WO1999033335A2

WO1999033335A2 - Composition and method for making a cat litter using ionic aluminosilicates

Info

Publication number: WO1999033335A2
Application number: PCT/US1998/027858
Authority: WO
Inventors: George A. Trabits
Original assignee: Addwest Minerals
Priority date: 1997-12-30
Filing date: 1998-12-30
Publication date: 1999-07-08
Also published as: AU2209699A

Abstract

The present invention provides an antimicrobial composition and a method for making the same. The antimicrobial composition comprises an aluminosilicate containing a transition metal ion. Preferably, the aluminosilicate is a zeolite, and more preferably clinoptilolite. The composition may be used as a litter to control odor.

Description

COMPOSITION AND METHOD FOR MAKING A CAT LITTER USING IONIC ALUMINOSILICATES

FIELD OF THE INVENTION

This invention relates to a method and a composition of aluminosilicates containing transition metal ions which are useful in inhibiting the growth of odor causing microbes in a litter and other odor inhibiting products.

BACKGROUND OF THE INVENTION

Most cat litters are composed of layered aluminosilicates and blends of three-dimensional porous aluminosilicates. Layered aluminosilicates include natural clays such as bentonite, palygorskite, montmorillonite, attapulgite and others. Three dimensional porous aluminosilicates include naturally occurring zeolites such as clinoptilolite and others. The preferred properties of all cat litters include absorption, odor control and longevity. Absorption is the penetration of a substance into the body of another, generally that of a fluid into the body of a solid. For cat litters, absorption is important to "trap" and contain urine. Odor control is a necessary quality of any cat litter since cat litter boxes are typically kept indoors. Thus, the occurrence of any odor is a significant problem with cat owners. Longevity relates to how often the cat litter in a litter box needs to be changed. For example, a litter box that requires the cat litter to be changed after each use by a feline would be of little value to the cat owner. Accordingly, longevity is directly dependent upon the formation of odor and, as perceived by the cat owner, the need to change the litter.

Cat litters that have a tendency to clump have a longer useful life than regular cat litters. Clumping or scoopable litters have the ability to form a clump of the litter material when it becomes wet with urine. This clump is then scooped out of the litter box by the cat owner and disposed of. Such mechanical maintenance of the litter box prolongs the life by removing the encapsulated waste. One particular key to the effectiveness of a clumping litter is the strength of the clump. When a cat covers the freshly soiled area, its covering action has the tendency to break the clump apart. Accordingly, not all the soiled litter will be removed during the maintenance performed by the cat owner. Clumping litters, consequently, still need to exhibit odor control capabilities.

Odor formation in cat litter is a biological process that is largely dependant upon bacterial action. Cat urine and fecal material naturally contain bacteria. Once inoculated by the cat, the litter box provides a favorable environment for bacteria growth. The moist conditions provided by urine along with the large surface area provided by the cat litter result in rapid bacteria development. Ammonia formation begins once the bacterial action has started. The formation of ammonia is the major odor associated with the litter box. In addition to the aforementioned bacterial action, research has shown that yeast, mold and fungi can develop in the litter box creating additional malodorous conditions. Two primary methods have been employed to control odor in an attempt to prolong the usable life of the cat litter. These methods include the addition of perfumes and chemical coatings. Perfumes are added to many cat litter products and serve only to mask odor. Perfumes do not inhibit odor formation but only hide urine odor with a stronger, less onerous fragrance. Chemicals such as hypochlorite and chlorine dioxide have been added as surface coatings on cat litter to suppress bacteria. Surface coatings are limited in effectiveness and tend to decrease litter porosity and thus interfere with odor absorption. Both perfumes and chemical coatings pose certain health risks for adults and children as well as cats. Some people have sensitivities to perfumes and can experience allergic reactions. Additionally, cat litter is a common household item that can easily come into contact with small children and be accidentally eaten. Cats are also at risk due to direct contact with the litter and the tendency to lick their paws during grooming, thereby ingesting treated particles. Additionally, chemical coatings can irritate the paws of cats and cause respiratory problems if the litter is dusty.

