Photoactivated chlorine dioxide releasing powder and method for producing same

Abstract

A method is provided for producing a light-activated powder that provides solid-state generation and release of chlorine dioxide without detectable amounts of any toxic by-products such as chlorine gas, chlorite, or chlorate. The powder does not need to be exposed to moisture, relative humidity, or acid before or during exposure of the powder to visible light to generate gas. The powder can also be prepared under conditions that minimize or prevent decomposition or oxidation of sodium chlorite, or premature light activation of the powder during the manufacturing process to maximize its activity.

Description

[Technical field]

[0001] Light-activated powders for use in the generation and release of chlorine dioxide and methods for their manufacture are provided. More specifically, light-activated powders are provided that are capable of solid-state generation and release of chlorine dioxide without any detectable amounts of toxic by-products, and that are prepared under conditions that maximize the activity of the powder for use in disinfection, sanitation, sterilization, and control of biological or pathogenic contamination. [Background technology]

[0002] Currently, ethylene oxide is used to sterilize medical devices and other products. Ethylene oxide is recognized by the U.S. Food and Drug Administration (FDA) as having potential adverse effects on the environment and public health. The FDA is encouraging changes to ethylene oxide sterilization processes and equipment that reduce the amount of ethylene oxide on medical devices.

[0003] Detectable amounts of toxic by-products, including chlorine gas, chlorate and / or chlorite, have been observed when chlorine dioxide is produced from several conventional chlorine dioxide products. Summary of the Invention

[0004] One option for reducing the concentration of ethylene oxide on medical devices is to completely replace it with a different gas produced by a process that has less impact on the environment and public health.

[0005] In a first aspect of the present invention, a method is provided for making a light-activated powder for providing a solid-state controlled release of chlorine dioxide. The method includes mixing a light-activated catalyst, a base, sodium chlorite, and water to form an aqueous suspension, and spray drying the suspension at an inlet temperature in the range of about 482 to about 537°C (900 to 1000°F) and an outlet temperature of 143°C (290°F) or less to form a powder. The mixing and spray drying steps are performed in the dark. Upon exposure to visible light, the powder is capable of producing a solid-state controlled release of chlorine dioxide from the powder in an amount effective for disinfection, sanitation, and sterilization without releasing detectable amounts of chlorine gas, chlorates, and / or chlorites.

[0006] The aqueous suspension may contain sodium chlorite of 85-99% purity.

[0007] Upon exposure to visible light, the powder can produce a solid-state controlled release of chlorine dioxide from the powder in amounts effective for disinfection, sanitation, and sterilization, without releasing detectable amounts of toxic by-products such as chlorine gas and / or chlorites, chlorates, etc.

[0008] The powders prepared by this method are capable of producing a solid-state controlled release of chlorine dioxide from the powder without exposing the powder to moisture, relative humidity, or an acid-releasing agent prior to or during exposure of the powder to visible light. The acid-releasing agent is either an acid, a substance that can be hydrolyzed to an acid (i.e., a substance that reacts with water diffusing into the powder to form an acid), or a mixture thereof. Hydronium ions resulting from acid hydrolysis, if present, diffuse through the powder and react with chlorite anions to produce chlorine dioxide.

[0009] In a second aspect of the present invention, a light-activated powder is provided. The light-activated powder is prepared by the method described in the first aspect and examples of the present invention. When exposed to visible light, the powder can produce a solid-state controlled release of chlorine dioxide from the powder in an amount effective for disinfection, sanitation, and sterilization without releasing detectable amounts of toxic by-products (e.g., chlorine gas and / or chlorite, chlorate).

[0010] Other objects and features will be in part apparent and in part pointed out hereinafter. [Brief description of the drawings]

[0011] Not applicable. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] A method for producing a light-activated powder has been discovered that provides solid-state generation and release of chlorine dioxide without detectable amounts of any toxic by-products such as chlorine gas, chlorates and / or chlorites. The method includes an inlet spray drying temperature that is much higher than the 180° C. decomposition temperature of sodium chlorite. The chlorine dioxide is generated and released from a “solid-state” powder, meaning that the powder does not contain a source of moisture that would initiate the release of chlorine dioxide, such as unbound water or acid. The powder does not need to be exposed to moisture, relative humidity, or acid before or during exposure of the powder to visible light in order to generate gas. When exposed to light, the powder can generate and release gas after activation of the catalyst by the light and oxidation or reaction of sodium chlorite.

[0013] The powder can be prepared under conditions that minimize or prevent decomposition or oxidation of the sodium chlorite or premature photoactivation of the powder during the manufacturing process to maximize its activity.

[0014] As a first aspect of the present invention, a method for making a light-activated powder for providing a solid-state controlled release of chlorine dioxide is provided. The method includes mixing a light-activated catalyst, a base, sodium chlorite, and water to form an aqueous suspension, and spray drying the suspension at an inlet temperature in the range of about 482 to about 537°C (900 to 1000°F) and an outlet temperature in the range of about 121°C (250°F) to about 143°C (290°F) to form a powder. The aqueous suspension includes sodium chlorite of 85 to 99% purity. The mixing and spray drying steps are performed in the dark.

[0015] When exposed to visible light, the powder can produce a solid-state controlled release of chlorine dioxide from the powder in disinfecting effective amounts without releasing detectable amounts of chlorine gas, chlorite, or chlorate.

