Chapter 6 Preparation of asymmetric ceramic membrane supports by dip-coating

This chapter discusses the preparation of asymmetric ceramic-membrane supports by dip-coating. Ceramic membranes are asymmetric, layered structures composed of a separation layer that fulfills the actual membrane function and a ceramic support structure comprising one to five layers. The support structure consists of a single- or multi-hole support tube to which as many ceramic layers are applied as are necessary to support the separation layer with the required selectivity. The higher the membrane selectivity required, the more support layers are needed. The chapter provides a qualitative description of forming support coatings by dip-coating as a form of colloidal processing. The chapter discusses the preparation of multi-layered supports for thin microporous membranes, including the preparation of simpler supports, such as for ultrafiltration membranes. It describes the way in which coating theory assists in the design and analyses of actual coating conditions and discusses the importance of wetting and de-wetting in withdrawal coating and the role of macromolecules to control the layer forming process. It illustrates the preparation of experiments in a development path of ceramic support coatings.