ALKYLAMINES AS BIOFILM DEACTIVATION AGENTS

Abstract: Aqueous industrial, recreational, and drilling systems comprising a biofilm deactivation agent consisting essentially of one or more alkylamines. The biofilm deactivation agent has a "minimum biofilm deactivation concentration" (MBEC) of 200 ppm or less. In a preferred embodiment, the biofilm deactivation agent consists essentially of primary alkylamines having from 12 to 14 carbon atoms, and an MBEC of 50 ppm or less, most preferably 30 ppm or less. A most preferred embodiment comprises a synergistic combination of specific quaternary ammonium salts with a primary alkylamine having from 12 to 14 carbon atoms. The invention also relates to the method of treating an aqueous system with these biofilm deactivation agents, either alone, or in the presence of an oxidizing agent for static control.

Description: ALKYLAMINES AS BIOFTLM DEACTIVATION AGENTS FIELD OF THE INVENTION The invention relates to agents for deactivating biofilms on surfaces in a variety of aqueous systems, including but not necessarily limited to recreational and industrial water systems, including drilling systems. BACKGROUND OF THE INVENTION Biological fouling is a serious economic problem in both industrial and recreational water systems. Biological fouling is the buildup of a biofilm on the surfaces that come into contact with the water in the system. A biofilm is the buildup of layers of microorganisms and/or extracellular substances and the dirt and/or debris that becomes trapped in that buildup Bacteria, fungi, yeasts, diatoms and protozoa are only some of the organisms that cause the buildup of a biofilm In recreational waters, biofilms tend to be slimy to the touch, and can create a health hazard. In industrial waters, biofouling can interfere with industrial processes, lowering the efficiency of the process, wasting energy, and reducing product quality. In drilling systems, biofouling contributes to the corrosion of expensive drilling equipment. Biofilm problems are encountered frequently in cooling water systems used in power- generating plants, refineries, chemical plants, and air conditioning systems. Cooling water systems commonly are contaminated with airborne organisms entrained by air/water contact in cooling towers as well as waterborne organisms from the systems makeup water supply. The water in such systems generally is an excellent growth medium for these organisms. If not controlled, the biofilm that results from such growth can plug towers, block pipelines, and coat heat transfer surfaces with layers of slime, thereby preventing proper operation and reducing the efficiency of the affected equipment Biofilms traditionally are controlled using oxidizing agents, which typically are based on chlorine or bromine. Oxidizing systems are effective to control biofilms, but such systems also can corrode valuable metal equipment and may irritate delicate and/or sensitive skin Non-oxidizing agents are available to control biofilms, and should avoid the foregoing problems; however, oxidizing biocides tend to be much more effective than non-oxidizing biocides at deactivating a biofilm. Biofilms also tend to require exposure to much higher doses of non-oxidizing agents for much longer periods of time than the dosage and time required to kill microorganisms in a suspension. As a result, non-oxidizing agents tend to be much more expensive to use as biofilm eradicating agents than oxidizing agents. The current trend is towards using continuous levels of oxidizing biocides to maintain clean water system surfaces and to decrease the risk of contamination by Legionella pneumophila, the bacteria responsible for Legionnaires disease. A continuous need exists for non-oxidizing biofilm agents for aqueous systems which are effective to deactivate biofilms at lower doses. SUMMARY OF THE INVENTION The invention provides a method for deactivating a biofilm in an aqueous medium, which method comprises introducing an effective amount of one or more alkylamines into said aqueous medium, wherein the alkyl portion of said one or more alklyamines contains from 8 to 16 carbon atoms. It also provides an aqueous system comprising a biofilm deactivation agent comprised of one or more alkylamines. In a preferred embodiment, the biofilm deactivation