On the local filtration properties of microcrystalline cellulose during dead-end filtration

Dead-end filtration is frequently used in solid–liquid separation. In order to increase understanding of the filtration of materials that form compressible cakes, local filtration properties need to be taken into consideration. The compressible nature of these filter cakes requires phenomena such as skin formation, a dense layer of high filtration resistance close to the filter medium and flow stabilisation to be considered. This study investigates local filtration properties, i.e. the hydrostatic pressure and solidosity, in the dead-end filtration of microcrystalline cellulose, using slurries of varying pH levels and concentrations and two different filter media. The local measurements indicated that a dense skin was formed. This could be avoided when the nature of the particle–particle and particle–filter medium interactions was altered, using the pH to regulate the surface charge. Local filtration properties were used to find a critical material dependent Reynolds number indicating a flow stabilisation behaviour.

► Local solidosity measurements showed that MCC forms compressible filter cakes.
► The filtration of MCC was facilitated by lowering of the pH.
► There were indications that MCC can form a skin with a high filtration resistance.
► A critical local Reynolds number could be found for cake collapse.