SOLVENT RESISTANT NANO FILTERS SRNF

Ceramic membranes, which are much stronger than polymer membranes, are conunonly made of Al, Si, Ti or Zr oxides and mixed oxides. The top layers of the membrane are prepared by sol-gel synthesis which converts a colloidal or polymeric solution of inorganic precursors (e.g. alkoxides or salts) to a gelatinous product. Viscous binders are usually added prior to layering followed by controlled calcination and finally sintering to form the ceramic membrane. The process can be controlled to provide membranes with specific MWCOs (molecular weight cut-offs) and which can sustain defined solvents, temperatures and pressures. 

Unfortunately at present not many of either type of membranes are available commercially, but undoubtedly many more will appear on the market in the near futnre. Commercially available SRNF include the SelRO membranes (Koch Membrane Systems, USA), Starmem membranes (Membrane Extraction Technologies, UK), SolSep membranes (SolSep, The Netherlands), and Desal-5 and Desal-5-DK membranes (GE/Osmomics, USA) designed for aqueous applications, as well as for SRNF. 

SRNFs have found applications in food chemistiy, catalysis, chiral separations, petrochemical industry and pharmaceutical manufacturing. The preparation, practical considerations, and theoretical transport mechanisms of SRNFs have been critically reviewed by P. Vanezande, L.E.M. Gevers and I.F.J. Vankelecom [Chem SocRev 37 365 2008], 

---