[0016] When the powder is exposed to light, such as visible light, the catalyst is activated and the chlorite anions oxidize or react to produce and release chlorine dioxide.

[0017] Powders prepared by this method are capable of producing a solid-state controlled release of chlorine dioxide from the powder without exposing the powder to moisture, relative humidity, or acid prior to or during exposure of the powder to visible light.

[0018] In preparing the aqueous suspension in the method of the present invention, a dispersant can be mixed with the catalyst, base, sodium chlorite and water. The dispersant can reduce the aggregation in the suspension. The dispersant can include a non-ionic surfactant. Examples of non-ionic surfactants include, but are not limited to, secondary alcohol ethoxylates, alkylphenol ethoxylates, alkyl ethoxylates, alkylaryl ethoxylates, polyethylene oxide-polypropylene oxide block copolymers, polyethylene glycol ethers of linear alcohols, reaction products of fatty acids with ethylene oxide and / or propylene oxide, polyvinyl alcohol, polyvinyl pyrrolidone, copolymers of polyvinyl alcohol and polyvinyl pyrrolidone, copolymers of (meth)acrylic acid and (meth)acrylic acid esters, or combinations thereof.

[0019] It is also preferred to maintain the aqueous suspension at a basic pH of from about 9 to about 14, preferably from about 9 to about 11. The pH can be maintained by adjusting the concentration of base added when forming the aqueous suspension.

[0020] The base in the aqueous suspension is believed to stabilize the chlorite anion during processing and participate in the electron transfer by generating hydroxyl radicals that aid in the oxidation of the anion. The amount of base in the powder can modify the duration of gas release and enhance thermal stability. Up to about 50% by weight of base can be included based on the total weight of the powder. Suitable bases include, but are not limited to, alkali metal hydroxides such as lithium hydroxide, sodium hydroxide or potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide or magnesium hydroxide, transition metal ions, hydroxide salts of protonated primary, secondary or tertiary amines, or quaternary amines such as ammonium hydroxide. Sodium hydroxide is preferred.

[0021] In the process of the present invention, the aqueous suspension can be an azeotrope. When the aqueous suspension is an azeotrope, the spray drying inlet temperature can be as high as 537°C (1000°F) and still avoid sodium chlorite decomposition. Azeotropes can include mixtures of solvents, including, but not limited to, acetone, acetonitrile, acrylonitrile, alcohols (e.g., ethanol, methanol, isopropanol, tert-butanol), alkenols, alkanes (e.g., hexane, 2-methylpentane), alkenals, haloalkanes (e.g., dichloromethane, trichlorotrifluoroethane), nitroalkanes (e.g., nitromethane), anilines, cycloalkanes (e.g., cyclopentane, cyclohexane), benzene, alkylbenzenes, halobenzenes, carbon disulfide, carbon tetrachloride, chloroform, epichlorohydrin, alkylamines, dialkylamines, alkyl halides (e.g., methyl iodide, ethyl iodide), alkyl ethers (e.g., isopropyl ether), alkyl acetates (e.g., methyl acetate), haloalkenes, alkenyl chlorides, trifluoroacetic acid, toluene, xylene, or any combination thereof.

[0022] For example, the aqueous suspension may comprise an azeotrope comprising acetone and one or more solvents including ethanol, methanol, isopropanol, tert-butanol, hexane, 2-methylpentane, dichloromethane, trichlorotrifluoroethane, nitromethane, cyclopentane, cyclohexane, carbon disulfide, carbon tetrachloride, chloroform, methyl iodide, ethyl iodide, isopropyl ether, methyl acetate, or trifluoroacetic acid.

[0023] The light used to activate the powder's photoactivated catalyst can be sunlight, fluorescent, incandescent, or ultraviolet light. Visible light, such as blue light, is the preferred light source. Additives such as UV blockers can also be included in the powder if it is desired to limit the range of wavelengths transmitted to the catalyst. Photosensitizers can be added to shift the absorption wavelengths of the powder, particularly to shift ultraviolet absorption wavelengths to visible absorption wavelengths, to improve activation with room lighting. UV absorbers can be added to the composition to slow down gassing and release rates.

[0024] Light-activated catalysts are commonly used to catalyze oxidation and reduction reactions. When a photon is absorbed by the catalyst, an electron is excited from the valence band to the conduction band, generating a valence band hole. The hole and electron diffuse to the surface of the catalyst particle, where each can chemically react. The valence band hole oxidizes a water molecule adsorbed on the surface of the catalyst, generating a hydroxyl radical.

[0025] Any semiconductor activated by light or particles or other materials incorporating such semiconductors can be used as a light-activated catalyst. Such semiconductors are generally metallic, ceramic, inorganic, or polymeric materials prepared by various processes known in the art, such as sintering. Catalysts for use in the present invention are commercially available in a wide range of particle sizes, from nanoparticles to granules.

[0026] The light-activated catalyst in the aqueous suspension may comprise a metallic oxide, a metallic sulfide, a metallic chalcogenide, a metallic phosphide, a metallic arsenide, a non-metallic semiconductor, a polymeric semiconductor, a photoactive homopolyanion, a photoactive heteropolyion, or a combination thereof. Preferably, the light-activated catalyst comprises a metal oxide.