agent also comprises a synergistically effective combination of the alkylamine with specified monomeric quaternary ammonium salts. The biofilm deactivation agent has a minimum biofilm deactivation concentration of 200 ppm or less. DETAILED DESCRIPTION OF THE INVENTION Very low concentrations of certain alkylamines completely deactivated biofilm bacteria during laboratory testing, both alone and synergistically in combination with certain monomeric quaternary ammonium salts. The biofilm deactivation agents of the present invention are useful in a wide variety of aqueous systems, including but not necessarily limited to recreational and industrial systems, including aqueous base drilling systems. Industrial systems in which the present invention may be used include, but are not necessarily limited to cooling water systems used in power- generating plants, refineries, chemical plants, air conditioning systems, process systems used to manufacture pulp, paper, paperboard, and textiles, particularly water laid non-woven fabrics. A wide variety of alkylamines are capable of deactivating biofilm bacteria according to the present invention if they are used at a high enough concentration. Suitable alkylamines are those with a "minimum biofilm eradication concentration" (MBEC) of 200 ppm or less, preferably 100 ppm or less, more preferably 50 ppm or less, and most preferably 30 ppm or less. The MBEC is a valuable measurement for determining whether the quantity of given agent that will be required to eradicate a biofilm will be economically and environmentally feasible. The MBEC test was developed by the University of Calgary to evaluate the efficacy of antibiotics and biocides towards biofilms. H. Ceri, et. al., "The MBEC Test: A New In Vitro Assay Allowing Rapid Screening for Antibiotic Sensitivity of Biofilm", Proceedings of the ASM, 98, p 525 (1998). Ceri, et. al., "Antifungal and Biocide Susceptibility testing of Candida Biofilms using the MBEC Device", Proceedings of the Interscience Conference on Antimicrobial Agents and Chemotherapy, vol. 38, p. 495 (1998); H. Ceri, et. al., "The Calgary Biofilm Device: A New Technology for the Rapid Determination of Antibiotic Susceptibility of Bacterial Biofilms", Journal of Clinical Microbiology 37 (1999) 1771-1776. The exclusive license for the MBEC technique is believed to be held by MBEC Biofilm Technologies, 665 - 8th Street S.W., Calgary, Alberta T2P 4H5 Canada. The MBEC technique consists of growing identical 24-hour biofilms on 96 pegs arrayed in 12 rows and 8 columns. The biofilms then are challenged with decreasing concentrations of selected antibiotics and/or biocides. After a certain challenge time (generally one hour), the biofilms are placed in 96 individual wells of growth media and ultra-sonicated to deactivate any surviving organisms. After culturing overnight, the wells are checked for turbidity. Clear, transparent wells indicate complete deactivation of the biofilm. Conversely, turbidity (growth) indicates lack of complete deactivation of the biofilm. The minimum biofilm deactivation concentration (MBEC) is defined as the minimum concentration of an agent that completely deactivates biofilm bacterial. The MBEC technique provides a potentially powerful and reproducible tool to study the efficacy of biocides and additives towards biofilm deactivation. Unless otherwise indicated, the biofilms used in the examples below consisted of a pure culture of Pseudomonas aeruginosa (ATCC 15442). The reason for this is that Pseudomonas aeruginosa often represents the major biofilm component in industrial and recreational water systems. J.W. Costerton and H. Anwar, Pseudomonas aeruginosa: The Microbe and Pathogen, in Pseudomonas aeruginosa Infections and Treatment, A.L. Baltch and R.P. Smith (eds), Marcel Dekker, New York, 1994. In addition, Pseudomonas aeruginosa is a gram-negative bacteria. Gram-negative bacteria tend to be more difficult to kill than gram-positive bacteria. In other words, if an agent is effective against Pseudomonas aeruginosa, then persons of ordin∑ ry skill in the art would find it reasonable to predict that the agent also would be effective agair st other microorganisms found in biofilms. As a general rule of thumb, .454 kilograms (1 pound) of a biofilm treatment agent will result