Aqueous solubility of PCBs

Sagan, M.T. and Inel, Y. (1993). Prediction of Aqueous Solubility of PCBs Related to Molecular Structure. Tr.J.Chemistry, 17,188-195. 

Suspended and bottom sediments are widely regarded as a sink for PCB s and other hydrophobic organic pollutants released Into aquatic systems. The mechanism commonly proposed to explain the affinity of PCB s for sediments Is equilibrium sorption or partitioning, which Is a function of the aqueous solubility of PCB Isomers and the attractiveness of the sedimentary matrix to PCB s (1-4). Field and laboratory studies Indicate that sedimentary organic matter plays a fundamental role In PCB-sedlment associations (5-12) and that humic substances are Important components of the sedimentary organic matrix for such associations (6,13-16). For example, Choi and Chen (O found that sedimentary PCB and DDT concentrations were linearly related to the humic acid content of sediments from Los Angeles Harbor. Fierce et al. (15) determined that humic acid could account... 

Notes (1) Aqueous solubility of PCB component of Askarel mixture. 

Nirmalakhandan, N. N., Speece, R. E. (1989) Prediction of aqueous solubility of organic chemicals based on molecular structure. 2. Application to PNAs, PCBs, PCDDs, etc. Environ. Sci. Technol. 23, 708-713. 

The first-derivative ESR spectra of 2-PCB and 4-PCB yielded interpretable signals, but no significant peaks were found when analyzing sonicated solutions of 2,4,5-PCB. The formation of organic radicals at a detectable level may have been hindered by the low aqueous solubility of 2,4,5-PCB. 

Aqueous solubility (see Sect. 2.1.1) controls the loss of PCBs via surface and groundwater migration and transport, and is a major factor in understanding the environmental fate of PCB contaminants. The solubility of PCB isomers decreases as the degree of chlorination increases, as shown in Fig. 5. It should be noted that solubility data included in Table 7 and shown in Fig. 5 are based upon pure isomers. When an isomer is part of a mixture such as the Aroclors, solubility is reduced. Figure 6 shows the relationship between the solubility of the pure... 

Environmental releases of PCBs often accompany releases of carriers from utility equipment. An example would be mineral oil released from oil filled transformers. When PCBs are present in a mineral oil-PCB mixture the aqueous solubility of the PCBs is reduced significantly. Two factors play a role in this reduction partitioning of the lipophilic (oil-loving) PCBs into the oil phase, and the reduced interaction of the PCBs with precipitation or groundwater caused by the hydrophobic nature of the oil matrix. Interpretation of aqueous PCB concentrations in the field must consider the presence of dissolved organic carbon (DOC) [382,386,397,403]. 

Huang, Q. and Hong, C.-S. Aqueous solubilities of non-ortho and mono-ortho PCBs at four temperatures, Water Res., 36(14) 3543-3552, 2002. 

The determination of the breakthrough time and the rate at which the particular PCB of this study permeated the various garment materials was performed by placing 110 mL of PCB (T=25°C) in the organic phase side of the permeation cell with the test material in place and with 120 mL of water and 40 mL of n-heptane atop the water in the cells aqueous phase side. The aqueous phase was stirred vigorously to allow the heptane to continuously extract the PCB from the water. This procedure was necessary because of the limited solubility of PCB constituents in water. 

Nirmalakhandan, N.N. and Speece, R.E. 1989. Prediction of Aqueous Solubility of Organic Chemicals based on Molecular Structure. 2. Applications to PNA s, PCB s, PCDD s, etc. Environ. Sci. Technol. 23 708-713. 

Mackay, D., Shiu, W.Y. (1977) Aqueous solubility of polynuclear aromatic hydrocarbons. J. Chem. Eng. Data 22, 399—402. Mackay, D., Shiu, W.Y, Billington, J.W., Haung, G.L. (1983) Physical chemical properties of polychlorinated biphenyls. In Physical Behavior of PCBs in the Great Lakes. Mackay, D., Paterson, S., Eisenreich, S.J., Simmons, M.S. Eds., pp. 59-69, Ann Arbor Sci. Publ., Ann Arbor, Michigan. 

The aqueous solubilities (-log S) of mono- through decaCDEs (106 PCDE congeners) range between 4.21 mol 1 1 and 12.95 mol 1 1 [59]. These values were calculated from high performance liquid chromatography (HPLC) data at 30°C. PCDEs are more soluble in water than PCBs, which have extremely low water solubilities. The water solubilities of PCBs range from 7 x 103 pg 1 1 to 0.02 pg 1 1 [3]. 

A comprehensive study of the relation between molecular structure and aqueous solubility of some 117 PCB congeners,has shown that solubility (as the mole fraction, x) can be expressed as a function of the van der Waal s surface,... 

In addition, it has been shown that the aqueous solubility of both PCB congeners and polynuclear aromatic hydrocarbons can be correlated with molecular volume that is not surprising since one would anticipate a relation between volume and surface area. 

Aqueous Solubility of Polychlorinated Biphenyls Related to Molecular Structure This paper contains solubility data for 44 PCB congeners and outlines correlations with molecular volume and surface area. Several values are listed and referenced for most congeners. 

Adsorption Henry s constants are central to adsorptive purification processes of dilute streams and also reach, as will be seen in the next section, into areas of environmental concern. To acquaint the reader with their magnitude, we have compiled values of H on carbon for some important trace solutes in aqueous solution, which are displayed in Table 6.4. Of note here is the extremely high value for PCBs, which dominates the table. The reader should be reminded, however, that this is partly offset by the extremely low solubility of PCBs. 

Aroclors possess properties different from their individual chlorobiphenyl compounds. For example, the individual compounds are solids at room temperature, whereas the Aroclors are either mobile oils (Aroclor 1221, 1232, 1242, and 1248), viscous liquids (Aroclor 1254), or sticky resins (Aroclor 1260 and 1262). PCBs are sparingly soluble in water, and the solubility decreases with increasing chlorine content (Table 9.5). Consequently, the aqueous solubilities of some Aroclors are also variable as follows 1242, 200 fig L 1248, 100 fig L 1254, 40 fig L and 1260, 25 figVK Bias in these results owing to selective solubilization of lower chlorinated biphenyls (LCBPs) should be taken into account in considering the environmental behavior of specific PCBs and their toxicity to organisms. The relative pattern of partitioning into tissues often reflects the differential water solubilities of the compounds rather than preferential uptake. 

Extraction, employs a liquid solvent to remove certain compounds from another liquid using the preferential solubility of these solutes in the MSA. For instance, wash oils can be used to remove phenols mid polychlorinated biphenyls (PCBs) from die aqueous wastes of synthetic-fuel plants and chlorinated hydrocarbons from organic wastewater. 

As described earlier, Henry s law constants can be calculated from the ratio of vapor pressure and aqueous solubility. Henry s law constants do not show a simple linear pattern as solubility, Kqw or vapor pressure when plotted against simple molecular descriptors, such as numbers of chlorine or Le Bas molar volume, e.g., PCBs (Burkhard et al. 1985b), pesticides (Suntio et al. 1988), and chlorinated dioxins (Shiu et al. 1988). Henry s law constants can be estimated from ... 

Abramowitz, R., Yalkowsky, S. H. (1990) Estimation of aqueous solubility and melting point of PCB congeners. Chemosphere 21, 1221-1229. 

Tulp, M. T. M., Hutzinger, O. (1978) Some thoughts on the aqueous solubilities and partition coefficients of PCB, and the mathematical correlation between bioaccumulation and physico-chemical properties. Chemosphere 7, 849-860. 

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