[0027] When the light-activated catalyst is a metal oxide, the metal oxide may be titanium dioxide, zinc oxide, tungsten trioxide, ruthenium dioxide, iridium dioxide, tin dioxide, strontium titanate, barium titanate, tantalum oxide, calcium titanate, iron (III) oxide, molybdenum trioxide, niobium pentoxide, indium trioxide, cadmium oxide, hafnium oxide, zirconium oxide, manganese dioxide, copper oxide, vanadium pentoxide, chromium trioxide, yttrium trioxide, silver oxide, or Ti. x Zr 1-x O2 (wherein x is 0 to 1). Transition metal oxides such as titanium dioxide and zinc oxide are preferred because they are chemically stable, non-toxic, inexpensive, exhibit high photocatalytic activity, and are available as nanoparticles useful for preparing transparent molded or extruded plastic products. Preferably, the photoactivated catalyst comprises titanium dioxide, more preferably rutile titanium dioxide.

[0028] Without being bound by any particular theory, when the powders produced as described herein comprise rutile titanium dioxide, it is believed that the titanium dioxide has a flat surface with high electron density that adsorbs atmospheric water. The sorbed water can be, for example, associated water molecules, dissociated hydroxyl groups in direct contact with the surface, or water molecules associated with the surface and hydrogen-bonded to structural oxygen atoms. The sorbed water content can be determined by differential scanning calorimetry. It is also believed that the dispersant, if present, can be bound to the titanium dioxide and provide a source of hydronium ions. The water adsorbed on the surface of the titanium dioxide is then available to cause the solid-state release of chlorine dioxide from the powder.

[0029] When the catalyst is a metal sulfide, the metal sulfide can include cadmium sulfide, zinc sulfide, indium sulfide, copper sulfide, tungsten disulfide, bismuth trisulfide, or cadmium zinc disulfide.

[0030] When the catalyst is a metal chalcogenide, the metal chalcogenide can include zinc selenide, cadmium selenide, indium selenide, tungsten selenide, or cadmium telluride.

[0031] When the catalyst is a non-metallic semiconductor, the non-metallic semiconductor may include silicon, silicon carbide, diamond, germanium, germanium dioxide, or germanium telluride.

[0032] Other representative catalysts include indium phosphide, gallium arsenide, polyacetylene, and W. 10 O 32 -4 Photoactive homopolyanions, including XM 12 O 40 -n Or X2M 18 O 62 -7 (wherein x is Bi, Si, Ge, P or As, M is Mo or W, and n is an integer of 1 to 12).

[0033] An inert atmosphere, such as a nitrogen blanket, can be used during the process. The inert atmosphere can be present during the entire process or during the mixing step, the spray drying step, when collecting the spray-dried product, and / or when storing the spray-dried product.

[0034] Aqueous suspensions can be prepared by mixing the components in any order of addition. For example, sodium chlorite can be mixed with water and base to form a solution, a solvent can be added to the solution to form an azeotrope, and a light-activated catalyst can be mixed with the solution or azeotrope to form a suspension. Alternatively, catalyst and solvent can be mixed to form a slurry, sodium chlorite can be added to the slurry to form a suspension, or both catalyst and sodium chlorite can be mixed with a solvent before mixing to form a suspension. When preparing a suspension, ultrasonic mixing, high shear mixing, or any conventional homogenization method can be used.

[0035] Once the suspension is formed, it can be spray dried to form a powder by any method known in the art, including any known atomization method, such as, for example, a nozzle or a rotating disk. Typically, the inlet and outlet temperatures are maintained in the range of about 482 to about 537°C (900 to 1000°F) and about 121°C (250°F) to about 143°C (290°F), respectively. The spray drying process is generally carried out quickly (e.g., within up to about 60 seconds). If desired, the powder may then be further dried by any conventional method.

[0036] After spray drying to form a powder, the powder can be mixed with a desiccant to further protect the powder from moisture activation. The desiccant can include, but is not limited to, silica, silicates, such as sodium silicate, sodium metasilicate, sodium sesquisilicate, sodium orthosilicate, borosilicate, aluminosilicate, zeolites, sodium sulfide, or combinations thereof.

[0037] The powder can then be packaged in a container that blocks wavelengths of light that can activate the catalyst.

[0038] The powder produced by the method of the present invention can contain about 50% to about 99.99% by weight of photocatalyst, about 0.01% to about 50% by weight of sodium chlorite, about 70% to about 97% by weight of photoactivated catalyst, and about 3% to about 30% by weight of sodium chlorite, or about 80% to about 95% by weight of photoactivated catalyst, and about 5% to about 20% by weight of sodium chlorite.

[0039] A disinfectant-effective chlorine dioxide release rate can range, for example, from about 0.08 ppm / min to about 8.0 ppm / min over a period of about 2 to about 72 hours.

[0040] In a second aspect of the present invention, a light-activated powder is provided. The light-activated powder is prepared by the method described in the first aspect and examples of the present invention. The powder, when exposed to visible light, can produce a solid-state controlled release of chlorine dioxide from the powder in a disinfecting effective amount without releasing detectable amounts of chlorine gas and / or chlorite, chlorate.

[0041] The applications of powders are numerous. They can be used in almost any environment where exposure to light can occur. Powders can be formed into solids by molding or sintering. Powders can also be impregnated, melt processed, sintered, blended with other powders, or otherwise incorporated into various materials to provide films, fibers, coatings, tablets, resins, polymers, plastics, tubes, membranes, industrial materials, paints, coatings, and adhesives for a wide range of end uses. Powders are particularly useful for preparing any injection molded, compression molded, thermo-formed, or extrusion formed products such as cast or blown films. The thermal stability of powders allows for their use in injection molding processes.

[0042] The powders of the present invention are preferably incorporated into injection molded, compression molded, thermoformed, or extrusion molded plastic products by compounding and pelletizing the powders via conventional means and mixing the pellets with materials prior to conventional forming or molding processes. Materials suitable for forming these products include any polymer, such as multicomponent polymers such as copolymers, terpolymers, or oligomers, and polymer alloys or blends thereof, or any wax. Representative polymers include polyolefins such as polyethylene and polypropylene, polyethylene terephthalate, polyvinyl chloride, polyurethane, metallocene polymers, polyesters, polyacrylates, acrylics, polystyrene, polycarbonates, polyamides, polyesteramides, ethylene-vinyl acetate copolymers, ethylene-methacrylate copolymers, and polyacetals. Suitable waxes include microcrystalline waxes, paraffin waxes, and synthetic waxes such as chlorinated waxes, polyethylene waxes, polyethylene glycols, and polypropylene glycols. Preferably, the polymers are biodegradable.

[0043] The formed or molded product preferably contains about 0.1 to about 70% by weight of the powder of the present invention and about 30 to about 99.9% by weight of the material, more preferably about 1 to about 50% by weight of the powder of the present invention and about 50 to about 99% by weight of the material, and most preferably about 2 to about 50% by weight of the powder of the present invention and about 50 to about 98% by weight of the material.

[0044] The formed or molded product can be made by any conventional polymer processing method. For example, the powder or powder pellets and material of the present invention can be mixed together in a mixer, such as a Henschel mixer, and fed to an extruder or molding device operated at a temperature not exceeding about 200°C to form a melt. The melt can be cast extruded as a film, molded into pellets on a vibrating conveyor using dry air cooling, or molded into the desired shape by conventional injection molding, thermoforming, or compression molding methods.

[0045] The melt can be applied to a surface as a film by using well-known hot melt, dip coat, spray coat, curtain coat, dry wax, wet wax, and lamination processes. If the powder is in nanoparticle form (e.g., 5-20 microns in diameter), a transparent film can be formed.

[0046] Conventional film forming additives can be added to the material as needed, including crosslinkers, UV stabilizers, flame retardants, emulsifiers, compatibilizers, lubricants, antioxidants, colorants, and dyes.

[0047] A multi-layer composite can be formed to generate gas within an enclosure formed of the composite. Such a composite includes a gas generating layer and a barrier layer. The gas generating layer includes a powder. The barrier layer is adjacent to a surface of the gas generating layer. The barrier layer is transparent to light so as to transmit light to the gas generating layer. However, the barrier layer is impermeable or only semi-permeable to the gas generated and released by the gas generating layer. When exposed to light, the gas generating layer can generate and release chlorine dioxide after activation of a catalyst and oxidation or reaction of chlorite anions.

[0048] The gas-releasing powders, films or other compositions of the present invention can be used to retard, kill, prevent or control microbiological contamination or biochemical degradation on the surface of a material, within the material, or in the atmosphere surrounding the material by placing the material adjacent to the composition of the present invention and exposing the composition to light to release chlorine dioxide from the composition into the atmosphere surrounding the material. Microbiological contaminants can include bacteria, viruses, molds, and fungi.

[0049] The compositions can also be used to retard, prevent or control biological contamination of the atmosphere by exposing the composition to light to generate chlorine dioxide from the composition, which is released into the atmosphere surrounding the composition.

[0050] As used herein, the retardation, prevention, or control of biological contamination is also referred to as "sanitization," "disinfection," or "sterilization." Biological contamination can include bacteria, viruses, such as coronaviruses (e.g., SARS-COV-2 and its variants, e.g., Delta or Omicron variants), molds, and fungi.

[0051] The compositions can also be used to delay, prevent or control biological contamination of a material by placing the material adjacent to the composition and exposing the composition to light to generate chlorine dioxide from the composition and release it into the atmosphere surrounding the material. For example, chlorine dioxide is used after biological warfare to inactivate biological contaminants (e.g., anthrax) or for other military decontamination.

[0052] As an example, the powder or any composition containing the powder, such as a film, can be placed in a sealable bag or other container used in sterilizing medical devices, or in a "red bag" used in decontaminating or disinfecting medical waste or personal protective equipment, such as masks, gowns and pants. Alternatively, the bag or container can be made from a film containing the powder of the present invention. The chlorine dioxide released by the powder or composition is effective against SARS-COV-2 and its variants, such as the Delta or Omicron variants.

[0053] Because the chlorine dioxide produced by the powders of the present invention is dry and not wet, the powders are also effective in disinfecting electronic devices without corroding them, which can be advantageous in combating the effects of pathogens on electronic devices in battlefield contamination resulting from the use of biological weapons.

[0054] The composition can also be used to deodorize the surface of a material or the atmosphere surrounding a material or to enhance the freshness of a material by placing the material adjacent to the composition and exposing the composition to light, which generates chlorine dioxide from the composition and releases it into the atmosphere surrounding the material.

[0055] The compositions can also be used to delay, prevent, inhibit, or control the chemotactic attraction of organisms to a material by placing the material adjacent to the composition and exposing the composition to light, causing the composition to generate chlorine dioxide, which is released into the atmosphere surrounding the material.

