Drug – bio-affecting and body treating compositions – Inorganic active ingredient containing – Elemental sulfur or compound thereof
Reexamination Certificate
1999-09-24
2001-11-27
Dees, Jose′ G. (Department: 1616)
Drug, bio-affecting and body treating compositions
Inorganic active ingredient containing
Elemental sulfur or compound thereof
C424S615000, C424S663000, C424S665000, C424S680000, C424S723000
Reexamination Certificate
active
06322822
ABSTRACT:
BACKGROUND
Bromine-based biocides have proven biocidal advantages over chlorination-dechlorination for the microbiological control of cooling waters and disinfection of waste treatment systems. The water treatment industry recognizes these advantages to be cost-effective control at higher pH values, almost no loss in biocidal activity in the presence of ammonia, and effective control of bacteria, algae and mollusks.
A common way of introducing bromine-based biocides into a water system is through the use of aqueous NaBr in conjunction with NaOCl bleach. The user feeds both materials to a common point whereupon the NaOCl oxidizes the bromide ion to HOBr/OBr
⊖
. This activated solution is then introduced directly into the water system to be treated. The feeding of the two liquids in this fashion is necessary because the HOBr/OBr
⊖
mixture is unstable and has to be generated on site just prior to its introduction to the water. Furthermore, the feeding and metering of two liquids is cumbersome, especially as the system has to be designed to allow time for the activation of bromide ion to occur. Consequently many biocide users have expressed the need for a single-feed, bromine-based biocide. Molecular bromine chloride has been considered to meet these demands. It is a liquid at room temperature and can be fed directly to the water system, where immediate hydrolysis occurs to yield HOBr.
BrCl+H
2
O→HOBr+HCl (1)
Properties of bromine chloride are listed in Table 1.
TABLE 1
Property
Bromine Chloride (BrCl)
Appearance
Fuming, red liquid or gas
Boiling Point
5° C.
Vapor Pressure (25° C.)
1800 mm
Corrosivity
Corrodes most metals in the presence of water
It can be seen that certain characteristics of this material—especially its corrosiveness, high vapor pressure and fuming tendency—necessitate care and skill in its handling and use.
Early efforts to provide a single-feed, bromine-based biocide comprised complexing bromine with excess bromide ion in the presence of strong acid and stabilizing the resultant solutions with ethanolamine. The resultant solutions of ethanolammonium hydrogen perbromide contained up to 38% by weight elemental bromine. See in this connection, Favstritsky, U.S. Pat. No. 4,886,915; and Favstritsky, Hein, and Squires, U.S. Pat. No. 4,966,716.
These solutions permitted introduction of biocidally active bromine to a water system using a single feed. As in the case of bromine chloride, the ethanolammonium hydrogen perbromide hydrolyzed in water to release HOBr. The vapor pressures of these solutions were lower than bromine chloride. Nevertheless, the solutions still possessed measurable vapor pressures, and thus tended to produce undesirable reddish-colored vapors during storage and use.
An economically acceptable way of stabilizing high concentrations of aqueous solutions of bromine chloride is described in U.S. Pat. No. 5,141,652 to Moore, et al. The solution is prepared from bromine chloride, water, and a halide salt or hydrohalic acid. These solutions were found to decompose at a rate of less than 30% per year and in cases of high halide salt concentration, less than 5% per year. Moreover, solutions containing the equivalent of 15% elemental bromine could be prepared. Unfortunately, the relatively high acidity of these solutions and their tendency to be corrosive and fuming impose limitations on their commercial acceptance.
Many solid bromine-based biocides such as BrClDMH (1,3-bromochloro-5,5-dimethylhydantoin) are limited in the amount of material that can be dissolved in water and fed as a liquid to the water treatment system. For example, the solubility of BrClDMH in water is only around 0.15%. Another limitation of such derivatives is that at neutral pH, HOBr rapidly decomposes, eventually forming bromide ions. Thus, the ability to store and transport these aqueous solutions is greatly limited and of questionable commercial feasibility.
