Solubility of Solid Polycyclic Aromatic Hydrocarbons in Pressurized Hot Water at Temperatures from 313 K to the Melting Point

Aqueous solubilities of two- to four-ring solid polycyclic aromatic hydrocarbons (PAHs) (naphthalene, anthracene, 1,2-benzanthracene, triphenylene, and p -terphenyl) were measured at temperatures within 313 K to the PAH melting point and pressures within the range (4 to 8) MPa by dynamic method combined with gas chromatography/mass spectrometry. A novel feature of the apparatus was the use of a capillary restrictor to minimize the system volume downstream of the sampling point. The results for naphthalene and anthracene compare favorably with the literature data whereas the solubilities of 1,2-benzanthracene, triphenylene, and p -terphenyl in pressurized hot water are reported for the first time. The solubilities (equilibrium mole fractions, x 2 ) of PAHs are discussed in terms of temperature and hydrocarbon structure. Mean values of the relative change in the PAH solubility with temperature, (∂ ln x 2 /∂ T ) σ, range from 5.4 × 10 -2 K -1 in naphthalene to 7.2 × 10 -2 K -1 in p -terphenyl. The ln x 2 versus T plot for 1,2-benzanthracene is curved in the opposite direction as compared with the plots for anthracene, triphenylene, and p -terphenyl.