The present invention relates generally to the use of chlorine dioxide gas for various treatments such as deodorizing, sanitizing, decontaminating, sterilizing, bleaching, disinfecting and the like, and more particularly to apparatus for generating chlorine dioxide gas and to methods for using such apparatus to treat biologically contaminated surfaces and articles.
The use of gas, and more particularly chlorine dioxide gas, as a sterilizing agent, e.g., as a bactericide, viricide and sporicide, is known. For example, U.S. Pat. Nos. 4,504,442 and 4,681,739 to Rosenblatt et al. disclose the use of chlorine dioxide gas as a chemosterilizing agent. However, due the instability of chlorine dioxide as well as inherent handling difficulties associated with chlorine dioxide, apparatus used to generate chlorine dioxide gas is typically limited to fixed equipment such as a gas generator and corresponding gas chamber in which articles to be sterilized are placed. That is, reaction components which, when mixed together, produce chlorine dioxide gas must be maintained separate until gas production is desired.
As a result, articles to be sterilized must be transported to the location of the sterilizing chamber or, where a room is to be sterilized, an elaborate and costly gas producing apparatus must be transported and erected within such a room. There is a need, therefore, for apparatus for producing chlorine dioxide gas which can be readily transported to a remote site of contaminated articles, or to a contaminated room, and quickly activated to produce chlorine dioxide gas in a sufficient concentration to serve as a treating agent.
In general, apparatus according to one embodiment of the present invention for producing chlorine dioxide gas comprises a first reaction component and a second reaction component. The first and second reaction components are separated by at least one rupturable membrane constructed of glass. Upon rupturing of the at least one membrane the first and second reaction components contact each other to form a reaction in which chlorine dioxide gas is produced within the apparatus. The apparatus is also adapted for exhausting the chlorine dioxide gas therefrom.
In another embodiment, apparatus for producing chlorine dioxide gas generally comprises a first container having an outer wall and an interior space defined by the outer wall. A first reaction component is disposed in the interior space of the first container and comprises one of a chlorite source and at least one of an oxidizing agent and an acid releasing agent. A second container has an outer wall and an interior space defined by the outer wall. The first container is disposed at least partially within the interior space of the second container. A second reaction component is disposed within the interior space of the second container and unconfined against movement therein. The second reaction component comprises the other one of the chlorite source and the at least one of the oxidizing agent and the acid releasing agent. The outer wall of the first container is rupturable to permit direct contact between the first reaction component and the second reaction component upon rupturing the first container to form a reaction in which chlorine dioxide gas is produced within the second container. The second container is adapted for exhausting the chlorine dioxide gas therefrom.
In yet another embodiment, apparatus for producing chlorine dioxide gas generally comprises a first container having an outer wall and an interior space defined by the outer wall. A first reaction component is disposed in the interior space of the first container. A tubular second container has an outer wall and an interior space defined by the outer wall. The first container is disposed at least partially within the interior space of the second container. A second reaction component is disposed within the interior space of the second container, with the outer wall of the first container being rupturable to permit contact between the first reaction component and the second reaction component upon rupturing the first container outer wall to form a reaction in which chlorine dioxide gas is produced within the second container. The second container is adapted for exhausting the chlorine dioxide gas therefrom.
One embodiment of a method of the present invention for treating at least one article contained within an enclosure generally comprises activating a chlorine dioxide producing apparatus to produce chlorine dioxide gas. The chlorine dioxide gas producing apparatus comprises a first reaction component contained therein and a second reaction component contained therein. The first and second reaction components are separated within the apparatus by at least one rupturable membrane constructed of glass. The step of activating the apparatus thus comprises rupturing the at least one membrane to permit contact between the first and second reaction components to facilitate a chemical reaction therebetween which produces chlorine dioxide gas within the apparatus. The apparatus is adapted for releasing chlorine dioxide gas produced therein. The apparatus is placed into the enclosure and the enclosure is closed to permit a concentration of chloride dioxide gas produced by the apparatus sufficient to treat the at least one article to fill the enclosure.
In another embodiment a method for treating postal articles generally comprises placing at least one postal article in a bag and activating a chlorine dioxide producing apparatus to generate chlorine dioxide gas. The chlorine dioxide producing apparatus is placed in the bag and the bag is closed such that a concentration of chlorine dioxide gas sufficient to treat the at least one postal article fills the bag.
Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.
The apparatus of the present invention for producing and releasing chlorine dioxide gas (e.g., ClO2) for use as a treating agent, such as for deodorizing, sanitizing, decontaminating, sterilizing, bleaching, disinfecting and the like, relies on the separate containment of two or more reactive components during transport to a remote location, followed by activation of the apparatus to permit chemically reactive mixing of the components to form a reaction in which a chlorine dioxide gas is produced and released from apparatus. The reactive components may be any combination of reactants capable of reacting to form chlorine dioxide gas.
Chlorine dioxide gas may be produced by mixing a first reaction component such as an acid releasing agent, an oxidizing agent or a mixture thereof with a second reaction component comprising a source of chlorite anions to form chlorine dioxide by acidification and/or oxidation of the chlorite source. For example, chlorine dioxide gas may be produced by the acidification of sodium chlorite (e.g., NaClO2) according to the following reaction:
i. 4H++5NaClO2→4ClO2+2H2O+5Na++Cl− Eq. 1
or by the oxidation of sodium chlorite by persulfate, according to the following reaction:
ii. 2NaClO2+NaS2O8→2ClO2+2Na2SO4 Eq. 2
Suitable chlorite sources include, for example, alkali metal chlorites such as sodium chlorite or potassium chlorite, alkaline-earth metal chlorites such as calcium chlorite, or chlorite salts of a transition metal ion or a protonated primary, secondary, tertiary or quaternary amine such as ammonium chlorite, trialkylammonium chlorite and quarternary ammonium chlorite.
The acid releasing agent may be any acid or substance that can be hydrolyzed to an acid which is capable of reacting with the chlorite source to form chlorine dioxide. Suitable acid releasing agents include, for example, carboxylic acids, anyhydrides, acyl halides, phosphoric acid, phosphate esters, trialkylsilyl phosphate esters, dialkyl phosphates, poly phosphates, condensed phosphates, sulfonic acid, sulfonic acid esters, sulfonic acid chlorides, phosphosilicates, phosphosilicic anhydrides, carboxylates of poly α-hydroxy alcohols such as sorbitan monostearate or sorbitol monostearate, phophosiloxanes, hydrochloric acid, boric acid, citric acid, malic acid, tartaric acid, mineral acids and metal salts with sufficiently acid aqueous ions such as zinc, aluminum and iron. It is understood that other acid sources may be used, but is preferably selected to cause the mixture of reactants to have a pH equal to or less than about 5.5.
Suitable oxidizing agents are any oxidizing agent which is a stronger oxidation potential than the chlorite source such as, for example, persulfate, chlorine gas and the like.
The reaction components of the apparatus of the present invention may each be in the form of a gas, a liquid, or a solid, or a combination of gas, liquid and/or solid. For example, in one reaction according to Eq. 1, one reaction component is a liquid solution prepared from sodium chlorite solution and sodium silicate solution and the other reaction component is an acid, such as hydrochloric acid, in either a liquid or solid form. In another embodiment, such as in accordance with Eq. 2, one reaction component is a liquid solution of sodium chlorite and the other reaction component is a mixture of sodium persulfate (e.g., Na2S2O8) powder in a silica gel.
As will be described in further detail below, the reaction components are generally contained in separate chambers within the apparatus with a rupturable membrane therebetween for safe and convenient transport of the reaction components to a remote site. The chlorine dioxide gas is produced by rupturing the membrane to permit reactive mixing of the reaction components within the apparatus and is then released from the apparatus. The rate at which the chlorine dioxide gas is released from the apparatus is generally a function of the rate at which the reaction components mix within the apparatus, the rate at which the reaction to produce the chlorine dioxide gas occurs and the rate at which the particular construction of the apparatus permits the chlorine dioxide gas to be released therefrom. The concentration and amount of chlorine dioxide gas to be produced is generally a function of the concentration and quantity of the reaction components, the completeness of the reaction and the size of an enclosed area to be treated.
