1. Fiber and Particle Engineering Research Unit, University of Oulu, P.O. Box 4300, FI-90014 Oulu, Finland
2. Fraunhofer Center for Chemical-Biotechnological Processes, 06237 Leuna, Germany
3. Helmholtz-Zentrum-Dresden-Rossendorf, Helmholtz Institute Freiberg for Resource Technology, 09599 Freiberg, Germany