Formation-structure-function links for porous nanocomposite membranes
- Graduate student: Julian Taurozzi (Environmental Engineering, MSU), Volodymyr Bosak (Kyiv-Mohyla Academy)
- Primary Adviser: Dr. Volodymyr Tarabara (Environmental Engineering, MSU)
- Collaborating Advisor: Anatoliy Burban (Kyiv-Mohyla Academy)
In collaboration with Volodymyr Bosak and Professor Anatoliy Burban from the National University of Kyiv-Mohyla Academy, Ukraine, we work on the synthesis of nanocomposite porous membranes and use such membranes as model systems to study the effect of particle incorporation on the structure and hydraulic properties of porous nanocomposites. In a paper recently accepted for publication in the Journal of Membrane Science, the effects of casting mixture composition and nanoparticle incorporation route on the morphology and separation properties of prepared membranes were studied. Silver nanoparticles were either synthesized ex-situ and then added to the casting solution as an organosol or produced in the casting solution via in-situ reduction of ionic silver by the polymer solvent.
Figure 1. SEM and TEM micrographs showing the distribution of silver nanoparticles in the cross-sections of silver-polysulfone nanocomposites prepared using different methods of silver incorporation. On TEM micrographs (A, C and D) the black dots with arrows pointing to them correspond to silver nanoparticles, while the SEM micrograph (B) shows the top cross section layer, with large silver clusters embedded into the polysulfone matrix.
Nanocomposite membranes of three types differing in skin porosity and macrovoid structure were prepared. The structure and properties of nanocomposites were interpreted in terms of the coupling between the processes of nanoparticle formation and gelling of the polymer-rich phase during phase inversion. Larger nanoparticles preferentially located in the skin layer were observed in composites prepared via the ex-situ method while in-situ reduction of silver led to formation of smaller nanoparticles homogeneously distributed along the membrane cross section. In some cases, incorporation of nanoscale silver formed ex-situ resulted in macrovoid widening and an order of magnitude decrease in hydraulic resistance accompanied by only a moderate decrease in rejection. The accessibility of the silver nanoparticles embedded in the membrane was quantitatively assessed by the degree of the growth inhibition of a membrane biofilm due to the ionic silver released by the nanocomposites and was found to depend on the method of silver incorporation. Based on the research results obtained by Julian Taurozzi and discussions between Julain and his French counterparts when Julian visited CEREGE in the Fall 2007, the collaboration on the development of nanocomposite membranes has been expanded recently to include another French research group, a potential member of PERMEANT. The ongoing research focuses on the development of membranes filled with inorganic nanotubes to study the effect of filler shape on the process of nanocomposite formation
J. Taurozzi, H. Arul, V. Z. Bosak, A. Burban, T. Voice, M. Breuning, V. Tarabara, Effect of filler incorperation route on properties of polysulfone-silver nanocomposite membranes of different prosities. J. Membr. Sci. 325 (2008) 58-68.