Dynamics and Structure of a Bitumen Emulsion as Studied by 1H NMR Diffusometry

Andrei Filippov; Hilde Soenen; Johan Blom; Oleg N Antzutkin

doi:10.1021/acsomega.3c05492

Dynamics and Structure of a Bitumen Emulsion as Studied by ¹H NMR Diffusometry

ACS Omega. 2023 Sep 21;8(39):36534-36542. doi: 10.1021/acsomega.3c05492. eCollection 2023 Oct 3.

Authors

Andrei Filippov¹, Hilde Soenen², Johan Blom³, Oleg N Antzutkin¹

Affiliations

¹ Chemistry of Interfaces, Department of Civil and Environmental Engineering, Luleå University of Technology, Luleå SE-97187, Sweden.
² Nynas N.V., 171 Groenenborgerlaan, Antwerp 2020, Belgium.
³ Faculty of Applied Engineering, EMIB-Research Group, University of Antwerp, 171 Groenenborgerlaan, Antwerp 2020, Belgium.

Abstract

Self-diffusion in a bitumen emulsion was studied by ¹H NMR. The emulsion forms two phases: continuous and dispersed. The continuous aqueous phase contains mainly water, with the energy of activation of the diffusion process equal to that of bulk water, while its diffusivity is smaller than that of bulk water by a factor of 2. The dispersed phase consists of bitumen droplets containing confined water, whose dynamics is characterized by a fully restricted diffusion regime in cavities with sizes of ∼0.11 μm. Therefore, the studied bitumen emulsion can be described by a model of a complex multiple emulsion of the water/oil/water (WOW) type. The suggested model does agree well with data from ¹H NMR spectroscopy and diffusometry of the bitumen emulsion doped with paramagnetic MnSO₄(aq) as well as with an additional ¹H NMR study of the emulsion structure, in which emulsion stability was compromised by freezing at 253 K.