[0056] In the above methods, the surface of the material or the entire material can be impregnated with the powder of the present invention or coated with the composition, the composition can be mixed with the material, the composition can be enclosed in a gas-permeable container, or the material and composition can be enclosed in a container. If the composition is enclosed in a container, the container can be sealed or partially sealed so that some gas escapes from the container.

[0057] Chlorine dioxide releasing powders can be impregnated into, for example, food, soaps, laundry detergents, documents, clothing, paints, seeds, medical instruments, devices and supplies such as catheters and sutures, personal care products, medical or biological waste, athletic shoes, ostomy bags, footwear, and containers used to store garbage. Such powders can also be impregnated into covers for medical, hospital, household or commercial equipment, or covers used in storage. Packets, sachets, "tea bags" or other gas permeable containers of powder can be included in the storage container to provide a chlorine dioxide microatmosphere upon activation. Chlorine dioxide releasing powders can also be impregnated into paper or polymeric materials (e.g., shower mats, shoe inserts or insoles, bandage material, meat cutting boards, food packaging, food packaging trays, seed packets, or air filters), incorporated into wax or polymer coatings applied to paperboard containers or other surfaces, incorporated into films such as packaging films or covers for storage or medical devices, hospital devices, household devices or commercial devices, formed into porous parts to sterilize water, mixed with materials to create a chlorine dioxide micro-atmosphere around the material (e.g., soil), or mixed with other powders to kill microorganisms, enhance freshness, or deodorize (e.g., powders for treating soft surfaces such as foot powders, bath powders, carpet powders, desiccants for moisture removal).

[0058] The powders can also be used to neutralize malodours, delay, prevent, inhibit or control chemotaxis (i.e., the attraction of living tissue to chemicals), or reduce or eliminate bacteria in animal feed, potentially reducing the bacterial load in the intestines of animals consuming the feed.

[0059] The compositions of the present invention effectively release gas at temperatures commonly encountered in the above uses, including refrigeration temperatures. The chlorine dioxide releasing compositions can be used, for example, in packaging medical supplies, food, or other materials that require refrigeration to sterilize or deodorize the materials. Multilayer films containing a barrier layer can also be used to form packaging such as those used for medical supplies or food. The barrier layer retains the generated gas within the packaging to, for example, extend shelf life, prevent mold growth in food, or enhance sterilization of medical supplies.

[0060] Having described the invention in detail, it will be apparent that modifications and variations are possible without departing from the scope of the invention as defined in the appended claims. EXAMPLES

[0061] The following non-limiting examples are provided to illustrate the present invention.

[0062] Example 1 A liquid slurry was prepared in a blending tank and spray dried to form a light-activated powder. The blending tank had an agitator that was on during the addition of all ingredients. The lighting in the manufacturing area was dimmed to less than 12 lumens.

[0063] First, the blend tank was filled with deionized water. Sodium hydroxide (1.2% by weight of a 50% solution) was added to the water to form a solution. Sodium chlorite powder (3.0% by weight) was slowly added to the solution, followed by 26.4% by weight of titanium dioxide to form a slurry. The amounts listed are based on the total weight of the liquid slurry before it was spray dried. The slurry was then transferred to a feed tank, again equipped with an agitator, leading to the spray dryer.

[0064] Approximately 57 kg (125 lbs) of liquid slurry containing dissolved sodium chlorite, sodium hydroxide, and suspended titanium dioxide was pumped to a spray dryer using a positive displacement pump. The absolute viscosity of the slurry ranged from 950 to 1750 centipoise at 29°C (85°F) and the pH was 12.3. The inlet temperature of the spray dryer ranged from 510°C (950°F) to 527°C (980°F) over the course of the run. The outlet temperature ranged from 121°C (250°F) to 124°C (255°F). A powder was produced by spray drying the slurry.

[0065] The resulting fine white powder was sieved through a 50 micron mesh into a poly-barrel lined with two opaque plastic bags. A perforated hose connected to a nitrogen gas cylinder was inserted into the barrel to facilitate cooling. Once the temperature had dropped to 32°C (90°F), the bag and drum were sealed. Multiple samples of the finished powder were collected throughout the experiment and tested for chlorine dioxide production when exposed to an LED light strip. Chlorine dioxide production of over 25 ppm was consistently observed after 5 grams of powder was exposed to the LED light source for 30 seconds.

[0066] Example 2 Titanium dioxide (99.9% rutile (Aldrich Chemical)) is mixed with a solution consisting of sodium chlorite (technical grade (Aldrich Chemical)), sodium hydroxide, acetone, a solvent that forms an azeotrope with acetone, and water to form a suspension, which is immediately spray dried in the dark (less than 12 lumens) and under a nitrogen blanket at an inlet temperature ranging from about 482 to about 537 °C (900 to 1000 °F) and an outlet temperature of 143 °C (290 °F) or less to form a white powder. The powder is placed in a jar and monitored with a 0 to 100 ppm chlorine dioxide electrochemical sensor. Chlorine dioxide is produced and released from the white powder over the test time when the powder is exposed to visible light. Gas release is suspended when the powder is kept in the dark and resumes when the powder is again exposed to visible light.

[0067] Pellet formation: The spray-dried powder is compounded into pellets using 2 melt index linear low-density polyethylene (LLDPE) resin (from Rexene) at a concentration of 20% powder and 80% resin. The pellets are produced in the dark under nitrogen. The pellets are stored in an aluminum foil / plastic laminate container to protect them from exposure to light.

