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Updated: May 19, 2026
07:57
Accurate Determination of the Equilibrium Surface Tension Values with Area Perturbation Tests
Published on: August 30, 2019
Compositional and pH effects on the interfacial tension between complex tar mixtures and aqueous solutions
Scott C Hauswirth1, Pamela B Schultz, Cass T Miller
1Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States. shaus@live.unc.edu
Environmental Science & Technology
|August 21, 2012
Summary
Former manufactured gas plant (FMGP) tars exhibit tar-water interfacial tension (IFT) highly dependent on pH. This property, crucial for tar transport, is influenced by tar composition, particularly carbonyl groups and base concentration.
Area of Science:
- Environmental Science
- Chemical Engineering
- Geochemistry
Background:
- Tars from former manufactured gas plants (FMGPs) pose significant environmental challenges.
- Tar-water interfacial tension (IFT) is a critical factor influencing tar mobility in subsurface environments.
- Understanding the relationship between tar composition and IFT is essential for effective remediation strategies.
Purpose of the Study:
- To investigate the relationship between the composition of FMGP tars and their tar-water interfacial tension (IFT).
- To determine how pH affects the IFT of tars, resins, and asphaltenes.
- To identify compositional parameters that correlate with IFT variations.
Main Methods:
- Characterization of nine field-collected FMGP tars and one commercial coal tar using fractionation, gas chromatography, Fourier transform infrared (FTIR) spectrometry, and vapor pressure osmometry.
- Measurement of tar-aqueous IFT for tars, resins, and asphaltenes across a range of pH values.
- Correlation analysis between IFT values and compositional data (FTIR-derived carbonyl groups, base concentration, aromaticity, asphaltene molar mass).
Main Results:
- Tar-water IFT was strongly dependent on pH, with minimum values observed at high pH.
- IFT reduction at high pH correlated with higher concentrations of carbonyl groups (indicated by FTIR I(C=O) values).
- IFT reduction at low pH correlated with higher extractable base concentrations, aromaticity, and asphaltene average molar mass.
Conclusions:
- The pH-dependent IFT of FMGP tars is significantly influenced by their chemical composition.
- Carbonyl groups and base content are key compositional factors affecting IFT at high and low pH, respectively.
- Aromaticity and asphaltene molar mass also play a role, suggesting source-related compositional patterns influencing tar behavior.
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