Macrostructure of asphaltene dispersions by small-angle X-ray scattering

Characterization of fractionated asphaltenes by UV–vis and NMR self-diffusion spectroscopy

“…Many different techniques, such as small angle neutron scattering (SANS) [44][45][46][47], small angle X-ray scattering (SAXS) [48][49][50][51], and fluorescence spectroscopy [52,53], have been employed for investigating the size of asphaltenes and various structures, such as disc-like and spherical, have been proposed to explain the data. For example, results from studies with SANS suggest that asphaltenes could have a disc-like geometry with radii between 30 and 100 Å [47], while SAXS studies have indicated that asphaltenes could be discs with a thickness of 3.4 Å and a radius between 12 and 800 Å [51].…”

Asphalt flocculation and deposition: II. Formation and growth of fractal aggregates

“…Since asphalt and asphaltene aggregates are fractal with complex shapes, one can estimate 1 only if the fractal aggregate is approximated by a simple shape. For example, Herzog et al (1988) and Acevedo et al (1994) suggested that one may represent asphalts roughly as relatively thin discs, ?hose thickness was estimated to be in the range 3.64.0 A, while the density of asphalt aggregates is typically about 1.1-1.3 g/cm3. Thus, if, as a rough estimate, we assume 1 to be the radius of the discs, given the weight and density of the asphalts in the soluiion and the thickness of the discs, which we took it to be 5.8 A, 1 can be estimated.…”

Asphaltenic aggregates are polydisperse oblate cylinders

“…Various experimental techniques have previously been applied to study the aggregation behavior of asphaltenes in solution including: near-infrared spectroscopy [10,11], pulsed-field gradient spin echo nuclear magnetic resonance [12,13], vapor pressure osmometry [8,14,15], viscosity measurements [16][17][18][19], small-angle X-ray scattering (SAXS) [14,17,[20][21][22][23][24][25], and small-angle neutron scattering (SANS) [8,14,16,[21][22][23][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. Small-angle scattering methods, such as SAXS and SANS, have been useful for deducing the sizes of asphaltenic aggregates in solution based on assumed particle morphologies.…”