TY - JOUR
T1 - Low-concentration tracer tests to measure air-water interfacial area in porous media
AU - Brusseau, Mark L.
AU - Lyu, Ying
AU - Yan, Ni
AU - Guo, Bo
N1 - Funding Information:
This work was supported by the NIEHS Superfund Research Program (grant no. P42 ES04940). Additional funding for Dr. Ying Lyu was provided by the National Natural Science Foundation of China (NO. 41902247) and China Postdoctoral Science Foundation (NO. 2018M640284). We thank the reviewers for their constructive comments.
Funding Information:
This work was supported by the NIEHS Superfund Research Program (grant no. P42 ES04940 ). Additional funding for Dr. Ying Lyu was provided by the National Natural Science Foundation of China (NO. 41902247 ) and China Postdoctoral Science Foundation (NO. 2018M640284 ). We thank the reviewers for their constructive comments.
Publisher Copyright:
© 2020 Elsevier Ltd
PY - 2020/7
Y1 - 2020/7
N2 - The aqueous-based interfacial tracer method employing miscible-displacement tests is one method available for measuring air-water interfacial areas. One potential limitation to the method is the impact of tracer-induced drainage on the system. The objective of this study was to investigate the efficacy of a low-concentration tracer test method for measuring air-water interfacial area. Tracer concentrations and analytical methods were selected that allowed the use of tracer input concentrations that were below the threshold of tracer-induced drainage. Multiple tracer tests were conducted at different water saturations. Interfacial areas increased from 34.8 to 101 cm−1 with the decrease in saturation from 0.86 to 0.62. The method produced relatively robust measurements of air-water interfacial area, with coefficients of variation ranging from 6 to 26%. A variably saturated flow and transport model that accounts for the effects of tracer on interfacial tension, and the retention of tracer at the air-water and solid-water interfaces, was used to test for potential tracer-induced drainage. The simulations showed that the use of low tracer-input concentrations eliminated this phenomenon. This is consistent with the measured data for effluent-sample masses, which exhibited minimal change during the tests, and with the observation that the interfacial areas obtained with the low-concentration-tracer method were consistent with values measured with two methods that are not influenced by tracer-induced drainage. These results demonstrate that the low-concentration miscible-displacement tracer test method is an effective approach for measuring air-water interfacial areas in porous media.
AB - The aqueous-based interfacial tracer method employing miscible-displacement tests is one method available for measuring air-water interfacial areas. One potential limitation to the method is the impact of tracer-induced drainage on the system. The objective of this study was to investigate the efficacy of a low-concentration tracer test method for measuring air-water interfacial area. Tracer concentrations and analytical methods were selected that allowed the use of tracer input concentrations that were below the threshold of tracer-induced drainage. Multiple tracer tests were conducted at different water saturations. Interfacial areas increased from 34.8 to 101 cm−1 with the decrease in saturation from 0.86 to 0.62. The method produced relatively robust measurements of air-water interfacial area, with coefficients of variation ranging from 6 to 26%. A variably saturated flow and transport model that accounts for the effects of tracer on interfacial tension, and the retention of tracer at the air-water and solid-water interfaces, was used to test for potential tracer-induced drainage. The simulations showed that the use of low tracer-input concentrations eliminated this phenomenon. This is consistent with the measured data for effluent-sample masses, which exhibited minimal change during the tests, and with the observation that the interfacial areas obtained with the low-concentration-tracer method were consistent with values measured with two methods that are not influenced by tracer-induced drainage. These results demonstrate that the low-concentration miscible-displacement tracer test method is an effective approach for measuring air-water interfacial areas in porous media.
KW - Fluid-fluid interfaces
KW - Interfacial adsorption
KW - Interfacial partitioning
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U2 - 10.1016/j.chemosphere.2020.126305
DO - 10.1016/j.chemosphere.2020.126305
M3 - Article
C2 - 32135438
AN - SCOPUS:85080097244
VL - 250
JO - Chemosphere
JF - Chemosphere
SN - 0045-6535
M1 - 126305
ER -