Characterization of asphaltene particles by light scattering and electrophoresis

The solubility of asphaltenes in heptane/toluene mixtures was studied at se veral temperatures. A significant increment in asphaltene solubility was ob served when the temperature increases from 0 degreesC to 20 degreesC and a moderate increase when the temperature rose from 20 degreesC to 50 degreesC . These results indicate that asphaltenes behave as a higher consulate temp erature system, similar to nonpolar waxes. Examined by photon correlation s pectroscopy, diameters from the particles formed a range between 125 and 40 0 nm, depending on the amount of non-solvent (n-heptane) used for the preci pitation process and the initial concentration of asphaltenes. The particle s presented a small positive surface potential that was not altered by the addition of resins.