in 10 ppm of actives in a 45,420 liter (12,000 gallon) aqueous system. Alkylamines and blends that are suitable for use in the invention have MBECs of 200 ppm or less, and require 9.072 kilograms (20 pounds) of the alkylamine or blend to effectively treat 45,420 liters (12,000 gallons) of water. Preferred alkylamines or blends have the following characteristics: an MBEC of 100 ppm or less, requiring 4.536 kilograms (10 pounds)/45,420 liters (12,000 gallons) of water; more preferably an MBEC of 50 ppm or less, requiring 2.268 kilograms (5 pounds)/45,420 liters (12,000 gallons) of water; and, an MBEC of 30 ppm or less requiring 1.361 kilograms (3 pounds)/45,420 liters (12,000 gallons) of water. The alkyl group of alkylamines that will produce an MBEC of 200 ppm or less have from 8 to 16 carbon atoms, more preferably from 10 to 16, even more preferably from 1 1 to 15 carbon atoms, and most preferably from 12 to 14 carbon atoms. Preferred alkylamines are primary alkylamines. Dimethylalkylamines also may satisfy the 200 ppm MBEC requirement when the alkyl group has from 10 to 16 carbon atoms, preferably from 12 to 16 carbon atoms. MBEC and carbon number are two ways to identify alkylamines that are useful in the present invention. Another way to identify a suitable alkylamine is by its octanol/water coefficient. The octanol/ water partition coefficient - K ow - is defined as the ratio of the solute concentration in the octanol phase to that in the water phase. It is usually expressed as the logarithm of the number. A logK ow of 3.0 means that the compound is 1000 times more soluble in octanol than in water. High K ow values can be an indicator of bioaccumulation whereby organisms retain a certain amount of a compound in their tissue. Octanol was chosen since it "mimics" the lipids found in organisms and thus forms the basis for a simple assay for potential biological interactions. The following are calculated octanol/ water partition coefficients for selected alkylamines and quaternary amines. It will be understood that the term "alkylamine" includes primary alkylamines such as butylamine, secondary alkylamines such as the dialkylamines, and tertiary alkylamines such as the alkyldimethylamines. Where available, experimentally determined values also are given [from N. Bodor, Z. Gabanyi, and C-K. Wang, Journal of the American Chemical Society, 111, 3783-3786 (1989)]. The calculated values were arrived at using the KowWLN program of the Environmental Science Center of Syracuse Research Corporation (http://esc.syrres.com esc.htm). ALKYLAMINES Sangster, 1993 ALKYLDIMETHYLAMINES (ADMAS) 1. HanshandLeo, 1985 DIALKYLAMINES 1. HanshandLeo, 1985 ALKYLDIMETHYLBENZYLAMMONIUM CHLORIDES (ADBACS) DIALKYLDIMETHYLAMMONIUM CHLORIDES (DIDACs) Octanol water coefficients may be measured or calculated using a variety of known methods. The values herein were calculated using the LogKow program developed by the Syracuse Research Center, which may be found on the Internet at http://esc.syrres.com/~esc/logkow.htm The Log Kow program estimates the log octanol/water partition coefficient (log P) of organic chemicals using the atom/fragment contribution method Based on the results of these calculations, persons of ordinary skill in the art would expect alkylamines having a calculated partition coefficient of from 3.5 to 7.5 to have an MBEC of 200 ppm or less. Persons of ordinary skill in the art also would expect alkylamines having a calculated partition coefficient of from 4 to 6 to have an MBEC that is 100 ppm or less, preferably 50 ppm or less, and more preferably 30 ppm or less Suitable alkylamines are commercially available from Aldrich Chemicals Ltd or Sigma Chemical Company. Persons of ordinary skill in the art also can make alkylamines using known procedures, such as those described in R Morrison and R. Boyd Organic Chemistry (5 lh Ed 1987) §§ 26.11-26.13, pp. 945-948, incorporated herein by reference Dodecylamine also is available from Akzo, Nobel Chemicals Inc. The alkylamines of the present invention are useful alone, or preferably combination with a suitable quaternary ammonium salt Suitable quaternary ammonium salts are available from a number of sources, including Albemarle Corporation Suitable combinations of quaternary ammonium salts and alkylamines have an MBEC