title: Spectral moments of polycyclic aromatic hydrocarbons. Solution of a kinetic problem.
abstract: The relationship between the rate of supercritical fluid extraction of polycyclic aromatic hydrocarbons (PAHs) from coal-tar pitch and some topological invariants are examined. The aim is to explain the appearance of a minimum value on the activation energy/molar mass curve of the PAHs. Rate constants are approximated using spectral moment expansion. It is shown that the size of the PAHs determines more than 95% of the extraction rate. Activation energy for the extraction of the PAHs was found to increase with increasing molar mass. The appearance of a minimum value on the activation energy/molar mass curve is the consequence of experimental difficulties resulting from the tendency of lower members of the PAHs to sublime.
authors.affiliation: Department of Chemistry and Physics, Technikon Pretoria, P.O. Box 56208, Arcadia 0007, Republic of South Africa. Mark5898@yahoo.com
authors.forename: Svetlana
authors.initials: S
authors.lastname: Marković
authors.forename: Zoran
authors.initials: Z
authors.lastname: Marković
authors.forename: Johan P
authors.initials: JP
authors.lastname: Engelbrecht
authors.forename: Robert I
authors.initials: RI
authors.lastname: McCrindle