Based on the numerous aforementioned problems associated with conventional cat litters, there remains a need to provide a cat litter material that safely eliminates the formation of odor, and which has a long, useful life.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a safe cat litter material which has superior odor suppression qualities, improved absorption rates and which can be manufactured in a cost effective manner. To achieve this object is based on the recognition that certain metal ions are toxic to microorganisms and can result in microbe death or inhibit reproduction, and that these metals can be preferentially exchanged with cations of ionic aluminosilicate cat litters. Further, by inhibiting microbe growth, odor formation can be significantly prevented.

The present invention provides a distribution of selected metal ions on the surface areas and microporous framework cavities of the aluminosilicate. The ion exchange process of the present invention does not plug or obstruct the aluminosilicate pores, and therefore does not interfere with odor absorption. The present invention provides a microbicidal metal in aluminosilicate in a form that is bioavailable to the organism, thus causing microbe death or reducing reproduction.

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a composition and a method for making an antimicrobial material which substantially inhibits the growth of microbes.

One particular embodiment of the present invention provides a composition and a method for inhibiting odor formation in cat litter. The present invention can also be used in odor control for the litter of other household pets as well as applications for odor control in horse stalls, dairy barns, hog lots, cattle feed lots and any other area where an odor control is desired. Thus, the present invention has universal applications in environments where odor suppression is desired as a result of animal urine or where high liquid absorption rates are desirable.

The present invention can also be used in litters in confined laboratory animals where a sterile environment is required, or in veterinary hospitals to prevent the spread of disease.

The present invention can further be used as air filtration systems in heating, cooling and ventilation systems as well as air conditioner condensate pans to retard the growth of odor causing bacteria, molds and fungi including the elimination of human pathogens such as Legionnaire's disease.

The composition of the present invention can also be used to selectively kill or inhibit bacteria or molds or fungi while allowing non-targeted microbes to thrive. This can be accomplished by selection of a metal or metals at a concentration toxic to the target microbe but not toxic to the non-targeted microbes. Such a composition can be used as a soil amendment or as a metal exchanged ionic aluminosilicate treatment bed in waste water processes to eliminate harmful microbes while not having any detrimental affect on beneficial microbes. The composition of the present invention can also be used for disrupting the food chain of higher organisms which rely on bacteria or molds or fungi to process otherwise indigestible organic or inorganic material. For example, organisms such as termites, fireants and other insects could feasibly be controlled.

The composition of the present invention can also be used as an additive to paints, foot powders, tile grout, bathroom caulking, outdoor caulking, roofing shingles, dry wall board, wood treatments and concrete to retard the growth of molds and fungi.

In one aspect of the invention, metal ions can be successfully exchanged with ionic aluminosilicates and that these metal ions exhibit varying degrees of microbial control. Preferably, the metal ion is a transition metal ion and any other metal ion which has an antimicrobial activity. More preferably, the metal ion is selected from the group consisting of zinc, copper, silver, titanium, nickel, silver, iron, cobalt, chromium, and mixtures thereof. In one particularly preferred embodiment of the present invention, the aluminosilicate is contacted with a ZnS0₄ solution under a condition and time sufficient to load 256 to 282 ppm of zinc per 10 grams of aluminosilicate. Alternatively, about 6 g of zinc is present per kilogram of aluminosilicate. Such composition can be prepared by, for example, contacting 1 M solution of a zinc salt with the aluminosilicate for about 0.2 h at room temperature and drying the resulting aluminosilicate.

In another preferred embodiment of the present invention, aluminosilicate is contacted with a CuCl₂ solution under a condition and time sufficient to load 416 to 588 ppm of copper per 10 grams of aluminosilicate.

