Henry's Law Constant for Trichloroethylene between 10 and 95 °C

Abstract

Experimental data on air−water partitioning of organic contaminants at temperatures above 40 °C is extremely scarce. We present Henry's law constants for trichloroethylene (TCE) in water between 10 and 95 °C determined using a modification of the Equilibrium Partitioning in Closed System (EPICS) procedure and calculated from vapor pressure and measured aqueous solubility data obtained by a column generator technique. The Henry's law constant for TCE increases by a factor of 20 between 10 and 95 °C, which is a dramatic change in volatility. Our results and a critical review of the thermodynamic equations suggest that the heat (enthalpy) of dissolution decreases with temperature and that Henry's law constants cannot be extrapolated to higher temperatures from the existing literature data. Heat of dissolution may be approximated by a linear function of temperature, leading to a simple equation for Henry's law constant ln kH = A − B/T + C ln T that fits the majority of the previously published experimental data. This equation is more precise than previously published equations, is valid for temperatures approaching 100 °C, and will assist in more accurate interpretation of Henry's law constant data for other chemicals of environmental concern.