Abstract:

In this paper, saturates, aromatics, resins and asphaltenes were separated from 380# residual fuel oil，and the content and structure of the fractions were investigated by EA, GPC, FT-IR and 1H NMR. The interfacial tension (IFT) of 380# residual fuel and its fractions was measured, and the effects of pH value and salt content of aqueous phase on interfacial tension were studied. The results indicate that the aromatic is the most component in 380# residual fuel oil. The total content of asphaltene and resin is approximately 30%. Asphaltene contains more heteroatoms than resin. The molecular weight and aromatic carbon ratio (fA) of asphaltene is the largest, and its hydrogen carbon atom ratio [n(H)/n(C)] is minimum. It is found that the polar groups (hydroxyl, amino, carboxyl, etc) content of asphaltene is more than that of resin by the FT-IR analysis, so the asphaltene has higher interfacial activity. The interfacial tension sequence of the components in 380# residual fuel oil is: saturate>aromatic>resin>asphaltene. Because the acidic groups are more than the basic groups in residual fuel oil and in its components, the oil-water interfacial tension is declining sharply at the strong alkaline condition. The influence of salt content in aqueous phase on the interfacial tension is very small.

Key words: marine fuel oil, polar components, structural characterization, interfacial tension, asphaltene