New Answers to the Optical Interrogation of Asphaltenes: Complex States of Primary Aggregates from Steady-State Fluorescence Studies

Evdokimov, Igor N.; Fesan, Aleksey A.; Losev, Aleksandr P.

doi:10.1021/acs.energyfuels.6b01943

Cited by 10 publications

(32 citation statements)

References 52 publications

(124 reference statements)

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“…Nevertheless, recent studies indicated that asphaltenes form primary aggregates at concentrations as low as ca. 0.7 mg/L, which is far below the value advocated by the modified Yen model [190]. Another model of asphaltene aggregates was proposed by Murray R. Gray et al [179].…”

Section: Asphaltene Aggregate Morphologiesmentioning

confidence: 76%

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Fractionation and Characterization of Petroleum Asphaltene: Focus on Metalopetroleomics

et al. 2020

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Asphaltenes, as the heaviest and most polar fraction of petroleum, have been characterized by various analytical techniques. A variety of fractionation methods have been carried out to separate asphaltenes into multiple subfractions for further investigation, and some of them have important reference significance. The goal of the current review article is to offer insight into the multitudinous analytical techniques and fractionation methods of asphaltene analysis, following an introduction with regard to the morphologies of metals and heteroatoms in asphaltenes, as well their functions on asphaltene aggregation. Learned lessons and suggestions on possible future work conclude the present review article.

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Section: Asphaltene Aggregate Morphologiesmentioning

confidence: 76%

“…Aggregation of asphaltenes occurs even in exceptionally diluted solutions. These aggregates dissociate with the decrease in concentration and increase in temperature [189,190]. In addition, metals and heteroatoms play an important role in asphaltene aggregation [113,191].…”

Section: Metals and Heteroatoms Involved In Asphaltene Aggregationmentioning

confidence: 99%

Fractionation and Characterization of Petroleum Asphaltene: Focus on Metalopetroleomics

et al. 2020

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“…Recently, it was experimentally proven [48][49][50][51][52] that basic asphaltene molecules (unimers, monomers) typically include very small, 1-3 ring, aromatic systems, in contrast to the popular notions about the predominance of large multiring fused systems [41,42]. These basic molecules become predominant equilibrium species only after dissolution of solid asphaltenes in "good" solvents (benzene, toluene, etc.)…”

Section: Plausible Constitution Of Multiple Structural Phases Of Asphmentioning

confidence: 99%

Density Anomalies in Crude Oil Blends Reflect Multiple Equilibrium States of Asphaltene Colloidal Aggregates

Evdokimov¹,

Fesan²,

Losev³

2018

Recent Insights in Petroleum Science and Engineering

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Density measurements revealed anomalies of nonideality (maxima of excess density) at some compositions in binary blends of light and heavy crude oils from diverse origins. By IR absorption measurements, density anomalies were attributed to increased contents of suspended asphaltene colloidal-sized particles/aggregates in the blends. By comparison with a database of world's native crude oils, it was concluded that density anomalies may correspond to different equilibrium structural states of asphaltene colloids that occur at several specific asphaltene contents, apparently common for petroleum media of any origin.

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“…Thereafter, further aggregation leads to the formation of nanoaggregates and larger clusters as described by the Yen-Mullins model. Inter-conversion between aggregated states is considered kinetically slow, 74 and it is therefore possible that the adsorption isotherms will be defined by the prevalent species at a given c0. Thus, with particular reference to Figs.…”

Section: Adsorption Models the Equilibrium Adsorptionmentioning

confidence: 99%

Adsorption Behavior of Asphaltenes and Resins on Kaolinite

Tsiamis

Taylor

2017

Energy Fuels

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Recent studies have shown that n-C7-precipitated asphaltenes adsorb onto nanoparticles to produce iso-therms that are significantly influenced by the dispersed states of both the adsorbate and adsorbent. In the present work, we investigate this behavior further by determining the adsorption of asphaltene and resin fractions isolated from four different sources onto kaolinite using the depletion method in toluene. Treated conventionally (amount adsorbed, , ver-sus equilibrium bulk concentration, ce), adsorption isotherms for fixed initial concentrations (c0) of C5 and C7 asphaltenes and variable kaolinite mass (ms) are found to be Type I as classified by IUPAC, whereas under the same experimental conditions C5-C7 resins exhibit Type III behavior. By fixing ms and varying c0, however, Type II isotherms are produced by the resins. All the adsorption results for the same fraction type were found to be very similar, irrespective of the source. The Types I and III isotherms are described very well by the thermodynamic solid-liquid equilibrium (SLE) model of Montoya et al. (Energy Fuels 2014, 28, 4963−4975) based on association theory of Talu and Meunier (AIChE J. 1996, 42, 809-819). Individual isotherms ( versus ce) are well-fitted by a shifted Langmuir equation for asphaltenes, and by a gen-eral Freundlich (power law) relationship for resins. The SLE results verify that in toluene solution the adsorption behavior is complicated by concentration-dependent nanoaggregation of asphaltene species, whereas resin-resin interactions are weaker, but accompanied by adsorbent particle aggregation. On the other hand, when the adsorption data for each frac-tion type is re-plotted in terms of the ratio of the experimental parameter c0/ms, as originally done by Wang et al. (Col-loids Surfaces A: Physicochem. Eng. Aspects 2016, 504, 280–286), each set of data merges to a single isotherm which is rea-sonably well approximated by a Langmuir-type relationship (we term this a “pseudo-Langmuir equation”), which allows the maximum adsorption to be determined for the different adsorbate/adsorbent systems. The average maximum ad-sorbed amounts calculated in this way for each of the component types are very similar, being slightly larger for C7A compared with C5A, with the values for the C5-C7R fractions being generally lower and more variable, possibly reflecting some source dependence

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New Answers to the Optical Interrogation of Asphaltenes: Complex States of Primary Aggregates from Steady-State Fluorescence Studies

Cited by 10 publications

References 52 publications

Fractionation and Characterization of Petroleum Asphaltene: Focus on Metalopetroleomics

Fractionation and Characterization of Petroleum Asphaltene: Focus on Metalopetroleomics

Density Anomalies in Crude Oil Blends Reflect Multiple Equilibrium States of Asphaltene Colloidal Aggregates

Adsorption Behavior of Asphaltenes and Resins on Kaolinite

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