144 A. S. Grandison and T.J. A. finnigan Surface view Zirconia mesh support membranes sy of SFEC):(b) different designs of Ceraver alumina membranes (re n of Membralox):(c)alumina membrane module (reproduced by permission of CeraMem) ;(d)ceramic/metal-mesh composite membrane (reproduced by permission of Nww Acumem Ltd powder and binder in aqueous media. The membrane layer may be coated directly onto the macroporous support where pore size is quite large, but for UF and the smaller pore size MF membranes an intermediate sintered, ceramic layer is necessary due to the surface rugosity of the support. The membrane layer (usually composed of alumina, titania or zirconia) is formed by coating the support with a colloidal suspension and firing at a lower temperature than the firing temperature of the support. To prevent rapid flux decline, the membrane thickness must not exceed a few microns- titanium and zirco- nium membranes of thickness 3-5 Am have been achieved. Accurate control of the col lodal particle size allows the possibility of producing membranes with an extremely narrow pore size distribution compared to conventional membranes. The final pore size is also related to the sintering temperature. An example of the structure of a sintered ce- ramic membrane is shown in Fig 5.3144 A. S. Grandison and T. J. A. Finnigan Surface view Cross-section I 1 I Nickellbased Zirconia meshsupport membranes Fig. 5.2. Some designs of inorganic membranes: (a) CARBOSEP membrane composed of zirconia on a carbon support (courtesy of SFEC); (b) different designs of Ceraver alumina membranes (reproduced by permission of Membralox@); (c) alumina membrane module (reproduced by permission of CeraMem); (d) ceramic/metal-mesh composite membrane (reproduced by permission of NWW Acumem Ltd). powder and binder in aqueous media. The membrane layer may be coated directly onto the macroporous support where pore size is quite large, but for UF and the smaller pore￾size MF membranes an intermediate sintered, ceramic layer is necessary due to the surface rugosity of the support. The membrane layer (usually composed of alumina, titania or zirconia) is formed by coating the support with a colloidal suspension and firing at a lower temperature than the firing temperature of the support. To prevent rapid flux decline, the membrane thickness must not exceed a few microns - titanium and zirco￾nium membranes of thickness 3-5 pn have been achieved. Accurate control of the col￾loidal particle size allows the possibility of producing membranes with an extremely narrow pore size distribution compared to conventional membranes. The final pore size is also related to the sintering temperature. An example of the structure of a sintered ce￾ramic membrane is shown in Fig. 5.3