Preparation of Improved PES Membranes for Medical and Food&Beverage Applications

Polymeric membranes are widely employed in microfiltration and ultrafiltration processes for medical and food&beverage applications, where high permeability, selectivity and fouling resistance are essential. Among the polymers commonly used, Polyethersulfone (PES) is preferred for its thermal, chemical, and mechanical stability. However, the hydrophobic nature of PES promotes protein adsorption and fouling phenomena, leading to flux decline and reduced performance. The thesis, carried out at GVS Filter Technology S.p.A., focuses on the characterization and optimization of their PES-based membranes produced at industrial scale. In the first phase of the work, membranes were characterized in terms of thickness, water permeability, bubble point, porosity, morphology and mechanical properties. The results confirmed compliance with technical specifications and process stability. Nevertheless, protein binding emerged as a critical limitation when compared to commercially available membranes for similar applications. The second phase of the study was dedicated to understanding protein adsorption mechanisms and developing strategies to reduce protein binding. Laboratory-scale casting trials were performed by modifying the polymeric solution formulation, increasing membrane hydrophilicity and introducing surface charge. Several formulations were evaluated through functional characterization and protein binding tests using BSA as a model protein. The results showed that enhancing membrane hydrophilicity through hydrophilic additives represents an effective approach to reduce protein adsorption while preserving functional properties. Conversely, surface charge modification via sulfonation showed antifouling behavior but introduced limitations related to membrane morphology and industrial feasibility. Among the investigated solutions, a formulation with increased hydrophilic additive content provided the best compromise between reduced protein binding and process compatibility.