Evaluation of variable pressure dead-end ultrafiltration behaviors of nanocolloids based on filter cake properties

Variable pressure dead-end ultrafiltration experiments including constant rate filtration experiments were performed for nanocolloids such as protein solutions of bovine serum albumin (BSA), lysozyme and myoglobin, and nano-silica sol. The relationships for representing the dependences of average specific cake resistance and average cake porosity on the pressure drop across the filter cake necessary for the evaluation of these filtration behaviors were determined from the temporal flux decline data obtained in a step-up pressure dead-end ultrafiltration experiment using a filter with an abrupt reduction in the effective filtration area. In case of a relatively high colloid concentration, it was necessary to acquire the porosity data for evaluation of ultrafiltration behaviors based on the compressible cake filtration model. The filtration behaviors were successfully evaluated even in a relatively high pressure rising rate. Moreover, the pressure variation calculated based on the constant rate filtration equation enabled us to maintain a constant filtration rate in dead-end ultrafiltration.