Modelling of dead-end microfiltration with pore blocking and cake formation

A series of dead-end filtration experiments are compared with a recently proposed pore blocking model that contains only one experimentally fitted parameter. This parameter has physical meaning and it can be verified by an independent check of the experimental data. The challenge suspension used was near monosized latex particles of ∼0.45 μm filtered on a track-etched membrane with similar sized pores of ∼0.4 μm. The filtered suspension concentration ranged from 0.00006 to 0.01% (w/w) and the transmembrane pressures varied from 1000 to 20,000 Pa. During the experiments three stages of microfiltration were observed. There was an initial stage that fitted a sieving (or pore blocking) model until the mass of latex deposited per unit membrane area (specific mass) reached 2×10−3 kg m−2. The model required a single parameter that was found to fit all the data under different experimental operating conditions. The second stage of pore blocking could also be fitted using a second parameter and the predicted flux at the end of the first stage of pore blocking. When the deposited particles had reached a depth of approximately 12 particle layers, or specific mass of 4.8×10−3 kg m−2, the flux then showed normal cake filtration behaviour.