Composition for generating chlorine dioxide

Compositions – Oxidative bleachant – oxidant containing – or generative – Free halogen or oxy-halogen acid type

Reexamination Certificate

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C252S186100, C252S187100, C252S187230, C252S187240, C252S187250, C252S187260, C252S187270, C252S187280, C252S187290, C252S187300, C424S661000

Reexamination Certificate

active

06602442

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, as well as, demand studies.
BACKGROUND OF THE INVENTION
The inventor has been developing solid mix formulations which will allow for the preparation of small quantities (normally one liter, but the same mix has been used to prepare up to 300 gallons or more) of an aqueous chlorine dioxide solution at repeatable and reproducible concentrations of up to and beyond 3,000 mg/l. In addition, the inventor has developed a wet and dry formulation for purposes of enhanced use.
Prior Art Patents
The chemistry for producing chlorine dioxide from dry components 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.
Mason et al in U.S. Pat. No. 4,547,381 discloses a dry composition for sustained, controlled production of gaseous chlorine dioxide. No water is added to the dry composition to produce the chlorine dioxide. Moreover, note that the composition of Mason et al requires a dry inert diluent added to the active chlorine dioxide producing components. On the other hand, applicant's formulation does not require an inert diluent added to the active ingredients. Moreover, the inventor intends to use his composition in a manner distinct from Mason et al. That is, the inventor intends to use his composition in water, Mason et al do not.
The prior art does not teach the chlorine dioxide releasing compositions yielding solutions of predetermined concentration 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 biological 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 3,000 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, aqueous or gaseous 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 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 still further object of this invention is to produce a combination dry and wet mix product which can be safely transported and can be used to accurately make large volume solutions of chlorine dioxide.
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 one minute, 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.
The effective amounts of the components of this invention are exemplified in the description and the examples.
BRIEF SUMMARY OF THE INVENTION
The dry mix formulation which is the heart of this invention incorporates lithium hypochlorite, 25-30 weight % LiOCI; 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,

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