An experimental study of asphaltene particle sizes in n-heptane-toluene mixtures by light scattering

The particle size of asphaltene flocculates has been the subject of many recent studies because of its importance in the control of deposition in petroleum production and processing. We measured the size of asphaltene flocculates in toluene and toluene - n-heptane mixtures, using the light-scattering technique. The asphaltenes had been extracted from Brazilian oil from the Campos Basin, according to British Standards Method IP-143/82. The asphaltene concentration in solution ranged between 10-6 g/ml and 10-7 g/ml. Sizes was measured for a period of about 10000 minutes at a constant temperature of 20 deg C. We found that the average size of the particles remained constant with time and increase with an increase in amount of n-heptane. The correlation obtained for size with concentration will be useful in asphaltene precipitation models. (author)