of 200 ppm or less, more preferably 100 ppm or less, even more preferably 50 ppm or less, and most preferably 30 ppm or less. The ratio of alkylamine to the quaternary ammonium salt may be from 10: 1 to 1 : 10. Preferably, the ratio is 1 : 1. A prefer ed embodiment is a 1 : 1 ratio of a primary alkylamine having from 10 to 16 carbon atoms to quaternary ammonium salts comprising functional groups independently selected from the group consisting of phenyl groups and alkyl groups having from 8 to 16 carbon atoms, preferably from 10 to 12 carbon atoms, provided that no more than one of said functional groups comprises a phenyl group. Even more preferably, the primary alkylamine has from 12 to 14 carbon atoms and the quaternary ammonium salt is a dialkyldimethyl quaternary ammonium salt wherein the alkyl groups have from 10 to 12 carbon atoms. A most preferred embodiment is didecyldimethyl-ammonium chloride with a primary alkylamine having from 12 to 14 carbon atoms, most preferably tetradecylamine, most preferably at a 1 1 ratio. Preferably, the quaternary ammonium compound either has a calculated partition coefficient of from 3 5 to 7 5, more preferably from 4 to 6, or the combination of a selected alkylamine and a selected quaternary ammonium compound has such a calculated partition coefficient Although the alkylamine or the combination of alkylamine and quaternary ammonium salt may be used as the sole treatment in a water system to deactivate biofilms, the treatment of the present invention also is useful in systems containing oxidizing agents, including but not necessarily limited to HOBr and HOC1 In a preferred embodiment, the oxidizing agents are used in an amount effective to maintain static control of an aqueous system, and the non- oxidizing agents of the present invention are provided at intervals in order to deactivate any biofilms that may develop in the system. The instant invention is generally practiced by introducing an effective amount of alkylamine-containing deactivating agent into the water system to be treated By effective amount, we mean at least that amount that will be capable of substantially deactivating the biofilm at treatment conditions It is preferred that an alkylamine be chosen, in an amount that will eradicate at least 50 wt.% of the biofilm This amount of course will vary depending on such things as the temperature of the water system, the particular biofilm to be eradicated, and other contaminants in the water system. This amount will typically correspond to a MBEC of 200 ppm or less. The invention will be better understood with reference to the following examples, which are illustrative only and should not be construed as limiting the invention to a specific embodiment. EXAMPLE 1 A series of tests was performed to assess the MBEC of a variety of biocides. The tests included, among others: chlorine- and bromine-based oxidizing biocides; several commercially available non-oxidizing biocides, such as glutaraldehyde and THPC (tetrakis(hydroxymethyl)- phosphonium chloride); and, the several alkylamines, namely octylamine, and dodecylamine The following protocol was used during the testing: Section A - Preparation and Activity Testing of Biocide Formulations Preparation of Synthetic Water Synthetic water (SW) was prepared by adding 0 22 g CaCl 2 , 0 168 g NaHCO^, and 0 014 g NaCl to 1 L of deionized, distilled water (DDW) The mixture was sterilized by filtration through a 0.2 im filter. The pH of this solution was 7 9 to 8 1 units and afforded a water containing 200 ppm Ca hardness (as CaCO 3 ), 150 ppm of alkalinity (as CaCO 3 ), and 150 ppm of chloride. Preparation of 400 ppm Octylamine Solution The stock 2500 ppm solution of octylamine in SW was prepared by diluting 0 05 g octylamine to 20.0 g in SW. A cloudy mixture resulted To help solubilize the amine, 5 drops of 4% aq. HC1 was added It is within the skill of those in the art that an acid can be used to help solubilize alkylamines Such acids are well known and can include both organic acids as well as inorganic acids. This afforded a slightly cloudy solution with some foam which was stirred continuously prior to diluting 3 2 g of stock to 20 0 g with SW Preparation of 100 ppm Dodecylamine Solution Stock 2500 ppm dodecylamine was prepared by diluting 0 038 g to 15.2 g in SW 5 drops of 4% aq HC1 was added and the mixture was heated and stirred to aid dissolution (dodecyl-amine is a solid at room temperature) This yielded a pearlescent suspension which was continually stirred prior to diluting 0 80 g of the stock solution to 20 0 g with SW Stock 400 ppm Glutaraldehyde Solution Glutaraldehyde (0.159 g, Aldrich 50 wt.