Note: Descriptions are shown in the official language in which they were submitted.
~L~ 7 ~ 3
The present invention relates to a novel biocidal mixture
comprising a hydroxy alkyl phosphine compound and a surfactant. Our
European Patent Application No. 84305804 describes the use as
biocides of organophosphine compounds of the formula [HORPR'n]yXn 2,
wherein n is 2 or 3 y is 1 when n is 2 or otherwise is equal to the
valency of X; R is an alkylene group of 1 to 4, preferably 1, carbon
atoms; each R1 may be the same or different and represents an alkyl
or alkenyl group having from 1 to 4 carbon atoms, or, preferably~ a
hydroxy alkyl group with 1 ~o 4 carbon atoms, and water soluble
condensates of the aforesaid organophosphine compounds. In
particular trishydroxymethyl phosphine and more especially the water
soluble ~etrakis hydroxy methyl phosphonium salts, such as tetrakis
hydroxy methyl phosphonium sulphate (THPS) are preferred for use
according to our aforesaid patent. However, the present invention
applies to all of the claimed biocide compounds described in our
aforesaid European appl;cation.
Surprisingly we have now discovered a synergism between the
aforesaid organophosphine compounds and surfactants which not only
improves biocidal efficacy but also facilitates biofilm penetration.
A surfactant is defined as a substance which, when present at a low
concentration in a system, has the property of adsorbing onto the
surfaces or interfaces of the system and of altering, to a marked
degree, the surface or interfacial free energies of those surfaces
(or interfaces). The term "interface" indicates a boun~ary between
any two immiscible phases; the term "surface" denotes an interface
where one phase is a gas, usually air.
Our invention provides a mixture of at least one compound of
the above formula with at least one anionic, non-ionic, cationic,
amphoteric and/or semi-polar surfactant.
Surfactants for use in our invention typically contain
hydrophobic groups such as alkenyl, cycloalkenyl, alkyl, cycloalkyl,
aryl, alkyl/aryl or more complex aryl (as in petroleum sulphonates)
moieties having from 8 to 22, preferably 10 to 20, typically 12 to
18 carbon atoms and a hydrophilic moiety. Other hydrophobic groups
included in the invention are polysiloxane groups.
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~Lff~ 5~
The surfactant may for example consist substantially of an at
least sparingly water-soluble salt of sulphonic or mono esterified
sulphuric acids, e.g. an alkylbenzene sulphonate, alkyl sulphate,
alkyl ether sulphate, olefin sulphonatP, alkane sulphonate,
alkylphenol sulphate, alkylphenol ether sulphate, alkylethanolamide
sulphate, alkylethanolamide ether sulphate, or alpha sulpho fatty
acid or its esters each having at least one alkyl or alkenyl group
with from 8 to 22, more usually 10 to 20, aliphatic carbon atoms.
The expression "ether" hereinbefore refers to compounds
containing one or more glyceryl groups and/or an oxyalkylene or
polyoxyalkylene group especially a group containing from 1 to 20
oxyethylene and/or oxypropylene groups. One or more oxybutylene
groups may additionally or alternatively be present. For example,
the sulphonated or sulphated surfactan~ may be sodium dodecyl
benzene sulphonate, potassium hexadecyl benzene sulphonate, sodium
dodecyl dimethyl benzene sulphonate, sodium lauryl sulphate, sodium
tallow sulphate, potassium oleyl sulphate, ammonium lauryl
monoethoxy sulphate, or monoethanolamine cetyl 10 mole ethoxylate
sulphate.
Other anionic surfactants useful according to the present
invention include alkyl sulphosuccinates, such as sodium di-2-
ethylhexylsulphosuccinate and sodium dihexylsulphosuccinate, alkyl
ether sulphosuccinates, alkyl sulphosuccinamates, alkyl ether
sulphosuccinamates, acyl sarcosinates, acyl taurides, isethionates,
soaps such as stearates, palmitates, resinates, oleates, linoleates,
and alkyl ether carboxylates. Anionic phosphate esters and alkyl
phosphonates, alkyl amino and imino methylene phosphonates may also
be used. In each case the anionic surfactant typically contains at
least one aliphatic hydrocarbon chain having from 8 to 22,
preferably 10 to 20 carbon atoms, and, in the case of ethers, one or
more glyceryl and/or from 1 to 20 oxyethylene and/or oxypropylene
and/or oxybutylene groups.