The rate at which the chlorine dioxide is produced and exhausted from the apparatus may be further affected by adding one or more adjuvant(s) to the first reaction component and/or the second reaction component. More precisely, by adding the appropriate adjuvant to the first and/or second reaction component(s), the rate at which the reactants are available to the reaction may be reduced thereby reducing the rate at which the chlorine dioxide gas is produced. This may also reduce the rate at which the chlorine dioxide gas is exhausted from the apparatus and inhibit liquid in the apparatus following mixing of the reaction components against spilling or otherwise leaking out of the apparatus. For example, one or more absorbent(s) may be added to either or both of the reaction components. The absorbent may reduce the rate at which the reaction occurs by simply diluting the concentration of the reactants and/or by absorbing one or more of the reactants thereby suppressing the rate at which the reactants contact each other by requiring one or both of the reactants to desorb from the absorbent prior to contacting the other reactant. In addition, an absorbent added to either reaction component may affect the rate at which the chlorine dioxide gas is evolved by causing the chlorine dioxide gas produced by the reaction to be partially or completely absorbed into the absorbent and then desorbed over time. Typical absorbents include zeolites, woven and non-woven and non-powdered polymers, natural fibers (e.g., cotton, sawdust or other cellulosic materials), and inorganic materials such glass wool and clays (including hydrophobic and hydrophillic clays.
Other diluents which do not absorb either the reaction components or chlorine dioxide gas product may be added to dilute the concentration of the reactants and therefore reduce the rate at which the reaction occurs. Typical diluents include water, silica gel, clays (including hydrophobic and hydrophillic clays), zeolites, metal oxides, carbides, nitrides and glass fibers.
Finally, the rate at which the chlorine dioxide gas is evolved may be increased by adding additional reactants to the first and/or second reaction component to cause the co-generation of one or more gaseous product(s) such as, for example, carbon dioxide or nitrogen which act as a propellant increasing the rate at which the chlorine dioxide gas evolves from the apparatus.
With reference now to the drawings, and in particular to
The second container 127 of the illustrated embodiment comprises a tube 135 having an inner diameter sized for receiving the ampule 131 therein, neck 133 end first, in generally sealing engagement with the tube to seal one end of the tube. The tube 135 is desirably flexible to permit bending thereof and is constructed of a generally gas and liquid impermeable material. For example, one preferred such material is polyvinyl chloride (PVC). An annular end cap 137 is fitted on the opposite end of the tube 135 and a closure 139 constructed of a gas permeable but liquid impermeable material is secured over a central opening 141 of the end cap. More particularly, the end cap 135 of the illustrated embodiment is constructed of glass and has exterior threads formed therein. The closure 139 is constructed of a single layer of a material available from Du Pont de Nemours of Wilmington, Del. under the tradename Tyvek® and is secured to the end cap 135 over the central opening 141 by an annular retaining ring 143 adapted for threaded engagement with the exterior threads of the end cap.
To construct the apparatus 121 of
In operation according to one method of the present invention for producing and releasing chlorine dioxide gas, the apparatus 121 is activated by flexing the tube 135 to apply a bending force to the ampule 131, thereby breaking the ampule at its neck 133. More broadly stated, the rupturable membrane (e.g., the wall of the first container 125) separating the first and second reaction chambers 125, 129 within the apparatus is ruptured. The operator then shakes the apparatus 121 to cause the reaction component in the ampule 131 to flow into the interior of the tube 135 for chemically reactive contact with the silica mixture. The solution is absorbed by the silica mixture, resulting in a semi-solid mixture which produces chlorine dioxide gas within the tube 135. Chlorine dioxide gas is exhausted from the apparatus 121 through the gas permeable closure 139. While the rate at which gas is exhausted from the apparatus 121 may be controlled by the gas permeability of the closure 139, the gas permeability of the closure 139 is desirably sufficient to allow gas to permeate therethrough at a rate substantially equal to or greater than the rate at which chlorine dioxide gas is produced within the tube 135. It is understood, however, that the gas permeability of the closure 139 may inhibit the exhaustion of gas from the tube 135 at the same or higher rate at which the gas is produced, as long as the tube, end cap 137, closure 139 and retaining ring 143 are sufficiently constructed and arranged to withstand the corresponding gas pressure build-up within the tube.
