Canadian Environmental Modelling Centre, Department of Chemistry, Trent University, Peterborough, ON, K9L 0G2, Canada.
Department of Earth Sciences, University of Toronto, Toronto, ON, M5S 3B1, Canada.
Chemosphere. 2024 Sep;364:143090. doi: 10.1016/j.chemosphere.2024.143090. Epub 2024 Aug 21.
Oil sands process-affected water (OSPW) is a source of atmospheric emission for polycyclic aromatic compounds (PACs), compounds known to have toxic effects on humans. Estimating emissions and assessing the chemical fate of PACs requires measured or predicted physical-chemical properties such as Henry's law constants (H), that can be used to predict chemical transfer into the atmosphere. OSPW is a complex water-based mixture that is highly variable in composition and nature and contains both organic and inorganic ions. This study uses COSMO-RS solvation theory to estimate and compare Henry's law constants for a set of PACs in both water and theoretically modelled OSPW, to assess the expected deviation that occurs from pure water H values due to the ionic content within OSPW. Experimental measurements of Henry's law constants for PACs in pure water and OSPW using EVA-coated passive dosing and sampler beads were also made in support of our theoretical predictions. For the theory work, OSPW composition data for the Athabasca oil sands in Alberta were used to model a simulated OSPW environment with realistic sodium, chloride, fluoride, sulfate, potassium, bicarbonate, and naphthenic acid concentrations. Theory results indicate that the combined presence of these ions at OSPW concentrations has a negligible effect on H values, causing on average a 3% or 0.014 log unit deviation. By comparison, temperature has a much larger influence on H values, with estimations showing an average 0.20 log unit increase for a 5 °C increase in temperature. The experimental results demonstrate that Henry's law constants can be accurately and precisely measured with this technique in pure water but with less precision in OSPW. Nevertheless, the experimental results support the conclusion that Henry's law constants for OSPW can be accurately estimated assuming a pure water phase.
油砂加工影响水（OSPW）是多环芳烃（PACs）大气排放的来源，这些化合物已知对人类具有毒性作用。估计排放并评估 PACs 的化学命运需要测量或预测物理化学性质，例如亨利定律常数（H），这可以用于预测化学物质向大气中的转移。OSPW 是一种复杂的水基混合物，在成分和性质上高度可变，含有有机和无机离子。本研究使用 COSMO-RS 溶剂化理论来估计和比较 PACs 在水和理论模拟的 OSPW 中的亨利定律常数，以评估由于 OSPW 中的离子含量而导致的与纯水 H 值的预期偏差。还使用 EVA 涂层被动给药和采样珠在纯水中和 OSPW 中对 PACs 的亨利定律常数进行了实验测量，以支持我们的理论预测。对于理论工作，使用艾伯塔省阿萨巴斯卡油砂的 OSPW 成分数据来模拟具有真实浓度的钠、氯、氟、硫酸盐、钾、碳酸氢盐和环烷酸的模拟 OSPW 环境。理论结果表明，这些离子在 OSPW 浓度下的共同存在对 H 值几乎没有影响，平均导致 3%或 0.014 个对数单位的偏差。相比之下，温度对 H 值的影响要大得多，估计表明温度升高 5°C，H 值平均增加 0.20 个对数单位。实验结果表明，该技术可在纯水中准确、精确地测量亨利定律常数，但在 OSPW 中的精度较低。尽管如此，实验结果支持这样的结论，即假设纯水溶液，OSPW 的亨利定律常数可以准确估计。