%) was diluted to 19.9 g with SW. The solution (1.99 g) was further diluted to 19.9 g with SW, providing a nominal 400 ppm glutaraldehyde solution for plate 7 and 8 biofilm experiments. Preparation of 200 ppm Tetrakis(hydroxymethyl)phosphonium Chloride Solution (THPC) THPC (0.125 g, Aldrich 80% active) was diluted to 10.0 g with SW. A portion of this solution (0.40 g) was diluted to 20.0 g with SW to provide a 200 ppm THPC solution for biofilm challenge. General Procedure - Preparation of Quaternary Ammonium Chloride Solutions The quats used in this work were all 50% active and consisted of Albemarle BQ 451-5 biocide, BQ 361-5 biocide, AC 76-5 biocide, and DAQ 1010-5 biocide. The following table provides the chemical composition of these quats. Quat solutions of 800 ppm activity were prepared from BQ 451, BQ 361, and AC 76 biocides by diluting the equivalent of 40 mg quat to 25 mL with SW. A solution of DAQ 1010 with 400 ppm activity was prepared by diluting the equivalent of 20 mg quat to 25 mL with SW. CHEMICAL COMPOSITIONS OF QUATERNARY AMINES Section B - Microbiological Procedures Biofilm Preparation and Biocide Challenge Pseudomonas aeruginosa (ATCC 15442) biofilms were prepared on the 96 pegs of the MBEC plate by aerobic incubation in simple salts medium with 0 1% glucose (24 hours, 35°C) The pegs were rinsed in synthetic water (SW) and then challenged by the biocide for one hour Following the biocide challenge, the pegs were rinsed twice with SW and then sonicated into Mueller-Hinton broth (2251L per well). The broth was then incubated for 18 hours at 35°C Determination of Minimum Biofilm Deactivation Concentration After the 18 hour incubation period, the recovery wells were checked for turbidity Clear, transparent wells indicated complete deactivation of the biofilm Conversely, turbidity indicated the lack of complete deactivation of the biofilm The minimum biofilm deactivation concentration (MBEC) is defined as the minimum concentration of agent which results in complete deactivation of the biofilm. MBEC endpoints were unambiguously determined by absorbance at 650 nm using UN visible spectroscopy An absorbance > 0 100 was considered a positive indication of growth MBEC values for duplicate runs on the same plate were typically the same In cases where duplicate runs were not the same, the difference almost always represented just one 50% dilution in biocide concentration or one well of the 96 well plate Control Data Formulations in all of this work were run in duplicate together with suitable controls Various microbiological controls and checks also were run to assure the integrity of the experimental methods employed For example, initial and final concentrations of inocula used to grow the biofilms (McFarland = 1 0) were checked using serial plating In addition to the above work, 12 peg sites (representing row 8 on each MBEC plate) also were used for various control purposes The biocide plates contained just synthetic water (no biocide) in row 8 Sterility controls were run by removing MBEC pegs in row 8, columns 1-3 prior to growth of the biofilm These were then taken through the entire procedure Since no biofilm could grow (pegs removed), no turbidity (indicates viable bacteria) should be observed 24-Hour biofilm controls were deteπ lined by removing pegs 4-6, row 8 immediately after 24 hour biofilm growth. The pegs were sc nicated in saline to remove the biofilm and serially plated. Biocide challenge controls were determined by removing pegs 7-9, row 8 following biocide challenge and treating the pegs as 4-6 above. Turbidity controls were run by taking pegs 10-12 through the entire MBEC procedure. Since the biofilms saw no biocide (only synthetic water), these samples should turn turbid. The control data indicated no unusual circumstances or contamination during these experiments. The average biofilm concentration on the pegs was 1.0 x 10 7 CFUs/ peg. Determination of Minimum Biofilm