Solid surfaces are charged in contact with aqueous solutions – by dissociation of functional groups and by adsorption of ions and molecules. Electrokinetic measurements determine the electrical potential at the interface to the surrounding solution, the electrokinetic or zeta potential. In our labs, we have a broad spectrum of electrokinetic techniques to determine the zeta potential of solids of different size and geometry – from nano- and microparticles, fibers and powders to thin films and extended solid surfaces. Time-, pH-, and concentration-dependent measurements give information on the acid/base behavior of surfaces, adhesion and swelling processes or chemical reactions. Additionally, the size distribution of dispersed micro- and nanoparticles can be measured.
Contact person:
Dr. Günter Auernhammer
Dr. Astrid Drechsler
Anja Caspari
Zetasizer nano ZS (MALVERN Panalytical Ltd., UK)
- determination of zeta potential and particle size
- method: electrophoresis, M3 - PALS (Phase Analysis Light Scattering), Dynamic Light Scattering
- samples: diluted particle dispersions (particle size: 5 nm to 10 µm, solid concentration: < 10 vol%)
- requirements: no interaction between particles, no sedimentation - minimum sample volume: 1 ml (single measurement), 50 ml (pH titration)
SurPASSTM 3 (ANTON PAAR GmbH, Graz, AT)
- determination of zeta potential and surface conductivity
- method: streaming potential and streaming current measurement
- samples: fibres, powders (particle size 20-200 µm), plates/foils 10x20 mm, membranes
- automatic pH titration: pH 6-2 /pH 6-12
- time- and concentration-dependent measurements
DT 1200 (Dispersion Technology, Inc., Beford Hills, USA)
- determination of zeta potential and particle size
- methods: colloidal vibration current (electroacoustics), ultrasound attenuation measurements
- samples: suspensions (particle size 1 nm – 100 µm, solid concentration: 0,1 to 50 vol%), emulsions
- minimum sample volume: 2 ml (single zeta potential measurement), 80 ml (particle size measurement), 160 ml (pH titration)
Electrokinetic Set-Up (Zetascience GmbH, Dresden, Germany)
- determination of zeta potential and surface conductivity
- method: streaming potential and streaming current measurement
- samples: fibres, powders (particle size 20-200 µm), plates /foils 10x20 mm or ø 26 mm
- automatic pH titration: pH 6-2 /pH 6- 12
- time- and concentration-dependent measurements
ZPA 20 (DataPhysics Instruments, Filderstadt, DE)
- Determination of zeta potential and surface conductivity
- Method: streaming potential and streaming current measurement (oscillating)
- Samples: Fibers, powders (particle size 20-200 µm), plates 10x20 mm, films, membranes.
- single measurements and automatic pH titration
- time and concentration dependent measurements
• Grundke, K. Characterization of polymer surfaces by wetting and electrokinetic measurements - contact angle, interfacial tension, zeta potential. In Stamm, M. (ed.) Polymer surfaces and interfaces. Springer, Berlin, Heidelberg (2008) 103-138.
• Bellmann, C.; Caspari, A.; Moitzi, C.; Babick, F. Dynamische und elektrophoretische Lichtstreuung - Leitfaden zur Partikelgrößenanalyse und Zetapotentialbestimmung. Anton Paar GmbH (2018)
• Drechsler, A. ; Caspari, A. ; Synytska, A. Influence of roughness and capillary size on the zeta potential values obtained by streaming potential measurements. Surface and Interface Analysis 52 (2020) 991-995
