1998 Progress Report: A Multi-Scale Investigation of Mass Transfer Limitations in Surfactant-Enhanced Aquifer RemediationEPA Grant Number: R825405
Title: A Multi-Scale Investigation of Mass Transfer Limitations in Surfactant-Enhanced Aquifer Remediation
Investigators: Mayer, Alex , Pope, Gary A.
Institution: Michigan Technological University , The University of Texas at Austin
Current Institution: Michigan Technological University , The University of Texas at Houston
EPA Project Officer: Chung, Serena
Project Period: October 1, 1996 through October 31, 1999 (Extended to October 31, 2000)
Project Period Covered by this Report: October 1, 1997 through October 31, 1998
Project Amount: $299,792
RFA: Environmental Fate and Treatment of Toxics and Hazardous Wastes (1996) RFA Text | Recipients Lists
Research Category: Hazardous Waste/Remediation , Land and Waste Management , Safer Chemicals
Objective:To assess the significance of mass transfer limitations in the solubilization of nonaqueous phase liquids.
Progress Summary:At Michigan Technological University (MTU), batch tests have been used to measure solubilization rates with time as a function of surfactant concentration, salinity, and other chemicals. Column experiment protocols have been developed for surfactant flooding tests, including analytical techniques. Researchers have conducted almost 40 column experiments, varying the column length, flooding velocities, initial NAPL saturations, surfactant concentration, and salinity. A Cytec Aerosol MA surfactant is being used. At least three other surfactants are to be used starting in the spring. Trichloroethylene (TCE) continues to be used for the nonaqeuous phase liquid (NAPL).
The batch tests are conducted under isothermal, completely mixed conditions. The batch test results indicate that equilibrium between the surfactant solution and the TCE is reached within tens of seconds or within about a minute with the Aerosol MA. A few quiescent batch tests have been conducted to measure rates of diffusion of TCE into the surfactant solution. The column tests indicate that equilibrium concentrations are achieved within about one pore volume. The equilibrium concentrations are maintained until the NAPL saturations are reduced to about 5 percent. At this point, the concentrations drop steeply below equilibrium levels.
A research collaboration was initiated in June 1997 with Dr. Robert Glass' group at Sandia National Laboratory involving surfactant floods in transparent micromodels. Lirong Zhong, a MTU Ph.D. student supported by this project, spend Summer 1998 at Sandia conducting several micromodel experiments. The advantage of these experiments is that observations of the NAPL-surfactant system can be made at the pore scale. In June 1998, a pore network simulator was obtained from Stanford University that is being used to obtain further insights into solubilization at the pore scale. A research assistant professor student is responsible for modifying and running the pore network simulator.
Drs. Gary Pope and Mojdeh Delshad at the University of Texas have modified the UTCHEM simulator to incorporate nonequilibrium dissolution models. Dr. Mayer will travel to UT in late April to discuss progress on the project and set future directions for the modeling research.
In Summer 1997, an undergraduate student worked on the project, supported by a NSF Research Experience for Undergraduates grant. In December 1997, a $32,000 grant from the Michigan Research Excellence Fund was awarded. These funds were used to purchase a spinning drop tensiometer, which can measure ultra-low interfacial tensions (IFTs). A second instrument will be purchased for measuring mid-level IFTs.
A Ph.D. student and four undergraduate research assistants have been utilized for the project. A suitable candidate for a postdoctoral research assistant was found and hired in December 1998.
Future Activities:Future experimental work will focus on using different surfactants with a range of behaviors in terms of rates of obtaining chemical equilibrium.
Journal Articles on this Report : 2 Displayed | Download in RIS Format
|Other project views:||All 31 publications||5 publications in selected types||All 5 journal articles|
||Mayer AS, Zhong LR, Pope GA. Measurement of mass transfer-rates for surfactant-enhanced solubilization of nonaqueous phase liquids. Environmental Science & Technology 1999;33(17):2965-2972.||
||Zhong LR, Mayer A, Glass RJ. Visualization of surfactant-enhanced nonaqueous phase liquid mobilization and solubilization in a two-dimensional micromodel. Water Resources Research 2001;37(3):523-537.||