Preferred anionic surfactants are sodium salts. Other salts of
commercial interest include those of potassium, lithium, calcium,
magnesium, ammonium, monoethanolamine, diethanolamine,
triethanolamine, alkyl amines containing up to seven aliphatic
carbon atoms,and alkyl and/or hydroxyalkyl phosphonium.
. ., ~ .
~ 7~ 3
The surfactant may optionally contain or consist of nonionic
surfactants. The nonionic surfactant may be3 e.g. a C10-22
alkanolamide of a mono or di- lower alkanolamine, such as coconut
monoethanolamide. Other nonionic surfactants which may optionally
be present, include tertiary acetylenic glycols, polyethoxylated
alcohols, polyethoxylated mercaptans, polyethoxylated carboxylic
acids, polyethoxylated amines, polyethoxylated alkylolamides,
polyethoxylated alkylphenols, polyethoxylated glyceryl esters,
polyethoxylated sorbitan esters, polyethoxylated phosphate esters,
and the propoxylated or ethoxylated and propoxylated analogues of
all the aforesaid ethoxylated nonionics, all having a Cg 22
alkyl or alkenyl group and up to 20 ethyleneoxy and/or propyleneoxy
groups. Also included are polyoxypropylene/polyethylene oxide
copolymers, polyoxybutylene/polycxyethylene copolymers and
polyoxybutylene/ polyoxypropylene copolymersO The polyethoxy,
polyoxypropylene and polyoxybutylene compounds may optionally be
end-capped with, e.g. benzyl groups to reduce their foaming
tendency.
Compositions of our invention may contain amphoteric
surfactant.
The amphoteric surfactant may for example be a betaine, e.g. a
betaine of the formula:- R3N+CH2COO-, wherein each R is an
alkyl, cycloalkyl, alkenyl or alkaryl group and preferably at least
one, and most preferably not more than one R, has an a~erage of from
8 to 20, e.g. 10 to 18 aliphatic carbon atoms and each other R has
an average of from 1 to 4 carbon atoms. Particularly preferred are
the quaternary imidazoline betaines of the form~la:
CH2--CIH2
N ~ +N- CH2COO-
C~ I
Rl
wherein R and R1 are alkyl, alkenyl, cycloalkyl, alkaryl or alkanol
groups having an average of from 1 to 20 aliphatic carbon atoms and
R preferably has an average of from 8 to 20, e.g. 10 to 18 aliphatic
carbon atoms and R1 preferably has 1 to 4 carbon atoms. Other
amphoteric surfactants for use according to our invention include
alkyl amine ether sulphates, sulphobetaines and other quaternary
amine or quaternised imidazoline sulphonic acids and their salts,
and other quaternary amine or quaternised imidazoline carboxylic
acids and their salts and Zwitterionic surfactants, e.g. N-alkyl
taurines, carboxylated amido amines such as RCONH(CH2)2N~
(CH2CH2CH3)2CH2C02, and amino acids having, in each case,
hydrocarbon groups capable of conferring surfactant properties (e.g.
alkyl, cycloalkyl, alkenyl or alkaryl groups having from 8 to 20
aliphatic carbon atoms). Typical examples include 2 tallow alkyl,
1-tallow amido alkyl, 1 carboxymethyl imida701ine and 2 coconut
alkyl N-carboxymethyl 2 (hydroxyalkyl) imidazoline. Generally
speaking any water soluble amphoteric or Zwitterionic surfactant
compound which comprises a hydrophobic portion including a Cg_20
alkyl or alkenyl group and a hydrophilic portion containing an amine
or quaternary ammonium group and a carboxylate, sulphate or
sulphonic acid group may be used in our invention.
Compositions of our invention may also include cationic
surfactants.
