Photolytic And Partitioning Behavior Of Polynuclear Aromatic Compounds, Aromatic Amines, And Phenols In Aqueous Coal Oil (photodegradation, Indole, Carbazole, Pah, Photooxidation).
Picel, Kurt Calvin
1985
Abstract
Aqueous fractions produced from mixing coal oil with water, simulating a spill, have been shown to be acutely and chronically toxic to several aquatic organisms. Identification of the chemical components of these solutions and studies of their behavior and persistence in aquatic systems are needed. The processes of oil/water partitioning and photodegradation, which are of particular importance to the aquatic fate of coal-oil components, were studied here. Analytical techniques were developed and used for the measurement of coal-oil components in both oil and aqueous phases for the determination of distribution coefficients (K(,D)s). It was observed that the addition of a ring carbon or alkyl group increased logK(,D) by 0.31 and 0.45, respectively. Projected aqueous concentrations of four- and five-ring polynuclear aromatic hydrocarbons (PAH) based on estimated K(,D)s were in the low ng/L range. In addition, aqueous concentrations can be predicted for related coal-conversion materials. To study photolytic behavior, aqueous coal-oil solutions were exposed to sunlight for up to 3 hr. The photolysis rate constants in pure water for pyrene (0.82 hr('-1)), benz(a)anthracene (1.0 hr('-1)), and benzo(a)pyrene (1.4 hr('-1)), were reduced 6-9 fold in the aqueous coal-oil matrix as determined using isotope dilution gas chromatography/mass spectrometry. The rate for fluoranthene (0.07 hr('-1)) was basically unchanged in the matrix. Bulk components of the acid, base and aromatic hydrocarbon fractions screened by gas chromatography were not photodegraded detectably in the 3-hr exposure. Minimum half-lives ranged from 5-290 hr. Indoles and carbazoles were found to photodegrade with half-lives of 2-19 hr. Autoxidation was observed for several indoles exposed to sunlight individually. In the aqueous coal-oil matrix it appears that indoles undergo sensitized photolysis. Carbazole (pure water rate, 0.51 hr('-1)) behaved similar to PAH (2.2 fold reduction). Indoles had very high quantum yields, approaching unity, due possibly to contributions from autoxidation. Products of indole photodegradation isolated from the aqueous coal oil appear to be o-acylamino-ketones. Products were also detected in the acid and base fractions spectrophotometrically. The measurement of K(,D)s and the photolytic studies performed here will contribute significantly to the understanding of the behavior of aqueous coal-oil solutions, and to the evaluation of the hazards associated with these materials.Subjects
Amines Aqueous Aromatic Behavior Carbazole Coal Compounds Indole Oil Pah Partitioning Phenols Photodegradation Photolytic Photooxidation Polynuclear
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