Dissolution of PCB congeners from an Aroclor and an Aroclor/hydraulic oil mixture

Few measurements of the dissolution of individual polychlorinated biphenyl (PCB) congeners dissolved from Aroclor mixtures in water have been reported, and there is no available information on how the aqueous solubilities of these compounds are affected by their presence in organic liquids such as hydraulic oils. A series of experiments were performed to study the dissolution of specific PCB congeners from Aroclor 1242 alone and from mixtures of Aroclor 1242 in an hydraulic oil (Fyrquel 220). Batch dissolution experiments were performed for time periods up to 20 weeks. The principal solutes from Aroclor 1242 were dichlorobiphenyls and trichlorobiphenyls, for a total PCB concentration of approximately 97 μg/L. In comparison to the composition of pure Aroclor 1242, the distribution of the mass of PCB congeners in the aqueous phase comprised significantly more dichlorobiphenyl congeners with less tetrachloro- and pentachlorobiphenyl congeners. PCB congener dissolution from 5% v/v Aroclor in hydraulic oil was decreased substantially relative to that observed for the pure Aroclor. Dissolution of PCBs from Aroclor and Aroclor/hydraulic oil mixtures occurred in approximate proportion to the congener pure liquid solubility and the mole fraction in organic liquid. This work demonstrates for a pure Aroclor and Aroclor mixtures in hydraulic oil that the aqueous leaching potential is skewed towards the lower-chlorinated homologs.