The cationic surfactant may for example be an alkylammonium
salt having a total of at least 8, usually 10 to 30, e.g. 12 to 24
aliphatic carbon atoms, especially a tri or tetra-alkylammonium
salt. Typically alkylammonium surfactants for use according to our
invention have one or at most two relatively long aliphatic chains
per molecule (e.g. chains having an average of 8 to 20 carbon atoms
each, usually 12 to 18 carbon atoms) and t~o or three relatively
short chain alkyl groups having 1 to 4 carbon atoms each, e.g.
methyl or ethyl groups, preferably methyl groups. Typical examples
include dodecyl trimethyl ammonium salts. Benzalkonium salts having
one 8 to 20 C alkyl group two 1 to 4 carbon alkyl groups and a
benzyl group are also useful.
Another class of cationic surfactants useful according to our
invention are N-alkyl pyridinium salts wherein the alkyl group has
......... ..
3-~7~5'j~
an average of from 8 to 22, preferably 10 to 20 carbon atoms. Other
similarly alkylated heterocyclic salts, such as N-alkyl
isoquinolinium salts, may also be used.
Alkylaryl dialkylammonium salts, having an average of from 10
to 30 aliphatic carbon atoms are useful, e.g. those in which the
alkylaryl group is an alkyl benzene group having an average of from
8 to 22, preferably 10 to 20 aliphatic carbon atoms and the other
two alkyl groups usually have from 1 to 4 carbon atoms, e.g. methyl
groups.
Other classes of cationic surfactant which are of use in our
invention include alkyl imidazoline or quaternised imidazoline salts
having at least one alkyl group in the molecule with an average of
from 8 to 22 preferably 10 to 20 carbon atoms. Typical examples
include alkyl methyl hydroxyethyl imidazolinium salts, alkyl benzyl
hydroxyethyl imidazolinium salts, and 2 alkyl-1-alkylamidoethyl
imidazoline salts.
Another class of cationic surfactant for use according to our
invention comprises the amido amines such as those formed by
reacting a fatty acid having 8 to 22 carbon atoms or an ester,
glyceride or similar amide forming derivative thereof, with a di or
poly amine, such as, for example, ethylene diamine or diethylene
triamine, in such a proportion as to leave at least one free amine
group. ~uaternised amido amines may similarly be employed.
Alkyl phosphonium and hydroxyalkyl phosphonium salts having one
C8 20 alkyl groups and three C1 4 alkyl or hydroxyalkyl
groups may also be used as cationic surfactants in our invention.
Typically the cationic surfactant may be any water soluble
compound having a positively ionised group9 usually comprising a
nitrogen atom, and either one or two alkyl groups each having an
average of from 8 to 22 carbon a~oms.
The anionic portion of the cationic surfactant may be any anion
which confers water solubilityg such as formate, aceta~e, lactate,
`r,~, tartrate, citrate, chloride, nitrate, sulphate or an alkylsulphate
~r'~;
ion having up to 4 carbon atoms such as a methosulphate. It is
preferably not a surface active anion such as a higher alkyl
sulphate or organic sulphonate.
Polyfluorinated anionic, nonionic or cationic surfactants may
also be useful in the compositions of our invention. Examples of
such surfactants are polyfluorinated alkyl sulphates and
polyfluorinated quaternary ammonium compounds.
Compositions of our invention may contain a semi-polar
surfactant, such as an amine oxide, e.g. an amine oxide containing
one or two (preferably one) Cg 22 alkyl group, the remaining
substituent or substituents being preferably lower alkyl groups,
e.g. C1 4 alkyl groups or benzyl groups.
Particularly preferred for use according to our invention are
surfactants which are effective as wetting agents, typically such
surfactants are effective at lowering the surface tension between
water and a hydrophobic solid surface. We prefer surfactants which
do not stabilise foams to a substantial extent.
Mixtures of two or more of the foregoing surfactants may be
used. In particular mixtures of non-ionic surfactants with cationic
and/or amphoteric and/or semi polar surfactants or with anionic
surfactants may be used. Typically we avoid mixtures of anionic and
cationic surfactants, which are oFten less mutually compatible.
PreFerably the hydroxyalkyl phosphine compound and the
surfactant are present in a relative weight concentration of from
1:1000 to 1000:1, more usually 1:50 to 200:19 typically 1:20 to
100:1, most preferably 1:10 to 50:1, e.g. 1:1 to 20:1 especially 2:1
to 15:1.
