Grantee Research Project Results
2000 Progress Report: Dissolved Humic Substances in Enhanced Dissolution of DNAPLs
EPA Grant Number: R826650Title: Dissolved Humic Substances in Enhanced Dissolution of DNAPLs
Investigators: Johnson, William P.
Institution: University of Utah
EPA Project Officer: Aja, Hayley
Project Period: September 1, 1998 through August 31, 2001
Project Period Covered by this Report: September 1, 1999 through August 31, 2000
Project Amount: $285,595
RFA: Exploratory Research - Environmental Chemistry (1998) RFA Text | Recipients Lists
Research Category: Sustainable and Healthy Communities , Land and Waste Management , Air , Safer Chemicals
Objective:
The work performed to date compared the fractionation of Aldrich humic acid (AHA) and a nonionic surfactant mixture during transport through sediment contaminated with dense non-aqueous phase liquid (DNAPL). The bulk nonionic surfactant mixture was known to have a factor of four greater solubilizing capacity relative to bulk AHA for the DNAPL (tetrachloroethene). It was hypothesized that preferential sorption of components of the nonionic surfactant and AHA mixtures would alter their respective solubilization capacities for the DNAPL, possibly mitigating the greater solubilizing capacity of the surfactant. Comparison of the fractionation behaviors of these two distributed mixtures was expected to illuminate similarities or differences in reactivities (with respect to adsorption and solubilization) of the various molecular weight (MW) fractions within the two mixtures.Progress Summary:
Comparison of fractionation of a nonionic surfactant mixture and AHA in low natural organic carbon content aquifer sediment was performed using high-pressure liquid chromatographic (HPLC) and high-pressure size exclusion analysis (HPSEC) of surfactant and humic concentrations, respectively. The comparison was performed in batch experiments and a series of three sediment columns that represented the up-gradient, residual-zone, and down-gradient portions of a DNAPL-contaminated site. The flow was split between each column to analyze for surfactant/humic and DNAPL compounds, allowing monitoring of changes in the makeup of the humic and surfactant mixtures during transport. The comparison showed that although nonionic surfactants and humic acids are highly distributed mixtures of molecules of varying molecular weights and polarities, the differences between MW fractions in the surfactant mixture were much greater than those in the AHA mixture. Much greater fractionation of the surfactant mixture was observed relative to AHA during transport in DNAPL-contaminated sediment. Fractionation was shown to compromise the solubilizing capacity of the surfactant mixture to the extent that the efficiency of DNAPL removal at low numbers of pore volumes was similar to AHA despite the nominal factor of four greater solubilizing capacity of the surfactant relative to AHA for the DNAPL.Future Activities:
Subsequent experiments will examine the solubilization of coal tar mixtures by humic acids and nonionic surfactants using the methodologies described earlier in this report. This work is motivated by the similar solubilizing capacities shown by surfactant and humic acids for coal tar contaminants. During fall 2000, an appropriate coal tar mixture will be developed, and refinement of the high pressure liquid chromatographic method for analysis of coal tar components will be complete. By the end of fall 2000, experiments examining solubilization of coal tar by the two humic acids and surfactants will commence.Journal Articles on this Report : 3 Displayed | Download in RIS Format
Other project views: | All 8 publications | 3 publications in selected types | All 3 journal articles |
---|
Type | Citation | ||
---|---|---|---|
|
Bao G, John WW, Johnson WP. Chromatographic alteration of a nonionic surfactant mixture during transport in dense nonaqueous phase liquid contaminated sediment. Environmental Science & Technology 2000;34(4):680-685. |
R826650 (2000) R826650 (Final) |
Exit |
|
John WW, Bao G, Johnson WP, Stauffer TB. Sorption of nonionic surfactant oligomers to sediment and PCE DNAPL: effects on PCE distribution between water and sediment. Environmental Science & Technology 2000;34(4):672-679. |
R826650 (2000) R826650 (Final) |
Exit |
|
Johnson WP, Bao G, John WW. Specific UV absorbance of Aldrich humic acid: changes during transport in aquifer sediment. Environmental Science & Technology 2002;36(4):608-616. |
R826650 (2000) R826650 (Final) |
Exit |
Supplemental Keywords:
remediation, groundwater, chromatography, dissolution, RFA, Scientific Discipline, Air, Toxics, Waste, Remediation, Environmental Chemistry, Chemistry, HAPS, chemical mixtures, Groundwater remediation, Engineering, Chemistry, & Physics, fate and transport, DNAPL, hydrocarbon, exposure, chemical composition, chemical transport modeling, PAH, Cresols/Cresylic acid (isomers and mixture), chemical kinetics, groundwater contamination, surfactants, creosoteProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.