WATE;R TREATM~NT BLEND IN SOLID FOE~M
Compositions which release chlorine into aqueous ~ media have been ~ound to be generally useful, such as ; for pr~paring a sterilizing solution~ For example it -~ has been taugh~ in U.S. Patent No. 4,134,0Z4 to sterilize an article at a temperature below that of boiling water with a sterilizing solution having active chlorine. A variety o~ ingredients havP been proposed for such a sterilizing solution. These ingredients include hypochlorite salts, toluene sulfochloroamide compounds, chlorine dioxide, chlorinated hydantoin, and trichloroisocyanuric acid and ;~ salts thereof.
Chloxine-containing compositions may also be utili~ed for treatment o~ specific media, e.g., swimming pools. In such use, compounds can be provided in a dispenser and the chemicals for water treatment thereby dispensed to the swimming pool.
Suitable chlorine donor chemicals that have been disclosed, e.gO, in British Patent NOr 1,327,763, include the chlorocyanuric acids, calcium hypochlorite and the halogenated hydantoins. It has also been known to provide a chemical dispenser of disinfecting agent ~:
for a toilet tank. As disclosed in U.S. Patent No.
4,709,423 such a dispenser for providing a disinfactant solution may contain a disinfectant such as halogenated hydantoin, trichloroisocyanuric acid, and inorganic hypochlorite salts, e.g., the salts of calcium, lithium and magnesium.
Compositions providing available chlorine may also be useful in dishwasher detergent compositions. Thus there has been disclosed in U.S. Patent No. 4,284,524 a cleaning composition for automatic dishwashers, which composition can contain available chlorine at a level of from about 0.5 to about 3 percent. To provide the available chlorine, there may be used chlorinat:ed trisodium phosphate as well as other materials such as chloroisocyanurates, chlorinated hydantoin, toluene sulfodichloroamides, hypochlorite salts, chlorinated melamine, chlorinated succinimide, or N-chloroacetyl urea and the like.
It has usually been proposed to provide various blends or mixtuxes of ingredients for thesa specific treating composition. For example U.S. Patent No.
4,709,423 recommends a mixture of trichloroisocyanuric acid plus cyanuric acid. British Patent No. 1,327,763 recommends a mixture containing cyanuric acid or salt thereo~. U~S. Patent No~ 3, 629,408 discloses a combination of hypochlorite salt with a chlorinated glycoluril.
It would however still be desirable to provide a disinfectant composition that combines a great variety of desirable charactaristics, e.g., economy of manufacture, enhanced disinfectant quality and controlled dissolve rate.
SUMMARY OF THE~ E~
There has now been devised a water treatment 3~
composition, in solid form, having much sought after disinfection characteristics for aqueous media. If desired, the composition will provide prolonged, controlled dissolve rate to such media. Moreover, the composition can exhibit viricidal properties in use, combined with extended shelf stability before use. The composition furthermore has suitable low toxicity in handlingt stoxage and use.
In one aspect, the present invention is directed to a new composition of matter comprising a solid composition in the form of particles blended together of one or more alkali metal or alkaline earth metal hypochlorite with one or more N-halogenated dialkylhydantoin. A particularly preferred blend is calcium hypochlorite with 1-bromo-3-chloro-5,5-dimethylhydantoin.
In anothex aspect the invention is directed to the method of treating an a~ueous media to provide available chlorine to such media.
2 0 DESCRIPTION OF THE PREFERRED EMBODIMI~NTS
The composition of the present inv~ntion can be used for treating a variety of fluid media. For example in water txeatment, it may be used generally to provide available chlorine to media containing biologically active components such as bacteria and viruses, e.g., it may be utilized for treating aqueous sewage rnedia, plant effluent, cooling towers, lagoons and secondary water recovery. The composition can also be used for specialty water treatment, e.g., in swimming pools. In general, the composition w.ill be utilized ~or providing available chlorine to media for bleaching, steri.lizing and disin~ecting appllcations.
The composition will provide available chlorine to the media to be treated. It is to be understood that 3~
the composition might not only dispense available chlorine, but may also provide bromine. Whether the composition provides chlorine or bromine or both, for purposes of convenience, unless otherwise expressly detailed, this will be referred to hereinafter simply as available chlorine. It will thereby be understood that when the word "halogen" is used herein, such will refer to chlorine, bromine, or bo-th.
The available chlorine is expressed as the amount, as a percentage, of the halogen, i.e., chlorine or bromine or both, that is available based upon the total of such halogens present in the solid composition. This availability may be determined by titration of an aqueous solution of the composition, such as with sodium thiosulphate. This available chlorine may therefore also be referred to as titratible chlorine. Although providing a high degree of available chlorine, the composition of the present invention has a most desirable low toxicity. Yet it will nevertheless provide excellent disinfection as well as viricidal characteristics while providing for bacteriological stabilization of aqueous media.
