Oil sands process-affected water composition effect on Henry's law constants for polycyclic aromatic compounds:...

Area of Science:

• Environmental Chemistry
• Atmospheric Science

Background:

• Oil sands process-affected water (OSPW) releases polycyclic aromatic compounds (PACs), which pose human health risks.
• Accurate Henry's law constants (H) are crucial for estimating PAC emissions and their environmental fate.

Purpose of the Study:

• To estimate Henry's law constants (H) for PACs in OSPW using COSMO-RS theory.
• To compare H values in OSPW with those in pure water, accounting for ionic content.
• To experimentally validate theoretical predictions.

Main Methods:

• COSMO-RS solvation theory was employed to model H values in simulated OSPW.
• Experimental measurements of H values were conducted using passive dosing and sampler beads in both pure water and OSPW.
• Simulated OSPW composition reflected Athabasca oil sands data, including various ions and naphthenic acids.

Main Results:

• Theoretical calculations showed that OSPW's ionic content has a negligible effect on H values (average 3% deviation).
• Temperature significantly influences H values, with a 5°C increase causing a 0.20 log unit rise.
• Experimental measurements confirmed H values in pure water but showed lower precision in OSPW.

Conclusions:

• The ionic composition of OSPW minimally impacts Henry's law constants for PACs.
• Temperature is a more critical factor than ionic content in determining H values.
• Henry's law constants for PACs in OSPW can be reliably estimated using pure water data and theoretical models.