Dataset Information

Determining the chemical activity of hydrophobic organic compounds in soil using polymer coated vials.

ABSTRACT:

Background

In soils contaminated by hydrophobic organic compounds, the concentrations are less indicative of potential exposure and distribution than are the associated chemical activities, fugacities and freely dissolved concentrations. The latter can be measured by diffusive sampling into thin layers of polymer, as in, for example, solid phase micro-extraction. Such measurements require equilibrium partitioning of analytes into the polymer while ensuring that the sample is not depleted. We introduce the validation of these requirements based on parallel sampling into polymer layers of different thicknesses.

Results

Equilibrium sampling devices were made by coating glass vials internally with 3-12 microm thick layers of polydimethylsiloxane (PDMS). These were filled with slurries of a polluted soil and gently agitated for 5 days. The concentrations of 7 polycyclic aromatic hydrocarbons (PAHs) in the PDMS were measured. Validation confirmed fulfilment of the equilibrium sampling requirements and high measurement precision. Finally, chemical activities of the PAHs in the soil were determined from their concentrations and activity coefficients in the PDMS.

Conclusion

PAHs' thermodynamic activities in a soil test material were determined via a method of uptake into PDMS. This can be used to assess chemical exposure and predict diffusion and partitioning processes.

SUBMITTER: Reichenberg F

PROVIDER: S-EPMC2409337 | biostudies-literature | 2008 May

REPOSITORIES: biostudies-literature

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Publications

Determining the chemical activity of hydrophobic organic compounds in soil using polymer coated vials.

Reichenberg Fredrik F Smedes Foppe F Jönsson Jan-Ake JA Mayer Philipp P

Chemistry Central journal 20080506

<h4>Background</h4>In soils contaminated by hydrophobic organic compounds, the concentrations are less indicative of potential exposure and distribution than are the associated chemical activities, fugacities and freely dissolved concentrations. The latter can be measured by diffusive sampling into thin layers of polymer, as in, for example, solid phase micro-extraction. Such measurements require equilibrium partitioning of analytes into the polymer while ensuring that the sample is not depleted ...[more]

PMID: 18460193

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Project description:Several synthetic methods have recently emerged to develop high-surface-area solid-state organic framework-based materials into free-flowing liquids with permanent porosity. The fluidity of these porous liquid (PL) materials provides them with advantages in certain storage and transport processes. However, most framework-based materials necessitate the use of cryogenic temperatures to store weakly bound gases such as H2, temperatures where PLs lose their fluidity. Covalent organic framework (COF)-based PLs that could reversibly form stable complexes with H2 near ambient temperatures would represent a promising development for gas storage and transport applications. We report here the development, characterization, and evaluation of a material with these remarkable characteristics based on Cu(I)-loaded COF colloids. Our synthetic strategy required tailoring conditions for growing robust coatings of poly(dimethylsiloxane)-methacrylate (PDMS-MA) around COF colloids using atom transfer radical polymerization (ATRP). We demonstrate exquisite control over the coating thickness on the colloidal COF, quantified by transmission electron microscopy and dynamic light scattering. The coated COF material was then suspended in a liquid polymer matrix to make a PL. CO2 isotherms confirmed that the coating preserved the general porosity of the COF in the free-flowing liquid, while CO sorption measurements using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) confirmed the preservation of Cu(I) coordination sites. We then evaluated the gas sorption phenomenon in the Cu(I)-COF-based PLs using DRIFTS and temperature-programmed desorption measurements. In addition to confirming that H2 transport is possible at or near mild refrigeration temperatures with these materials, our observations indicate that H2 diffusion is significantly influenced by the glass-transition temperature of both the coating and the liquid matrix. The latter result underscores an additional potential advantage of PLs in tailoring gas diffusion and storage temperatures through the coating composition.

Dataset Information

Determining the chemical activity of hydrophobic organic compounds in soil using polymer coated vials.

Background

Results

Conclusion

Publications

Determining the chemical activity of hydrophobic organic compounds in soil using polymer coated vials.

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