Effective doses of the mixture are typically from 2 ppm to 2000
ppm more usually 20 ppm to 1,000 ppm e.g. 50 ppm to 500 ppm
especially 100 to 250 ppm.
` :
The composition may additionally contain other biocides, water,
dispersants, antifoams, solvents9 scale inhibitors, corrosion
~ 7~ 3
inhibitors, oxygen scavengers and/or flocculants.
Our invention includes aqueous solutions containing a
biocidally active concentration of a composition of the invention.
Such solutions may be water systems or aqueous based products
containing functional ingredients as described in our aforesaid
European Patent Application. Our invention also includes anhydrous,
and concentrated aqueous, formulations adapted to provide the
aforesaid products on dilution with water.
Scale or corrosion inhibitors which may be added to the water
to be treated in conjunction with the present invention include
phosphonates, polymaleates, polyacrylates, polymethacrylates,
polyphosphates, phosphate esters, soluble zinc salts, nitrite,
sulphite, benzoate, tannin, ligninsulphonates, benzotriazoles and
mercaptobenzothiazoles all added in conventional amounts. The scale
and/or corrosion inhibitors may be added to the water separately
from or in association with the phosphonium compound and surfactant.
There may be added to the water to be treated oxygen scavengers,
flocculants such as polyacrylamide dispersants, antifoams such as
silicones or polyethyleneoxylated antifoams or other biocides such
as tin compounds or isothiazolones.
The anion X of the organophosphonium salt may be chloride
sulphate or phosphate. Nitrates are possible but may prove
unstable. Other anions that may be present as the component X in
conjunction with the organophosphonium cation include organic anions
that form water soluble THP salts, such as formate, acetate,
citrate, tartrate and lactate, halides such as fluoride, bromide,
and iodide, bisulphite, borate, silicate, phosphonates such aceto di
phosphonate and amino tris methylene phosphonate, polyphosphates
such pyrophosphate, tripolyphosphate and tetraphosphate, phosphite,
and hypophosphite. It is also possible to combine the THP cation
and the surfactant by forming the THP salt of an anionic surfactant
acid e.g. a tetrakis(hydroxymethyl) phosphonium C12 14 linear
alkyl benzene sulphonate or an alkyl sulphate, alkyl ether sulphate
or alkyl sulphosuccinate.
The present invention also provides for a composition for
r~ t~3
treating water containing aquatic microorganisms which comprises an
organophosphine compound as aforesaid and a surfactant, together
with one or more other biocides and/or scale or corrosion
inhibitors, oxygen scavengers, flocculants, dispersants and/or
antifoams.
The mixture according to our invention may be prepared ~n situ
by adding the organophosphine compound and the surfactant separately
to the water system to be treated. Alternatively and preferably the
components may be premixed, either alone, provided that they are
miscible in the desired proportions, or with water or other solvents
including C1 4 monohydric and polyhydric alcohols or ketones,
dispersants such as polyelectrolytes or solubilizers such as
hydrotopes, e.g. sodium toluene sulphonate or sodium xylene
sulphonate, sufficient to ensure a stable homogeneous mixture.
Typically trishydroxymethyl phosphonium salts are miscible with
cationic surfactants of the quaternary ammonium and phosphonium
type, but mixtures with non-ionic surfactants many require dilution
with water or solvents.
The microorganisms to be treated are usually bacteria, fungi,
yeasts, and algae that grow in aquatic environments. Included in
this classification are sulphate reducing bacteria, e.g.
Desulphovibrio, which may occur in oil installations, iron bacteria,
e.g~ Gallionella and slime forming bacteria, e.g. Pseudomonas, which
last are particularly troublesome in aerated aqueous systems.
A microorganism which causes particular concern in cooling
water or in air conditioning systems is Legionella Pneumophila,
which is responsible for Legionaires Disease. When this occurs in
systems contaminated with bacterial slime conventional biocides used
in water treatment are relatively ineffective against Legionella.
THP salts used alone in conventional amounts also have a reduced
effectiveness under these conditions. We have found that mixtures
of THP salts and surfactant have a substantially enhanced biocidal
effect against Legionella and other microorganism in the treatment
of such systems.
