Compositions – Oxidative bleachant – oxidant containing – or generative – Free halogen or oxy-halogen acid type
Reexamination Certificate
1999-02-25
2001-03-06
Warden, Jill (Department: 1743)
Compositions
Oxidative bleachant, oxidant containing, or generative
Free halogen or oxy-halogen acid type
C252S186100, C252S187100, C252S187230, C252S187240, C252S187250, C252S187260, C252S187270, C252S187280, C252S187290, C252S187300, C424S661000
Reexamination Certificate
active
06197215
ABSTRACT:
FIELD OF THE INVENTION
The invention finds applicability in fields where chlorine dioxide is generally used and particularly in the fields of disinfection and odor treatment and demand studies.
BACKGROUND OF THE INVENTION
The inventor has been working on developing solid mix formulations which will allow the preparation of small quantities (normally one liter, but the same mix can be used to prepare up to 300 gallons or more) of an aqueous chlorine dioxide solution at repeatable and reproducible concentration of up to and beyond 3000 mg/l.
Prior Art Patents
The chemistry for producing chlorine dioxide is well known and has been the subject of at least two patents, U.S. Pat. No. 5,399,288 and U.S. Pat. No. 4,104,190.
Marzouk et al in U.S. Pat. No. 5,399,288 teaches solid chlorine dioxide releasing compositions involving the use of a triazinetrione.
Hartshorn in U.S. Pat. No. 4,104,190 discloses a dry composition for releasing chlorine dioxide containing dichloroisocyanurate as the chlorine releasing compound.
The prior art does not teach lithium hypochlorite in chlorine dioxide releasing compositions as taught by the herein disclosed invention.
Chlorine dioxide is a powerful, selective oxidant which finds use as a drinking water disinfectant, in cooling tower bilogical control, as a paper pulp bleach, a disinfectant in fruit, vegetable and poultry processing, for oil well and water injection well stimulation, in wastewater treatment, as an algaecide, and as an odor control agent. Almost all applications use gaseous chlorine dioxide as a dilute aqueous solution, usually at or below 3000 ppm. This solution cannot be supplied to the end user ready for use. Aside from the unattractive economics of shipping a solution which is 99.7% water, shipment is forbidden by the DOT. Unlike liquefied chlorine, the condensed liquefied gas cannot be prepared and shipped in cylinders because of its extreme shock sensitivity. As a consequence, it is necessary that chlorine dioxide be prepared on site at the time of use by combining the appropriate precursors in a chlorine dioxide generator. These precursors include aqueous solutions of sodium chlorate or sodium chlorite, mineral or organic acids, chlorine, sodium hypochlorite, or some combination of these, usually as aqueous solutions which are metered out in the appropriate amounts and combined under controlled conditions by the chlorine dioxide generator. The need for a generator has usually limited use of this oxidant to those situations which justified the expense of installing and maintaining the necessary equipment. Typically, the smallest generators commercially available make 30 pounds per day of gaseous chlorine dioxide. This invention allows the use of chlorine dioxide treatment in those situations where the product's unique capabilities are attractive, but which are too small to justify installation and use of a generator.
OBJECTS OF THIS INVENTION
The inventor expects there to be strong consumer interest in using non-toxic, inorganic dry mix packets to prepare chlorine dioxide and particularly for disinfecting drinking water. The inventor's intent is that the composition be employed both for short term use, such as, for preparing emergency drinking water, and for treating drinking water for daily consumption.
An important object of this invention is to provide a disinfecting composition without there being organic material being present.
The herein disclosed invention has for an object providing a convenient way to prepare small quantities of chlorine dioxide which are safe for treating drinking water or for disinfecting fruits and vegetables and like products.
Another object of this invention is to produce a product which will give consistent results for disinfecting drinking water and especially poor quality drinking water which might be available in emergency situations.
A further object of this invention is to produce a product which is non-toxic when used as directed.
A major object of this invention is to produce a dry mix formulation which produces hypochlorous acid precursor on addition of water to the dry mix and which does not introduce objectionable organic by-products.
A critical part of this invention is the incorporation in the mix of a component which rapidly generates hypochlorous acid on contact with water. The inventor has developed a formulation suitable for the disinfection of drinking water. The new formulation contains three components: lithium hypochlorite, sodium bisulfate and sodium chlorite. The inventor has found that when these three solids in various quantities are added to a suitable quantity of water, the solids dissolve completely within 45 seconds, and at the end of this brief period, have generated as much chlorine dioxide as the mix will form. The system generates chlorine above its solubility in water, and so the gas bubbles generated agitate the mixture and speed up reaction and solution of components. The rapidity of solution is surprising.
These and other objects of the present invention will become apparent from a reading of the following specification taken in conjunction with the enclosed drawing.
BRIEF SUMMARY OF THE INVENTION
The dry mix formulation which is the heart of this invention incorporates lithium hypochlorite, 25-30 weight % LiOCl; sodium hydrogen sulfate (synonym: sodium bisulfate), NaHSO
4
; and 80% dry solid sodium chlorite, NaClO
2
.
Regarding the LiOCl
2
25-30 wt %, the composition used in this invention is:
COMPONENT
WT %
Lithium Hypochlorite
25-30
Sodium Chloride
36
Sodium Sulfate
13
Potassium Sulfate
6
Lithium Chloride
4
Lithium Carbonate
2
Lithium Chlorate
2
Lithium Hydroxide
1
Water
7
The ingredients other than the lithium hypochlorite were inert and are not necessary to the performance of this invention. These inert components could be substituted with other inert compatible salts or the like as would be understood by those skilled in the art. A product providing the above formulation can be obtained from FMC Corporation or could be readily formulated by those skilled in the art.
The 80% dry solid sodium chlorite product employed in the examples of this invention is as follows:
COMPONENT
SPECIFICATIONS
Sodium Chlorite, wt % as NaClO
2
77.5-82.5
Sodium Chlorate, wt % as NaClO
3
4 max.
Sodium Chloride, wt % as NaCl
11-19
Sodium Hydroxide, wt % as NaOH
3 max.
Sodium Carbonate, wt % as Na
2
CO
3
2 max.
Sodium Sulfate, wt % as Na
2
SO
4
3 max.
Hydrogen Peroxide, wt % as H
2
O
2
0.01 max.
Water (by difference), wt %
6 max.
It is to be understood that the main active ingredient is the Sodium Chlorite and the other components are ancillary thereto and are deemed to be inert. These inert ingredients are not essential to the invention and could be replaced by other like inert ingredients as readily understood by those skilled in the art.
In its preferred embodiment, the lithium hypochlorite and sodium bisulfate are packaged together in one pouch or container, and the sodium chlorite is packed separately in another pouch or container which may or may not be connected. This two-packet system has two purposes; one is to improve storage stability, especially under conditions of elevated temperature. The other purpose is to allow the components to be mixed in a prescribed manner to ensure a specific known, final concentration of generated chlorine dioxide. A single packet containing a stable mix of all three components is also possible, but this single packet must be maintained at a temperature below 140° F. (preferably below 125° F.) to avoid decomposition. This single mix has a further disadvantage of generating chlorine dioxide of variable and unpredictable concentrations as a function of variations in the method of mixing (See FIG.
1
).
A solid mix has been devised which rapidly generates chlorine dioxide when added to water. The mix will allow the generation of a known quantity of aqueous chlorine dioxide in a predictable concentration to be used for the disinfection of drinking water, fruits and vegetables, biocidal treatment of cooling towers, treatment of medical wa
Bloom Leonard
Cole Monique T.
Vulcan Chemicals
Warden Jill
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