United States Patent (19) 11 Patent Number: 4,731,193 Mason Et Al

United States Patent (19) 11 Patent Number: 4,731,193 Mason et al. (45) Date of Patent: Mar. 15, 1988 54 AQUEOUSFOAMCONTAINING CHLORINE 56) References Cited DOXDE COMPOSITION AND PREPARATION THEREOF U.S. PATENT DOCUMENTS 2,392,936 1/1946 Mattin et al. ......................... 134/42 2,678,922 5/1954 Stone.......................... 252/187.22 X 75) Inventors: John Y. Mason, Plymouth; Bruce W. 3,278,447 10/1966 McNicholas ............... 252/187.21 X Hicks, Rio Linda; Donald C. English, 4,084,747 4/1978 Alliger ....................... 252/187.23 X Carmichael, all of Calif. 4,104,190 8/1978 Hartshorn ...................... 252/187.21 4,330,531 5/1982 Alliger ................................ 424/149 73) Assignee: Rio Linda Chemical Company, Inc., Primary Examiner-Arthur L. Corbin Sacramento, Calif. Attorney, Agent, or Firm-Leonard Bloom (21) Appl. No.: 879,907 57 ABSTRACT An aqueous solution, preferably an aqueous disinfectant solution, containing chlorine dioxide and which is capa 22 Filed: Jun. 30, 1986 ble of forming a foam, and methods for the preparation and use thereof. An aqueous disinfectant solution capa Related U.S. Application Data ble of forming a foam is prepared adding a foaming agent, i.e., a suitable surfactant, to water. Chlorine diox 63 Continuation of Ser. No. 636,309, Jul. 31, 1984, aban ide may then be added to the solution or it may be doned. generated in situ by reacting an oxidizing agent, a cati onic exchange resin in the acidic form, or an acid with 51 Int. Cl.' ................................................ C11D 3/48 a metal chlorite dissolved therein. The resultant foam 52 U.S.C. ........................................ 252/95; 134/42; solution may subsequently be foamed by being mixed 252/90; 252/100; 252/106; 252/187.21; 422/29; with air in a foam generator. The foam solutions of the 422/37 instant invention are useful as cleaning and/or sanitizing 58) Field of Search ...................... 134/36, 42; 252/95, agents. 252/100, 103, 106, 187.21, 187.22, 307, 90; 422/29, 37; 423/477; 424/149 2 Claims, No Drawings 4,731, 193 1 2 ties as well as its extremely fast rate of disinfection. The AQUEOUS FOAM CONTAINING CHLORINE use of chlorine dioxide in a foam system would greatly DOXDE COMPOSITION AND PREPARATION enhance the art of sanitizing. THEREOF Prior to this invention, the use of chlorine dioxide in 5 foams or foam cleaners for the disinfection of microor This application is a continuation, of application Ser. ganisms was not known. Chlorine dioxide is irritating No. 636,309, filed July 31, 1984, now abandoned. and has a very noxious odor at concentrations as low as 0.5 ppm in a water system. Moreover, chlorine dioxide BACKGROUND OF THE INVENTION does not undergo hydrolysis so its irritating and noxious It is widely recognized in commercial packing and 10 properties persist. It was previously thought that it was food processing plants as well as in the paper and phar impossible to use chlorine dioxide in an aqueous foam maceutical industries, as well as other industries, that system at relatively high chlorine dioxide concentra cleaning and/or sanitizing of equipment can be greatly tions since its strong, unpleasant odor when dissolved in enhanced by the use of foam rather than high pressure water makes it impossible to spray at concentrations sprayed water. It is also common for these industries to 15 necessary to achieve sanitization in, for example, food utilize both portable and/or central clean-in-place sys processing plants where personnel are working in the tems to achieve and maintain sanitary conditions. close vicinity. A portable foam cleaner is usually a batch system, Another reason that chlorine dioxide has not previ one such system being disclosed in U.S. Pat. No. ously been used in a foam system at relatively high 3,797,744. Utilizing a plurality of tanks, a foam with or 20 chlorine dioxide concentrations is that it is such a strong without a sanitizer can be generated. The system utilizes oxidizing agent that it was thought that it would destroy compressed air and chemicals under pressure to gener or break down the organic compounds that make up the ate foam through a foam generator. foam generating chemical. Another reason that chlorine A central clean-in-place foam system utilizes a con dioxide has not previously been used in a foam system is tinuous process. The foam generating chemical and the 25 that it was thought that the chlorine dioxide would sanitizing chemical are usually educted into a large undergo rapid degradation and lose its disinfectant and mixing tank along with the water driving the eductor. biocidal properties. An automatic level control activates the eductor water Surprisingly, the use of chlorine dioxide in a foam source to keep the tank filled at all times. Feed-rates, system, in accordance with the practice of this inven and thus