Flocculation Behavior of Asphaltenes in Solvent/Nonsolvent Systems

Östlund, Jenny Ann; Löfroth, Jan‐Erik; Holmberg, Krister; Nydén, Magnus

doi:10.1006/jcis.2002.8516

Cited by 31 publications

(26 citation statements)

References 29 publications

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“…Ostlund et al 58 reported diffusion coefficients of asphaltenes in toluene solutions to be on the order of 10 -10 m 2 /s, which is in good agreement with the current study.…”

Section: Resultssupporting

confidence: 92%

Understanding Mechanisms of Asphaltene Adsorption from Organic Solvent on Mica

et al. 2014

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The adsorption process of asphaltene onto molecularly smooth mica surfaces from toluene solutions of various concentrations (0.01 -1 wt%) was studied using a Surface Forces Apparatus (SFA). Adsorption of asphaltenes onto mica was found to be highly dependent on adsorption time and concentration of the solution. The adsorption of asphaltenes led to an attractive bridging force between the mica surfaces. The adsorption process was identified to be controlled by diffusion of asphaltenes from the bulk solution to the mica surface with a diffusion coefficient on the order of 10 -10 m 2 /s at room temperature, depending on asphaltene bulk concentration. This diffusion coefficient corresponds to a hydrodynamic molecular radius of approximately 0.5 nm, indicating that asphaltene diffuses to mica surfaces as individual molecules at very low concentration (e.g. 0.01 wt%). Atomic force microscopy (AFM) images of the adsorbed asphaltenes on mica support the results of the SFA force measurements. The results from the SFA force measurements provide an insight on the molecular interactions (e.g. steric interaction, bridging attraction as a function of distance) of asphaltenes in organic media and hence their roles in crude oil and bitumen production.

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“…Ostlund et al 58 reported diffusion coefficients of asphaltenes in toluene solutions to be on the order of 10 -10 m 2 /s, which is in good agreement with the current study.…”

Section: Resultssupporting

confidence: 92%

Understanding Mechanisms of Asphaltene Adsorption from Organic Solvent on Mica

et al. 2014

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“…However, asphaltenes from NM1 and NM5 crudes as well as from vacuum residue from a Venezuelan oil were also used in this study. The asphaltenes from NM1 and NM5 crudes were extracted as described here, whereas the asphaltenes from the vacuum residue were extracted in a similar manner, which has been reported elsewhere [27].…”

Section: Extraction Of Asphaltenesmentioning

confidence: 99%

“…Inc., USA. Due to very rapid T 2 relaxation of the protons in the alkyl chains of the asphaltenes [27], a stimulated echo pulse sequence [29] was used to study the diffusion of asphaltenes. The gradient pulse duration (δ) was kept at 4 ms and the time between the gradients, the experimental observation time (∆), was kept at 70 ms for all experiments.…”

Section: Nmr Self-diffusion Studiesmentioning

confidence: 99%

“…We have thus studied the differences in self-association tendency as well as solubility between the subfractions of asphaltenes. Furthermore, we have used the NMR self-diffusion technique [23][24][25], previously found to be applicable to asphaltenic systems [26][27][28], to obtain information about the average diffusion and consequently the average size of asphaltenes from the different subfractions.…”

Section: Introductionmentioning

confidence: 99%

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

Östlund

Wattana

Nydén

et al. 2004

Journal of Colloid and Interface Science

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“…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.…”

Section: Introductionmentioning

confidence: 99%