ABSTRACT
NO2 CASRN: 100-02-7; DOT: 1663; DOT label: Poison; molecular formula: C6H5NO3; FW: 139.11; RTECS: SM2275000; Merck Index: 12, 6718 Physical state, color, and odor: Colorless to pale yellow, odorless crystals Melting point (°C): 112-114 (Dean, 1987) 114 (quoted, Standen, 1967) Boiling point (°C): 279 (Aldrich, 1990) Density (g/cm3): 1.479 at 20 °C, 1.270 at 120 °C (quoted, Standen, 1967) Diffusivity in water (x 10-5 cm2/sec): At ceff = 120 µM: 0.474 at 4.0 °C, 0.919 25.0 °C, 1.518 at 50.0 °C; 0.930 (ceff = 580 µM) at 25.0 °C (Niesner and Heintz, 2000)
Dissociation constant, pKa: 7.17 at 25 °C (quoted, Rosés et al., 2000) 7.08 at 21.5 °C (Schwarzenbach et al., 1988) Flash point (°C): Not pertinent (combustible solid, Weiss, 1986) Entropy of fusion (cal/mol⋅K): 15.0 (Campbell and Campbell, 1941) 11.27 (Poeti et al., 1982) 18.7 (Singh and Kumar, 1986) Heat of fusion (kcal/mol): 5.80 (Campbell and Campbell, 1941) 4.36 (Poeti et al., 1982) 7.20 (Singh and Kumar, 1986) Henry’s law constant (atm⋅m3/mol): 3.85 x 10-10 at 25 °C (Parsons et al.,1971) 1.63 x 10-7 at 5 °C (average derived from six field experiments, Lüttke and Levsen, 1997)
9.52 (Gordon and Ford, 1972) Bioconcentration factor, log BCF: 1.04 (Chlorella fusca, Geyer et al., 1981) 1.48 (algae, Geyer et al., 1984) 1.48 (activated sludge), 1.60 (golden ide) (Freitag et al., 1985) 1.90, 2.44 (fathead minnow, Call et al., 1980) 2.10 (fathead minnow, Veith et al., 1979) Soil organic carbon/water partition coefficient, log Koc: 1.75-2.73 (average = 2.33 for 10 Danish soils, Løkke, 1984) 1.74 (Brookstone clay loam, Boyd, 1982) 1.94 (loamy sand, Kjeldsen et al., 1990) 2.18 using mobile phase buffered to pH 3 (estimated from HPLC capacity factors, Hodson and
Williams, 1988) Kd = 34 mL/g on a Cs+-kaolinite (Haderlein and Schwarzenbach, 1993) Octanol/water partition coefficient, log Kow: 1.68 (HPLC, Unger et al., 1978) 1.85, 1.92 (Geyer et al., 1984) 1.93 (Beltrame et al., 1993) 2.04 (Schwarzenbach et al., 1988) 1.96 at 25 °C (shake flask-UV spectrophotometry, Fujita et al., 1964; RP-HPLC, Garst and
Wilson, 1984) Solubility in organics: Soluble in benzene (9.2 g/kg at 20 °C), ethanol (1,895 g/kg at 25 °C), and toluene (227 g/kg at 70 °C) (Palit, 1947). Also soluble in isooctane and n-butyl ether at 0.046 and 176.7 mg/L at 25 °C, respectively (Anderson et al., 1971) Solubility in water: 32.8 g/kg at 40 °C (Palit, 1947) 16,000 mg/L at 25 °C, 269,000 mg/L at 90 °C (Smith et al., 1976) 10.162, 15.599, 19.600, and 26.846 g/L at 15.3, 25.0, 30.3, and 34.9 °C, respectively (shake flask-
conductimetry, Achard et al., 1996) 11.57 g/L at 20 °C in a buffered solution (pH 1.5, Schwarzenbach et al., 1988) 0.1 M at 25 °C (Caturla et al., 1988) 14,746 mg/L at 25 °C (Riederer, 1990) At 20 °C: 97, 77.6, 78.4, and 77.6 mM in doubly distilled water, Pacific seawater, artificial
seawater, and 35% NaCl, respectively (modified shake flask-fluorometry, Hashimoto et al., 1984)
In g/L; 8.05 at 10.00 °C, 12.2 at 20.00 °C, 17.8 at 30 °C (shake flask-UV spectrophotometry, Beneš and Dohnal, 1999)
In mmol/kg solution: 57.5 at 11.1 °C, 62.5 at 12.7 °C, 65.2 at 13.5 °C, 69.0 at 14.6 °C, 72.3 at 15.5 °C, 73.4 at 15.8 °C, 81.2 at 17.8 °C, 82.5 at 18.1 °C, 85.0 at 18.7 °C, 88.9 at 19.6 °C, 93.9 at 20.7 °C, 97.2 at 21.4 °C, 105.6 at 23.1 °C, 108.2 at 23.6 °C, 112.0 at 24.3 °C, 117.5 at 25.3 °C, 123.2 at 26.3 °C, 135.5 at 28.3 °C, 160.9 at 32.0 °C, 167.6 at 32.9 °C, 168.4 at 33.0 °C, 172.3 at 33.5 °C, 176.2 at 34.0 °C, 180.3 at 34.5 °C, 203.4 at 37.2 °C, 215.4 at 38.5 at °C, 222.1 at 39.2 °C, 235.1 at 40.5 °C, 236.1 at 40.6 °C, and 240.3 at 41.0 °C (light transmission technique, Jaoui et al., 2002)
