Turbulence Effects on Volatilization Rates of Liquids and Solutes

Volatilization rates of neat liquids (benzene, toluene, fluorobenzene, bromobenzene, ethylbenzene, m-xylene, o-xylene, o-dichlorobenzene, and 1-methylnaphthalene) and of solutes (phenol, m-cresol, benzene, toluene, ethylbenzene, o-xylene, and ethylene dibromide) from dilute water solutions have been measured in the laboratory over a wide range of air speeds and water-stirring rates. The overall transfer coefficients (K_L) for individual solutes are independent of whether they are in single- or multi-solute solutions. The gas−film transfer coefficients (k_G) for solutes in the two-film model, which have hitherto been estimated by extrapolation from reference coefficients, can now be determined directly from the volatilization rates of neat liquids through a new algorithm. The associated liquid−film transfer coefficients (k_L) can then be obtained from measured K_L and k_G values and solute Henry law constants (H). This approach provides a novel means for checking the precision of any k_L and k_G estimation methods for ultimate prediction of K_L. The improved k_G estimation enables accurate K_L predictions for low-volatility (i.e., low-H) solutes where K_L and k_GH are essentially equal. In addition, the prediction of K_L values for high-volatility (i.e., high-H) solutes, where K_L ≅ k_L, is also improved by using appropriate reference k_L values.