Filtration of protein-based solutions with ceramic ultrafiltration membrane. Study of selectivity, adsorption, and protein denaturation

Proteins are widely used in food or pharmaceutical industry and are often pumped in complex flow systems. Their biological activity is intrinsically related to their conformation in solution. In this work, we studied the state and behavior of proteins in solution during separation/concentration operation in terms of adsorption, molecule agglomeration, and denaturation. Solutions of lysozyme have been filtrated on a ceramic ultrafiltration membrane at high flow velocity and different transmembrane pressures to investigate the effect of flow parameters on the protein conformation in solution assessed by size-exclusion chromatography. A shift of 0.4 min in elution time of the peak corresponding to lysozyme is observed between retentate and permeate solutions, indicating that the lysozyme molecules exhibit drastic conformation changes after filtration. In addition, the effect of the filtrated solute nature on the pore surface (adsorption phenomena) is investigated by following the evolution of the hydraulic and selectivity membrane performances.