Biocide system

Van Acker, J. and Stevens, M. (2000). Increased biological durability differs for traditional wood preservation and new non-biocidal systems (NBS). International Research Group on Wood Preservation, Doc. No. IRGAVP 00-20212. 

The ruptured tank had been connected to the cooling tower system that had not been operated since the startup of the biocide system. This stagnated condition and the unusu-ally high ambient temperatures contributed to the explosion. [6]... 

The activity mechanism of macromolecular biocides has not been fully explained [105]. Most macromolecular biocide systems studied contain BujSn-groups, fixed by hydrolyzable (amide or ester) or nonhydrolyzable bonds. The former are of advantage in sea applications, where the biocidal moiety BujSnOH can be released. 

Details are given of the use of an environmentally friendly biocide system during the production of synthetic latex emulsions. Data concerning the type of polymer emulsion, pH value, expected stability and final use of the product are briefly discussed. 

A. Milne, M. E. Callow, R. Pitchers Control of Fouling by Non-Biocidal Systems," in Evans Hoagland (eds.) Algal Biofouling, Elsevier, Amsterdam 1986, pp. 145-158. 

Capraru, A.M., Ungureanu, E., Popa, V.I. Aspects concerning some biocides systems based on natural aromatic compounds aromatic compounds and their copper complexes. 15th International Symposium on Wood, Fibre and Pulping Chemistry, Oslo, Norway, Proceedings CD 15-18 June, 2009... 

Ungureanu, E., Popa, V.I., Todorciuc, T. Biocides systems based on natural products with application in protecting the lignocellulose materials. The 7th Romanian-Italian Seminar on Pulp and Paper, Iasi, Romania 6-8 Sept 2007... 

Hazardous Decomp. Prods. Heated to decomp., emits very toxic fumes of NOx and SOx Uses Biocide systemic fungicide Manuf./Disthb. Sinochem Jiangsu Wuxi http //www.sinochemwuxi. com... 

Bronopol is rarely used alone for the preservation of polymer dispersions, being most commonly part of a combination biocide system, e.g. with chloromethyl/methyl isothiazolinone. In such formulations it helps to eliminate the weakness of 5-chloro-2-methyl-4-isothiazolin-3-one against anaerobic sulphate reducing bacteria and has been shown to be effective against slow growing acidophilic species such as Gluconoacetobacter liquefaciens (Herrick, 2001). 

Broad spectrum biocides are generally preferred for water-based paints, but environmental, toxicity and cost considerations often necessitate tailoring of the biocide system for maximum effectiveness at minimum use levels. This involves identifying the partieular types of microorganisms requiring control in both the manufacturing and end use enviromnents. To avoid development of biocide resistance in the manufacturing enviromnent, it is not uncommon for producers to periodically switch between preservative systems with different biocidal mechanisms. 

Cooling water systems are dosed with corrosion inhibitors, polymers to prevent solid deposition, and biocides to prevent the growth of microorganisms. 

Emulsion Adhesives. The most widely used emulsion-based adhesive is that based upon poly(vinyl acetate)—poly(vinyl alcohol) copolymers formed by free-radical polymerization in an emulsion system. Poly(vinyl alcohol) is typically formed by hydrolysis of the poly(vinyl acetate). The properties of the emulsion are derived from the polymer employed in the polymerization as weU as from the system used to emulsify the polymer in water. The emulsion is stabilized by a combination of a surfactant plus a coUoid protection system. The protective coUoids are similar to those used paint (qv) to stabilize latex. For poly(vinyl acetate), the protective coUoids are isolated from natural gums and ceUulosic resins (carboxymethylceUulose or hydroxyethjdceUulose). The hydroHzed polymer may also be used. The physical properties of the poly(vinyl acetate) polymer can be modified by changing the co-monomer used in the polymerization. Any material which is free-radically active and participates in an emulsion polymerization can be employed. Plasticizers (qv), tackifiers, viscosity modifiers, solvents (added to coalesce the emulsion particles), fillers, humectants, and other materials are often added to the adhesive to meet specifications for the intended appHcation. Because the presence of foam in the bond line could decrease performance of the adhesion joint, agents that control the amount of air entrapped in an adhesive bond must be added. Biocides are also necessary many of the materials that are used to stabilize poly(vinyl acetate) emulsions are natural products. Poly(vinyl acetate) adhesives known as "white glue" or "carpenter s glue" are available under a number of different trade names. AppHcations are found mosdy in the area of adhesion to paper and wood (see Vinyl polymers). 

Resistance to antimicrobial agents is of concern as it is well known that bacterial resistance to antibiotics can develop. Many bacteria already derive some nonspecific resistance to biocides through morphological features such as thek cell wall. Bacterial populations present as part of a biofilm have achieved additional resistance owkig to the more complex and thicker nature of the biofilm. A system contaminated with a biofilm population can requke several orders of magnitude more chlorine to achieve control than unassociated bacteria of the same species. A second type of resistance is attributed to chemical deactivation of the biocide. This deactivation resistance to the strong oxidising biocides probably will not occur (27). 

Tributyl(tetradecyl)phosphonium chloride was developed specifically (26,27) as a broad-spectmm biocide for the control of biological fouling in cooling water systems where it is particularly effective (see Industrialantimicrobialagents). 

CPA. Copolymer alloy membranes (CPAs) are made by alloying high molecular weight polymeries, plasticizers, special stabilizers, biocides, and antioxidants with poly(vinyl chloride) (PVC). The membrane is typically reinforced with polyester and comes in finished thicknesses of 0.75—1.5 mm and widths of 1.5—1.8 m. The primary installation method is mechanically fastened, but some fully adhered systems are also possible. The CPA membranes can exhibit long-term flexibiHty by alleviating migration of the polymeric plasticizers, and are chemically resistant and compatible with many oils and greases, animal fats, asphalt, and coal-tar pitch. The physical characteristics of a CPA membrane have been described (15). 

Oil Field and Petroleum Processing. Sodium chlorite is finding increasing use as the choice precursor for generating chlorine dioxide for biocidal control in the production of cmde oil (see Petroleum). The use of water in the oil field pumping and processing systems presents significant... 

Recommendations were made to begin treatment with corrosion inhibitors and to make system operation changes to reduce grease and oil fouling. Other water chemistry recommendations involved reducing the amount of aggressive anion in solution and pursuing biocidal treatment. 

Removing suspended solids, decreasing cycles of concentration, and clarification all may be beneficial in reducing deposits. Biodispersants and biocides should be used in biofouled systems. Simple pH adjustment may lessen precipitation of certain chemical species. The judicious use of chemical corrosion inhibitors has reduced virtually all forms of aqueous corrosion, including underdeposit corrosion. Of course, the cleaner the metal surface, the more effective most chemical inhibition will be. Process leaks must be identified and eliminated. 

From the orientation of the tubelike organisms it was clear that they were flourishing even though the system was periodically chlorinated (Fig. 6.25). Clearly, the biocidal treatment was inadequate. 

Metalworking fluids contain mineral oils (refer to p. 80) or synthetic lubricants they are used neat or in admixture with water. They may contain small amounts of biocides, stabilizers, emulsifiers, coiTosion inhibitors, fragrances and extreme pressure additives. The formulations render them suitable for application to metal being worked, generally from a recirculatory system, to provide lubrication, corrosion protection, swarf removal and cooling of the tool and machined surface. 

The aerosols formed in an open system, if inhaled, can cause various forms of Legionella. No one biocide is adequate to control these, as there are some 30 known groups, the most virulent being Legionella pneumophila. 

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