In still another preferred embodiment of the present invention, aluminosilicate is contacted with a CuS0₄ solution under a condition and time sufficient to load 368 to 371 ppm of copper per 10 grams of aluminosilicate.

In another aspect of the present invention, a method for manufacturing the antimicrobial aluminosilicate cat litter is provided. The process includes contacting the aluminosilicate with a 1.0% weight percent solution of the metal salt and stirring the mixture for about two hours. The aluminosilicate is then removed and dried, for example, in a fluid bed drier at a temperature of about 100°C, until the final moisture of aluminosilicate reaches from about 10 to about 15 percent. As appreciated by one skilled in the art, the time of exposure, concentration and temperature may be modified depending on numerous factors such as the ambient humidity, the entrained moisture in the aluminosilicate, etc. Alternatively, the antimicrobial aluminosilicate can be prepared by spraying the aluminosilicate with the metal salt solution; for example, this can be achieved by passing the aluminosilicate beneath a spray bar on a moving conveyor. The moving conveyor can be made to turn the aluminosilicate during the process so that all surfaces become moistened with the metal salt solution. The aluminosilicate is then thermally or air dried to a final moisture content of from about 10 to about 15 percent.

Yet another method for preparing the antimicrobial aluminosilicate includes contacting the aluminosilicate to a fume of a metal salt, e.g., a zinc metal salt such as zinc chloride or zinc sulfate, in an enclosed vessel at a controlled temperature and pressure. In this process the metal salt is heated until it becomes a vapor. The metal salt vapor is then contacted with a bed of aluminosilicate. The aluminosilicate can then be removed in a dry state. It should be recognized, however, that at high temperature some aluminosilicate may decompose or the structure of the aluminosilicate may change. Therefore, the metal salt should be heated below this aluminosilicate decomposition temperature. For example, when a zinc salt is vaporized and contacted with zeolite, the vaporization temperature is kept at below about 1100 °F. Preferably, the zinc salt is heated to about 500 °F.

Additional objects, advantages, and novel features of this invention will become apparent to those skilled in the art upon examination of the following examples thereof, which are not intended to be limiting.

EXAMPLES Examples 1-10

These examples illustrates the amount of metal incorporation into the aluminosilicate using a various concentration of metal salt solutions.

For the test, metal ion solutions were sampled before and after exposure to the aluminosilicate and then analyzed for metal content by Atomic Absorption Spectrophotometry. Preferably, loading for CuS0₄ and ZnS0₄ is 0.5% solution. As used in this invention, "loading" refers to an ion exchange wherein the metal ions in the solution becomes incorporated into aluminosilicate.

Table 1 as shown below, presents the results of the testing of metal ions:

Table 1. Atomic Absorption Results Metal Exchange Capacity

While the zinc ion provided superior antimicrobial qualities in the present invention, other metal salts including, but not limited to, other zinc metal sources such as ZnCl₂, and titanium salts, iron salts, cobalt salts, nickel salts, chromium salts, silver salts and any other metal salts which has antimicrobial activity can be used.

Examples 11-22 These examples illustrates the effect of aluminosilicate containing a metal ion on the microbial growth.

A study on the effects on microbial growth was carried out by variously exchanging metal ions with an aluminosilicate. The metal ions exchanged were those of zinc and copper. The aluminosilicate used was clinoptilolite. The cation exchange capacity of the clinoptilolite used averaged between 1.8 and 2.2 meg/g. Prior to ion exchange the clinoptilolite was sized to a 20X40 mesh material which approximated a clumping cat litter and a 8X20 mesh material which approximated a regular cat litter. This sized material was then exposed to 0.1%, 0.5% and 1.0% weight percent solutions of ZnS0₄, CuCl₂ and CuS0₄. Following preparation of the ion exchanges 25 grams of urine-contaminated cat litter was homogenized in 225 mL lOmM phosphate buffer at pH 7. The homogenate was serially diluted in molten trypticase soy agar at 44 °C and poured into 100 X 15 mm standard petri dishes at 15 mL/plate. After cooling, the ion exchanged clinoptilolites were placed on top of the agar approximately 2 cm from the edge of the plate and allowed to stand for 15 minutes at room temperature. The plates were then inverted and incubated at 37° C for 72 hours. The diameter of inhibition of microbial growth around each exchanged clinoptilolite was measured at 24, 48 and 72 hours. Results of the microbial procedure are summarized in Table 2 below: Table 2. Relative Effects on Microbial Growth