The water to be treated may be industrial cooling water, e.g.
rjrj~
for power stations or chemical plants or for steel or paper or
brewing and may be used in closed circuit or in open circuit
involving evaporation in cooling towers. Alternatively the water may
be process water, especially process water containing significant
sources of nutrients for microorganisms such as process water for
paper making plants and breweries. Injection water or drilling
fluids for oil fields or wa~er produced from oil fields or water
used in reverse osmosis plants, e.g. to provide industrial processes
or boiler feed water, may be treated.
Other aquatic environments which may be treated with the
hydroxy-alkyl phosphorus compounds and surfactants according to the
method for the invention are cooling or process water in board
mills, fertilizer manufacture, oil refineries, primary metals
manufacture, e.g. steel or copper, petrochemicals, rubber
manufacture, textile and fabric industries, industrial gas
manufacture, minerals recovery, glass and ceramic manufacture, food
industry, leather manufacture, heavy and light engineering,
including metal fabrication and automotive engineering, furniture
manufacture, electronics industry and surface coatings and adhesives
manufacture and other manufacturing industries.
The process is also applicable to the treatment of geothermal
water, water in domestic, industrial and institutional central
heating and air conditioning systems and water used for hydrostatic
testing of pipelines and vessels, swimming baths and as cooling
water for ships and marine engines.
The invention is also applicable to the control or microbial
contamination in a wide variety of aqueous based products. For
example the aforesaid organophosphine compounds and surfactants may
be added to a variety of solutions and emulsion compositions such as
paints, cutting oils, bitumen and tar emulsions, adhesives,
weedkillers and insecticides, as well as ~o solid or concentrated
compositions for addition to water in the preparation of such
products. The invention, therefore, further provides aqueous based
products which are subject to microbial spoilage to which has been
added a bacteriostatic or bactericidal quantity of an
organophosphine compound as aforesaid plus surfactant. Typically
3 ~3
such compositions consist of aqueous solutions, suspensions or
emulsions of at least one functional ingredient, together with a
minor proportion of a phosphorus compound plus surfactant of the
invention, sufficient to inhibit growth of microorganisms therein.
The systems to which the invention is particularly applicable
are those involving the circulation or storage of substantial
quantities of water under conditions favouring the multiplication of
bacteria, especially hardy bacteria such as P Aeruginosa, e.g.
conditions involving maintaining or periodically raising th~ water
to super ambient temperatures favouring bacterial proliferation, or
maintaining nutrients for the bacteria in the water systems.
The invention is illustrated by the following examples:
Example 1
A formulation was made by blending together 1 part by weight of
"EMPIGEN"R BAC ~"EMPIGEN" is a Registered Trademark of Albright &
Wilson Limited; BAC is a 50% aqueous solution of alkylbenzylammonium
chlorides) with 2 parts by weight of THPS -7~ (a 75% aqueous
solution of tetrakishydroxymethylphosphonium sulphate). This was
formulation 1. The performance of formulation 1 as a biocide was
compared to that of the THPS - 75 solution in the following test:
Biocide Test
Mixed population biofilms were built up by exposing lcm
diameter mild steel studs to a circulating seawater based medium
which contained sulphate reducing bacteria and also a mixed bioflora
which included aerobic and anaerobic bacteria. Over a period of 2
weeks a stable biofilm was built up on the studs and they were then
extracted for use in the biocide test.
The biofilm coated studs were placed in beakers and solutions
of the appropriate biocide, made up in seawater, were added and left
in conta t with the studs for 6 hours. At the end of this period,
test were performed ~o measure the number of sulphate reducing
bacteria on each stud. A control experiment was also carried out
5~3
11
where no biocide was added to the seawater.
Results
Biocide Concentration Sulphate Reducing Bacteria per Stud
(ppm of formulated solution) THPS - 75 Formulation 1
alone
0 104 104
250 104 0
500 102 0
The surfactant alone has been found substantially less
biocidally active than THPS.
EXAMPLE 2 - Plant Trial 1
. . _ . .
A full scale trial was carried out on an industrial open
evaporative cooling system with the following parameters.