10 at 20 °C (Schwarzenbach et al., 1988) 30 at 30 °C (extrapolated, McCrady et al., 1985) 4.05 at 25 °C (Riederer, 1990) Environmental fate: Biological. Under anaerobic conditions, 4-nitrophenol may undergo nitroreduction producing 4aminophenol (Kobayashi and Rittman, 1982). Estuarine sediment samples collected from the Mississippi River near Leeville, LA were used to study the mineralization of 4-nitrophenol under aerobic and anaerobic conditions. The rate of mineralization to carbon dioxide was found to be faster under aerobic conditions (1.04 x 10-3 µg/day/g dry sediment) than under anaerobic conditions (2.95 x 10-5 µg/day/g dry sediment) (Siragusa and DeLaune, 1986). In lake water samples collected from Beebe and Cayuga Lakes, Ithaca, NY, 4-nitrophenol at 50, 75, and 100 µg/L was not mineralized after 7 d. When the lake water samples were inoculated with the microorganism Corynebacterium sp., extensive mineralization was observed. However, at a concentration of 26 µg/L the extent of mineralization was much lower than at higher concentrations. The presence of a eucaryotic inhibitor (cycloheximide) also inhibited mineralization at the lower concentration but did not affect mineralization at the higher concentrations (Zaidi et al., 1989). 4-Nitrophenol degraded rapidly from flooded alluvial and pokkali (organic matter-rich acid sulfate) soils that were inoculated with parathion-enrichment culture containing 5-day-old cultures of Flavobacterium sp. ATCC 27551 and Pseudomonas sp. ATCC 29353 (Sudhaker-Barik and Sethunathan, 1978a). 4-Nitrophenol disappeared completely with the formation of nitrite, particularly in the inoculated soils rather than in the uninoculated soils. In activated sludge, 0.5% mineralized to carbon dioxide after 5 d (Freitag et al., 1985). Intermediate products include 4-nitrophenol, which degraded to hydroquinone with lesser quantities of oxyhydroquinone (Nyholm et al., 1984). When 4-nitrophenol was statically incubated in the dark at 25 °C with yeast extract and settled domestic wastewater inoculum, 100% biodegradation with rapid adaptation was achieved after 7 d (Tabak et al., 1981). In the presence of suspended natural populations from unpolluted aquatic systems, the second-order microbial transformation rate constant determined in the laboratory was reported to be 3.8 ± 1.4 x 10-11 L/organism⋅h (Steen, 1991). In activated sludge inoculum, 95.0% COD removal was achieved. The average rate of biodegradation was 17.5 mg COD/g⋅h (Pitter, 1976). Spiess et al. (1998) reported that the Mycobacterium sp. Strain HL 4-NT-1 utilized 4nitrophenol as a sole source of nitrogen, carbon, and energy. Under anaerobic conditions, 4nitrophenol completely degraded to 6-amino-3-methylphenol via the intermediate 4hydroxyaminotoluene. Under aerobic conditions, 4-nitrophenol degraded slightly releasing small amounts of ammonia. Surface Water. Photodegration half-lives of 5.7, 6.7, and 13.7 d were reported at pH values of 5, 7, and 9, respectively (Hustert et al., 1981). Groundwater. Nielsen et al. (1996) studied the degradation of 4-nitrophenol in a shallow, glaciofluvial, unconfined sandy aquifer in Jutland, Denmark. As part of the in situ microcosm study, a cylinder that was open at the bottom and screened at the top was installed through a cased borehole approximately 5 m below grade. Five liters of water