Determination of the Henry's law constants of low-volatility compounds via the measured air-phase transfer coefficients
| Autor: | Cary T. Chiou, Jiunn-Fwu Lee, Huan-Ping Chao |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Environmental Engineering
Chemical Phenomena Kinetics Thermodynamics 02 engineering and technology 010501 environmental sciences 01 natural sciences Water Purification 020401 chemical engineering Air layer Pesticides 0204 chemical engineering Waste Management and Disposal 0105 earth and related environmental sciences Water Science and Technology Civil and Structural Engineering Pollutant Chemistry Ecological Modeling Water Pollution Henry's law Chemical species Gases Volatilization Volatility (chemistry) |
| Zdroj: | Water Research. 120:238-244 |
| ISSN: | 0043-1354 |
| DOI: | 10.1016/j.watres.2017.04.074 |
| Popis: | Accurate Henry's law constants (H) are unavailable for the majority of organic pollutants, especially those having a low volatility. A novel kinetics-based experimental method is introduced to determine H for a wide range of low-H compounds. The method consists of measuring independently the water-to-air transfer coefficient (KL) and the associated air-phase transfer coefficient (kG) of a low-H chemical (solute) in water when KL ≅ kGH prevails according to the two-film theory. The kG for a solute is obtained via a developed gas-dynamic equation that relates kG to the solute molecular weight and the solute-vapor escaping efficiency (β) through a boundary air layer. The value of β is only a function of the in situ air turbulence level, independent of the chemical species. Thus, the required β for solutes can be estimated from the evaporative rates of pure volatile liquids under the same ambient setting. By relating the estimated kG with the measured KL of a low-H solute, the solute H is established. The H values of 45 low-H chemicals, including many complex pesticides, in the range of ∼10−7 to ∼10−3 have thus been determined. The accountability of the method is underscored by the consistency of the measured and credible literature H values for a number of the low-H compounds studied. |
| Databáze: | OpenAIRE |
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