Eradication Concentration The activities of octylamine and dodecylamine were tested individually. We also tested glutaraldehyde and tetrakis(hydroxymethyl)phosphonium chloride (THPC) for comparison purposes. Results are summarized in the following Table: a. Growth at 200 ppm Cl 2 level in one case Surprisingly, dodecylamine proved extremely effective at biofilm deactivation (MBEC = 25 ppm). The length of the alkyl group of the alkylamine apparently plays a critical role as octylamine (MBEC=400 ppm) was much less active than dodecylamine (MBEC = 25 ppm) Dodecylamine was more active than any other single non-oxidizing biocide tested in this work. EXAMPLE 2 A series of primary fatty amines with alkyl groups having a variety of carbon atom lengths and configurations were tested. The following protocols were used in these tests. Note: Unless otherwise specified, all chemicals were purchased from Sigma-Aldrich, Canada and used without further purification. Section A - Preparation and Activity Testing of Biocide Formulations Preparation of Synthetic Water Synthetic water (SW) was prepared as in Example 1. Preparation of Primary Alkylamine Solutions Stock 2500 ppm solutions were prepared by diluting 0.05 g alkylamine to 20 g with SW. It was necessary to add at least one drop of acid (38% aq. HCl) to obtain stable solutions from amines of C 10 alkyl chain length and higher. Solutions for MBEC tests were prepared by further diluting the appropriate amount of stock solution with SW. Preparation of Alkyldimethylamine (ADM A) Solutions Stock 2500 ppm solutions of alkyldimethylamines were prepared as above by diluting ADMA (0.05 g) to 20g with SW. It was necessary to add one drop of acid (38% aq. HCl) to all of the systems to obtain stable solutions. Further dilution of the stock solutions with SW afforded the solutions needed for MBEC tests. All the ADMA 00 amines used in this work were supplied by Albemarle Corporation. Preparation of Dialkylmelhylamine (DAMA) Solutions Stock 2500 ppm solutions of dialkylmethylamines were formulated as described above for the alkyldimethylamines. The didecylmethylamine (DAMA 00 1010 amine) was supplied by Albemarle Corporation. Preparation of Secondary Alkylamine Solutions Solutions of containing 1600 ppm dibutyl-, dipentyl-, and dihexylamines were prepared by diluting 0.032 g of amine to 20 g with SW. It was necessary to add 1 drop acid (38% aq. HCl) in order to obtain stable solutions with dipentyl- and dihexylamine. Section B - Microbiological Procedures Biofilm Preparation and Biocide Challenge Pseudomonas aeruginosa (ATCC 15442) biofilms were prepared as described in Example I. The 7-day biofilms were prepared by a modification of the above procedure. Each day, spent media was replaced with fresh media and inocula. Determination of Minimum Biofilm Eradication Concentration The MBEC was determined using the same procedure as in Example 1. The following Table gives the dosing for the biocides and controls to investigate the series of primary fatty amines. Control Data Formulations in all of this work were run in duplicate together with suitable controls. Various microbiological controls and checks again were run to assure the integrity of the experimental methods employed. For example the final concentrations of inocula broth used to grow the biofilms were checked using serial plating techniques. In addition, 12 peg sites (representing row 8 on each MBEC plate) also were used for various control purposes. The data indicated no unusual circumstances or contamination occurred during these experiments. The average biofilm population for the plates used in this study range from 1.0 to 1.8 x 10 7 CFU's/ peg* A. C 6 to C, 6 Primary Fatty Amines: The following Table presents MBEC results for one-hour exposures of the series of C 6 to C 16 primary fatty amines. Activity increased with alkyl chain length up tø C and then decreased at C 16 . Dodecylamine and tetradecylamine were by far the most effective compounds in the series with MBECs of 38 and 25 ppm, respectively. Decylamine and hexadecylamine were next in activity with MBECs of 200 ppm for both. B. Alkyldimethylamines A series of alkyldimethylamines, commercially available from Albemarle Corporation as ADMA ® amines, having from 8 to 18 carbon atoms were tested for activity