Magnetic field influence on asphaltene aggregation monitored by diffusion NMR spectroscopy: Is aggregation reversible at high magnetic fields?. Issue 2 (28th January 2020)

• Record Type: Journal Article
• Authors: Parlov Vuković, Jelena; Novak, Predrag; Jednačak, Tomislav; Kveštak, Martina; Kovačević, Davor; Smrečki, Vilko; Mikulandra, Ivana; Djetelić Ibrahimpašić, Mateja; Glanzer, Simon; Zangger, Klaus
• Is Part Of: Journal of dispersion science and technology. Volume 41:Issue 2(2020)
• Page Start: 179
• Page End: 187
• Publication Date: 2020-01-28
• Subjects: Asphaltenes -- aggregation -- DOSY NMR -- convection currents -- magnetic field dependence; Emulsions -- Periodicals; Suspensions (Chemistry) -- Periodicals; Emulsions; Suspensions; 541.34
• DOI: 10.1080/01932691.2018.1561302
• Languages: English
• ISSNs: 0193-2691

Abstract

Abstract: We have shown that asphaltene self-association induces temperature gradients and convection currents and it is necessary to suppress these effects to obtain accurate data by DOSY NMR techniques. An interesting finding of this investigation is that aggregation process has been found to be affected by the magnetic field. The obtained results have shown for the first time a significant increase in diffusion coefficients of aggregates upon the increase in the magnetic field strength indicating higher molecular mobility of the present species and possible degradation of aggregates. We have shown that changes in diffusion coefficients are not a consequence of relaxation or viscosity effects. It is not yet clear what the reason for such behavior is and whether this effect is intrinsic. Traces of paramagnetic metals present in asphaltene samples may play a role in this process but this hypothesis is yet to be explored. Furthermore, this study has revealed a similar concentration range in which the Middle East crude oil asphaltenes aggregate being in agreement with previous results. Aggregates form different molecular weight species with different composition and number of monomer units. Ongoing experiments will throw more light on the magnetic field dependent asphaltene aggregation. This may have an impact on developing strategies for resolving asphaltene precipitation issues. GRAPHICAL ABSTRACT: