Department Process Engineering

Particle Laboratory

Nano-materials (including engineered nanoparticles (NP), as well as nano-structure materials) are increasingly used in many consumer products due to their ‘beneficial’ properties. However, while these materials are certainly beneficial regarding their respective application, they might not be as beneficial in the aquatic environment. The (unintended) release and the fate of these nano-materials in the aquatic environment are only poorly understood mainly due to the he lack of adequate analytical techniques to detect and characterize these materials in the environment. Our research, therefore, aims at combining well established standard characterization methods from colloidal sciences, with new methods from materials science and with own developments to detect, quantify and understand the effects of the ‘nano-materials’ in the aquatic environment.


Dr. Ralf KägiTel. +41 58 765 5273Send Mail

Calculator for Centrifugation Time at 25 °C

Distance from rotational centerMedium
Sample Surface from center [cm]: Liquid density [g/cm3]:
Sample Bottom from center [cm]: Viscosity [P]:
Speed of RotationParticle Characteristics
RPM [min-1]: Size [nm]:
Density [g/cm3]:

Time in sec:
Time in minutes:
Time in Hours:
G Force:

Calculator for TEM Grid Coverage

Particle size diameter [nm]:
Density [g/cm3]:
Solution height above grid [mm]:
ROI Size [um]:
Particle per ROI:
Camera Resolution MP:

Concentration mg/L:
Particles per Liter:
% Coverage of Grid:
Pixels per nm:
Pixels per Particle:

Selected Projects

  • Behavior of silver nanoparticles in a wastewater treatment plant - Opportunities and Risks of Nanomaterials, National Research Programme NRP 6
  • Nanodefine (FP7) - Development of full automation of electron microscopy operation allowing rapid particle sizing and elemental identification
  • Fundamental and Applied Studies of Nanoparticle Detection using LIBD / LIBS  - Laser Induced Breakdown Detection / Spectroscopy (SNF)

Completed Projects

  • Formation of Fe(III)-precipitates - Formation of Fe(III)-precipitates formed in aerated Fe(II) and As(III) containing water
  • Particles (> 500 nm) in ice cores - Climatic indications of particles (>500nm) in Ice cores
  • Laser Induced Breakdown Detection (LIBD) - Development of a Laser Induced Berakdown Detection (LIBD) system for fast on-line analysis of nanosized materials in the environment
  • Engineered NP in the environment - Fate and behavior of engineered NP in the environment

Selected Publications

Kaegi, R.; Voegelin, A.; Ort, C.; Sinnet, B.; Thalmann, B.; Krismer, J.; Hagendorfer, H.; Elumelu, M.; Mueller, E. (2013) Fate and transformation of silver nanoparticles in urban wastewater systems, Water Research, 47(12), 3866-3877, doi:10.1016/j.watres.2012.11.060, Institutional Repository
Kaegi, R.; Voegelin, A.; Sinnet, B.; Zuleeg, S.; Hagendorfer, H.; Burkhardt, M.; Siegrist, H. (2011) Behavior of metallic silver nanoparticles in a pilot wastewater treatment plant, Environmental Science and Technology, 45(9), 3902-3908, doi:10.1021/es1041892, Institutional Repository
Kaegi, R.; Voegelin, A.; Sinnet, B.; Zuleeg, S.; Siegrist, H.; Burkhardt, M. (2015) Transformation of AgCl nanoparticles in a sewer system - a field study, Science of the Total Environment, 535, 20-27, doi:10.1016/j.scitotenv.2014.12.075, Institutional Repository
Thalmann, B.; Voegelin, A.; von Gunten, U.; Behra, R.; Morgenroth, E.; Kaegi, R. (2015) Effect of ozone treatment on nano-sized silver sulfide in wastewater effluent, Environmental Science and Technology, 49(18), 10911-10919, doi:10.1021/acs.est.5b02194, Institutional Repository