Zeta-potential and local filtration properties: Constitutive relationships for TiO2 from experimental filtration measurements

The use of filtration to separate solid from liquids is a commonly-used unit operation employed in a range of different applications. The development of accurate models is therefore important in facilitating e.g. design, scale-up and troubleshooting. Accurate constitutive relationships between local filtration properties need to be formulated in order to form precise models of the filtration process. One important parameter that is seldom considered explicitly in filtration models is the inter particle forces, e.g. electrostatic forces. The aim of this study is to investigate local filtration properties, under controlled conditions, for the model material TiO2 where the ζ-potential, and thereby one important parameter affecting the inter-particle interactions, is altered. In this study the local solidosity is measured during filtration by γ-attenuation, the local pressure is measured using capillary tubes. These data are used to calculate the local specific filtration resistance. The compressibility of the filtration cake was changed substantially by altering the ζ-potential. Several published constitutive relationships between local data and specific filtration resistance were applied; they yielded very similar parameters that were in good accordance with the characterization of the material.

► Compressibility of the filter cake is influenced by the ζ-potential of the TiO2 particles.
► Local filtration properties measured were described successfully by published models.
► Different models yield same particle size when local specific filtration resistance is fitted.
► Indications of agglomeration can be detected in the parameters obtained from several models.