Note: Descriptions are shown in the official language in which they were submitted.
2~33~7
D-721
BIOCIDAL COMPOSITIONS AND USE THEREOF CONTAINING A
SYNERGISTIC MIXTURE OF 3-IODO-2-PROPYNYL-BUTYL CARBAMATE
AND 2-N-OCTYL-4-ISOTHIAZOLIN-3-ONE
BACKGROUND OF THE INVENTION
The formation of slimes by microorganisms is a problem
that is encountered in many aqueous systems. For example, the
problem is not only found in natural waters such as lagoons,
lakes, ponds, etc., and confined waters as in pools, but also in
such industrial systems as cooling water systems, air washer
systems and pulp and paper mill systems. All possess conditions
which are conducive to the growth and reproduction of slime-
forming microorganisms. In both once-through and recirculating
cooling systems, for example, which employ large quantities of
water as a cooling medium, the formation of slime by micro-
organisms is an extensive and constant problem.
Airborne organisms are readily entrained in the water
from cooling towers and find this warm medium an ideal environment
for growth and multiplication. Aerobic and heliotropic organisms
flourish on the tower proper while other organisms colonize and
grow in such areas as the tower sump and the piping and passages
of the cooling system. The slime formation not only aids in the
2~3~7
deterioration of the tower structure in the case of wooden towers,
but also promotes corrosion when it deposits on metal surfaces.
Slime carried through the cooling system plugs and fouls lines,
valves, strainers, etc., and deposits on heat exchange surfaces.
In the latter case, the impedance of heat transfer can greatly
reduce the efficiency of the cooling system.
In pulp and paper mill systems, slime formed by micro-
organisms is commonly encountered and causes fouling, plugging, or
corrosion of the system. The slime also becomes entrained in the
paper produced to cause breakouts on the paper machines, which
results in work stoppages and the loss of production ti~e. The
slime is also responsible for unsightly blemishes in the final
product, which result in rejects and wasted output.
The previously discussed problems have resulted in the
extensive utilization of biocides in cooling water and pulp and
paper mill systems. Materials which have enjoyed widespread use
in such applications include chlorine, chlorinated phenols,
organo-bromines, and various organo-sulfur compounds. All of
these compounds are generally useful for this purpose but each
is attended by a variety of impediments. For example, chlorina-
tion is limited both by its specific toxicity for slime-forming
organisms at economic levels and by the tendency of chlorine to
react, which results in the expenditure of the chlorine before its
full biocidal function is achieved. Other biocides are attended
by odor problems and hazards with respect ~o storage, use or
2~3~7
--3--
handling which limit their utility. To date, no one compound or
type of compound has achieved a clearly established predominance
with respect to the applications discussed. Likewise, lagoons,
ponds, lakes, and even pools, either used for pleasure purposes
or used for industrial purposes for the disposal and storage of
industrial wastes, become, during the warm weather, besieged by
slime due to microorganism growth and reproduction. In the case
of industrial storage or disposal of industrial materials, the
microorganisms cause additional problems which must be eliminated
prior to the materials' use or disposal of the waste.
Naturally, economy is a major consideration with respect
to all of these biocides. Such economic considerations attach to
both the cost of the biocide and the expense of its application.
The cost performance index of any biocide is derived from the
basic cost of the material, its effectiveness per unit of weight,
the duration of its biocidal or biostatic effect in the system
treated, and the ease and frequency of its addition to the system
treated. To date, none of the commercially available biocides has
exhibited a prolonged biocidal effect. Instead, their effective-
ness is rapidly reduced as a result of exposure to physical condi-
tions such as temperature, association with ingredients contained
by the system toward which they exhibit an affinity or substan-
tivity, etc., with a resultant restriction or elimination of their
biocidal effectiveness, or by dilution.
2~3~
As a consequence, the use of such biocides involves their
continuous or frequent addition to systems to be treated and their
addition to multiple points or zones in the systems to be treated.
Accordingly, the cost of the biocide and the labor cost of applying
it are considerable. In other instances, the difficulty of access
to the zone in which slime formation is experienced precludes the
effective use of a biocide. For example, if in a particular system
there is no access to an area at which slime formation occurs the
biocide can only be applied at a point which is upstream in the
flow system. However, the physical or chemical conditions, e.g.,
chemical reactivity, thermal degradation, etc., which exist between
the point at which the biocide may be added to the system and the
point at which its biocidal effect is desired render the effective
use of a biocide impossible.
