Precipitation number asphalt

The foremnner of the modern methods of asphalt fractionation was first described in 1916 (50) and the procedure was later modified by use of fuller s earth (attapulgite [1337-76-4]) to remove the resinous components (51). Further modifications and preferences led to the development of a variety of fractionation methods (52—58). Thus, because of the nature and varieties of fractions possible and the large number of precipitants or adsorbents, a great number of methods can be devised to determine the composition of asphalts (5,6,44,45). Fractions have also been separated by thermal diffusion (59), by dialysis (60), by electrolytic methods (61), and by repeated solvent fractionations (62,63). 

To simplify asphalt analysis, a common practice is to fractionate the material to divide it into groupings of simpler constitution. A large number of methods have been proposed, but most are based on either selective solvent extraction or chromatographic separation or, frequently, a combination of solvent precipitation and chromatographic separation. 

Asphaltene particles are dispersed in saturates and aromatic hydrocarbons (gas-oil) with resins as peptizing agents in asphalt or heavy oil. The interaction between resin and asphaltene micelles is not well understood. In the present study, asphaltene has been dispersed into aromatic hydrocarbons (such as toluene), and the precipitations due to additions of paraffinic hydrocarbons (such as pentane) in the presence of a number of amphiphiles have been studied. These amphiphiles certainly affect the asphaltene precipitation, either by retardation or by enhancement, depending on the structural types and quantities of the amphiphiles. We have found that the nature of resin is that it behaves as an amphiphile, since the polar fractions of resin do contain amphiphiles. The solubility parameter spectra of these asphaltenes are discussed. 

Later wc will represent the precipitated phase by L2. We assume a total of c components/pseudocomponents in the crude oil. The component indices for the asphaltenes and resins are c and (c — 1), respectively. Therefore, the number of species in the asphalt-free oil is c — 2). The... 

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