[0068] Film formation: The pellets are blown into a film using 2 melt index Rexene LLDPE resin (50% let down). The resulting film contains approximately 10% powder by weight. Film preparation is carried out in the dark under nitrogen. The films are stored in aluminum foil / plastic laminate containers to protect them from exposure to light.

[0069] Photoactivation of films under dry conditions: film samples are placed in a jar (containing a desiccant to create 0% relative humidity) with a 0-10 ppm chlorine dioxide electrochemical detector attached to the lid and covered with aluminum foil for several days to exclude light. During this time, no chlorine dioxide is produced. Irradiation of the sample by ambient fluorescent room lighting causes the immediate production of chlorine dioxide.

[0070] Photoactivation of film by photocycle: A 1 g sample of film was placed in a 500 ml jar with a 0-10 ppm 15 chlorine dioxide electrochemical detector attached to the lid and covered with aluminum foil for approximately 10 minutes to exclude light. During this time, no chlorine dioxide is generated. Irradiation of the sample with ambient fluorescent room lighting for approximately 10-30 minutes causes the immediate generation of chlorine dioxide. The film is covered with foil, during which time no chlorine dioxide is generated. When the foil is removed and the film is exposed to room light, chlorine dioxide is generated.

[0071] definition The term "suitable substituent" as used herein is intended to mean a chemically acceptable functional group, preferably a moiety that does not negate the activity of the compound of the present invention.Such suitable substituents include, but are not limited to, halo group, perfluoroalkyl group, perfluoroalkoxy group, alkyl group, alkenyl group, alkynyl group, hydroxy group, oxo group, mercapto group, alkylthio group, alkoxy group, aryl or heteroaryl group, aryloxy or heteroaryloxy group, aralkyl or heteroaralkyl group, aralkoxy or heteroaralkoxy group, HO-(C=O)- group, heterocyclic group, cycloalkyl group, amino group, alkylamino group and dialkylamino group, carbamoyl group, alkylcarbonyl group, alkoxycarbonyl group, alkylaminocarbonyl group, dialkylaminocarbonyl group, arylcarbonyl group, aryloxycarbonyl group, alkylsulfonyl group, and arylsulfonyl group.Those skilled in the art will understand that many substituents can be substituted by further substituents.

[0072] The term "alkyl," as used herein, refers to a straight-chain, branched, or cyclic hydrocarbon group preferably having 1 to 32 carbon atoms (i.e., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 39, 30, 31, or 32 carbons), more preferably having 1 to 18 carbon atoms. Alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, iso-butyl, sec-butyl, and tert-butyl. An alkyl group can be unsubstituted or substituted by one or more suitable substituents.

[0073] The term "alkenyl" as used herein refers to a straight-chain, branched-chain, or cyclic hydrocarbon group having preferably 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 39, 30, 31, or 32 carbons, more preferably 1 to 18 carbon atoms, and having one or more carbon-carbon double bonds. Alkenyl groups include, but are not limited to, ethenyl, 1-propenyl, 2-propenyl (allyl), iso-propenyl, 2-methyl-1-propenyl, 1-butenyl, and 2-butenyl. Alkenyl groups may be unsubstituted or substituted by one or more suitable substituents, as defined above.

[0074] The term "alkynyl" as used herein refers to a straight-chain, branched-chain, or cyclic hydrocarbon group having preferably 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 39, 30, 31, or 32 carbons, more preferably 1 to 18 carbon atoms, and having one or more carbon-carbon triple bonds. Alkynyl groups include, but are not limited to, ethynyl, propynyl, and butynyl. Alkynyl groups may be unsubstituted or substituted by one or more suitable substituents, as defined above.

[0075] The term "aryl" or "ar" as used herein alone or as part of another group (e.g., aralkyl) refers to a monocyclic, bicyclic, or tricyclic aromatic group such as phenyl, naphthyl, tetrahydronaphthyl, indanyl, and the like, optionally substituted with one or more suitable substituents, preferably 1 to 5 suitable substituents, as defined above. The term "aryl" also includes heteroaryl.

[0076] "Arylalkyl" or "aralkyl" means an aryl group attached to a parent molecule via an alkylene group. The number of carbon atoms in the aryl and alkylene groups is selected so that there are a total of about 6 to about 18 carbon atoms in the arylalkyl group. A preferred arylalkyl group is benzyl.

[0077] The term "cycloalkyl," as used herein, refers to a monocyclic, bicyclic, or tricyclic carbocyclic group, optionally containing one or two double bonds, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclopentenyl, cyclohexenyl, bicyclo[2.2.1]heptanyl, bicyclo[3.2.1]octanyl, and bicyclo[5.2.0]nonanyl. Cycloalkyl groups can be unsubstituted or substituted with one or more suitable substituents, preferably 1 to 5 suitable substituents, as defined above.

[0078] As used herein, "dark" means light intensity of about 129 lux (i.e., 12 foot-candles) or less to avoid photoactivation of the photoactivated catalyst.

[0079] The term "-ene" used as a suffix as part of another group denotes a divalent group in which a hydrogen atom has been removed from each of the two terminal carbons of the group, or, if the group is cyclic, from each of two different carbon atoms in the ring. For example, alkylene denotes a divalent alkyl group such as ethylene (-CH2CH2-) or isopropylene (-CH2(CH3)CH2-). For clarity, the addition of the -ene suffix is ​​not intended to alter the definition of the head term other than to denote a divalent group. Thus, continuing with the above example, alkylene denotes a straight chain saturated divalent hydrocarbon group, optionally substituted.

