Asphaltene fractionation based on adsorption onto calcium carbonate: Part 3. Effect of asphaltenes on wax crystallization

Ruwoldt, Jost; Subramanian, Sreedhar; Simon, Sébastien; Oschmann, Hans-Jörg; Sjöblom, Johan

doi:10.1016/j.colsurfa.2018.06.025

Cited by 31 publications

(29 citation statements)

References 35 publications

(77 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The irreversibly adsorbed fraction, containing the highest concentration of carbonyl, carboxylic acid, or derivative groups was found to have a significantly higher tendency to self-associate and form larger aggregates than other fractions did, which exhibited similar properties with the fraction precipitating first from the sequential precipitation procedure [135]. The effect of these three asphaltene fractions on wax crystallization was also studied, and results showed that the irreversibly adsorbed fraction containing the most polar species induced the largest changes in wax-crystal morphology [136].…”

Section: Adsorption Onto Porous Mediummentioning

confidence: 88%

“…Recently, a new fractionation procedure was developed on the basis of the adsorption of asphaltenes onto a porous medium, CaCO 3 . Three asphaltene fractions were obtained: the bulk (non-adsorbed) asphaltene that stayed in the bulk solution, the adsorbed asphaltene that was obtained by desorption of asphaltenes adsorbed on CaCO 3 using tetrahydrofuran, and the irreversibly adsorbed asphaltene that was obtained after CaCO 3 dissolution [134][135][136]. The irreversibly adsorbed fraction, containing the highest concentration of carbonyl, carboxylic acid, or derivative groups was found to have a significantly higher tendency to self-associate and form larger aggregates than other fractions did, which exhibited similar properties with the fraction precipitating first from the sequential precipitation procedure [135].…”

Section: Adsorption Onto Porous Mediummentioning

confidence: 99%

See 1 more Smart Citation

Fractionation and Characterization of Petroleum Asphaltene: Focus on Metalopetroleomics

et al. 2020

View full text Add to dashboard Cite

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.

show abstract

Section: Adsorption Onto Porous Mediummentioning

confidence: 88%

Section: Adsorption Onto Porous Mediummentioning

confidence: 99%

Fractionation and Characterization of Petroleum Asphaltene: Focus on Metalopetroleomics

et al. 2020

View full text Add to dashboard Cite

show abstract

“…The fractionation process involved passing the asphaltene solution in toluene through a calcium carbonate packed bed column. 28 The most polar subfraction with the strongest affinity to the CaCO 3 surface is called irreversibly adsorbed (IA) asphaltenes (MW = 442), whereas the least polar asphaltenes that remain unadsorbed are called bulk asphaltenes (MW = 508). 29 The crude oil contained about 2.8 wt % asphaltenes, of which approx.…”

Section: ■ Experimental Methodsmentioning

confidence: 99%

“…The asphaltene subfractions used in this study are obtained by fractionation of whole asphaltenes extracted from a heavy crude oil from a Norwegian continental shelf. The fractionation process involved passing the asphaltene solution in toluene through a calcium carbonate packed bed column . The most polar subfraction with the strongest affinity to the CaCO 3 surface is called irreversibly adsorbed (IA) asphaltenes (MW = 442), whereas the least polar asphaltenes that remain unadsorbed are called bulk asphaltenes (MW = 508) .…”

Section: Experimental Methodsmentioning

confidence: 99%

Experimental Evidence of Enhanced Adsorption Dynamics at Liquid–Liquid Interfaces under an Electric Field

