Elemental analysis, Fourier transform infrared
(FTIR), 1H-NMR, fluorescence spectroscopy, and surface
tension methods have been used to characterize the
molecular structure and the aggregation behaviors of two
asphaltenic fractions derived, respectively, from an Algerian
petroleum well and a corresponding storage tank
deposit. Elemental analysis, FTIR, 1H-NMR, and fluorescence
spectroscopy were used to investigate the chemical
composition and structural parameters of asphaltenes,
while the surface tension method was used to measure the
critical micelle concentration (CMC) in organic solvents
with different solubility parameters and polarities in order
to characterize the asphaltenes’ aggregation behaviors.
Results show that the unstable asphaltenes fraction
extracted from the storage tank deposit possesses a higher
polarity (higher heteroatoms content) and a lower aromaticity
than stable asphaltenes from the petroleum well.
The CMC results indicate that asphaltenes with high
polarity and low aromaticity have a high solubility in polar
solvents such as nitrobenzene, whereas asphaltenes with
low polarity and high aromaticity are more soluble in
solvents with weak polarity, like toluene. It is concluded
that the difference of structure of asphaltene samples and
polarity of solvents can lead to difference of aggregation
behaviors.