was aerated with atmospheric air to ensure aerobic conditions were maintained. Groundwater was analyzed weekly for approximately 3 months to determine 4-nitrophenol concentrations with time. The experimentally determined first-order biodegradation rate constant and corresponding half-life were 0.2/d and 3.47 d, respectively. Photolytic. An aqueous solution containing 200 ppm 4-nitrophenol exposed to sunlight for 1-2 months yielded hydroquinone, 4-nitrocatechol, and an unidentified polymeric substance (Callahan et al., 1979). Under artificial sunlight, river water containing 2 to 5 ppm 4-nitrophenol photo-
yield of 39.5% was achieved when 4-nitrophenol adsorbed on silica gel was irradiated with light (λ >290 nm) for 17 h (Freitag et al., 1985). Chemical/Physical. Wet oxidation of 4-nitrophenol at 320 °C yielded formic and acetic acids (Randall and Knopp, 1980). Wet oxidation of 4-nitrophenol at an elevated pressure and temperature gave the following products: acetone, acetaldehyde, formic, acetic, maleic, oxalic, and succinic acids (Keen and Baillod, 1985). In an aqueous solution, 4-nitrophenol (100 µM) reacted with Fenton’s reagent (35 µM). After 15 min into the reaction, the following products were identified: 1,2,4-trihydroxybenzene, hydroquinone, hydroxy-p-benzoquinone, p-benzoquinone, and 4-nitrocatechol. After 3.5 h, 90% of the 4-nitrophenol was destroyed. After 7 h, no aromatic oxidation products were detected. The pH of the solution decreased due to the formation of nitric acid (Lipczynska-Kochany, 1991). In a dilute aqueous solution at pH 6.0, 4-nitrophenol reacted with excess hypochlorous acid forming 2,6-dichlorobenzoquinone, 2,6-dichloro-4-nitrophenol, and 2,3,4,6-tetrachlorophenol at yields of 20, 1, and 0.3%, respectively (Smith et al., 1976). At influent concentrations (pH 3.0) of 1.0, 0.1, 0.01, and 0.001 mg/L, the GAC adsorption capacities were 80, 54, 37, and 25 mg/g, respectively. The GAC adsorption capacities at pH 7.0 were 76, 43, 24, and 14 mg/g and at pH 9.0 the were 71, 38, 20, and 11 mg/g (Dobbs and Cohen, 1980). Toxicity: EC10 and EC50 concentrations inhibiting the growth of alga Scenedesmus subspicatus in 96 h were 8.0 and 32.0 mg/L, respectively (Geyer et al., 1985). EC50 (48-h) for Daphnia magna 7.68 mg/L (Keen and Baillod, 1985). EC50 (15-min) for Photobacterium phosphoreum 27.8 mg/L (Yuan and Lang, 1997). IC50 (24-h) for river bacteria 30.4 mg/L (Yuan and Lang, 1997). LC50 (contact) for earthworm (Eisenia fetida) 0.7 µg/cm2 (Neuhauser et al., 1985). LC50 (8-d) for fathead minnows 49 to 40 mg/L (Spehar et al., 1982). LC50 (96-h) for bluegill sunfish 8.3 mg/L, fathead minnows 59 to 62 mg/L (Spehar et al., 1982), Cyprinodon variegatus 27 ppm using natural seawater (Heitmuller et al., 1981). LC50 (72-h) for Cyprinodon variegatus 27 ppm (Heitmuller et al., 1981). LC50 (48-h) for red killifish 100 mg/L (Yoshioka et al., 1986), fathead minnows 10 mg/L (quoted, RTECS, 1985), Daphnia magna 22 mg/L (LeBlanc, 1980), Cyprinodon variegatus 28 ppm (Heitmuller et al., 1981). LC50 (24-h) for Daphnia magna 24 mg/L (LeBlanc, 1980), Cyprinodon variegatus 28 ppm (Heitmuller et al., 1981). Acute oral LD50 for mice 380 mg/kg, rats 250 mg/kg (quoted, RTECS, 1985). Heitmuller et al. (1981) reported a NOEC of 24 ppm. Drinking water standard: No MCLGs or MCLs have been proposed, however, a DWEL of 300 µg/L was recommended (U.S. EPA, 2000). Uses: Fungicide for leather; production of parathion; preparation of p-nitrophenyl acetate and other organic compounds.
