Cat litter boxes are stinky due to volatile sulfur-containing decomposition products of cat waste. Probably in nature these products help cats mark territory. In the home, they just stink.
Reduced sulfur compounds can be treated with oxidation, which kills the associated odors. This process can be catalyzed by copper ions (citation 1). In the petrochemical industry, molecules with reduced sulfur are removed by oxidation catalyzed by copper catalysts. Rather than invent something new for use in kitty litter, products currently on the shelf for this use could be added to kitty litter. These products would already be optimized for cost, surface area, toxicity and other properties all desirable in a kitty litter. Citation 2 is a link to a product brochure for the PERCO copper catalyst, which already has a more than passing resemblance to kitty litter to my eye. It is provided as an example of a commercial copper catalyst; there may be others better suited for the kitty litter application. I called and learned the PERCO copper catalyst costs $2.50/lb when bought in bulk which to me looks reasonable. One would do experiments to find the optimal ratio of catalyst to conventional kitty litter or filler.
An alternative would be to simply dope an existing kitty litter product with a solution of liquid copper sulfate then bake it dry. I suspect the PERCO product is probably something very like this. A zeolite type kitty litter would absorb the copper and so function as described above, in addition to the other advantages of zeolite litter. This would be very cheap and easy to test.
In addition to oxidizing sulfur molecules, an added benefit to the use of copper for kitty litter is that copper ion has strong antimicrobial properties, a quality which has been recognized and applied for over a century (citation 3). The presence of copper ion dissolved by the passage of cat urine should decrease the microbial propulations whose metabolism is responsible for the generation of malodorous sulfides.
As fortune would have it, in the months since devising this idea a cat has arrived at our house. I got to experience kitty litter smell for the first time and remembered this scheme. Preliminary tests (copper sulfate solution sprayed on litter during gentle mixing with trowel, no baking) suggest that it works well to reduce odor. Copper sulfate was obtained at HomeDepot where it is marketed as root killer. Cat seems healthy. I invite other bakers to give it a try and submit their results.-- bungston, Aug 19 2011 http://www.springer...t/xv0665038465n0g1/ Conjugated oxidation of thiols and amines in the presence of copper complexes. G. Tarkhanova, M. G. Gantman, A. O. Chizhov and V. V. Smirnov Reaction Kinetics, Mechanisms and Catalysis Volume 101, Number 2, 267-278, DOI: 10.1007/s11144-010-0230-y [bungston, Aug 19 2011] (?) Brochure for PERCO copper catalyst, used to “sweeten” petrochemicals by catalyzing oxidation of reduced sulfur molecules. http://www.chemical...a/PERCObrochure.pdf [bungston, Aug 19 2011] (?) 3. http://www.ncbi....thpap00006-0179.pdf H. W. Clark and Stephen DeM. Gage. On the Bactericidal Action of Copper Public Health Pap Rep. 1905; 31(Pt 2): 175–204. PMCID: PMC2222273 [bungston, Aug 19 2011] I wish litter was a bit heavier (would this help?) - fluffy kicks the damned stuff all over the house.-- po, Aug 19 2011 Kicking it around probably helps reduce smell: more surface area exposed to air, more oxidation. I have seen various schemes to address scatter including top-entry cat litter boxes, boxes with high sides etc.-- bungston, Aug 19 2011 If you add iron filings to your cat's food, not only will you help to prevent it from becoming anaemic, but you can also use a powerful magnet to contain and/or collect the excrement. Or indeed the cat.-- MaxwellBuchanan, Aug 19 2011 I think the filings would oxidize as they traversed the cat, and so lose their magnetizability. There must be another word for magnetizability.-- bungston, Aug 19 2011 Magnetic permiability, but iron oxide still has it.-- MechE, Aug 19 2011 You are saying rust dust is magnetic?-- bungston, Aug 19 2011 // Cat seems healthy. //
Major, major snag, then.
Not an idea for electroplating cats with copper, then ?-- 8th of 7, Aug 19 2011 Reminds me of my project where copper and zinc compounds were fed to cats in an effort to make brass shell casings. Project was discontinued by the QA Dept due to caliber inconsistencies. Stupid cats.-- AusCan531, Aug 20 2011 More seriously [bungston] I think your idea has merit but disposal of the end product (no pun intended) would be an issue. Cumulative buildup of CuSO4 around your yard probably wouldn't be nice.-- AusCan531, Aug 20 2011 yes cumulative copper would kill plants. Must be trashed.-- bungston, Aug 20 2011 Stupid plants.-- AusCan531, Aug 20 2011 Would the CuSO4 be toxic to the family dogs that see the kitty box as an alternative to the doggie bowl? [+]-- Klaatu, Aug 21 2011 in nature, their dung smells like nothing. Try feeding you cat pure raw meat. You will be blown away.-- fishboner, Aug 21 2011 I've been meaning to ask you [21 Quest], any relation to Jonny? Is the good Dr. still with us? How about Race Bannon - long retired I suppose.-- AusCan531, Aug 21 2011 random, halfbakery