Destabilization of emulsions in contact with inorganic solid surfaces

Internship proposal 2021-2022

Soft Matter Science and Engineering Laboratory, (SIMM)

Address: ESPCI, 10 Rue Vauquelin 75005 Paris

Chair: Etienne Barthel

Supervisors: N. SANSON (nicolas.sanson (arobase) espci.fr), C. Monteux (cecile.monteux (arobase) espci.fr) et A. Kovalenko (artem.kovalenko (arobase) espci.fr)

Scientific description:

In the field of road surfaces, a bitumen emulsion is mixed with solid particles composed of either silica (quartz, granite), silicates (mica, diorite) or carbonates (calcite, dolomite). In this process, a rupture of the emulsion followed by the removal of the water ultimately leads to the formation of a continuous film of bitumen (coating) on the particles ensuring the adhesion of the particles between them.
Among the hypotheses that can explain the destabilization of the emulsion in contact with the aggregate, we can mention an adsorption of surfactants on the mineral surface, which would then unfold the oil drops or a precipitation of the surfactant because of a local change in pH due to the dissolution of the aggregates.
The goal of the internship is a thorough understanding of the rupture mechanisms that control this destabilization by focusing mainly on the behavior of surfactants in different physicochemical parameters such as the nature of the solid surface, pH, ionic strength, ...
For this, we will first study the interaction between surfactants and a suspension of model solid particles (silica or calcite) by tracing adsorption isotherms at different pH. Then we will produce model emulsions and study the stability of these emulsions in contact with solid particles as a function of pH. Finally, we will study the behavior of a single oil droplet in water when it is put in contact with a solid surface. We will study by interferometry the stability of the aqueous wetting film between the drop and the solid.

Keywords: emulsions, surfactants, solid-liquid and liquid-liquid interfaces

Techniques/methods in use: microscopy, interferometry, interfacial tension, TOC (Total Organic Carbon).

Applicant skills:
-  General knowledge of soft matter, physical-chemistry of interfaces
-  Experimental skills
-  Reporting and communication skills

Industrial partnership: with Colas

Internship location: Soft Matter Science and Engineering (SIMM) laboratory at ESPCI, a joint CNRS-ESPCI-SU laboratory, 10 rue Vauquelin 75005 Paris

Possibility for a Doctoral thesis: to be discussed later in 2022

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Practical information

Sciences et Ingénierie de la Matière Molle

Soft Matter Enginering and Science Laboratory - UMR 7615

10 rue Vauquelin
75231 PARIS CEDEX 05
FRANCE

  • Chair : E. Barthel
  • Vice Chairs : J.B. d’Espinose & G. Ducouret
  • Administration : F. Decuq, M.-T. Mendy & M. Hirano-Courcot
  • Communication : A. Hakopian & M. Ciccotti
  • Information Technology : A. Hakopian
  • Safety, Health and Environment Assistant : F. Martin

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