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Perfluoroalkyl Acids: A Review of Monitoring and Toxicological Findings

This paper presents a review of catalytic ozonation and methods of enhancing molecular ozone reactions in water treatment. It is also an attempt to propose general ideas about mechanisms governing catalytic ozone reactions. Catalytic ozonation is a new means of contaminants removal from drinking water and wastewater. Its application is mainly limited to laboratory use. However, due to successful results further investigation is to be carried out. The majority of models proposed represent more of a speculative approach to the problem than a hypothesis based on experimental data. It is therefore useful to provide a summary of the accomplishments concerning catalytic ozonation and methods of enhancing molecular ozone reactions that were published so far. A survey of the application of several homo- and heterogeneous catalysts, their activity and the parameters influencing the efficiency of catalytic systems is presented here as a short overview, the aim of which is to raise awareness of possible new approaches to water purification.

Catalytic ozonation and methods of enhancing molecular ozone reactions in water treatment

Rainbow trout (Oncorhynchus mykiss) were exposed simultaneously to a homologous series of perfluoroalkyl carboxylates and sulfonates in a flow-through system to determine compound-specific tissue distribution and bioconcentration parameters for perfluorinated acids (PFAs). In general, PFAs accumulated to the greatest extent in blood > kidney > liver > gall bladder. Carboxylates and sulfonates with perfluoroalkyl chain lengths shorter than seven and six carbons, respectively, could not be detected in most tissues and were considered to have insignificant bioconcentration factors (BCFs). For detectable PFAs, carcass BCFs increased with increasing length of the perfluoroalkyl chain, ranging from 4.0 to 23,000, based on wet weight concentrations. Carboxylate carcass BCFs increased by a factor of eight for each additional carbon in the perfluoroalkyl chain between 8 and 12 carbons, but this relationship deviated from linearity for the longest PFA tested, possibly because of decreased gill permeability. In general, half-lives (3.9-28 d) and uptake rates (0.053-1.700 L/kg/d) also increased with increasing length of the perfluoroalkyl chain in all tissues. Sulfonates had greater BCFs, half-lives, and rates of uptake than the corresponding carboxylate of equal perfluoroalkyl chain length, indicating that hydrophobicity, as predicted by the critical micelle concentration, is not the only determinant of PFA bioaccumulation potential and that the acid function must be considered.

Bioconcentration and tissue distribution of perfluorinated acids in rainbow trout (Oncorhynchus mykiss)

Since the early 1980s, there has been a steady increase in the use of nonvolatile fluorinated organic compounds for a variety of industrial and commercial applications. The industrial use of these relatively stable compounds has initiated debate over the fate of fluorochemicals in the environment and, ultimately, the bioavailability of these compounds. In this manuscript, we present quantitative results from a study of 65 human sera samples purchased from biological supply companies that provide characterization of specific organic fluorochemicals present in the sera of nonindustrially exposed humans. Summed together, the compound-specific characterization data reported here agree closely with levels of nonspeciated organic fluorine that were originally reported to be present in sera in 1970. The compound-specific method for the extraction of extremely low levels of several commercial organic fluorochemicals from sera and liver with quantitative detection by negative ion electrospray tandem mass spectrometry described represents a robust, previously undescribed approach to quantifying specific organic fluorochemicals in biological matrices.

Compound-Specific, Quantitative Characterization of Organic Fluorochemicals in Biological Matrices

https://zenodo.org/record/1259371/files/article.pdf

The developmental toxicity of perfluoroalkyl acids and their derivatives

The use of organofluorine compounds has increased throughout this century, and they are now ubiquitous environmental contaminants. Although generally viewed as recalcitrant because of their lack of chemical reactivity, many fluorinated organics are biologically active. Several questions surround their distribution, fate, and effects. Of particular interest is the fate of perfluoroalkyl substituents, such as the trifluoromethyl group. Most evidence to date suggest that such groups resist defluorination, yet they can confer significant biological activity. Certain volatile fluorinated compounds can be oxidized in the troposphere yielding nonvolatile compounds, such as trifluoroacetic acid. In addition, certain nonvolatile fluorinated compounds can be transformed in the biosphere to volatile compounds. Research is needed to assess the fate and effects of nonvolatile fluorinated organics, the fluorinated impurities present in commercial formulations, and the transformation products generated by biochemical pr...

Fluorinated Organics in the Biosphere

Little is known of the potential for biodegradation of fluorinated sulfonates. To evaluate this potential, the following model compounds were selected:  difluoromethane sulfonate (DFMS), trifluoromethane sulfonate (TFMS), 2,2,2-trifluoroethane sulfonate (TES), perfluorooctane sulfonate (PFOS), and 1H,1H,2H,2H-perfluorooctane sulfonate (H-PFOS). A laboratory isolate designated Pseudomonas sp. strain D2 completely defluorinated DFMS under aerobic, sulfur-limiting conditions in a defined mineral medium. Strain D2 utilized DFMS as the sole source of sulfur, but not as a source of carbon or energy. DFMS utilization was inhibited by other forms of sulfur, and noncompetitive inhibition kinetics were observed, with Ki values of 3−4 μM for sulfate, sulfite, methane sulfonate, and cystine. Strain D2 was subsequently used to evaluate degradation of other fluorinated sulfonates. Growth and defluorination were only observed for those compounds containing hydrogen (TES and H-PFOS). TFMS and PFOS were not degraded. TES ...

Defluorination of Organofluorine Sulfur Compounds by Pseudomonas Sp. Strain D2

Densities and ultrasonic velocities of NaCl−CaCl2 aqueous mixtures at 25 °C have been measured for the ionic strength range I=0.30–20.0. Where NaCl solubility permitted, both properties were measured over the range of compositions from pure NaCl to pure CaCl2 at constant I. Apparent molar volumes and apparent molar compressibilities of the mixtures were calculated. The Pitzer form of the specific interaction theory is used to predict the properties of the binary mixtures from the properties of the single salt solutions. It provides a good fit over the full range of ionic strength for apparent molar volumes but a much inferior fit for compressibilities. It is also clear that in the high ionic strength range, explicit mixing parameters must be included for an excellent fit.

Thermodynamics of concentrated electrolyte mixtures. II. Densities and compressibilities of aqueous NaCl−CaCl2 at 25 °C

The Thermodynamics of Scale Prediction

The solubility of SrSO 4 (s) was determined in water and in 05, 1, 2, 3, and 4 m aqueous sodium chloride solutions for temperatures ranging from 25 to 250 o C and pressures ranging from 1 to greater than 500 bar The range in each of the three independent variables was covered completely, and the solubility is reported at 80 unique points on the sodium chloride concentration-temperature-pressure grid An expression for the temperature and pressure dependence of the thermodynamic solubility product and an empirical expression for calculating the mean activity coefficient as a function of temperature, pressure, and ionic strength are given

Thermodynamics of "scale" mineral solubilities. 4. Experimental measurements of strontium sulfate(s) in water and aqueous sodium chloride from 25 to 250 .degree.C and from 1 to 500 bar

Robert D. Howell

Papers

Fluorinated Organics in the Biosphere

Defluorination of Organofluorine Sulfur Compounds by Pseudomonas Sp. Strain D2

Thermodynamics of concentrated electrolyte mixtures. II. Densities and compressibilities of aqueous NaCl−CaCl2 at 25 °C

The Thermodynamics of Scale Prediction

Thermodynamics of "scale" mineral solubilities. 4. Experimental measurements of strontium sulfate(s) in water and aqueous sodium chloride from 25 to 250 .degree.C and from 1 to 500 bar