Dr. Cornelia Bellmann

The investigation of electrokinetic phenomena is one of the main tasks of research in the Department of Surface Chemistry of the IPF (fundamentals in [5,6]). The team wants to make a contribution to theory and methods of characterization of solid surfaces in combination with other physico-chemical methods (XPS, AFM etc.). Some years ago a commercial device for measuring the streaming potential for powders, fibres, plates and membranes was developed in co-operation with scientists in Graz (Austria) - the Electrokinetic Analyzer (EKA) Anton Paar KG. A stochastical searching procedure according to Gouy-Chapman-Stern-Grahame model developed by co-workers of the IPF allows to calculate thermodynamic parameters of solid surfaces from zeta potential values in dependence of pH and ion concentration. The measured and calculated electrokinetic parameters permit to describe technological processes involving interfaces like adsorption processes, dispersion and coagulation processes, and adhesion processes.

Fields of Research

• electrokinetic measurements (streaming potential, electroosmosis, electrophoresis, electroacoustics) / contributions to developing new methods
• study of electrokinetic phenomena in combination with other thermodynamic, spectroscopic and direct force methods
• characterization of solid surfaces
  • dissociation processes
  • adsorption processes
  • electron transfer processes
  (biocompatibility, fibre preparation, surface modification with polyelectrolytes, surfactants, physical or chemical processes)
• characterization of solid / solid interactions
  • colloid stability
  • adhesion process
  • acid base interactions
  (polymer blends, fibre-polymer matrix composites, filled polymers, latices, coatings)

Projects

• BMBF-project „Innovative methods" (MPI Mainz, DKI-Darmstadt)
• DFG project "Investigation of separation properties of ceramic filters" (management: Bergakademie Freiberg)

Equipment

• Electrokinetic analyzer EKA, by A. Paar (AU)
  • streaming potential measurements with solids of any shape
• Electrokinetic analyser ZetaSizer 3, by Malvern Instruments (GB)
• Electrokinetic analyser ZetaSizer 3000, by Malvern Instruments (GB)
  • electrophoresis with diluted dispersions
  • determination of particle sizes by photon correlation spectroscopy
• Electroacoustic measuring system, by Matec (USA)
  • electrophoresis of concentrated dispersions