The influence of different organic solvents on the size and shape of asphaltene aggregates studied via small-angle X-ray scattering and scanning tunneling microscopy

An influence of various organic compounds on aggregation of asphaltenes separated from Tartar oil was studied by small-angle X-ray scattering and scanning tunneling microscopy methods. The compounds such as cyclohexane, methanol, formic acid, heptane, tetrabutylammonium fluoride, acetonitrile, decane, hexanol-1, furfural, and octene-1, added to the solution of asphaltenes in toluene, were shown to produce a considerable aggregation of asphaltene particles of similar to 10-13nm size and of an oblong ellipsoid shape along the longer axis. Decalin, dimethylformamide, dimethylsulfoxide, nitrobenzene, aniline, cyclohexanol, monoethanolamine, triethanolamine, 1-methylnaphtalene, and dichloroethane cause asphaltene aggregate sizes to decrease essentially. Acetone, glycerin, ethyl acetate, dioxane, benzyl alcohol, oleic acid, limonene, alpha-pinene, cycloheptatrien, and nitromethane were shown to influence weakly on aggregation/disaggregation processes of asphaltenes. Conceivable reasons of the observed effects are discussed from general physico-chemical properties of the compounds used.