Perfluorooctanoates solubility

Polymerization of vinylidene fluoride by emulsion or suspension polymerization in water is conducted at conditions of 10-130 °C and 10-200 bar. In the emulsion polymerization, either water-soluble peroxides or monomer-soluble peroxy or organic peroxides are used as initiators [ 17]. Fluorinated surfactants, such as ammonium perfluorooctanoate, are used as dispersing agents. Chain transfer agents, such as acetone, chloroform, or trichlorofluoromethane, may be... 

Tardiff RG, Carson ML, Sweeney LM, Kirman CR, Tan YM, Andersen M, Bevan C, Gargas ML (2009) Derivation of a drinking water equivalent level (DWEL) related to the maximum contaminant level goal for perfluorooctanoic acid (PFOA), a persistent water soluble compound. Food Chem Toxicol 47(10) 2557-2589... 

The surface tension data for the mixtures containing sodium dodecyl sulfate and 1.0, 0.75, and 0.20 mole fractions of perfluorooctanoic acid are plotted as a function of perfluorooctanoic acid concentration in Fig. 4.23. All three systems attain the same low and constant surface tension value after a sharp change in the slope corresponding to the formation of perfluorooctanoic acid micelles. The cmc values for the 1.0 and 0.75 molar systems are indistinguishable, indicating that the solubility of sodium dodecyl sulfate is insignificant in those micelles. The curve... 

The solubility of fluorinated surfactants depends on the hydrophile of the surfactant, in addition to the structure of the fluorinated group. The solubility of perfluoroalkanoic acids in water, like the solubility of nonfluorinated alkanoic acids, decreases with increasing chain length. At 25°C, perfluorohexanoic acid and shorter-chain perfluoroalkanoic acids are miscible with water in all proportions. However, perfluorooctanoic acid and perfluorodecanoic acid are only slightly soluble in water [4]. 

Teddy and Wheeler [201] have described the three-component phase diagram for the ammonium perfluorooctanoate/octanol-water system. The phase structure was determined by optical microscopy. Octanol was found to be four times less soluble in ammonium perfluorooctanoate solutions than in sodium oc-tanoate solutions. The low solubility of octanol was attributed to a low mutual solubility of fluorocarbon and hydrocarbon chains and not to different counterions, ammonium versus sodium. However, the ammonium counterion may have contributed to the high solubility of ammonium perfluorooctanoate in octanol. 

Bongiovanni et al. [215] solubilized peifluorocarbons in aqueous solutions of commercial-grade perfluorooctanoic acid (about 80% Cg) and its sodium salt. The observed increase in solubility of perfluorooctanoic acid when neutralized with sodium hydroxide was related to lowering of the Ki afft point. W/0 and OAV isotropic monophasic liquid systems were obtained by changing the pH of the system. 

Fig. 6.41 Solubility of gas (moles of gas absorbed in 1000 g of water containing sodium perfluorooctanoate) as a function of surfactant concentration at 25°C. (From Ref. 219. Reproduced by permission of Academic Press.)...

Fig. 7.5 Equilibrium compositions of micelles and monomers in the sodium do-decyl sulfate and perfluorooctanoic acid system. Two types of micelles are present with limited mutual solubility. (From Ref. 33. Reproduced by permission of the American Chemical Society.)...

The effect of additives on mesophases of fluorinated surfactants has been studied by Tiddy and Wheeler [ 163] and Rosenblatt [176]. Tiddy and Wheeler described the effects of -octanol on the ammonium perfluorooctanoate-water system with a three-component phase diagram (Fig. 7.39). The main differences between phase diagrams for this system and that for sodium octanoate- octanol-water were related to mutual phobicity between fluorocarbon and hydrocarbon chains. Octanol was found to be less soluble in the aqueous micellar phase of ammonium perfluorooctanoate than that of sodium octanoate. However, ammonium perfluorooctanoate is more soluble in octanol than sodium octanoate. This solubility difference is probably related to the effect of counterions, as ammonium salts are usually more soluble in octanol than sodium salts. 

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