Coalescence in complex physicochemical systems


The mechanisms of coalescence is of huge importance in the process of soft matter and divided materials such as emulsions and foams. It controls their stability and their final properties in many applications including cosmetics, food engineering, energy, biotechnology etc. It has a significant influence in wastewater treatment. Actually oil removal relies on gravitational methods that are favored by coalescence. In Enhanced Oil Recovery, water treatment is all the more challenged by residual polymers and surfactants that constitute complex physico-chemical systems. The objective of the thesis is to characterize the mechanisms involved in the coalescence of such complex systems. Three main configurations will be investigated: coalescence between two oil droplets, coalescence between oil droplet and interface and heterocoalescence between oil droplet and gas bubble (in the case of flotation). Each case includes successive drainage and rupture steps during which both hydrodynamic and molecular forces are implied at different scales between viscoelastic interfaces. Their relative influence will be identified and studied using appropriate physico-chemical compositions : brines of different salinities, various organic phases, polymers and surfactants solutions, They will allow to deal with various interfaces and thin films. Interfaces will be characterized by IFT measurements and interfacial rheology. Flow properties of the thin films will be addressed using rheometers and microfluidic devices. A dedicated set-up will enable to film the coalescence of an oil droplet with various interfaces at mesoscopic scales. Film thining will be characterized by induction times using a high speed camera. Their thickness evolving will be measured by interferometry. Additional macroscopic experiments will be performed. Lab flotation column will be used for the study of oil droplets and air bubbles attachment. Centrifugation and bottle tests will assess the tendency of oil droplets to merge. This set of experiments will demonstrate how small scale phenomena can govern macroscospic ones. The obtained results will promote understanding of the coalescence and identification of key parameters. They will constitute relevant data to achieve coalescence physical modeling.

Keywords: coalescence, interface, rheology, polymers, surfactants

  • Academic supervisor    Dr, HDR, DALMAZZONE Christine IFPEN
  • Doctoral School    ED 388
  • IFPEN supervisor    Dr, HENAUT Isabelle
  • PhD location    IFPEN Rueil-Malmaison FRANCE
  • Duration and start date    3 years, starting not earlier than November 2020
  • Employer    IFPEN Rueil-Malmaison FRANCE
  • Academic requirements    University Master degree in physical sciences, chemistry or materials
  • Language requirements    Fluency in French or English, willingness to learn French
Encadrant IFPEN 
Dr, HENAUT Isabelle
Texte libre

IFP Energies nouvelles is a French public-sector research, innovation and training center. Its mission is to develop efficient, economical, clean and sustainable technologies in the fields of energy, transport and the environment. For more information, see 
IFPEN offers a stimulating research environment, with access to first in class laboratory infrastructures and computing facilities. IFPEN offers competitive salary and benefits packages. All PhD students have access to dedicated seminars and training sessions.