Mechanistic insights into the membrane fouling mechanism during ultrafiltration of high-concentration proteins via in-situ electrical impedance spectroscopy (EIS)

Membrane fouling by the high protein concentrations used in biopharmaceutical industry remains poorly understood. In this study, feed of up to 10,000 ppm bovine serum albumin (BSA) were investigated with three polymeric membranes, two which had same molecular weight cut-off (namely, PES100 and PSF100), membrane material PES10). A crossflow ultrafiltration (UF) setup equipped electrical impedance spectroscopy (EIS) was used. Results indicate that predominantly external for all cases, except (i.e., most porous) at BSA, whereby internal led greatest flux decline. For (i) PSF100 Nyquist plots shifted left initially, then right as BSA deposition started, but (ii) tighter PES10 membrane, shifts kept going leftwards due NaCl accumulation out-pacing build-up. The main takeaway filtering feeds is higher steady-state could be achieved averting fouling, either through using membranes dense structures or lower MWCO.