Synergistic systems

Olefin Polymers. The flame resistance of polyethylene can be increased by the addition of either a halogen synergist system or hydrated fillers. Similar flame-retarder packages are used for polypropylene (see Olefin polymers). Typical formulations of the halogen synergist type are shown in Table 15 the fiUer-type formulations are in Table 16. 

These equations do not provide complete definition of the reactions that may be of significance in particular solvent extraction systems. For example, HTTA can exist as a keto, an enol, and a keto-hydrate species. The metal combines with the enol form, which usually is the dominant one in organic solvents (e.g., K = [HTTA]en i/[HTTA]]jet = 6 in wet benzene). The kinetics of the keto -> enol reaction are not fast although it seems to be catalyzed by the presence of a reagent such as TBP or TOPO. Such reagents react with the enol form in drier solvents but cannot compete with water in wetter ones. HTTA TBP and TBP H2O species also are present in these synergistic systems. However, if extraction into only one solvent (e.g., benzene) is considered, these effects are constant and need not be considered in a simple analysis. 

Watanabe, M., Mirvaliev, R., Tachimori, S. et al. 2004. Selective extraction of americium(III) over macroscopic concentration of lanthanides(III) by synergistic system of TPEN and D2EHPA in 1-octanol. Solvent Extr. Ion Exch. 22 (3) 377-390. 

The choice is wide for the formulation of the chemical system developed to separate the target species (e.g., number and nature of the extracting agent(s), including the use of binary synergistic systems or phase modifiers, concentration of species, nature of the organic diluent). 

FIGURE 3.17 Synergistic system process flowsheet tested at the CEA Marcoule on a surrogate An(III) + Ln(III) product. (Courtesy of Madic, C., Lecomte, M., Baron, P., Boullis, B., Compte-Rendu de Physique, 3, 797-811, 2002.)... 

Cordier, P.Y., Francois, N., Boubals, N., Madic, C., Hudson, M.J., Liljenzin, J.O. 1999. Synergistic systems for the selective extraction of trivalent actinides from mixtures of trivalent actinides and lanthanides. ISEC 99 Conference on Solvent Extraction for the 21st Century, July, Barcelona, Spain. 

Andersson, S., Ekberg, C., Foreman, M.R.S., Hudson, M.J., Liljenzin, J.O., Nilsson, M., Skamemark, G., Saphiu, K. 2003. Extraction behavior of the synergistic system 2,6-bis-(benzoxazolyl)-4-dodecyloxylpyridine and 2-bromodecanoic acid using Am and Eu as radioactive tracers. Solvent Extraction and Ion Exchange 21(5) 621-636. 

The new features are detailed in this review most using diamide as a model system and illustrated with published data on other extractant systems. Figure 7.1 summarizes the structure of the different extractants cited in this chapter. The mixture of extractants as synergistic systems and extractants, such as the N-polydentate ligands BTP (39, 40), BTBP (41, 42), or bis-malonamide (43), will not be treated here. These extractants have low solubility in alkane and are generally used in chlorinated solvent or octanol or diamide/alkane solution to enhance their solubility. 

Mechanism of Condensed Phase Action of Synergistic Systems Based... 

MECHANISM OF CONDENSED PHASE ACTION OF SYNERGISTIC SYSTEMS BASED ON HALOGEN-METAL COMPOUNDS... 

Costa, L. Luda, M. P Trossarelli, L. Mechanism of condensed phase action in flame retardants. Synergistic systems based on halogen-metal compounds, Polymer Degradation and Stability, 2000, 68(1), 67-74. 

Consumption of halogenated additives is expected to decline as the market moves towards synergistic systems that mix flame retardants such as antimony oxide, phosphorus, and zinc borate with a halogen [15],... 

Table VII summarizes the results for the synergistic systems. The most significant points are ...

In most cases, a given fire retardant operates by several of these mechanisms, and much research has been done to determine the magnitude and role of each of these mechanisms in fire retardancy. The influence of the combining effect of several of these mechanisms is illustrated by phosphorus-nitrogen synergism. The theories involved in this synergistic system are discussed to demonstrate this interaction between mechanisms. Some mechanisms apply only to... 

There are a number of practical synergistic systems that make use of organophosphorus compounds. A classic example is the combination of HDEHP and TOPO. The TOPO is thought to replace water or HDEHP in the coordination sphere of the metal. Some early work in this area included a study of the extraction of uranium in such systems (82). Commercial processes now exist for the recovery of uranium from wet-process phosphoric acid utilizing synergistic systems (83,84). Descriptive studies of such systems have also been made (85,86). 

Synergistic systems have also been reported in which one of the adducts is in the aqueous phase. The combination of TOPO (in CCI4) and benzoic acid (in aqueous and organic) was shown to extract uranium with a synergistic effect. The organic-phase adduct was reported to be 1102(0104) C COO TOPO. An optimum benzoic acid/TOPO ratio exists, above which compound formation between TOPO and benzoic acid decreases the synergistic effect (91). 

Baker, G.J. (1963). The dual synergist system of piperonyl butovide and MGK 264. Pyreth. Post 7, 16 18. 

Biting flies are a serious pest of hogs because both the face fly and house fly transmit hog cholera and these pests breed in tremendous numbers in hog lots. Insecticides are also used to eonlrol the hog louse and hog mites. Fogging with 1.00% pyrethrins synergized with 2.00% PBO is a standard fly treatment in hog operations, and the same formulation can be applied directly to the animals. Other fogging formulations containing 0-50% pyrethrins and 1.00% PBO in a dual-synergist system are also frequently used. 

Tick-killing products usually have more than one active ingredient in conjunction with PBO, One very successful veterinary product combines two insecticides ipermethrin and pyrethrins in a dual-synergist system PBO and MGK 264) and twro repellents to provide effective control of not only ticks and fleas, but also of lice, diiggers. gnats, and mosquitoes. 

Cats and kittens may be more sensitive to many insecticides than other pets, and are often nervous about treatments. For this reason, foams that can be applied to the palm of the hand before application and then massaged into the hair arc the preferred treatments, and pyrethrins and PBOare the most commonly nseductive ingredients. Foam products, containing 0.15% pyrethrins and 0.70% PBO in a dual-synergist system, provide rapid flea kill and at least 8 days of residual control of fleas on cats. 

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