| Title: | Determination of the Henry's law constants of low-volatility compounds via the measured air-phase transfer coefficients |
| Author(s): | Chao HP; Lee JF; Chiou CT; |
| Address: | "Department of Environmental Engineering, Chung Yuan Christian University, Chung-Li 32023, Taiwan. Electronic address: hpchao@cycu.edu.tw. Graduate Institute of Environmental Engineering, National Central University, Chung-Li 32001, Taiwan. Department of Environmental Engineering, National Cheng Kung University, Tainan 70101, Taiwan. Electronic address: carychio@mail.ncku.edu.tw" |
| DOI: | 10.1016/j.watres.2017.04.074 |
| ISSN/ISBN: | 1879-2448 (Electronic) 0043-1354 (Linking) |
| Abstract: | "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 (K(L)) and the associated air-phase transfer coefficient (k(G)) of a low-H chemical (solute) in water when K(L) congruent with k(G)H prevails according to the two-film theory. The k(G) for a solute is obtained via a developed gas-dynamic equation that relates k(G) to the solute molecular weight and the solute-vapor escaping efficiency (beta) through a boundary air layer. The value of beta is only a function of the in situ air turbulence level, independent of the chemical species. Thus, the required beta for solutes can be estimated from the evaporative rates of pure volatile liquids under the same ambient setting. By relating the estimated k(G) with the measured K(L) 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 approximately 10(-7) to approximately 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" |
| Keywords: | *Chemical Phenomena Gases Pesticides Volatilization Water *Water Purification Air-water partition coefficients Henry's law constants Low-volatility compounds Two-film resistance theory Vapor-phase transfer coefficients; |
| Notes: | "MedlineChao, Huan-Ping Lee, Jiunn-Fwu Chiou, Cary T eng England 2017/05/13 Water Res. 2017 Sep 1; 120:238-244. doi: 10.1016/j.watres.2017.04.074. Epub 2017 May 1" |
