Developing interphase mass transfer correlations for non-aqueous phase liquid to gas in porous media with thermal enhancement

An in-depth understanding of interphase mass transfer from a non-aqueous phase liquid (NAPL) to a gas is crucial and indispensable for properly designing and optimizing remediation schemes in NAPL-contaminated sites involving thermal treatment. A series of polluted soil column venting experiments were conducted to thoroughly evaluate this nonequilibrium behavior at both the initial steady-state stage and transient stage of mass transfer. Two new correlations are proposed to predict the mass transfer efficiency and duration of the steady-state stage. Additionally, it is proposed the disparity of behavior in the transient stage is caused by different modes of interfacial area reduction, which are controlled by two competing phenomena: NAPL film spreading, and evaporation at the NAPL-gas interface. These processes are described by specific mathematical expressions. These findings provide deep insight into thermally enhanced NAPL-gas interfacial mass transfer and have the potential to be applied to modeling studies and field applications of multiphase extraction. (C) 2022 Elsevier Ltd. All rights reserved.