[0080] The term "ether," as used herein, refers to a divalent (ie, difunctional) group that contains at least one ether linkage (ie, --O--).

[0081] The term "heteroaryl," as used herein, refers to a monocyclic, bicyclic, or tricyclic aromatic heterocyclic group containing in one or more rings one or more heteroatoms (e.g., 1 to 3 heteroatoms) selected from O, S, and N. Heteroaryl groups include, but are not limited to, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, thienyl, furyl, imidazolyl, pyrrolyl, oxazolyl (e.g., 1,3-oxazolyl, 1,2-oxazolyl), thiazolyl (e.g., 1,2-thiazolyl, 1,3-thiazolyl), pyrazolyl, tetrazolyl, triazolyl (e.g., 1,2,3-triazolyl, 1,2,4-triazolyl), oxadiazolyl (e.g., 1,2,3-oxadiazolyl), thiadiazolyl (e.g., 1,3,4-thiadiazolyl), quinolyl, isoquinolyl, benzothienyl, benzofuryl, and indolyl. A heteroaryl group can be unsubstituted or optionally substituted with one or more suitable substituents, preferably 1 to 5 suitable substituents, as defined above.

[0082] The term "hydrocarbon" as used herein describes compounds or radicals consisting solely of the elements carbon and hydrogen.

[0083] The term "substituted" means that in the group in question, at least one hydrogen atom bonded to a carbon atom is replaced with one or more substituents, such as hydroxy (-OH), alkylthio, phosphino, amido (-CON(RA)(RB), where RA and RB are independently hydrogen, alkyl, or aryl), amino (-N(RA)(RB), where RA and RB are independently hydrogen, alkyl, or aryl), halo (fluoro, chloro, bromo, or iodo), silyl, nitro (-NO), ether (-ORA, where RA is alkyl or aryl), ester (-OC(O)RA, where RA is alkyl or aryl), keto (-C(O)RA, where RA is alkyl or aryl), heterocyclo, and the like. When the term "substituted" introduces or follows a list of possible substituted groups, it is intended that the term apply to all members of that group. That is, the phrase "optionally substituted alkyl or aryl" should be interpreted as "optionally substituted alkyl or optionally substituted aryl." Similarly, the phrase "optionally substituted alkyl or aryl" should be interpreted as "optionally substituted with fluorine or optionally substituted with fluorine."

[0084] When introducing elements of the present invention or preferred embodiments thereof, the articles "a," "an," "the," and "said" are intended to mean that there are one or more 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.

[0085] In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

[0086] Because various changes can be made in the products and methods described above without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims

1. 1. A method of making a light-activated powder for providing a solid-state controlled release of chlorine dioxide, comprising: mixing a light-activated catalyst, a base, sodium chlorite, and water to form an aqueous suspension, the aqueous suspension comprising 85-99% pure sodium chlorite; spray drying the suspension at an inlet temperature in the range of 482-537°C (900-1000°F) and an outlet temperature of 143°C (290°F) or less to form a powder; the powder does not contain a source of moisture capable of initiating chlorine dioxide release; The mixing and spray drying steps are performed in the dark; wherein said powder upon exposure to visible light is capable of producing said solid state controlled release of chlorine dioxide from said powder in a disinfecting effective amount without releasing detectable amounts of chlorine gas, chlorate and / or chlorite.

2. further comprising combining a dispersing agent with the catalyst, the base, the sodium chlorite, and the water to form the aqueous suspension, the dispersing agent comprising a non-ionic surfactant; or the mixing step and / or the spray drying step are carried out under an inert atmosphere; or the aqueous suspension is an azeotrope; and the azeotrope in the aqueous suspension comprises acetone, acetonitrile, acrylonitrile, an alcohol, an alkenol, an alkane, an alkenal, a haloalkane, an aniline, a cycloalkane, benzene, an alkylbenzene, a halobenzene, carbon disulfide, carbon tetrachloride, chloroform, epichlorohydrin, an alkylamine, a dialkylamine, an alkyl halide, an alkyl ether, an alkyl acetate, a haloalkene, an alkenyl chloride, toluene, or xylene; or the azeotrope comprises acetone and one or more solvents including ethanol, methanol, isopropanol, tert-butanol, hexane, 2-methylpentane, dichloromethane, trichlorotrifluoroethane, nitromethane, cyclopentane, cyclohexane, carbon disulfide, carbon tetrachloride, chloroform, methyl iodide, ethyl iodide, isopropyl ether, methyl acetate, or trifluoroacetic acid; or the catalyst comprises a metal oxide, a metal sulfide, a metal chalcogenide, a metal phosphide, a metal arsenide, a non-metal semiconductor, a polymeric semiconductor, a photoactive homopolyanion, a photoactive heteropolyion, or a combination thereof; and the metal oxide is titanium dioxide, zinc oxide, tungsten trioxide, ruthenium dioxide, iridium dioxide, tin dioxide, strontium titanate, barium titanate, tantalum oxide, calcium titanate, iron (III) oxide, molybdenum trioxide, niobium pentoxide, indium trioxide, cadmium oxide, hafnium oxide, zirconium oxide, manganese dioxide, copper oxide, vanadium pentoxide, chromium trioxide, yttrium trioxide, silver oxide, or Ti x Zr 1-x O 2 wherein x is 0-1; the metal sulfide comprises cadmium sulfide, zinc sulfide, indium sulfide, copper sulfide, tungsten disulfide, bismuth trisulfide, or zinc cadmium disulfide; the metal chalcogenide comprises zinc selenide, cadmium selenide, indium selenide, tungsten selenide, or cadmium telluride; the metal phosphide comprises indium phosphide; the metal arsenide comprises gallium arsenide; the non-metal semiconductor comprises silicon, silicon carbide, diamond, germanium, germanium dioxide, or germanium telluride; the polymer semiconductor comprises polyacetylene; the photoactive homopolyanion comprises W 10 O 32 -4 ; the photoactive heteropolyion comprises XM 12 O 40 -n or X 2 M 18 O 62 -7 2. The method of claim 1, comprising: wherein x is Bi, Si, Ge, P or As; M is Mo or W; and n is an integer from 1 to 12.

