ABSTRACT
Based on photodechlorination of other polychlorobenzenes under similar conditions, it was suggested that dichlorobenzenes, chlorobenzene, benzene, phenol, hydrogen, and chloride ions would form as photodegradation products. The photodecomposition half-life for this reaction, based on the first-order photodecomposition rate of 1.07 x 10-3/sec, is 10.8 min (Chu and Jafvert, 1994). Peijnenburg et al. (1992) investigated the photodegradation of a variety of substituted aromatic halides using a Rayonet RPR-208 photoreactor equipped with 8 RUL 3,000-Ǻ lamps (250-350 nm). The reaction of 1,3,5-trichlorobenzene (initial concentration 10-5 M) was conducted in distilled water and maintained at 20 °C. Though no products were identified, the investigators reported photohydrolysis was the dominant transformation process. The measured pseudo-firstorder reaction rate constant and corresponding half-life were 0.003/min and 205.5 min., respectively. Toxicity: EC50 (48-h) for Daphnia magna 2.66 mg/L (Marchini et al., 1999), Pseudokirchneriella subcapitata 3.11 mg/L (Hsieh et al., 2006). LC50 (14-d) for Poecilia reticulata 7.4 µg/L (Könemann, 1981). Drinking water standard: No MCLGs or MCLs have been proposed, however, a DWEL of 200 µg/L was recommended (U.S. EPA, 2000). Uses: Organic synthesis.