Similarly, in a system experiencing relatively slow flow,
such as a paper mill, if a biocide is added at the beginning of the
system, its biocidal effect may be completely dissipated before it
has reached all of the points at which this effect is desired or
required. As a consequence, the biocide must be added at multiple
points, and even then a diminishing biocidal effect will be exper-
ienced between one point of addition to the system and the next
point downstream at which the biocides may be added. In addition
to the increased cost of utili7in~ and maintaining multiple feed
points, gross ineconomies with respect to the cost of the biocide
are experienced. Specifically, at each point of addition, an
excess of the biocide is added to the system in order to compensate
2~3~0~
for that portion of the biocide which will be expended in reacting
with other constituents present in the system or experience physi-
cal changes which impair its biocidal activity.
SUMMARY OF THE INVENTION
The biocidal compositions of the present invention
comprise, as active ingredients, 1) 3-iodo-2-propynyl-butyl
carbamate (IPBC) and 2) 2-n-octyl-4-isothiazolin 3-one (OIT).
These constituents are commercially available. The synergistic
effect obtained by combining IPBC and OIT has not been previously
disclosed.
DETAILED DESCRIPTION OF THE INVENTION
Surprisingly, the present inventors have found that mix-
tures of IPBC and OIT are especially efficacious in controlling
the growth of bacterial microbes, specifically the Klebsiella
Dneumoniae species. This particular species is a member of the
capsulated, facultative class of bacteria and is generally present
in air, water and soil. These bacteria continually contaminate
open cooling systems and pulping and papermaking systems and are
among the most common slime formers. The slime may be viewed as
2~ being a mass of agglomerated cells stuck together by the cementing
action of the gelatinous polysaccharide or proteinaceious secre-
tions around each cell. The slimy mass entraps other debris,
restricts water flow and heat transfer, and may serve as a site
for corrosion.
2~3~
The fact that the Klebsiella species used in the tests is
a facultative species is important as, by definition, such bacteria
may thrive under either aerobic or anaerobic conditions. Accord-
ingly, by reason of demonstrated efficacy in the growth inhibition
of this particular species, one can expect similar growth inhibi-
tion attributes when other aerobic or anaerobic bacterial species
are encountered. It is also expected that these compositions will
exhibit similar growth inhibition attributes when fungi and algae
species are encountered.
In accordance with the present invention, the combined IPBC
and OIT treatment may be added to the desired aqueous system in need
of b;ocidal treatment, in an amount of from about 0.1 to about 200
parts of the combined treatment to one million parts (by weight) of
the aqueous medium. Preferably, about 5 to about 50 parts of the
combined treatment per one million parts (by weight) of the aqueous
medium is added.
The combined treatment is added, for example, to cooling
water systems, paper and pulp mill systems, pools, ponds, lagoons,
lakes, etc., to control the formation of bacterial microorganisms,
which may be contained by, or which may become entrained in, the
system to be treated. It has been found that the compositions and
methods of utilization of the treatment are efficacious in control-
ling the facultative bacterium, Klebsiella ~neumoniae, which may
populate these systems. It is thought that the combined treatment
composition and method of the present invention will also be effi-
cacious in inhibiting and controlling al1 types of aerobic and
anaerobic bacteria.
2~3~
Surprisingly, it has been found that when the ingredients
are mixed, in certain instances, the resulting mixtures possess a
higher degree of bactericidal activity than that of the individual
ingredients comprising the mixture. Accordingly, it is possible to
produce a highly efficacious bactericide. Beca~lse of the enhanced
activity of the mixture, the total quantity of 1:he bacterial treat-
ment may be reduced. In addition, the high degree of bactericidal
effectiveness which is provided by each of the ingredients may be
exploited without use of higher concentrations of each.
The following experimental data were developed. It is
to be remembered that the following examples are to be regarded
solely as being illustrative and not as restricting the scope of
the invention.