against biofilm bacteria. These alkyldimethylamines did not eradicate biofilm at the maximum test concentrations of 200 to 800 ppm. The following Table highlights MBEC results, which indicate that these compounds exhibit a much lower activity relative to the primary fatty amines having 12 and 14 carbon atoms discussed above. ADMA 14 and ADMA 16 amines showed evidence of biofilm deactivation at 200 ppm (as indicated by regrowth optical density measurements). We estimate the MBECs for these compounds as 400 to 800 ppm~which means that these alkyldimethylamines were an order of magnitude less active than the best performing primary fatty amines. C. Dialkylmethylamines A series of dialkylmethylamines with alkyl groups having from 4 to 10 carbon atoms were tested for activity. None of the dialkylmethylamines tested eradicated the biofilm at 200 ppm or less. The following Table compares the activities of several dialkyl and dialkylmethylamines. Albemarle's DAMA 00 1010 amine (didecylmethylamine) performed the best (MBEC = 400 ppm). The octyl analog was second in terms of activity (MBEC = 800 ppm). As with the primary fatty amines, alkyl chain length played an important role in activity Dioctylmethylamine had an MBEC of 800 ppm, the dihexyl and dibutyl analogs had MBECs of >800 ppm Secondary dialkylamines generally displayed low activity The MBEC of dioctylamine, for example, was 1600 ppm The MBEC of dihexylamine was estimated at 2400 ppm EXAMPLE 3 Older biofilms offer increased resistance to biocides Studies were extended to 7-day biofilms formed using P. aeruginosa. The procedure used to foπn the 7-day biofilm was the same as in Example 1, except that each day, spent media was replaced with fresh media and inocula This biofilm was then challenged with oxidizing and non-oxidizing biocides The stock hypochlorous acid solution was prepared from sodium hypochlorite solution (0.41, >4%, actual ~ 2 7%) diluted to 100 g with SW The solution was stored in a 4 oz amber glass bottle in the refrigerator Stock hypobromous acid was blended from sodium hypochlorite (0.42 g, 0 15 mmol ) as above and sodium bromide (0 028 g, 0 27 mmol) The solution was also stored in a 4 oz amber glass bottle in the refrigerator overnight The halogen donor solutions were prepared by dissolving BCDMH (0 0054 g), DBDMH (0 0054 g), or trichloroisocyanuric acid (0.0033 g) in 20 g SW with stirring The stock solution was diluted 1 10 for MBEC testing The solutions were further characterized by performing another 1 10 dilution and analyzing for free or total chlorine by the DPD method using a Hach DR 700 spectrophotometer The actual starting oxidant levels are shown in the following Table ACTUAL LEVELS OF OXIDIZING BIOCIDES USED WITH 7-DA Y BIOFILMS The 7-day biofilm proved moie difficult to eradicate than 24-hour biofilms Initial results (plate 24) indicated that several formulations failed to deactivate the biofilm at the initial concentrations employed We therefore challenged a second plate with higher concentrations of biocides (Example 4). EXAMPLE 4 Another 7-day biofilm was prepared from P. aeruginosa, as in Example 3. This biofilm was then challenged with several common oxidizing and non-oxidizing biocides The results are given in the following Table PERFORMANCE OF SELECTED BIOCIDES TOWARDS A 7-DA Y BIOFILM Br-based biocides in general were more active than Cl-based biocides For example, the Cl-based biocides bleach or trichlor required 20 ppm residual to completely deactivate the biofilm The data indicate that the Br-based biocides are more effective than Cl-based biocides against aged, more-difficult-to kill biofilms The MBEC for glutaraldehyde on a 7-day biofilm was 200 ppm, compared to 50 to 100 ppm on 24-hour biofilms Dodecylamine and DAQ 1010 required twice the concentration to kill the 7-day biofilm (MBECs = 75 ppm) as for the 24-hour biofilm (MBECs - 38 ppm from previous work) EXAMPLE 5 Certain fatty amines were tested in combination with the Albemarle quat DAQ 1010 (didecyldimethyl-ammonium chloride) Test solutions were prepared using initial concentrations of 100 ppm of each material and then successively diluted with synthetic water in the MBEC device. The data in the following Table indicates that the combination of DAQ 1010 and C 14 fatty amine gave the best performance