Nanofiltration (NF) is a pressure-driven membrane process, intermediate between reverse
osmosis and ultrafiltration. Commercially available polymeric membranes have been used in a wide
range of applications, such as drinking, process industry and waste water treatment. For all the
applications requiring high stability and harsh washing procedures inorganic membranes are
preferred due to their high chemical inertia. Typically, γ – Al2O3 as well as TiO2 and ZrO2 selective
layers are used; the latter show higher chemical stability in a wide range of pH and temperatures.
In this work the experimental characterization of two different type of membrane has been
performed in order to investigate permeation properties, separation performance and efficiency with
aqueous solutions containing strong inorganic electrolytes. The influence of salt concentration and
feed pH as well as the role of concentration polarization and electrolyte type on the membrane
behavior are investigated.
Experimentation was performed testing a multi–layer structured NF membrane in α-Al2O3,
TiO2 and ZrO2, and a polymeric membrane, in polyamide supported on polysulfone, with binary
aqueous solutions containing NaCl, Na2SO4 or CaCl2; the effect of salt composition and pH in the
feed side was studied both on flux and salt rejection.
All the NF experimental data available for the two membranes were used to evaluate the
volumetric membrane charge (X) corresponding to each operative conditions investigated, through
the Donnan Steric Pore Model and Dielectric Exclusion (DSPM&DE). The results obtained allow to
understand which are the main phenomena at the basis of the different behaviors observed.
| Identifer | oai:union.ndltd.org:unibo.it/oai:amsdottorato.cib.unibo.it:903 |
| Date | 16 June 2008 |
| Creators | Mazzoni, Carolina <1979> |
| Contributors | Bandini, Serena |
| Publisher | Alma Mater Studiorum - Università di Bologna |
| Source Sets | Università di Bologna |
| Language | Italian |
| Detected Language | English |
| Type | Doctoral Thesis, PeerReviewed |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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