Tuning size and electrostatics in non-polar colloidal asphaltene suspensions by polymeric adsorption

The effect of solvent and counterion variation on inverse micelle CMCs in hydrocarbon solvents

“…Experimentalists, however, have succeeded in measuring transitions that are consistent with a step change from monomers to inverse micelles at a critical concentration [14][15][16][17][18][19][20][21][22]. Accurate and consistent values of CMCs for inverse micelle formation are lacking in the literature.…”

Colloidal asphaltene deposition in laminar pipe flow: Flow rate and parametric effects

“…However, we can estimate particle size based on our previous light scattering results measuring the aggregation and growth of precipitating asphaltenes. 2,24 Asphaltenes precipitating from a variety of petroleum fluids, including those studied here, grow from the molecular scale to the order of 100 nm within just seconds of mixing the petroleum fluid with heptane, our asphaltene precipitant, and further to the micron scale after several minutes. Recall also that given D ∼ 1/a.…”

“…Electrostatic interactions have been shown to drive the aggregation of colloidal asphaltene particles in suspension, and so we choose n = 5 based on the assumption of electrostatic interactions holding the deposit together. 24,25 In a low dielectric medium like petroleum fluid, with dielectric constant ϵ ∼ 2, E = e 2 /(4πϵ 0 ϵr) = 5k B T is sufficient to separate two oppositely charged particles by a distance r ∼ 6 nm, where e is the elementary charge and ϵ 0 is the permittivity of free space.…”

Asphaltene adsorption on quartz sand in the presence of pre-adsorbed water

“…It was proposed that observations of increased surface precipitation of dispersed asphaltenes at a silica surface are explained by electrostatic attraction [48]. Asphaltenes dispersed in non-polar media are known to be electrically charged [49][50][51][52][53][54], and depending on the method of preparation and the type and concentration of solvent, electrodeposition experiments, in particular, have shown that asphaltene particles carry either positive or negative charges [52,54]. However, in pure solvents, and specifically when indigenous resins or added surface-active species are absent, dispersed asphaltenes (which will comprise clusters and larger aggregates derived from nanoaggregates) are positively charged [53,55].…”