(a) System Capacity : 5,000 gallons
(b) Recirculation Rate : 500 gallons
(c) Cooling Towers : Marley Double Flow
(d) Temperature drop : 5C
The cooling system was in continuous use and immediately prior
to the trial the level of planktonic (i.e. free swimming) bacteria
was 106/ml. There was a 2 inch thickness of bacterial slime in the
dis~ribution trays on the cooling tower with many of the
distribution holes blocked by bacterial slime.
The system was shot dosed with THPS-75 to give a level in the
system water of 150ppm. After 4 hours, the level of planktonic
bacteria in the system water was less than 103/ml representing a
kill rate of greater than 99%. However7 there was little, if any,
, ~,
12
impact on the bacterial slime and 24 hours later the water had been
reinfected by the slime to give a bacterial level of 106/ml.
3 weeks later a second shot dose was carried out, this time
using the same level of THPS-75 (i.e. 150ppm) but also adding 75ppm
of "EMPIGEN"R BAC. This time, in addition to killing the
planktonic bacteria, the slime layer broke up and became dispersed
into the system water. One week later the system was re-examined
and it was found that the cooling tower distribution channels were
substantially clean (i.e. at least 80-90% removal of slime had
occurred).
EXAMPLE 3 - Plant Trials 2 and 3
Two further plant trials were carried out and these also
demonstrated the improvement in performance obtained when THPS was
used in combination with surfactant. The details are as follows:
Plant Trial 2
This plant was an open evaporative cooling system with the
following parameters:
(a) System Capacity : 203,000 gallons
(b) Recirculation rate : 30,000 gallons/hr
(c) Cooling Towers : 3, forced draught
(d) Temperature drop : 6C
(e) Concentration factor : 1.5
The cooling system was in continuous use and immediately prior
to the trial the level of plank~onic bacteria in the system was
2 x 104/mlO Bacterial slime was present in the system pipework and
; on corrosion coupons placed in the system.
`
Four, weekly, shot doses of THPS-75 (i.e. no surfactant) to
give a level of 50ppm in the recirculating water, were carried out
and although the level of planktonic bacteria and algae in the
system water were substantially reduced immediately a~ter each shot
dose, the bacterial slime was not removed.
13
Plant Trial 3
-
This plant was also an open evaporative cooling system and its
parameters were as follows:
(a) System Capacity : 10,500 gallons
(b) Recirculation rate : 1000 gallons/hr
(c) Cooling Towers : 1 induced draught
(d) Temperature drop : 9C
(e) Concentration factor : 1.5
The cooling system was in continuous use and immediately prior
to the trial the level of planktonic bacteria was 104/ml. The
distribution channels in the coo~ing towers were heavily fouled with
up to 4 inches depth of a green mixed algal and bacterial slime,
leading to a significant reduction in tower efficiency.
One shot dose of formulation 1 (see Example 1) was added to
give 50ppm in the system water. One hour after the addition, the
level of planktonic bacteria in the system water was down to zero
and the slime had started to break up. A week later, half of the
slime had been removed and a further SOppm shot dose of formulation
1 was added. After a further week it was observed that only about
10% of the original slime remained in the distribution channels and
this had changed colour from green to brown indicating that the
algal component was now dead. Because of the improved distribution
of water in the tower, the tower efficiency had been markedly
improved.
This result, when compared with plan~ trial 2, demonstrates the
improvement in effectiveness associated with using a surfactant in
combination with THPS-75.
Example 4 - Plant Trials 4 and 5
Two plant treatment programmes were carried out on a cooling
water system known to be infected with legionella bacteria. In this
14
case, treatment with THPS-75 alone fai1ed to eliminate the bacteria
whereas when used in conjuction with a nonionic surfactant,
elimination was achieved.