Microscopic examination showed that microbial growth, including yeast-mold-fungi and bacteria, is substantially inhibited by the ion exchanged clinoptilolite. Control sample, i.e., Example 17, of non-ion exchanged clinoptilolite did not inhibit microbe growth. Samples of two typical "antibacterial" chemically treated commercial cat litters, i.e., Examples 21 and 22, produced minimal to no inhibition of microbe growth. Subsequent testing of the present invention as a household litter demonstrated an improvement in odor control with a corresponding increase in the useable life of the cat litter. Without being bound to any one particular theory, the effectiveness of the present invention in controlling odor is believed to be associated with the selection of a metal ion whose cation exchange selectivity is less than that of ammonia.

Those skilled in the art will appreciate that numerous changes and modifications may be made to the preferred embodiments of the invention and that such changes and modifications may be made without departing from the spirit of the invention. It is therefore intended that the appended claims cover all such equivalent variations as fall within the true spirit and scope of the invention.

Claims

What is claimed is:

1. An antimicrobial composition comprising an aluminosilicate containing a transition metal ion in an amount effective to inhibit the growth of a microbial organism.

2. The antimicrobial composition of Claim 1, wherein said aluminosilicate is a zeolite.

3. The antimicrobial composition of Claim 2, wherein said zeolite is clinoptilolite.

4. The antimicrobial composition of Claim 3, wherein said transition metal ion is selected from the group consisting of zinc, copper, silver, titanium, nickel, silver, iron, cobalt, chromium, and mixtures thereof.

5. The antimicrobial composition of Claim 3, wherein said transition metal ion is zinc.

6. The antimicrobial composition of Claim 5, wherein the ratio of said zinc to said clinoptilolite is at about 6 g/Kg.

7. The antimicrobial composition of Claim 3, wherein said transition metal is copper.

8. The antimicrobial composition of Claim 7, wherein the amount of copper present in said clinoptilolite is from about 416 ppm to about 588 ppm per 10 grams of clinoptilolite .

9. The antimicrobial composition of Claim 1, wherein said composition is used as an animal litter for controlling odor.

10. A cat litter composition comprising an aluminosilicate containing an odor-controlling-effective amount of a transition metal ion.

11. The litter composition of Claim 10, wherein said aluminosilicate is a zeolite.

12. The litter composition of Claim 11, wherein said zeolite is clinoptilolite.

13. The litter composition of Claim 12, wherein said transition metal ion is selected from the group consisting of zinc, copper, silver, titanium, nickel, silver, iron, cobalt, chromium, and mixtures thereof.

14. The litter composition of Claim 13, wherein the ratio of said transition metal to said clinoptilolite is about 6 g/Kg.

15. A method for producing a cat litter composition comprising contacting an aluminosilicate with a transition metal salt.

16. The method of Claim 15, wherein said aluminosilicate is clinoptilolite.

17. The method of Claim 15, wherein said transition metal salt is selected from the group consisting of zinc salts, copper salts, silver salts, titanium salts, nickel salts, silver salts, iron salts, cobalt salts, chromium salts, and mixtures thereof.

18. The method of Claim 15, wherein said transition metal salt is in a solution.

19. The method of Claim 18, wherein the concentration of said transition metal salt solution is about 1 M.

20. The method of Claim 18, further comprising drying said aluminosilicate.