Abstract
| - This paper investigates the hypothesis that observedpolycyclic aromatic hydrocarbon (PAH) concentrations inan aqueous system are equal to the sum of the organic phaseand soluble phase molar concentrations. While theorganic phase concentrations are proportional to the PAHmole fraction in the oil, the soluble phase molarconcentrations are estimated using Raoult's law. A batchlaboratory mixing vessel with a scalable mixing energywas loaded initially at various oil layer thicknesses (0.4−3.2 mm) which correspond to oil surface loadings (40−310 mg/cm2). The vessel was agitated at constant mean shearrates (Gm = 5, 20 s-1). Total petroleum hydrocarbon (TPH)samples were taken periodically to estimate the entrainmentrate as a function of initial oil layer thickness. TPHconcentrations were measured in-situ using a laserscattering instrument (LISST-100) and ex-situ using gravimetricanalysis. At a steady-state TPH concentration (>72 h),additional samples were analyzed for PAH concentrationusing GC/MS analysis. TPH concentrations increased overtime according to a first-order kinetic model. Generally,the first-order rate constant and steady-state concentrationboth increased with increased oil loading and withincreased Gm. In addition, measured PAH concentrationscorrelated well (r2> 0.96) with those predicted by a partitioningmodel. These results are useful for assessing the effectsof mixing and oil loading conditions on crude oil entrainmentand PAH partitioning.
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