The plant parameters were as follows:
(a) System capacity: 51,000 gallons
(b) Recirculation rate : 100,000 gallons/hr
(c) Cooling towers : 3, forced draught
(d) Temperature drop : 5C
(e) Concentration factor : 2.0
Parts of the plant were known to be fouled with inorganic
sludge and bacterial slime and this was harbouring a variety of
bacteria. In particular, the system was infected with Legionella
Pneumophila and this was causing concern to the operators. The
initial Legionella level measured was 300 bacteria per litre and the
system was then treated, consecutively, with two proprietary
biocides, based respectively on isothiazolone and on a mixture of an
organo tin biocide and quaternary ammonium surfactant, at shot dose
levels in the region of 500 ppm. Subsequent to this treatment, it
was found that the level of Legionella in the system had risen to
3000 bacteria per litre.
Plant Trial 4
When the system is treated with a single shot dose of THPS-75
to give a peak level of 500 ppm in the system water the level of
Legionella bacteria falls to about 2,500 bacteria per litre i.e. the
treatment arrests the growth but fails to eliminate the bacteria.
Plant Trial 5
The same system was then treated with one shot dose each of
~`
~,
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~ J
THPS-75 and "EMPILAN"R KCMP 0703/F to give peak levels of 400 ppm
and 20 ppm respectively in the system water. This resulted in the
complete elimination of Legionella bacteria from the system.
N _
"EMPILAN" is a Registered Trade Mark of Albright & ~lilson
Limited; KCMP 0703/F is a nonionic surfactant. It is a mixed
ehtylene oxide/propylene oxide condensate wi~h a fatty alcohol.
Examples 5 to 10
; Mixed population biofilms were built up by exposing 1 cm
diameker mild steel studs to a circulating, bacterially contaminated
cooling water (see Table 1). Over a period of three weeks, a stable
biofilm was built-up on the studs and they were then extracted for
use in biocide tests.
The biofilm coated studs were suspended in beakers and a
solution of the appropriate biocide system, made up in cooling water
(Table 1), was added to each beaker. The water in each beaker was
stirred with a magnetic follower and left in contact with the studs
at 25C for 6 hours. At the end of this period, tests were
performed to measure the live bacterial levels on each stud.
TABLE 1 - Cooling Water Analysis
., .
1. pH Value : 8.8
2. Total Dissolved Solids : 650 ppm CaC03
3. 'P' alkalinity : 70 ppm CaC03
4. 'M' Alkalinity : 450 ppm CaC03
5. Calcium Hardness : 280 ppm CaC03
16
6. Total Hardness : 510 ppm CaC03
7. Chloride : 50 ppm
Example 5 to 10 are listed in Table 2:
TABLE 2
EXAMPLE BIOCIDE SYSTEM CONCENTRATION CHEMICAL TYPE OF
SURFACTANT
THPS-75 200 Fatty alcohol condensed with
"EMPIGEN"R KCMP 0703/F 20 10 moles ethylene/propylene
. oxides
6 THPS-75 200 Alkylbenzyldimethylammonium
"EMPIGEN"R BAC 20 Chloride
7 THPS-75 200 Docecylbenzene Sodium
"NANSA"R HS 80 20 Sulphonate
8 THPS 75 200 Alkyl Dimethyl Betaine
"EMPIGEN"R BB 20
9 THPS-75 200 Potassium Perfluoroalkyl
"FLUORAD"R FC 95 20 Sulphona~e
THSP-75 200 Alkyl Dimethyl Amine Oxide
"EMPIGEN"R OB 20
EMPILAN, EMPIGEN, NANSA and FLUORAD are Registered Trade Marks.
"''
,.
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3~
In each case the mixture of the invention substantially reduces or
eliminates the bacteria compared with THPS alone.
The majority of the surfactants which are mentioned hereinbefore for
use according to the invention have little or no inherent biocidal
activity. Certain surfactants, such as the quaternary amines, are known
to be bioc;dally active. In such cases we have shown that the biocidal
activity of the surfactant alone is substantially less than that of THP
salts at the same dosage levels. Our examples ~hus demonstrate an
important and striking synergism between the organophosphine compounds
and the surfactant.
NOTE all references herein and in the claims to adding a mixture to
a water system or an aqueous based composition are to be construed
as including both the addition of the preformed mixture, and the
addition of the separate or partially premixed components thereof to
form the mixture ln situ in said water syst~n or aqueous based
composition, and also addition of the mixture or its components to a
concentrate or anhydrous product which is subsequently diluted to
form said system or composition.
