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, (partial derivative ln x(2)partial derivative T)(sigma), range from 5.4 x 10(-2) K-1 in naphthalene to 7.2 x 10(-2) K-1 in p-terphenyl. The In 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.