Matches in SemOpenAlex for { <https://semopenalex.org/work/W2012199132> ?p ?o ?g. }
- W2012199132 endingPage "16276" @default.
- W2012199132 startingPage "16266" @default.
- W2012199132 abstract "The mean molecular weight and particle size of asphaltene aggregates extracted from Buzurgan feedstock have been evaluated by measuring the diffusivity by means of 1H diffusion-ordered spectroscopy (DOSY) nuclear magnetic resonance (NMR). This technique, recently applied in the petroleum industry, appeared as a key tool to investigate the behavior of asphaltenes diluted in toluene over a wide range of concentrations (from 0.01 to 15 wt %). The results show that the diffusivity is highly dependent upon solute concentration. Indeed, interactions occurring in dilute systems differ from interactions occurring in the semi-dilute regime. In the dilute regime (below 0.25 wt %), physical characterization of the nanoaggregates detected by 1H DOSY NMR could be achieved. An average molecular weight of roughly 6900 g mol−1 (taken at the highest diffusion peak and given as a polystyrene equivalent) with a range of 1500−85000 g mol−1 was obtained, while a mean radius of 15.6 Å was determined from the solute diffusivity at infinite dilution [D∞asp ∼ (2.4 ± 0.1) × 10−10 m2 s−1 for Buzurgan asphaltenes]. Average masses (Mn and Mw) were also calculated from DOSY NMR data and compared to results obtained from size exclusion chromatography (SEC) analyses. We also used DOSY NMR techniques to investigate the molecular dynamics of asphaltenes. A concentration of 0.25 wt % was found to represent the onset of the aggregation process. We believe DOSY NMR allowed us to observe the beginning of aggregation in phase transition. The asphaltene system is very polydisperse. At low concentrations, it is a polydisperse diluted system, but increasing the solute concentration induces a distinction of different aggregates, presenting various sizes in a macroscopic homogeneous phase. When the distinction occurs, there is a zone that is richer in high molecular weight aggregates of asphaltenes, and as a result, a second zone is impoverished in high molecular weight aggregates. In a microscopic point of view, there is a difference in nano or macroaggregate concentration, whereas in a macroscopic point of view, an average density is observed. For the first time, a clear separation between two families of aggregates of asphaltenes is presented in the diffusion dimension for concentrations higher than 3 wt %. 1H DOSY spectra and diffusion profiles confirm these results. The key point of this study resides in the detection and presentation of two classes of aggregates of asphaltenes achieved for concentrated solutions, without any assumption concerning the composition of the mixture." @default.
- W2012199132 created "2016-06-24" @default.
- W2012199132 creator A5036247960 @default.
- W2012199132 creator A5037633972 @default.
- W2012199132 creator A5038721117 @default.
- W2012199132 creator A5067967488 @default.
- W2012199132 creator A5085751915 @default.
- W2012199132 creator A5089852932 @default.
- W2012199132 date "2009-08-19" @default.
- W2012199132 modified "2023-10-18" @default.
- W2012199132 title "Aggregation States of Asphaltenes: Evidence of Two Chemical Behaviors by <sup>1</sup>H Diffusion-Ordered Spectroscopy Nuclear Magnetic Resonance" @default.
- W2012199132 cites W181671371 @default.
- W2012199132 cites W1965271245 @default.
- W2012199132 cites W1967195137 @default.
- W2012199132 cites W1967394989 @default.
- W2012199132 cites W1967637434 @default.
- W2012199132 cites W1970755955 @default.
- W2012199132 cites W1979615597 @default.
- W2012199132 cites W1980947453 @default.
- W2012199132 cites W1981596913 @default.
- W2012199132 cites W1982433118 @default.
- W2012199132 cites W1983738930 @default.
- W2012199132 cites W1985641759 @default.
- W2012199132 cites W1985861320 @default.
- W2012199132 cites W1986894944 @default.
- W2012199132 cites W1987390747 @default.
- W2012199132 cites W1988680835 @default.
- W2012199132 cites W1989383039 @default.
- W2012199132 cites W1990249109 @default.
- W2012199132 cites W1993377130 @default.
- W2012199132 cites W1994442520 @default.
- W2012199132 cites W1996588711 @default.
- W2012199132 cites W1996636548 @default.
- W2012199132 cites W1997134113 @default.
- W2012199132 cites W1998206608 @default.
- W2012199132 cites W1999185695 @default.
- W2012199132 cites W2000234636 @default.
- W2012199132 cites W2000922191 @default.
- W2012199132 cites W2003401092 @default.
- W2012199132 cites W2004874380 @default.
- W2012199132 cites W2004918262 @default.
- W2012199132 cites W2005683528 @default.
- W2012199132 cites W2005692644 @default.
- W2012199132 cites W2005756457 @default.
- W2012199132 cites W2007002347 @default.
- W2012199132 cites W2007030540 @default.
- W2012199132 cites W2010526792 @default.
- W2012199132 cites W2013795141 @default.
- W2012199132 cites W2017463329 @default.
- W2012199132 cites W2023715854 @default.
- W2012199132 cites W2025316066 @default.
- W2012199132 cites W2026886939 @default.
- W2012199132 cites W2030712936 @default.
- W2012199132 cites W2033466978 @default.
- W2012199132 cites W2035621719 @default.
- W2012199132 cites W2038358462 @default.
- W2012199132 cites W2041848091 @default.
- W2012199132 cites W2042087839 @default.
- W2012199132 cites W2043031607 @default.
- W2012199132 cites W2047559810 @default.
- W2012199132 cites W2048187279 @default.
- W2012199132 cites W2049310199 @default.
- W2012199132 cites W2051322276 @default.
- W2012199132 cites W2053114808 @default.
- W2012199132 cites W2053718838 @default.
- W2012199132 cites W2054108219 @default.
- W2012199132 cites W2054551075 @default.
- W2012199132 cites W2055857218 @default.
- W2012199132 cites W2057019675 @default.
- W2012199132 cites W2058839373 @default.
- W2012199132 cites W2065633892 @default.
- W2012199132 cites W2065654187 @default.
- W2012199132 cites W2066999227 @default.
- W2012199132 cites W2067566877 @default.
- W2012199132 cites W2068755165 @default.
- W2012199132 cites W2072169311 @default.
- W2012199132 cites W2072973127 @default.
- W2012199132 cites W2073401867 @default.
- W2012199132 cites W2073755889 @default.
- W2012199132 cites W2076166680 @default.
- W2012199132 cites W2077150810 @default.
- W2012199132 cites W2078086121 @default.
- W2012199132 cites W2082994302 @default.
- W2012199132 cites W2083719607 @default.
- W2012199132 cites W2084761689 @default.
- W2012199132 cites W2090498064 @default.
- W2012199132 cites W2090564869 @default.
- W2012199132 cites W2090585691 @default.
- W2012199132 cites W2090793515 @default.
- W2012199132 cites W2090824354 @default.
- W2012199132 cites W2092941218 @default.
- W2012199132 cites W2094559255 @default.
- W2012199132 cites W2094917763 @default.
- W2012199132 cites W2097011904 @default.
- W2012199132 cites W2102634095 @default.
- W2012199132 cites W2112859882 @default.
- W2012199132 cites W2122914136 @default.
- W2012199132 cites W2124155259 @default.