Fig. 5 shows that the permeation flux increases slowly with
increasing transmembrane pressure for both alumina and titania
precursor slurries, and, at the same transmembrane pressure, the
flux of titania precursor is much higher than that of alumina, even
though the former precursor slurry has a higher solid content.
For instance, at a transmembrane pressure of 0.08 MPa, the permeation
flux of alumina slurry is about 255 L/(m2 h) compared to
460 L/(m2 h) for titania slurry. Such big difference is considered to
be highly related to the different shapes and sizes of titania and alumina
precursors. Because of its spherical particle shape, a special
structure of filter cake should be easily formed for alumina precursor
particles, which is denser than the filter cake of titania precursor
particles. As a result, the alumina precursor slurry displays lower
permeation flux (Fig. 5). On the contrary, the filter cakes of tita-