It is contemplated that the ampule 131 containing the first reaction component may be ruptured by mechanical stimuli other than bending, such as by applying compression (e.g., by squeezing the tube 135 and the ampule therein), pushing, pulling and/or shaking, by an ultrasonic stimuli, by an electromagnetic stimuli (e.g., electrical, infrared and the like), a thermal stimuli or other suitable stimuli for rupturing the ampule without departing from the scope of this invention.
To construct the apparatus 221 of this second embodiment, the ampule 231 is filled with a first reaction component, such as concentrated hydrochloric acid (liquid), and sealed. One end of the flexible tube 235 is closed, such as by being heat sealed, and the filled ampule 231 is inserted through the other, open end of the tube into the interior of the tube. A second reaction component, such as a solution prepared from equal parts of a sodium chlorite solution and a sodium silicate solution, is dispensed into the interior of the tube 235 and the open end of the tube is then closed, such as by being heat sealed, to fully enclose the filled ampule 231 and the second reaction component within the tube.
It is contemplated that the ampule 231 may be of any shape, such as ovate, spherical, etc., and may have narrowed and/or scored portions similar to the neck of the ampule shown in
In operation, the apparatus 221 is activated by bending the flexible tube 235 to apply a bending force to the ampule 231 to thereby rupture the ampule. More preferably, the tube 235 is bent repeatedly to cause several breaks along the length of the ampule 231. The apparatus 221 is then shaken vigorously to cause the first reaction component contained in the ampule 231 to mix with the second reaction component within the tube 235. The mixing results in a rapid precipitation of the silicate, leaving a generally solid mixture within the tube 235 whereby chlorine dioxide gas is produced as the mixture becomes acidic. The chlorine dioxide gas is exhausted from the apparatus 221 by diffusing out through the gas permeable wall of the tube.
In a third apparatus 321 of the present invention as shown in
A protective liner 353 surrounds the glass ampule 331 within the pouch 351 to protect the pouch against puncture by glass shards while rupturing the ampule. One preferred such protective liner 353 is constructed of a sheet of PVC having a thickness of about 5 mil and is formed, e.g., rolled, into a generally tubular configuration. The protective liner 353 may alternatively be constructed of a polyethylene or other polymer sheet, a woven mesh or other suitable material as long as it is sufficiently flexible to allow breaking of the ampule 331 within the pouch 351.
The apparatus 321 is assembled by first forming the pouch as described above. The ampule 331 is filled with a first reaction component, such as a sodium chlorite solution, and sealed. The protective liner 353 is formed into a generally tubular configuration around the ampule 331 and the liner and ampule are together placed inside the pouch 351 along with a mixture of sodium persulfate powder and silica gel as described above with respect to the first embodiment of
The apparatus 321 is activated by crushing the ampule 331, such as by squeezing or bending the pouch 351, to permit the sodium chlorite solution to leak from the ampule into the interior of the pouch. The sodium chlorite solution contacts and reacts with the mixture contained in the pouch 351 to produce chlorine dioxide gas therein. The chlorine dioxide gas diffuses out from the apparatus 321 through the gas permeable walls of the pouch 351 while remaining liquid is absorbed by the silica and is inhibited against leaking out of the pouch, e.g., since the walls of the pouch are liquid impermeable.
With reference now to
To construct the apparatus of this fourth embodiment, the ampule 431 is filled with a first reaction component, such as a sodium chlorite solution, and sealed. One end cap 437 is secured to an end of the tube 435 in sealing engagement therewith and a closure 439 is secured over the central opening 441 of the end cap. The ampule 431 is then inserted through the open end of the tube 435 into the interior thereof and a second reaction component, such as a mixture of sodium persulfate powder and silica gel is dispensed into the tube. The other end cap 437 and closure 439 are then secured to the open end of the tube 435 in sealing engagement therewith to seal the ampule 431 and second reaction component within the interior of the tube. The apparatus 421 is activated by repeatedly bending the tube 435 to break the ampule 431, thereby permitting chemically reactive contact between the reaction components. Chlorine dioxide gas is thus produced and exhausted from the apparatus 421 by diffusing through the gas permeable closures 439 at the ends of the tube.
