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| United States Patent |
5,424,079 |
| Yu |
June 13, 1995 |
Solid, dry, chlorine-free antimicrobial compositions, and method
of use
Abstract
A biocidal composition comprising a dry, water soluble mixture of a solid
bromide and a stable, solid peracetylperoxyborate compound useful as a
chlorine-free water treatment system, said peracetylperoxyborate composition
generating hypobromous acid upon addition of water. Methods of treating water
with said compositions are also disclosed.
| Inventors: |
Yu; Bing (Horsham, PA) |
| Assignee: |
Rohm and Haas Company (Philadelphia, PA)
|
| Appl. No.: |
127409 |
| Filed: |
September 27, 1993 |
| Current U.S. Class: |
424/723; 210/754; 504/125;
504/151; 504/153; 514/64 |
| Intern'l Class: |
A01N 055/08; A01N 059/00 |
| Field of Search: |
424/723 514/64 504/151,153,125
|
References Cited [Referenced
By]
U.S. Patent Documents
| 4338210 |
Jul., 1982 |
Clements et al. |
252/96. |
| 4822512 |
Apr., 1989 |
Auchincloss |
252/106. |
| 5208057 |
May., 1993 |
Greenley et al. |
426/332. |
| Foreign Patent Documents |
| 2056503 |
Nov., 1991 |
CA. |
|
Primary
Examiner: Robinson; Allen J.
Assistant Examiner: Bembenick; B.
Attorney, Agent or Firm: Fein; Michael B.
Claims
What is claimed is:
1. A biocidal composition comprising a dry,
water soluble mixture of a solid bromide and a stable, solid
peracetylperoxyborate compound useful as a chlorine-free water treatment system,
said composition generating hypobromous acid upon addition of water.
2.
Composition according to claim 1 wherein said peracetylperoxyborate compound has
an active oxygen content of about 2 to 8% by wt., a peracetic acid content which
can be liberated by dissolution of said peracetylperoxyborate compound in water
of at least about 10% by weight, and a hydrogen peroxide content of less than
about 4% by weight.
3. Composition according to claim 2 wherein said
peracetylperoxyborate compound is the product of a reaction (a) of a solid
boron-oxygen compound with acetic acid and hydrogen peroxide; (b) of a solution
of peracetic acid in acetic acid with a solid boron-oxygen compound; or (c)
acetic acid with a solid boron-oxygen compound containing peroxygen.
4.
Composition according to claim 1 having a decomposition temperature of at least
50.degree. C.
5. Composition according to claim 1 in powder, granular,
or tablet form.
6. Composition according to claim 1 wherein said
peracetylperoxyborate compound has an oxidation potential of at least about 1.6.
7. Aqueous solution of a composition according to claim 1 having a total
residual oxidant level of less than about 0.04 mg/1.
8. Composition
according to claim 1 consisting essentially of said bromide and said
peracetylperoxyborate compound.
9. A method of treating water to inhibit
the growth of microorganisms comprising introducing a composition according to
claim 1 in an effective amount of hypobromous acid in a locus containing water.
10. Method according to claim 9 wherein said locus is a swimming pool,
spa, cooling tower, the white water of a pulp or paper process, and waste water.
Description
FIELD OF THE INVENTION
This invention relates to the field of
non-chlorinated biocides.
BACKGROUND OF THE INVENTION
Non-chlorinated biocides have been proposed and used in the past.
Greenley, et al., U.S. Pat. No. 5,208,057, for example, suggests a process for
treating water used in fowl butchering processes with a bromide and an oxidant.
Dry, water soluble chlorine containing biocides suggested by Auchincloss, U.S.
Pat. No. 4,822,512, have sodium chloride as the preferred inorganic halide, an
oxidizing agent such as potassium persulphate triple salt, and several other
required components such as sulfamic acid, a non-reducing organic acid, and an
anhydrous alkali metal phosphate.
In the field of bleaching agents,
Clements, et al., U.S. Pat. No. 4,338,210, teaches a composition comprising
sodium bromide and a peracid precursor system, typically diphthaloyl peroxide or
sodium perborate plus tetraacetyl ethylenediamine, and an optional scavenger
system such as catalase.