concentrations and foam characteristics, can 30 be controlled by use of rotometers. From the mixing tion, does not result in any chlorine dioxide odor at tank, the solution is pumped under pressure throughout relatively high concentrations up to 1200 ppm. More the plant to the individual foam generating stations. A over, it does not destroy the organic foam generating gas, such as compressed air, is introduced at this point to compounds. In effect, if formulated correctly, the chlo generate the foam. The foam is then delivered through 35 rine dioxide foam solution of this invention is very sta a hose or otherwise conducted to the surfaces to be ble and produces a foam of exceptionally high quality. cleaned and sanitized. U.S. Pat. No. 3,823,727 discloses In addition, it has been found that chlorine dioxide in one type of foam generating station utilized in a central foam solutions is very stable and remains potent as a foam system. Many other types are currently on the biocide for up to at least 72 hours or even longer. market. The term "foam solution' as used herein means an The foam covers and adheres to the surface to be aqueous disinfectant solution containing a foam generat cleaned. Some cleahing, penetrating and loosening ac ing chemical and which is capable of producing a foam tion can occur, depending on the formulation of the when mixed with a gas such as air in, for example, a foam generating chemical. To achieve microbiological foam generator. The foam generating chemical is typi control, a sanitizer, or disinfectant chemical, is used in 45 cally one or more surfactants. A suitable surfactant may the foam system. be cationic, nonionic, or anionic, as long as it is capable One of the advantages of using foam to achieve mi of forming an aqueous foam. The choice of surfactant is crobiological control is that, since it adheres to the within the skill of the art. The disinfectant is primarily surface and remains for a period of time, it allows more chlorine dioxide. time for the disinfectant to do its work. Although the 50 Three well known reactions for generating chlorine foam prolongs the contact time, those disinfectants that dioxide from sodium chlorite are as follows: have rapid rate of kill are preferred in order to obtain the maximum benefit. 2NaClO2-Cl2-2ClO2--2NaCl (1) The sanitizing, or disinfectant, chemical is essential in 2NaClO2+HOCl-2CO2+-NaCl-NaOH (2) order to obtain the desired destruction of the microor 55 ganisms, e.g., bacteria, molds, fungi, spores, and viruses. 5NaClO2-4HCl-4ClO2+5NaCl-I-2H2O (3) Common inorganic disinfectants currently in use are exemplified by chlorine and iodine. Examples of or Equation (1) exemplifies the generation of chlorine ganic disinfectants are carbamates or quaternary ammo dioxide by the action of an oxidizing agent, i.e., chlo nium compounds. Although the foregoing disinfectants rine, on a metal chlorite, i.e., sodium chlorite. Equation are somewhat effective and are widely used in the cur (2) exemplifies the generation of chlorine dioxide by the rent state of the art, they have many limitations. The use action of an oxidizing acid, i.e., hypochlorous acid, on a of a more powerful, more rapid disinfectant would metal chlorite. Equation (3) illustrates the production of greatly enhance the sanitizing effectiveness of foam chlorine dioxide by the action of an acid, i.e., hydro systems. 65 chloric acid, on a metal chlorite. It will be understood The use of chlorine dioxide in many disinfection ap that the above reactions are not limited to the metal plications is growing widely because of its superior chlorite, oxidizing agents and acids illustrated and that bactericidal, sporicidal, fungicidal, and viricidal proper the choice of reactants is within the skill of the art. 4,731, 193 3 4. By means of the foregoing reactions, chlorine dioxide The foregoing and other objects are accomplished by may be obtained by, for example, use of a commercially the practice of this invention. Broadly, viewed in one of available chlorine dioxide generator and dissolved in its principal aspects, this invention consists of an aque the foam solution. A chlorine dioxide generating appa ous solution having disinfectant properties and the ca ratus is described in U.S. Pat. No. 4,247,531. Alterna pability of forming a stable foam, said solution compris tively, chlorine dioxide may be generated in the foam ing a major proportion of water having dissolved solution via one of the above reactions. therein an effective amount of a foam generating agent U.S. Pat. No. 2,392,936 discloses aqueous oxidizing and an effective amount of chlorine dioxide wherein foam solutions which are taught to be useful in decon said chlorine dioxide may be generated outside the solu taminating areas contaminated with, for example, nox 10 tion and subsequently dissolved therein, or it may be ious or poisonous chemicals.

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