DESCRIPTION OF PREFERRED EMBODIMENT
IPBC and OIT were added in varying ratios and over a wide
range of concentrations to a liquid nutrient medium which was sub-
sequently inoculated with a standard volume of a suspension of the
facultative bacterium Klebsiella Dneumoniae. Growth was measured
by determining the amount of radioactivity accumulated by the cells
when 14C-glucose was added as the sole source of carbon in the
nutrient medium. The effect of the biocide chemicals, alone and in
combination, is to reduce the rate and amount of 14C incorporat;on
into the cells during incubation, as compared to controls not
treated with the chemicals. Additions of the biocides, alone and
in varying combinations and concentrations, were made according
2 ~
to the accepted "checkerboard" technique described by M. T. Kelley
and J. M. Matsen, Antimicrobial Agents and ChemotheraPv. 9:440
(1976). Following a two hour incubation, the amount of radio-
activity incorporated in the cells was determined by counting
(14C liquid scintillation procedures) for all treated and untreated
samples. The percent reduction of each treated sample was calcu-
lated from the relationship:
Control 14C(cpm) - Treated 14C(cpm3 x 100 = % reduction
Control 14C(cpm)
Plotting the % reduction of 14C level against the concen-
tration of each biocide acting alone results in a dose-response
curve, from which the biocide dose necessary to achieve any given
% reduction can be interpolated.
Synergism was determined by the method of calculation
described by F. C. Kull, P. C. Eisman, H. D. Sylwestrowicz and R.
L. Mayer, Applied Microbiologv 9,538 (1961) using the relationship:
QA QB
+ = synergism index (SI)
Qa Qb
where:
Qa = quantity of compound A, acting alone, producing an end point
Qb = quantity of compound B, acting alone, producing an end point
QA = quantity of compound A in mixture, producing an end point
QB = quantity of compound B in mixture, producing an end point
2 ~
The end point used in the calculations is the % reduction
caused by each mixture of A and B. QA and QB are the
individual concentrations in the A/B mixture causing a given %
reduction. Qa and Qb are determineli by interpolation from the
respective dose-response curves of A and B as those concentrations
of A and B acting alone which produce the same % reduction as each
specific mixture produced.
Dose-response curves for each active acting alone were
determined by linear regression analysis of the dose-response
data. Data were fitted to a curve represented by the equation
shown with each data set. After linearizing the data, the
contributions of each biocide component in the biocide mixtures to
the inhibition of radioisotope uptake were determined by
interpolation with the dose-response curve of the respective
biocide. If, for example, quantities of QA plus QB are
sufficient to give a 50% reduction in 14C content, Qa and Qb
are those quantities of A or B acting alone, respectively, found
to give 50% reduction in 14C content. A synergism index (SI) is
calculated for each combination of A and B.
Where the SI is less than 1, synergism exists. Where the
SI=l, additivity exists. Where SI is greater than 1, antagonism
exists.
The data in the following tables come from treating
Klebsiella Dneumoniae, a common nuisance bacterial type found in
industrial cooling waters and in pulping and paper making systems,
with varying ratios and concentrations of IPBC and OIT. Shown
for each combination is the % reduction of 14C content ~% I), the
calculated SI, and the weight ratio of IPBC and OIT.
~3~7
-10-
TABLE I
