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Sorption kinetics of selected volatile organic compounds in humin
Yang-Hsin Shih1, Shian-Chee Wu
1Graduate Institute of Environmental Engineering, National Taiwan University, Taipei, Republic of China. yhshih@mit.edu
Environmental Toxicology and Chemistry
|October 10, 2002
Summary
This study investigated the sorption of volatile organic compounds (VOCs) in humin soil components. Humin demonstrated higher sorption capacity for polar VOCs, with varying persistence against desorption for different compounds.
Area of Science:
- Environmental Chemistry
- Soil Science
- Organic Geochemistry
Background:
- Soil components exhibit unique sorption behaviors for organic contaminants.
- Understanding sorption kinetics is crucial for predicting contaminant fate in soil.
Purpose of the Study:
- To investigate the sorption kinetics of volatile organic compounds (VOCs) in pressed humin disks.
- To compare the sorption behavior of humin with Aldrich humic acid.
- To determine the persistence of sorbed VOCs against desorption.
Main Methods:
- Sorption kinetics were measured by tracking weight changes of humin disks using a microbalance.
- C13 nuclear magnetic resonance (NMR) spectroscopy was used to assess humin's hydrophilicity.
- Desorption experiments were conducted to evaluate sorbate persistence.
Main Results:
- Humin showed a higher sorption capacity for more polar VOCs compared to Aldrich humic acid.
- Apparent diffusivities of acetone, toluene, and hexane in humin disks ranged from 10^-8 to 10^-10 cm²/s.
- Acetone and hexane exhibited persistence against desorption from humin, with significant residue remaining.
Conclusions:
- Humin's hydrophilic nature influences its sorption behavior towards VOCs.
- The persistence of acetone and hexane in humin suggests potential long-term soil contamination.
- Sorption kinetics and desorption persistence vary among different VOCs and soil organic matter components.