Stable, solid acetylperoxyborate compounds have
been disclosed by Roesler, et al, Canadian Pat. Appl. 2,056,503, to be useful in
the fields of washing, bleaching and cleaning agent and disinfectant
applications, and as an oxidizing agent in organic synthesis.
No one,
however, has suggested a non-chlorinated biocidal composition which can be
provided as powder, tablet, or granular form.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a non-chlorinated
biocidal composition which can be provided as powder, tablet, or granular form.
It is another object to provide such a composition which generates
hypobromous acid when dissolved in water.
It is another object to
provide simple, cost effective, stable, and safe water treatment biocides which
are chlorine-free.
These objects, and others which will become apparent
from the following disclosure, are achieved by the present invention which
comprises in one aspect a biocidal composition comprising a dry, water soluble
mixture of a solid bromide and a stable, solid peracetylperoxyborate compound
useful as a chlorine-free water treatment system, said composition generating
hypobromous acid upon addition of water.
In another aspect the invention
comprises a method of inhibiting the growth of microorganisms comprising
introducing such a composition in an effective amount to a locus containing
water.
DETAILED DESCRIPTION OF THE INVENTION
Suitable bromide
compounds are any known species, for example, potassium, ammonium, or sodium
bromides, or mixtures thereof. The bromide is provided in solid form.
Suitable peracetylperoxyborate compounds are those disclosed in the
aforementioned Canadian patent application of Roesler, et al. Preferred
peracetylperoxyborate compounds have an active oxygen content of about 2 to 8%
by wt., a peracetic acid content which can be liberated by dissolution of said
peracetylperoxyborate compound in water of at least about 10% by weight, and a
hydrogen peroxide content of less than about 4% by weight. As taught in said
Canadian patent application, the peracetylperoxyborate compound can be the
product of a reaction (a) of a solid boron-oxygen compound with acetic acid and
hydrogen peroxide; (b) of a solution of peracetic acid in acetic acid with a
solid boron-oxygen compound; or (c) acetic acid with a solid boron-oxygen
compound containing peroxygen. Preferred peracetylperoxyborate compounds release
an oxidant having an oxidation potential of at least about 1.6 volts.
The bromide and the peracetylperoxyborate compound are combined in any
way, for example by dry mixing, and in any ratios, for example front 1:100 to
100:1 (molar). Preferred molar ratios are about 1:10 to about 10:1.
The
compositions can be provided as tablets, powders, or granular form, or any other
convenient dry form. The compositions can even be provided as a two package
system, if desired, to be added to water loci separately or sequentially, but
this would seem to be much less convenient.
Preferred compositions
consist essentially of the two components, but optional additives to control
solution rate of the composition, stabilize the composition, and/or enhance UV
resistance of the composition can be incorporated in the compositions. Suitable
additives include (a) disintegrants such as carboxy methyl cellulose,
water-soluble inorganic salts, sugars, lignin sulfates and low molecular weight
water-soluble polymers; (b) UV stabilizers such as benzotriazole and
benzophenone derivatives, oligomeric hindered amine light stabilizers and
triazine derivatives; (c) anticaking agents and dispersants such as polyaromatic
sulfonates, xylene or toluene sulfonate salts (potassium, sodium or ammonium),
alkyl(C.sub.10 to C.sub.20) amine acetates, fatty amines and alkyl naphthalene
sulfonates; and (d) solid defoamers such as complex phosphate esters.
The concentration level of additives in the compositions is from 0% to
10% by weight, preferred from 0.5% to 5% by weight.
Suitable amounts of
composition are introduced in the water-containing locus so as to provide an
effective amount of active bromine (i.e., all species of bromine exhibiting
microbicidal activity, including hypobromous acid and Br.sub.2) to inhibit the
growth of microorganisms. Usually about 25 ppm to 250 ppm or more (of
composition) are effective. As long as at least about 1 ppm of hypobromous acid
is present, the composition is effective.
One advantage of the
compositions of the invention are the high decomposition temperatures,
preferably at least 50.degree. C. Another significant and surprising advantage
is the low total residual oxidant ("TRO") levels of less than about 0.04 mg/l
which are achieved, usually in the range of about 0.01 to 0.04 mg/l, wherein the
maximum permitted under U.S. and German regulations is 0.2 mg/l. Prior art
biocidal bromide compositions of bromide and liquid peracetic acid have typical
TRO's of about 0.85 to 1.05 mg/l.