IPBC vs. ~IT
PI PBC 1 oPT2 I PBC 0 I T % I S I
0 100:0 79
0 100:0 71
12.5 0 100:0 52
6.25 0 100:0 29
3. ~3 0 100:0 26
1.56 0 100:0 7
0 20 0: 100 87
0 10 0: 100 71
0 5 0:100 58
0 2.5 0:100 42
0 1.25 0:100 31
0 0.63 0:100 18
2.5: 1 g4 1.23
1.25:1 94 0.94*
12.5 20 1:1.60 92 0.88*
6.25 20 1:3.20 90 0.91*
3.13 20 1: 6.40 88 0.95*
1.56 20 1:12.8 87 O.9g
5.0:1 92 1.01
2.50:1 ~1 0.71*
12.5 10 1.25:1 86 0.72*
6.25 10 1:1.60 80 0.82*
3-13 10 1:3.20 75 0.95*
1.56 10 1:6.40 75 0.90*
2 ~
TABLE I (Cont'd)
IPBC vs. OIT
ppm ppm Ratio
IPBCl OIT2 IPEJC:OIT %I SI
10.0:1 89 0.93*
5.00: 1 87 0.63*
12.5 ~ 2.50:1 76 0.75*
6.25 5 1.25:1 65 0.97
3.13 5 1:1.60 61 1.01
1.56 5 1:3.20 60 1.01
2.5 20. O: 1 86 0.95*
2.5 10.0:1 82 0.65*
12.5 2.5 5.00:1 65 0.89*
6.25 2.5 2.50:1 52 1.19
3.13 2.5 1.25:1 45 1.32
1.56 2.5 1:1.60 4$ 0.97
1.25 40. O: 1 84 0.96
1.25 20.0:1 80 0.54*
12.5 1.25 10.0:1 62 0.83*
6.25 1.25 5.00:1 45 1.14
3.13 1.25 2.50:1 36 1.28
1.56 1.25 1.25:1 38 0.90*
0.63 79.4:1 85 0.92*
0.63 39.7: 1 75 0.74*
12.5 0.63 19.8:1 56 0.95*
6.25 0.63 9.92:1 41 1.12
3.13 0.63 4.96:1 31 1.13
1.56 0.63 2.48:1 32 0.75*
1 product containing 17% actives IPBC
30 2 product con~aining 45% actives OIT
2 ~
TABLE I I
IPBC vs. OIT
ppm ppm Ratio
IPBCl oIT2 --BC:OIT %I SI
0 11~0:0 84
0 1~0:0 76
12.5 0 1~0:0 58
6.25 0 100:0 36
3.13 0 100:~ 21
1.56 0 100:0 14
0 20 0: 100 86
0 10 0: 100 76
o 5 0: 100 53
0 2.5 0:100 46
0 1.25 0: 100 32
0 0.63 0: 100 21
2.5: 1 g5 1.32
1.25: 1 95 1.00
12.5 20 1:1.60 93 0.88*
6.25 20 1: 3.20 gl 0.89*
3.13 20 1:6.40 88 0.96
1.56 20 1:12.8 87 0.98
5.0:1 93 1.13
2.50:1 92 0.76*
12.5 10 1.25:1 88 0.6~*
6.25 10 1: 1.60 Bl 0.83*
3.13 10 1:3.20 77 0.90*
1.56 10 1:6.40 75 0.94*
20~3~0~
TABLE II (Cont'd)
IPBC vs. OIT
ppm ppm Ratio
IPBCl oIT2 PBC:OIT %I SI
10.0:1 90 1.09
5.00:1 8g 0.67*
12.5 5 2.50:1 81 0.67*
6.25 5 1.25:1 68 O.g4*
3.13 5 1:1.60 64 ~.97
1.56 5 1:3.20 61 1.~0
2.5 20.0:1 88 1.08
2.5 10.0:1 86 0.65*
12.5 2.5 5.00:1 76 0.63*
6.25 2.5 2.50:1 5i 1.05
3.13 2.5 1.25:1 52 1.05
1.56 2.5 1:1.60 49 1.03
1.25 40.0:1 87 1.08
1.25 20.0:1 83 0.69*
12.5 1.25 10.0:1 69 0.71*
6.25 1.25 5.00:1 50 1.07
3.13 1.25 2.50:1 42 1.07
1.56 1.25 1.25:1 38 1.03
0.63 79.4:1 86 l.Og
0.63 39.7:1 80 0.74*
12.5 0.63 19.8:1 65 0.76*
6.25 0.63 9.92:1 44 1.11
3.13 0.63 4.96:1 35 1.08
1.56 0.63 2.48:1 31 0.93*
1 product containing 17% actives IPBC
2 product containing 45% actives OIT
2~3~7
Asterisks in the SI column indicate synergistic combinations in
accordance with the Kull method supra.
In Tables I and II, differences seen between the replicates
are due to normal experimental variance.
In accordance with Tables I-II supra., unexpected results
occurred more frequently within the product ratios of IPBC to OIT
of from about 1:6.4 to 80:1. Since the IPBC product contains about
17% active biocidal component and thè OIT product contains about
45% active biocidal component, when based on the active biocidal
component, unexpected results appear more frequently within the
range of active component of IPBC:OIT of about 1:16.9 to 30:1. At
present, it is most preferred that any commercial product embodying
the invention comprises a weight ratio of active component of about
1:1 IPBC:OIT.
While this invention has been described with respect to
particular embodiments thereof, it is apparent that numerous other
forms and modifications of this invention will be obvious to those
skilled in the art~ The appended claims and this invention
generally should be construed to cover all such obvious forms and
modifications which are within the true spirit and scope of the
present invention.