3. the powder comprises 50% to 99.99% by weight of the light-activated catalyst and 0.01% to 50% by weight of sodium chlorite; or the powder comprises 70% to 97% by weight of the light-activated catalyst and 3% to 30% by weight of sodium chlorite; or the powder comprises 80% to 95% by weight of the light-activated catalyst and 5% to 20% by weight of sodium chlorite; or the disinfecting effective amount ranges from 0.08 ppm / min to 8.0 ppm / min for a period of 2 to 72 hours; or the powder is capable of effecting the solid-state controlled release of the chlorine dioxide from the powder without exposing the powder to moisture, relative humidity, or acid prior to or during exposure of the powder to visible light; or The method according to claim 1 or 2, wherein the pH of the aqueous suspension is from 9 to 11.

4. A photoactivated spray-dried powder comprising 50% to 99.99% by weight of a photocatalyst, 0.01% to 50% by weight of sodium chlorite having a purity of 85-99%; the light-activated spray-dried powder is free of a moisture source capable of initiating chlorine dioxide release; Upon exposure to light, the light-activated spray-dried powder is capable of producing the solid-state controlled release of chlorine dioxide from the powder in a disinfecting effective amount without releasing detectable amounts of chlorine gas, chlorate and / or chlorite; and The photoactivated spray dried powder comprises: mixing a light-activated catalyst, a base, sodium chlorite, and water to form an aqueous suspension; spray drying the suspension at an inlet temperature in the range of 482-537°C (900-1000°F) and an outlet temperature of not more than 143°C (290°F) to form the photoactivated powder; and preparing the product by a process comprising: The mixing and spray drying steps are carried out in the dark. Light-activated spray-dried powder.

5. The powder further comprises a dispersant, wherein the dispersant is mixed with the catalyst, the base, the sodium chlorite, and the water to form the aqueous suspension, the dispersant comprising a non-ionic surfactant, or the powder further comprises a desiccant, the desiccant being mixed with the powder, the desiccant comprising silica, silicate, borosilicate, aluminosilicate, zeolite, sodium sulfide, or any combination thereof; or The catalyst comprises a metal oxide, a metal sulfide, a metal chalcogenide, a metal phosphide, a metal arsenide, a non-metal semiconductor, a polymer semiconductor, a photoactive homopolyanion, a photoactive heteropolyion, or a combination thereof, and the metal oxide is titanium dioxide, zinc oxide, tungsten trioxide, ruthenium dioxide, iridium dioxide, tin dioxide, strontium titanate, barium titanate, tantalum oxide, calcium titanate, iron (III) oxide, molybdenum trioxide, niobium pentoxide, indium trioxide, cadmium oxide, hafnium oxide, zirconium oxide, manganese dioxide, copper oxide, vanadium pentoxide, chromium trioxide, yttrium trioxide, silver oxide, or Ti x Zr 1-x O 2 wherein x is 0-1; the metal sulfide comprises cadmium sulfide, zinc sulfide, indium sulfide, copper sulfide, tungsten disulfide, bismuth trisulfide, or zinc cadmium disulfide; the metal chalcogenide comprises zinc selenide, cadmium selenide, indium selenide, tungsten selenide, or cadmium telluride; the metal phosphide comprises indium phosphide; the metal arsenide comprises gallium arsenide; the non-metal semiconductor comprises silicon, silicon carbide, diamond, germanium, germanium dioxide, or germanium telluride; the polymer semiconductor comprises polyacetylene; the photoactive homopolyanion comprises W 10 O 32 -4 ; the photoactive heteropolyion comprises XM 12 O 40 -n or X 2 M 18 O 62 -7 wherein x is Bi, Si, Ge, P or As, M is Mo or W, and n is an integer from 1 to 12; 5. The powder according to claim 4.

6. The powder comprises 70% to 97% by weight of the photoactivated catalyst and 3% to 30% by weight of sodium chlorite, or the powder comprises 80% to 95% by weight of the light-activated catalyst and 5% to 20% by weight of sodium chlorite; or the disinfecting effective amount ranges from 0.08 ppm / min to 8.0 ppm / min for a period of 2 to 72 hours; or the powder is capable of effecting the solid-state controlled release of the chlorine dioxide from the powder without exposing the powder to moisture, relative humidity, or acid prior to or during exposure of the powder to light; or the mixing step and / or the spray drying step are carried out under an inert atmosphere; or the pH of the aqueous suspension is between 9 and 11; or The aqueous suspension is an azeotrope.

5. The powder according to claim 4.

7. A film comprising the light-activated spray-dried powder of any one of claims 4 to 6 and a biodegradable polymer.