A fifth embodiment of apparatus 521 of the present invention as shown in
In a sixth embodiment of apparatus 621 (
Apparatus 121 of the first embodiment described above and shown in
The effectiveness of the apparatus 121 in a generally cold sterilization application was evaluated using biological indicators to confirm sterilization. More particularly, each apparatus 121 was placed in a sterilization bag along with two humidification sources (e.g., such as are commonly available from H. W. Andersen Products, Inc. of North Carolina, U.S.A. under the trade name Humidichips), a biological indicator, and two minor packs, each having gas permeable outer walls and containing three biological indicators as well as various medical devices and materials to be sterilized. The sterilization bag was placed in a sterilization chamber and pre-conditioned for four hours at about 50° C. The apparatus 121 was then activated within the sterilization bag to generate and disperse chlorine dioxide gas within the bag. Sterilization continued for about 15.25 hours. After consecutive purge cycles of about 0.5 hours and 0.25 hours, respectively, the biological indicators were removed and incubated for about 48 hours. Inspection of the biological indicators removed from the sterilization bags indicated sterility (e.g., >6 logs kill) in all of the biological indicators.
Apparatus 221 of the type described above in connection with the second embodiment and shown in
The apparatus 221 were activated and placed in separate 16 oz. jars each having a lid fitted with an electrochemical sensor capable of monitoring the chlorine dioxide concentration within the jar.
Apparatus 321 of the type described above with respect to the third embodiment and shown in
For each apparatus 321, the glass ampule 331 was filled with the specified amount and concentration of sodium chlorite solution and placed in a tubular protective liner 353 constructed from a PVC sheet having a thickness of about 5 mil. The liner 353 and ampule 331 were together placed in a pouch 351 constructed from Tyvek®, as described previously, along with the specified amount and concentration of sodium persulfate and silica gel mixture. Each apparatus 321 was tested by activating the apparatus and placing it in a sealable polyethylene (e.g., gas impermeable) bag, having a size of about 28 inches by 32 inches, along with several postal articles including a box, a 9 inch×12 inch envelope and a standard 4 inch×9 inch envelope.
The bag and postal articles were configured to allow sampling of the chlorine dioxide gas within the bag and within each article therein by a gas-tight syringe inserted through a septum port of the bag. The chlorine dioxide gas was sampled via the syringe and immediately injected into a vial containing 20 ml of solution prepared from 1% potassium iodide (KI) solution and 5 ml of acetic acid. The resulting iodine was titrated using sodium thiosulfate and a starch indicator.
The table below identifies the chlorine dioxide concentration, in parts per million (ppm) measured within the bag enclosure for each of the three variations of apparatus 321 tested.
As a further test, additional apparatus 321 of the type described above with respect to the third embodiment and as shown in
For each apparatus 321, the glass ampule 331 was filled with a sodium chlorite solution in the specified concentration and amount and was inserted into a tubular protective liner 353 constructed from a PVC sheet having a thickness of about 5 mil. The liner 353 and ampule 331 were together placed in a pouch 351 constructed of Tyvek®, as described previously, along with the sodium persulfate and silica gel mixture in the specified concentration and amount.
Each apparatus 321 was activated and placed in a 12.8 liter glass flask and the flask was sealed with a tight fitting rubber stopper. A gas tight syringe was inserted through a septum covered syringe port of the stopper to periodically remove a sample of chlorine dioxide gas from the flask. The resulting chlorine dioxide concentration within the flask was then determined by iodometric titration as described previously in Experiment 3. The concentration in each flask was sampled for a period of about 1.5 hours. However, for one tested apparatus 321 the concentration was sampled over a period of about four hours to illustrate the persistence of the chlorine dioxide gas concentration in the flask, without further generation of the gas.
