Effects of dialyzer reuse on convective and diffusive particle transports through membranes during hemodialysis process

This study investigated the effects of dialyzer reuse on both convective and diffusive mass transport, using model solutes of different molecular sizes. Membrane permeability was used to evaluate convective transport, while solute clearance under co-current flow conditions was used to evaluate the diffusive performance. Three dialyzer types (ATA, PEPA, and PES membranes) were evaluated over seven reuse cycles. It was found that permeability decreased progressively with reuse at rates of −5.47, −4.10, and −3.55 mL min -1 cycle -1 for ATA, PEPA, and PES dialyzers, respectively. In contrast, urea clearance remained stable or showed a slight increase, with corresponding slopes of 2.87, 2.09, and 1.49 mL·min -1 ·cycle -1 for PEPA, ATA, and PES. Maltodextrin clearance demonstrated a more noticeable decline; however, the overall change remained minimal, ranging from −1.05 to +1.02 mL·min -1 ·cycle -1 depending on the membrane type. These results demonstrate that convective transport is more sensitive to reuse than diffusive transport, reflecting the stronger influence of membrane fouling and structural alteration on permeability. SEM observations revealed distinct pore structures among membranes and subtle surface changes after reuse, supporting the observed transport trends. The use of controlled model solutions enabled isolation of physical transport mechanisms from biological variability. These findings provide a mechanistic basis for understanding reuse-induced performance changes and could inform membrane selection and reprocessing strategies to maintain dialysis efficacy.