of any non-oxidizing biocide system tested so far Just 12.5 ppm total biocide completely eradicated biofilm bacteria This compares with values of 38 ppm for DAQ 1010 alone and 25 ppm for C 14 fatty amine alone Activities of Quat/ Amine Blends MBECS FOR BLENDS BASED ON TOTAL AMOUNT OF COMPONENTS (1:1 RA TIO) 1. Previous Work 2 Growth at 25 ppm in one case The combinations of quaternary ammonium compounds, specifically Albemarle quat DAQ 1010 (didecyldimethylammonium chloride) and primary fatty amines proved very effective against biofilm bacteria The DAQ 1010 and tetradecylamine mixture was highly active against biofilm bacteria and one of the best performing non-oxidizing biocide systems (MBEC = 12 5 ppm total additive loading - 6 2 ppm each) Persons of ordinary skill in the art will recognize that many modifications may be made to the present invention without departing from the spirit and scope of the invention The embodiment described herein is meant to be illustrative only and should not be taken as limiting the invention, which is defined in the following claims

Claims: CLAIMS: I. A method for deactivating a biofilm in an aqueous medium, which method comprises introducing an effective amount of one or more alkylamines into said aqueous medium, wherein the alklyamines contains from 8 to 16 carbon atoms. 2. The method of claim 1 wherein at least one of said one or more alklyamines is reacted with an organic or inorganic acid, in water, to form an aqueous solution of the corresponding alkylamine salt prior to the one or more alkylamine being introduced into said aqueous medium containing said biofilm. 3. The method of claim 2 wherein the acid is hydrochloric acid. 4. The method of claim 1 wherein said alkylamine is a primary alkylamine. 5. The method of claim 4 wherein said one or more alkylamines is selected from the group consisting of decylamine, undecylamine, dodecylamine, tridecylamine, tetradecyclamine, pentadecylamine, and hexadecylamine. 6. The method of claim 1 wherein said one or more alkylamines has a minimum biofilm eradication concentration of 200 ppm or less. 7. The method of claim 1 wherein there is also introduced into said aqueous medium an effective amount of at least one quaternary ammonium salt. 8. The method of claim 7 wherein said quaternary ammonium salt has an octanol/water coefficient of 3.5 to 7.5. 9. The method of claim 7 wherein the ratio of alkylamine to quaternary ammonium salt is from 10: 1 to 1 : 10. 10. The method of claim 7 wherein the quaternary ammonium salt is selected from the group consisting of hexadecyldimethylbenzylammonium chloride, octadecyldimethylbenzylammonium chloride, didecyldimethyl ammonium chloride, didodecyldimethylammonium chloride, and mixtures thereof. I I . The method of claim 1 wherein there is also introduced into said aqueous medium an effective amount of an oxidizing agent for static control. 12. The method of claim 1 1 wherein said oxidizing agent is a halogen-containing oxidizing agent. 13. The method of claim 12 wherein the halogen is selected from chlorine, bromine, and bromine chloride. 14. A biofilm deactivating system comprised of: a) water; b) one or more alklyamines which are effective for deactivating a biofilm in an aqueous medium; and c) one or more quaternary ammonium salts having an octanol/water coefficient of 3.5 to 7.5. 15. The biofilm deactivating system of claim 14 wherein the said one or more alkylamines contains from 8 to 16 carbon atoms. 16. The biofilm deactivating system of claim 15 wherein said alkylamine is a primary alkylamine. 17. The biofilm deactivating system of claim 14 wherein said alklyamine has a minimum biofilm eradication concentration of 200 ppm or less. 18. The biofilm deactivating system of claim 14 wherein said quaternary ammonium salt is selected from the group consisting of hexadecyldimethylbenzylammonium chloride, octadecyldimethylbenzylammonium chloride, didecyldimethyl ammonium chloride, and didodecyldimethylammonium chloride. 19. The biofilm deactivating system of claim 14 wherein the ratio of alkylamine to quaternary ammonium salt is from 10: 1 to 1 : 10.

Inventors: NALEPA CHRISTOPHER J, NALEPA, CHRISTOPHER, J.
Applicants: ALBEMARLE CORP, ALBEMARLE CORPORATION
Application year: 2001
Main classification: C02F1
IPC codes: A01N33, C02F1