Another experiment was conducted to determine the effect of various apparatus constructions of the present invention on the production of chlorine dioxide gas. The experiment also evaluated the effect on chlorine dioxide gas production of using different combinations of reaction components and reaction component concentrations in the apparatus of the present invention. To conduct the experiment, various apparatus 321, 421, 521, 621, 721 of the types described above and shown in
The sodium chlorite solution contained in the glass ampules of the various apparatus had a sodium chlorite concentration of about 30%, with the exception of one apparatus in which a sodium chlorite concentration of about 5% was used. Several alternate reactants were also tested by filling the pouches 351 of apparatus 321 constructed in accordance with the third embodiment, as shown in
Each apparatus was activated and placed in a 12.8 liter glass flask. The flask was then sealed with a tight-fitting rubber stopper. A 50 ml gas tight syringe was inserted through a septum covered syringe port provided in the stopper to periodically sample the atmosphere within the flask. The sample was immediately injected into a capped, 40 ml vial containing 20 ml 1% potassium iodide (KI) and 5 ml acetic acid. The resulting iodine produced in the oxidation of the iodide by the chlorine dioxide gas was immediately titrated using sodium thiosulfate titrant and a starch indicator.
Results of the tests are shown in
It will be recognized that the apparatus of the present invention are useful in various treatments of biologically contaminated surfaces and articles, including deodorizing, sanitizing, decontaminating and/or sterilizing such surfaces and articles. For example, in accordance with one method of the present invention for treating surfaces such as walls, furniture, machinery, etc. within an enclosure (e.g., a room), the apparatus is transported to within the enclosure in its assembled, ready-to-use form with the reaction components separately contained within the apparatus. The operator then activates the apparatus by rupturing the membrane separating the containers of the apparatus. The operator then leaves the enclosure while chlorine dioxide gas is generated by the apparatus and released into the interior of the enclosure for treating exposed surfaces therein.
In accordance with another method of the present invention, the apparatus are used to treat small articles, and in particular postal articles. In such a method, the articles to be treated are placed in a bag, and more preferably a substantially gas impermeable bag. For example, one preferred such bag is constructed of polyethylene. The operator activates the apparatus by rupturing the membrane which separates the first and second containers of the apparatus. The operator then places the activated apparatus into the bag containing the postal articles. The bag is closed, and more preferably sealed, and the chlorine dioxide gas generated and released by the apparatus fills the bag to treat the articles contained in the bag.
It is contemplated that the apparatus may instead be placed in the bag prior to being activated and then activated before or after the bag is closed without departing from the scope of this invention. For example, the bag may be constructed to have a sealable port to permit insertion of a rod therethrough for contact with the apparatus to rupture the membrane separating the containers. As another example, the membrane separating the containers of the apparatus may be ruptured by external stimuli such ultrasonic, electromagnetic or thermal stimuli.
The rate at which chlorine dioxide gas is generated and released by the apparatus into the bag containing the postal articles may be varied depending on the construction of the apparatus. Where a rapid increase in gas concentration within the bag is desired, the second container of the apparatus is preferably constructed of a generally gas permeable material. More preferably, the apparatus is constructed in accordance with the apparatus 321 of the third embodiment described above and shown in
The apparatus of the present invention are shown and described herein as having a first container containing a first reaction component and being disposed within a second container along with a second reaction component, so that the first container broadly defines the rupturable membrane separating the reaction components. However, it is understood that other apparatus constructions may be used without departing from the scope of this invention. For example, while not shown in the drawings, the apparatus may comprise independent first and second containers respectively containing the first and second reaction components therein. Each container may be rupturable, such that the outer walls of the containers define a pair of rupturable membranes separating the reaction components. The containers may be placed in a surrounding container, such as a pouch or a tube, whereby both the first and second containers would be ruptured within the surrounding container to permit contact between the reaction components for producing chlorine dioxide gas within the surrounding container. It is also contemplated that the apparatus may comprise integrally formed first and second containers having a common outer wall that broadly defines the rupturable membrane separating the reaction components.
In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained. When introducing elements of the present invention or the preferred embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
This application is a continuation of U.S. patent application Ser. No. 10/261,037 filed Sep. 30, 2002.
Number | Date | Country | |
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Parent | 10261037 | Sep 2002 | US |
Child | 11146704 | Jun 2005 | US |