| Volatilization | The Henry's Law constant for 2-methylpyridine is 9.96X10-6 atm-cu m/mole(1). This Henry's Law constant indicates that 2-methylpyridine is expected to volatilize from water surfaces(2). Based on this Henry's Law constant, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(2) is estimated as 4 days(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(2) is estimated as 30 days(SRC). 2-Methylpyridine's Henry's Law constant(1) indicates that volatilization from moist soil surfaces may occur(SRC). 2-Methylpyridine is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 11.2 mm Hg at 25 deg C(3). 2-Methylpyridine is a weak base with a pKa of 5.96(4), which indicates this compound will partially exist in the protonated form in acidic conditions, and no volatilization from water or moist soil will occur for the cation(SRC). In mineral salts-soil suspensions incubated at 28 deg C, 15% was volatilized in 24 days(5). Volatilization from soil alone was only 2-3% after 60 days(6).
Literature: (1) Andon RJL et al; J Amer Chem Soc 76: 3188-96 (1954) (2) Lyman WJ et al; Handbook of Chemical Property Estimation Methods. Washington, DC: Amer Chem Soc pp. 15-1 to 15-29 (1990) (3) Chao J et al; J Phys Chem Ref Data 12: 1033-63 (1983) (4) Scriven EFV et al; Pyridine and Pyridine Derivatives. Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2014). New York, NY: John Wiley & Sons. Online Posting Date: Dec 2, 2005. (5) Sims GK, Sommers LE; Environ Toxicol Chem 5: 503-9 (1986) (6) Sims GK, Sommers LE; J Environ Qual 14: 480-4 (1985) |
| Soil Adsorption | The sorption behavior of 2-methylpyridine was studied in soil column tests using 5 Eurosoil reference soils having organic carbon content ranging from 0.33-1.85% and pH ranging from 5.2-8.6(1); measured Kd values ranging from 0.08 to 6.52(1) correspond to calculated Koc values of 4, 38, 70, 100 and 215(SRC); the lowest Koc value of 4 corresponds to Eurosoil 2 which had the highest pH value(8.6). The pKa of 2-methylpyridine is 5.96(2), indicating that this compound will exist partially in cation form in the environment and cations generally adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts(3). In the Eurosoil column tests(1), lowest adsorption occurred when 2-methylpyridine was in non-ionized form(1). Sorption of 2-methylpyridine to soil is primarily controlled by cation exchange and surface complex formation(1,4). According to a classification scheme(5), the Koc values suggest that 2-methylpyridine is expected to have very high to moderate mobility in soil.
Literature: (1) Bi E et al; Environ Sci Technol 40: 5962-5970 (2006) (2) Scriven EFV et al; Pyridine and Pyridine Derivatives. Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2014). New York, NY: John Wiley & Sons. Online Posting Date: Dec 2, 2005. (3) Doucette WJ; pp. 141-188 in Handbook of Property Estimation Methods for Chemicals. Boethling RS, Mackay D, eds. Boca Raton, FL: Lewis Publ (2000) (4) Bi E et al; Environ Sci Technol 41: 3172-3178 (2006) (5) Swann RL et al; Res Rev 85: 17-28 (1983)
Literature: #Spectral studies of 2-methylpyridine adsorbed to hydrated and dehydrated silica indicate that hydrogen bonding occurs with silica surface silanols via the nitrogen atom on the pyridine ring and that this interaction is stronger than that between this compound and water(1). 2-Methylpyridine emerged under 2 soil column void volumes; soil columns were packed with soil cores from Rock Springs, WY to the original 1016 mm depth and shale-oil process water was used as the mobile phase(2); the pH and clay content of the soil were not specified(2); this indicates that soil is an effective adsorbent when less than this void volume of retort water is applied (as in small spills)(2); rainfall leaching after a spill will also probably enhance solute migration(2). When 2-methylpyridine was incubated at 28 deg C in a soil inoculum, 4.8% was sorbed by soil(3).
Literature: (1) Ringwald SC, Pemberton JE; Environ Sci Technol 34: 259-65 (2000) (2) Leenheer JA, Stuber HA; Environ Sci Technol 15: 1467-75 (1981) (3) Sims GK, Sommers LE Environ Toxicol Chem 5: 503-9 (1986) |
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