Solid vapor pressure for five heavy PAHs via the Knudsen effusion method

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are compounds resulting from incomplete combustion and many fuel processing operations, and they are commonly found as subsurface environmental contaminants at sites of former manufactured gas plants. Knowledge of their vapor pressures is the key to predict their fate and transport in the environment. The present study involves five heavy PAHs, i.e. benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[ghi]perylene, indeno[1,2,3-cd]pyrene, and dibenz[a,h]anthracene, which are all as priority pollutants classified by the US EPA. The vapor pressures of these heavy PAHs were measured by using Knudsen effusion method over the temperature range of 364 K to 454 K. The corresponding values of the enthalpy of sublimation were calculated from the Clausius-Clapeyron equation. The enthalpy of fusion for the 5 PAHs was also measured by using differential scanning calorimetry and used to convert earlier published sub-cooled liquid vapor pressure data to solid vapor pressure in order to compare with the present results. These adjusted values do not agree with the present measured actual solid vapor pressure values for these PAHs, but there is good agreement between present results and other earlier published sublimation data.

RETRACTED: Temporal Variations of Polycyclic Aromatic Hydrocarbons in the Seawater at Tsukumo Bay, Noto Peninsula, Japan, during 2014–2018

“…For particulate PAHs, 4-5-ring PAHs were predominant, contributing 29%-43% of Σ 13 PAH in seawater and 22%-54% in river water; whereas 3-4-ring PAHs were predominant in the dissolved phase, contributing 43%-50% in seawater and 44%-52% in river water. A similar predominance of lower-molecular-weight PAHs in the dissolved phase was observed in previous studies of PAHs in seawater [16][17][18] and river water [24], and was attributed to increasing PAH solubility with decreasing molecular size, which in turn is related to differences in PAH vapor pressure [16,[25][26][27]. Although the relative compositions of 3-6-ring PAHs in the particulate and dissolved phases were similar for seawater and river water, relative fractions of particulate and dissolved PAHs and individual dissolved PAHs differed, with Fle, Flu, and Pyr being predominant in seawater and Ace, Fle, and Pyr in river water.…”

Vapor pressure of three brominated flame retardants determined by using the Knudsen effusion method

“…To verify the reliability of the experimental technique, the reference compound anthracene was periodically employed to test the performance of the Knudsen effusion apparatus, and the results were in good agreement with literature values [22–25]. More details of this technique can be found in Fu and Suuberg [17], Fu et al [18], Fu and Suuberg [19], and Oja and Suuberg [20]. …”

“…There is an unresolved issue related to the correction of the values of vapor pressure and enthalpy of sublimation from the subcooled liquid state to the ambient temperature solid state of practical relevance [17, 19]. This has been shown to not work reliably in a previous publication [19]. Therefore, caution is advised in attempting to apply subcooled liquid state data, such as those in Figure 1, to predicting vapor pressure behavior at ambient temperature conditions.…”

“…The uncertainty in the DSC measurement is about ± 5 J/g. More details of this technique can be found in previous publications [18,19]. …”

Polycyclic Aromatic Hydrocarbons in Surface Water of the Southeastern Japan Sea

“…The vapor pressure of Ace, a 3-ring PAH is 3.86 Pa, while the vapor pressure of 4-to 6-ring PAHs are in the range of 1.08×10 −3 Pa (Flu) to 2.80×10 −9 Pa (DBA). 18,19) Accordingly, the water solubility of PAHs decreases with increasing ring number.…”