STYRENE

Note: Normally inhibited with 8-12 ppm 4-tert-butylcatechol to prevent polymerization. According to Chevron Phillips Company (March 2002), 99.93% styrene contains the following components (ppm): benzene (<1), toluene (<1), ethylbenzene (50), α-meth-ylstyrene (175), m + pxylene (120), o-xylene (125), isopropylbenzene (100), n-propylbenzene (60), m + p-ethyltoluene (20), vinyltoluene (10), phenylacetylene (50), m + p-divinylbenzene (<10), o-divinylbenzene (<5), aldehydes as benzaldehyde (15), and peroxides as benzoyl-peroxides (5). CASRN: 100-42-5; DOT: 2055; DOT label: Flammable or combustible liquid; molecular formula: C8H8; FW: 104.15; RTECS: WL3675000; Merck Index: 12, 9028 Physical state, color, and odor: Clear, colorless, watery liquid with a penetrating or pungent rubber-like odor. Becomes yellow to yellowish-brown on exposure to air. Experimentally determined odor threshold concentrations in air for inhibited and unhibited styrene were 0.1 and 0.047 ppmv, respectively (Leonardos et al., 1969). Experimentally determined detection and recognition odor threshold concentrations were 220-640 µg/m3 (52-150 ppbv) and 64 µg/m3 (15 ppbv), respectively (Hellman and Small, 1974). At 40 °C, the average odor threshold concentration and the lowest concentration at which an odor was detected were 65 and 37 µg/L, respectively. At 25 °C, the lowest concentration at which a taste was detected was 94 µg/L, respectively (Young et al., 1996). The average least detectable odor threshold concentrations in water at 60 °C and in air at 40 °C were 3.6 and 120 µg/L, respectively (Alexander et al., 1982). Melting point (°C): -33 (Huntress and Mulliken, 1941) Boiling point (°C): 145.2 (Weast, 1986) Density (g/cm3): 0.9148 at 10 °C, 0.9059 at 20 °C, 0.8880 at 40 °C, 0.8702 at 60 °C (quoted, Standen, 1969) 0.9016 at 25.00 °C, 0.8971 at 30.00 °C, 0.8926 at 35.00 °C (Aminabhavi and Patil, 1998) Diffusivity in water (x 10-5 cm2/sec): 0.81 at 20 °C using method of Hayduk and Laudie (1974) Dissociation constant, pKa: >14 (Schwarzenbach et al., 1993) Flash point (°C): 31 (NIOSH, 1997)

0.9 (NIOSH, 1997) Upper explosive limit (%): 6.8 (NIOSH, 1997) Entropy of fusion (cal/mol⋅K): 10.79 (Guttman et al., 1943; Pitzer et al., 1946) 10.8 (Lebedev et al., 1985) 10.83 (Warfield and Petree, 1961) Heat of fusion (kcal/mol): 2.617 (Guttman et al., 1943; Pitzer et al., 1946; Lebedev et al., 1985) 2.620 (Warfield and Petree, 1961) Henry’s law constant (x 10-3 atm⋅m3/mol): 3.91 at 25 °C (static headspace-GC, Welke et al., 1998) Interfacial tension with water (dyn/cm at 19 °C): 35.48 (Demond and Lindner, 1993) Ionization potential (eV): 8.47 (Franklin et al., 1969) 8.71 (Rav-Acha and Choshen, 1987) 8.86 (Krishna and Gupta, 1970) Bioconcentration factor, log BCF: 1.13 (goldfish, Ogata et al., 1984) Soil organic carbon/water partition coefficient, log Koc: 5.06 (aquifer sand), 4.25 (Lima loam), 3.65 (Edwards muck) (Fu and Alexander, 1992) Octanol/water partition coefficient, log Kow: 2.76 (Fujisawa and Masuhara, 1981) 2.95 (Chou and Jurs, 1979) 3.16 at 23 °C (shake flask-HPLC, Banerjee et al., 1980) Solubility in organics: Soluble in acetone, ethanol, benzene, ether, carbon disulfide (Weast, 1986) Solubility in water: 1.54 mM at 25.0 °C (shake flask-LSC, Banerjee et al., 1980) 300 mg/L solution at 25 °C (shake flask-UV spectrophotometry, Andrews and Keefer, 1950a) 9.6 g/kg at 60.3 °C (Fordyce and Chapin, 1947) 24.9 mM at 60 °C (multiple headspace extraction-GC, Chai et al., 2005) In wt %: 0.029 at 7 °C, 0.033 at 24 °C, 0.036 at 32 °C, 0.040 at 40 °C, 0.045 at 45 °C (shake flask-

cloud point, Lane, 1946) 3.19 x 10-3 at 25 °C (mole fraction, inert gas stripping-GC, Li et al., 1993) Vapor density: 4.26 g/L at 25 °C, 3.60 (air = 1)