U.S. Pat. No. 3,558,503 to Goodenough et al. describes certain aqueous bromine solutions stabilized with various stabilizing agents and various uses to which such solutions can be put. The compositions described in the patent comprise an aqueous bromine solution having from about 0.01 to about 100,000 parts per million by weight of bromine values wherein the molar ratio of bromine to nitrogen present in the bromine stabilizer ranges from about 2.0 to 1 to about 0.5 to 1. The stabilizer used is biuret, succinimide, urea, a lower aliphatic mono- or disubstituted urea containing from about 2 to about 4 carbon atoms in each substituent group, sulfamic acid, or an alkyl sulfonamide of the formula RSO
3
NH
2
where R is a methyl or ethyl group. The solution also contains sufficient hydroxide additive to provide a pH in the solution ranging from about 8 to about 10, the hydroxide additive being an alkaline earth hydroxide or an alkali metal hydroxide.
U.S. Pat. No. 5,683,654 to Dallmier et al. discusses the preparation of aqueous alkali metal or alkaline earth metal hypobromite solutions by mixing an aqueous solution of alkali or alkaline earth metal hypochlorite with a water soluble bromide ion source to form a solution of unstabilized alkali or alkaline earth metal hypobromite. To this solution is added an aqueous solution of an alkali metal sulfamate having a temperature of at least 50° C. and in an amount that provides a molar ratio of alkali metal sulfamate to alkali or alkaline earth metal hypobromite of from about 0.5 to about 6 whereby a stabilized aqueous alkali or alkaline earth metal hypobromite solution is formed. The Dallmier et al. patent teaches that much higher levels of available halogen for disinfection were attained by this approach as compared to the Goodenough et al. approach. But the Dallmier et al. patent acknowledges that in their process, the stabilization must occur quickly after the unstable NaOBr is formed.
Thus, there remains a need for methods of disinfecting surfaces and of sanitizing bodies of water using a single-feed, bromine-based biocide that is water-soluble, non-acidic, and noncorrosive.
THE INVENTION
This invention provides methods for disinfecting surfaces and for sanitizing bodies of water using a single-feed, bromine-based biocide. Examples of surfaces that may be disinfected using the methods of this invention include kitchen counters, bathroom counters, walls, and floors. The bodies of water that may be sanitized using the methods of this invention include cooling water systems, waste water effluents, pulp and paper mills, oilfields, air washers, fire reservoirs, and evaporative condensers. These methods use concentrated liquid biocide compositions comprising biocidally active bromine as the single-feed, bromine-based biocide. This invention further involves a process of forming aqueous solutions of bromine chloride, and in so doing, provides novel and eminently useful concentrated solutions of biocidally active bromine. These solutions of bromine chloride perform as well as bleach towards planktonic (solution) bacteria. Further, these solutions of bromine chloride are more effective than bleach versus biofilm (surface) bacteria, which are more difficult to kill than planktonic bacteria.
In one embodiment of this invention, a method for disinfecting a surface is provided. This method comprises applying to the surface a concentrated liquid biocide composition comprised of (a) bromine chloride and (b) an aqueous solution of alkali metal salt of sulfamic acid having a pH of at least about 7. The amounts of (a) and (b) are such that (i) the active bromine content of the composition is at least about 100,000 ppm (wt/wt), and (ii) the atom ratio of nitrogen to active bromine in the composition is greater than 0.93.
Another embodiment of this invention provides a method of sanitizing a body of water which method comprises introducing into the body of water a concentrated liquid biocide composition. The biocidal composition is comprised of (a) bromine chloride and (b) an aqueous solution of alkali metal salt of sulfamic acid having a pH of at least about 7.
Moore, Jr. Robert M.
Nalepa Christopher J.
Albemarle Corporation
Dees Jose′ G.
Pryor A Hon
Spielman, Jr. E. E.
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