal or copper oxide or manganese dioxide with powdered aluminium oxide and a cold setting double salt of calcium and magnesium aluminate, and granulating the resulting mixture into hard, porous, temperature-resistant granules.

18. An apparatus according to claim 3, wherein the electrical heating means for heating the adsorbent produce an increasing temperature gradient, whereby better sterilization and desorption of adsorbed organic substances in sequence is achieved.

19. An apparatus according to claim 1, further comprising a heat exchanger for cooling decontaminated air prior to exiting the apparatus.

20. An apparatus according to claim 19, wherein the decontaminated air is cooled to body temperature or below prior to exiting the apparatus.

21. An apparatus according to claim 1, further comprising a filter for filtering decontaminated air prior to exiting the apparatus.

22. An apparatus according to claim 21, wherein said filter comprises an activated charcoal and cotton fiber filter pad.

23. An apparatus according to claim 1, wherein said catalyst is admixed with a reversible oxygen donor substance.

24. An apparatus according to claim 1, wherein the heating means comprise an induction heating means.

25. A process for decontaminating contaminated air to make it suitable for breathing comprising the steps of:

- introducing contaminated air into a first chamber of a multi-chamber module heated to a temperature sufficient to kill pathogenic organisms;

- conveying heated air from said first chamber to a second heated chamber of said module containing an adsorbent which adsorbs organic substances; and

- conveying air from said second chamber to a third heated chamber of said module containing a catalyst selected from the group consisting of noble metals, copper, manganese and mixtures thereof, which catalytically oxidizes organic substances at a temperature of at most about 100°C, whereby toxic substances and pathogenic organisms in the air are destroyed.

26. A process according to claim 25, further comprising passing the air from the third chamber to a heat exchanger and subjecting the air to heat exchange to cool the air to a temperature of at most 37°C.

27. A process according to claim 26, wherein the air is cooled to a temperature of at most 30°C.

28. A process according to claim 27, wherein the air is cooled to a temperature of at most 25°C.

29. A process according to claim 25, wherein after a predetermined period of use, a second module is substituted for the used one, and the used module is purged with a clean stream of exhaled air at high temperature to regenerate and sterilize the adsorbent and reactivate the catalyst.

30. A process according to claim 25, further comprising passing heated exhaust air through a second three chamber air purifying module to regenerate the catalyst and adsorbent material, and periodically switching the modules between air purification and regeneration modes of operation.

31. A process according to claim 25, wherein the heated air from the first chamber is first subjected to a catalytic oxidation treatment before being conveyed to the adsorbent-containing chamber.