Influence of configuration and substrate on the properties of dynamically formed membranes

Dynamically formed membranes (DFMs) are produced by forming a chemical sub-layer on an inert porous support surface (substrate). In this study, various DFM substrates have been examined: a tubular carbon substrate coated with a ZrO₂-TiO₂ layer, a flat sheet ceramic substrate supported by a stainless steel mesh, a selection of polypropylene woven media and an extruded polymeric microfiltration membrane. The woven media used are made from combinations of monofilament, multifilament and staple fibres - and a surface-coated polyester weave has also been examined. Zirconium (IV) oxide and polyacrylic acid (ZrO/PAA) are used to form the DFM on the substrates. The influence of the configuration and substrate material on the performance of the DFM has been studied in terms of the normalised permeate flux and salt rejection. A stable DFM was formed on the carbon, ceramic and the extruded polymer substrates. An unstable Zr(IV)O membrane was formed on the surface-coated polyester substrate and a fumed silica precoat has been used to form a DFM on one of the woven polypropylene media. However, the DFM formed on the latter did not exhibit a rejection performance comparable to the other DFMs formed.