title: Solubility and interaction parameters as references for solution properties II: precipitation and aggregation of asphaltene in organic solvents.
abstract: The total combinatory Gibbs free energy was successfully used to model the solubility of two purified asphaltenes in pure and mixed solvents, as well as the precipitation of asphaltenes from mixed solvents. Intrinsic viscosity and aggregate size both sensitively reflected the state of the asphaltenes in homogeneous solution and were used for determining the solubility parameters of the asphaltenes. Phase separation was clearly reflected by a dramatic increase in aggregate size. The interaction parameter was subdivided into enthalpy and entropy contributions. All parameters indicate an extensive association or phase transition when the phase boundary was followed by simultaneously varying the temperature and the solubility parameter of the solvent. However, the interaction parameter is frequently derived in two ways. We show that, depending on the definition, the enthalpy and entropy contributions lead to conflicting results. These were evaluated on thermodynamic grounds.
authors.affiliation: Center of Excellence for Functional Materials, Department of Physical Chemistry, Abo Akademi University, Abo, Finland.
authors.forename: Bjarne
authors.initials: B
authors.lastname: Johansson
authors.forename: Rauno
authors.initials: R
authors.lastname: Friman
authors.forename: Hannele
authors.initials: H
authors.lastname: Hakanpää-Laitinen
authors.forename: Jarl B
authors.initials: JB
authors.lastname: Rosenholm
mesh_terms: D006841:Hydrocarbons, Aromatic / Q000737:chemistry*; D010316:Particle Size; D044367:Phase Transition; D012995:Solubility; D012996:Solutions; D012997:Solvents / Q000737:chemistry*; D013816:Thermodynamics; D014783:Viscosity
chemical_list: D006841:Hydrocarbons, Aromatic; D012996:Solutions; D012997:Solvents