2020

Self Cite

View full text Add to dashboard Cite

In this work we investigate adsorption of surface active compounds at water-oil interface subjected to an electric eld. A uid system comprising a pendent water drop surrounded by an asphaltene-rich organic phase is exposed to a DC uniform electric eld.Two sub-fractions of asphaltenes having contrasting anities to water-oil interface are used as surface active compounds. The microscopic changes in the drop shape, as a result of asphaltene adsorption, are captured and the drop proles are analyzed by using our in-house code for axisymmetric drop shape analysis (ADSA) under electric eld.The estimates of dynamic interfacial tension under dierent strengths of the eld (E 0 ) and concentrations of the asphaltene sub-fractions (C) are used to calculate adsorption dynamics and surface excess. The experimental observations and careful analysis of the data suggest that the externally applied electric eld signicantly stimulates the mass transfer rate at a liquid-liquid interface. The enhancement in mass transport at 1 water-oil interface can be attributed to the axisymmetric electrohydrodynamic uid ows generated on either sides of the interface. The boost in mass transport is evident from the growing decay in equilibrium interfacial tension (γ eq ) and increased surface excess (Γ eq ) upon increasing strength of the applied electric eld. The mass transfer intensication does not increase monotonously with the electric eld strength above an optimum E 0 , which is in agreement with previous theoretical studies in the literature.However, these rst explicit experimental measurements of adsorption at an interface under electric eld suggest that the optimum E 0 is determined by characteristics of the surface active molecules.

show abstract

“…Asphaltene samples and their subfractions were prepared at the Ugelstad Laboratory in NTNU. Asphaltenes were precipitated from a North Sea crude oil using n -hexane following the procedure described in ref . This will be further on referred to as the “whole asphaltenes” sample, whose results are discussed in the first part of the results section.…”

Section: Methodsmentioning

confidence: 99%

Assessing the Interfacial Activity of Insoluble Asphaltene Layers: Interfacial Rheology versus Interfacial Tension

Alicke

Simon²,

Sjöblom³

et al. 2020

Langmuir

Self Cite

View full text Add to dashboard Cite

Asphaltenes have been suggested to play an important role in the remarkable stability of some water-in-crude oil emulsions, although the precise mechanisms by which they act are not yet fully understood. Being one of the more polar fractions in crude oils, asphaltenes are surface active and strongly adsorb at the oil/water interface, and as the interface becomes densely packed, solid-like mechanical properties emerge, which influence many typical interfacial experiments. The present work focuses on purposefully measuring the rheology in the limit of an insoluble, spread Langmuir monolayer in the absence of adsorption/desorption phenomena. Moreover, the changes in surface tension are deconvoluted from the purely mechanical contribution to the surface stress by experiments with precise interfacial kinematics. Compression “isotherms” are combined with the measurement of both shear and dilatational rheological properties to evaluate the relative contributions of mechanical versus thermodynamic aspects, i.e., to evaluate the “interfacial rheological” versus the standard interfacial activity. The experimental results suggest that asphaltene nanoaggregates are not very efficient in lowering interfacial tension but rather impart significant mechanical stresses. Interestingly, physical aging effects are not observed in the spread layers, contrary to results for adsorbed layers. By further studying asphaltene fractions of different polarity, we investigate whether mere packing effects or strong interactions determine the mechanical response of the dense asphaltene systems as either soft glassy or gel-like responses have been reported. The compressional and rheological data reflect the dense packing, and the behavior is captured well by the soft glassy rheology model, but a more complicated multilayer structure may develop as coverage is increased. Potential implications of the experimental observations on these model and insoluble interfaces for water-in-crude oil emulsion stability are briefly discussed.

show abstract

Asphaltene fractionation based on adsorption onto calcium carbonate: Part 3. Effect of asphaltenes on wax crystallization

Abstract: Asphaltenes fractionation procedures were developed and tested in two preceding articles (doi:

Cited by 31 publications

References 35 publications

Fractionation and Characterization of Petroleum Asphaltene: Focus on Metalopetroleomics

Fractionation and Characterization of Petroleum Asphaltene: Focus on Metalopetroleomics

Experimental Evidence of Enhanced Adsorption Dynamics at Liquid–Liquid Interfaces under an Electric Field

Assessing the Interfacial Activity of Insoluble Asphaltene Layers: Interfacial Rheology versus Interfacial Tension

Contact Info

Product

Resources

About