5 at 20 °C, 9.5 at 30 °C (quoted, Verschueren, 1983) 4.3 at 15 °C (ACGIH, 1987) 2.88 at 12.5 °C, 6.31 at 25.0 °C, 12.71 at 37.5 °C (Pitzer et al., 1946) Environmental fate: Biological. Fu and Alexander (1992) observed that despite the high degree of adsorption onto soils, styrene was mineralized to carbon dioxide under aerobic conditions. Rates of mineralization from highest to lowest were sewage sludge, Lima soil (pH 7.23, 7.5% organic matter), groundwater (pH 8.25, 30.5 mg/L organic matter), Beebe Lake water from Ithaca, NY (pH 7.5, 50 to 60 mg/L organic matter), aquifer sand (pH 6.95, 0.4% organic matter), Erie silt loam (pH 4.87, 5.74% organic matter). Styrene did not mineralize in sterile environmental samples. Oié et al. (1979) reported BOD and COD values of 1.29 and 2.80 g/g using filtered effluent from a biological sanitary waste treatment plant. These values were determined using a standard dilution method at 20 °C and stirred for a period of 5 d. When a sewage seed was used in a separate screening test, a BOD value of 2.45 g/g was obtained. The ThOD for styrene is 3.08 g/g. Photolytic. Irradiation of styrene in solution forms polystyrene. In a benzene solution, irradiation of polystyrene will result in depolymerization to presumably styrene (Calvert and Pitts, 1966). Atkinson (1985) reported a photooxidation reaction rate of 5.25 x 10-11 cm3/molecule⋅sec for styrene and OH radicals in the atmosphere. A reaction rate of 1.8 x 10-4 L/molecule⋅sec at 303 K was reported for the reaction of styrene and ozone in the vapor phase (Bufalini and Altshuller, 1965). Chemical/Physical. In the dark, styrene reacted with ozone forming benzaldehyde, formaldehyde, benzoic acid, and trace amounts of formic acid (Grosjean, 1985). Polymerizes readily in the presence of heat, light, or a peroxide catalyst. Polymerization is exothermic and may become explosive (NIOSH, 1997). De Visscher et al. (1996) investigated the sonolysis of styrene and other monocyclic aromatic compounds in aqueous solution by 520 kHz ultrasonic waves. The experiments were performed in a 200-mL glass reactor equipped with a cooling jacket maintained at 25 °C. At initial styrene concentrations and sonication times of 0.25 mM and 40 min, 0.49 mM and 80 min, and 0.97 mM and 80 min, the first-order reaction rates were 0.03292, 0.02409, and 0.01262/min, respectively. Styrene will not hydrolyze because it does not contain a hydrolyzable functional group (Kollig, 1993). At an influent concentration of 180 mg/L, treatment with GAC resulted in an effluent concentration of 18 mg/L. The adsorbability of the carbon used was 28 mg/g carbon (Guisti et al., 1974). Similarly, at influent concentrations of 10, 1.0, 0.1, and 0.001 mg/L, the GAC adsorption capacities were 440, 120, 33, and 9.0 mg/g, respectively (Dobbs and Cohen, 1980). Exposure limits: NIOSH REL: TWA 50 ppm (215 mg/m3), STEL 100 ppm (425 mg/m3), IDLH 700 ppm; OSHA PEL: TWA 100 ppm, ceiling 200 ppm, 5-min/3-h peak 600 ppm; ACGIH TLV: TWA 20 ppm, STEL 40 ppm (adopted). Symptoms of exposure: Irritates, eye, skin, and mucous membranes. Narcotic at high concentrations (Patnaik, 1992). An irritation concentration of 430.00 mg/m3 in air was reported for uninhibited styrene (Ruth, 1986). Toxicity: EC50 (48-h) for Daphnia magna 4.7 mg/L (Cushman et al., 1997). LC50 (14-d) for Eisenia fostida 120 mg/kg (Cushman et al., 1997). LC50 (96-h) for Pimephales promelas 10 mg/L, Hyalella azteca 9.5 mg/L, Selenastrum

LC50 (48-h) for Daphnia magna 23 mg/L (LeBlanc, 1980). LC50 (24-h) for Daphnia magna 27 mg/L (LeBlanc, 1980); Oncorhynchus mykiss 2.5 mg/L (Qureshi et al., 1982), Cyprinodon variegatus 9.1 mg/L (Heitmuller et al., 1984). LC50 (inhalation) for mice 21,600 mg/m3/2-h, rats 24 g/m3/4-h (quoted, RTECS, 1985). Acute oral LD50 for mice 316 mg/kg, rats 5,000 mg/kg (quoted, RTECS, 1985). TLm values for brine shrimp after 24 and 48 h of exposure were 68 and 52 mg/L, respectively (Price et al., 1974). Source: Based on laboratory analysis of 7 coal tar samples, styrene concentrations ranged from ND to 2,500 ppm (EPRI, 1990). A high-temperature coal tar contained styrene at an average concentration of 0.02 wt % (McNeil, 1983). Styrene occurs naturally in benzoin, rosemary, sweetgum, cassia, Oriental styrax, and Peru balsam (Duke, 1992). Identified as one of 140 volatile constituents in used soybean oils collected from a processing plant that fried various beef, chicken, and veal products (Takeoka et al., 1996). Drinking water standard (final): MCLG: 0.1 mg/L; MCL: 0.1 mg/L. In addition, a DWEL of 7 mg/L was recommended (U.S. EPA, 2000). Uses: Preparation of polystyrene, styrene oxide, ethylbenzene, ethylcyclohexane, benzoic acid, synthetic rubber, resins, protective coatings, and insulators.