The following examples set forth a few
embodiments of the invention.
EXAMPLES
Example 1--Dry, Solid
Biocidal Composition
A 1/1 molar ratio of sodium bromide and acetyl
peroxyborate ("APBC") which was prepared substantially according to Example 1 of
the aforementioned Canadian patent was prepared by mixing dry powders of said
sodium bromide and APBC.
Example 2--Dry, Solid Biocidal Composition
A composition was prepared according to Example 1, supra, except in a
molar ratio of 1/3.
Example 3--(Comparative)--Liquid Biocidal
Composition
Two liquid mixtures of sodium bromide in peracetic acid were
prepared, the first in a 1/1 molar ratio (Example 3A) and the second in a 1/3
molar ratio (Example 3B). In both cases, the peracetic acid also contained a
small amount of acetic acid and was about 32% by weight concentration in water.
Example 4
This experiment is to determine active bromine
generation. Aqueous solutions of the following compounds or compositions were
prepared and observed for the typical Br.sub.2 yellow color.
TABLE 1
______________________________________
Compound Color
______________________________________
NaBr clear
APBC clear
Example 1 yellow
Example 2 yellow
Example 3A yellow
Example 3B yellow
liquid peracetic acid
clear
blank clear
______________________________________
Example 5--(Comparative)--Microbicidal Activity
The solid
compositions were shown to have equal microbicidal activity vs. P. aeruginosa in
a synthetic cooling tower water.sup.1) at pH=8.5, as shown in the following
results which were conducted according to the following procedure:
.sup.1) Containing per liter of water (a) a nutrient component
consisting of ammonium nitrate (5.28 g), potassium phosphate (2.08 g), dextrose
(4.62 g), sodium carbonate (21.5 g), and potassium sulfate (40.2 g); and (b) a
hardness component consisting of CaCl.sub.2 (59.4 g), MgCl.sub.2 (45.0 g),
FeCl.sub.3 (0.18 g), CuCl.sub.2 (0.06 ) and EDTA (0.24 g).
The mixtures
of compounds in the indicated ratios were dissolved in water at 1%, and then
were added to the synthetic cooling tower water to make a final concentration of
compounds as shown in Table 2. Then the samples were innoculated with
Pseudomonas aeruginosa (ATCC#15442) to a final concentration of 10 billion cells
per ml. After the indicated intervals samples were removed and survival cells
were allowed to re-grow by 10-fold serial dilutions of a sample into Trypticase
Soy Broth containing a reducing agent and incubating at 30.degree. C. for 2
days. Log reduction reported in Table 2 is the difference in end-point of
re-growth of said 10-fold serial dilution samples between a treated sample and a
control sample with no exposure to the test compound.
TABLE 2
______________________________________
(ppm) Log Reduction
Microbicide of
Wt. Concentration
after (minutes)
Example of Active Ingredients
1 3 5 10
______________________________________
1 500/500 4 7 7 6
2 250/750 (NaBr/APBC)
6 8 8 8
3A 500/500 8 8 8 8
3B 250/750 8 8 8 8
(NaBr/Peracetic acid)
______________________________________
Example 6--Comparative TRO
Total residual oxygen (TRO) of
compositions according to the invention vs. comparative compositions had lower
TRO which is highly advantageous environmentally.
The test used was the
standard N,N-diethyl-p-phenylenediamine ("DPD") test..sup.2)
.sup.2)
Standard method for examination of water and wastewater. Clesceri, et al.,
pp.4-58 to 4-64 (17th Ed.,) Am. Pub. Health Assoc.
TABLE 3
______________________________________
Example Composition ppm (weight)
TRO (mg/l)
______________________________________
2 NaBr/APBC 50/184 0.01
2 NaBr/APBC 100/369 0.04
2 NaBr/APBC 200/738 0.04
3A NaBr/peracetic acid
50/115 0.85
3A NaBr/peracetic acid
100/231 1.05
3A NaBr/peracetic acid
200/461 0.93
______________________________________
While this invention has been described in sufficient detail for
those skilled in the art to be able to make and use it, various modifications,
and improvements should become apparent from the foregoing disclosure without
departing from the spirit and scope of the invention.
* * * * *
