Temperature dependence of Henry's law constant in an extended temperature range

Miklós Görgényi, Jo Dewulf, Herman Van Langenhove

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Abstract

The Henry's law constants H for chloroform, 1,1-dichloroethane, 1,2-dichloropropane, trichloroethene, chlorobenzene, benzene and toluene were determined by the EPICS-SPME technique (equilibrium partitioning in closed systems - solid phase microextraction) in the temperature range 275-343 K. The curvature observed in the 1n H vs. 1/T plot was due to the temperature dependence of the change in enthalpy ΔH0 during the transfer of 1 mol solute from the aqueous solution to the gas phase. The nonlinearity of the plot was explained by means of a thermodynamic model which involves the temperature dependence of ΔH0 of the compounds and the thermal expansion of water in the three-parameter equation In (HΡTT) = A2/T + BTB + C2, where ΡT is the density of water at temperature T, TB = 1n(T/298) + (298 - T)/T, A2 = -ΔH2980/R, ΔH2980 is the ΔH0 value at 298 K, B = ΔCP0/R, and C2 is a constant. ACp0 is the molar heat capacity change in volatilization from the aqueous solution. A statistical comparison of the two models demonstrates the superiority of the three-parameter equation over the two-parameter one 1n H vs. 1/T). The new, three-parameter equation allows a more accurate description of the temperature dependence of H, and of the solubility of volatile organic compounds in water at higher temperatures.

Original languageEnglish
Pages (from-to)757-762
Number of pages6
JournalChemosphere
Volume48
Issue number7
DOIs
Publication statusPublished - Jan 1 2002

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Keywords

  • Air-water partitioning
  • Heat capacity of hydration
  • Henry's law constant
  • Hydration thermodynamics
  • Solid-phase microextraction

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Chemistry(all)
  • Pollution
  • Health, Toxicology and Mutagenesis

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