The hypochlorite, which may also be referred to herein as the hypochlorite salt, will be an alkali metal or alkaline earth metal hypochlorite. The metal of the salt will most often be sodium, potassium, lithium, calcium or magnesium. Mixtures of these salts may also be used, such as mixtures includin~ alkali metal plus alkaline earth metal salts, e.g., lithium hypochlorite mixed with calcium hypochlorite. Preferably for economy of the composition as well as efficiency of available chlorine, the hypochlorite salt will simply be calcium hypochlorite. In the blended, solid composition the hypochlorite salt can be expected to provide from about 65 to 75 percent available chlorine, or about 55 to 75 percent available chlorine in the composition.
: ' ~
The hydantoin used will be an N-halogenated dialkylhydantoin. The halogen for this hydantoin will be one or more of chlorine or bromine. For example, there may be used 1-bromo-3-chloro-5,5-dimethylhydantoin (which may be referred to hereina:Eter simply as "BCDMH"). Advantageously for economy, the alkyl of the dialkylhydantoin will be either or both of methyl or ethyl. For example there may be supplied as the hydantoin 1,3-dichloro-5-ethyl-5-rnethylhydantoin. The hydantoin used can be expected to provide from 4~ to 72 percent available chlorine or about 0.5 to 18 percent available chlorine in the composition as either bromine or chlorine or both. In addition to the hydantoins mentioned above, other suitable compounds that may be used include 1,3-dibromo-5,5-dimethylhydantoi.n and 1,3-dichloro-5,5-dimethylhydantoin. Additionally, mixtures of hydantoins may be utilized in the composition. For example a mixture containing a minor amount of 1,3-dichloro-5-ethyl-5-methylhydantoin may be useful where the major portion of the mixture is supplied by 1,3-dichloro-5,5 dimethylhydantoin~ It is to be understood that for economy the hydantoins that will be used will most always be the commercially available materials that can range from about 90 to more than 99 percent active ingredient, with a balance typically of incidental inerts. Preferably for efficient dispensing of available chlorine, the hydantoin used will be BCDMH.
The hypochlorite salt may be available in powder or flake form. However, other particulate, solid form, e.g., granules, can be particularly serviceable, especially where such are comminuted prior to use.
Usually, for blending with the hydantoin, the hypochlorite salt will be a free-flowing particulate having particle size within the range from about 12 to about 100 mesh. Hypochlorite salt more finely divided than about 100 mesh can lead to problems such as dusting 3~
when blending with the hydantoin. Salt particles of greater size than abou~ 12 mesh will most always detract from obtaining a uniform blend of the solid particulates. Preferably, for best blending the hypochlorite salt will be a granular material having a particle size within the range of from about 16 mesh ko about 40 mesh.
The hydantoins are usually commercially available as dry, free-flowing solids in powder or granular or flake form. Typically, as with the hypochlorite salts, the hydantoin will be in granular form and will have particle slæe from about 12 to 100 mesh. For initiating preparation of the composition, as with the hypochlorite salt, it is preferred to start with a hydantoin in granular form, e.g., to avoid dusting during blending.
- In preparing the composition, there will be used from 75 to 99 weight percent of the hypochlorite salt and from 1 to 25 weight percent of the hydantoin, basis 100 weight percent of these ingredients. UsP of less than about 75 weight percent of the hypochlorite salt will be insufficient for providing desixeable available chlorine. On the other hand, less than about 0.9 weight percent of hydantoin will be insufficient to provide beneficial effect from the hydantoin. These materials in finely divided form, e.g., as granules, can then be brought together by any mixing means, preferably by mechanical mixing means which are typically utilized for forming blends of dry ingredients. These may include, for example, stirring and tumbling means or the like.
It is advantageous that mixing be carried out in such a manner that the particle size of the ingredients being mixed is not appreciably altered during the mixing of the dry materials. A preferred dry blending operation is accomplished with a ribbon blender. Particularly where the blending is initiated with ingredients in very finely divided form, and the blending operation is to . ' ', form granules of the ingredients in mixture, the~e may be utili~ed a granulating operation, e.g., roller compacting of a moistened ingredient mix followed by granulating. By any manner of blending there will result a solid, particulate composition which will typically have a highly desirable shPlf stahility on storage, e.g., as a packaged blend of particulate solids. In use, the particles may for example be simply mixed with a liquid medium for desired treatment, or the liquid can flow by, e.g., through or over, the solid, water treatment blend particles.
It is to be understood that there may be present in the composition additional ingredients, such as binding agents, surface active agents, and the like.
For a representative composition there was blended together a commercial grade, granular calcium hypochlorite having a particle size between 16-40 mesh and containing 72-75 percent available chLorine. With this calcium hypochlorite there was blended a commercially available, 1-bromo-3-chloro-5,5-dimethylhydantoin ~BCDMH). This commercial BCDMH was 93.5 percent active ingredient, with a balance of incidental inerts, having about 59 percent available chlorine and was a granular material having particle size between 12-40 mesh. The blending was done for about 10 minutes in a double spiral blade ribbon blender. The resulting blend was a white granular solid and contained 5 weight percent BCDMH and 95 we:ight percent calcium hypochlorite, the water having been essentially volatilized during the blending operation.
This solid granular composition was 70 percent minimum active halogen, expressed as available chlorine. The pH
of a 1 percent solution of this solid, granular mixture, as determined by dissolving 1 gram of the blend in 100 milliliters of deionized water, was 9.15 at 20 C.
: ' .; ' .