Application of 4T-PET fibers/nonwovens for leucocyte filters

Polyethylene terephthalate (PET) fiber with four T-lobe cross section (4T-fiber) has been applied to textile products due to the structural characteristic of micro-grooved channels to provide the high wicking, warming, and elastic properties. In this study, nonwoven (NW) filters composed of one layer of 4T-PET NW (containing 65% 4T-fibers) with one, three, or five layers of polypropylene (PP) NW (4T-PET NW + PP NW × 1, 3, or 5) were proposed for blood filtration to remove leucocytes to reduce blood transfusion-related adverse reactions. The removal rate of leucocytes could be enhanced when the PP NW layers were increased. The presence of the 4T-PET NW on the surface of five layers of PP NW (4T-PET NW + PP NW × 5) filters resulted in a higher erythrocyte recovery rate without losing the capability to remove leucocytes and platelets. Based on the theoretical analysis, leucodepletion filters were further prepared by stacking four 4T-PET NW + PP NW × 5 units together. The optimum filtration results of the filters for filtrating 110 mL of red blood cell concentrates could be prepared when four units of 4T-PET NW + PP × 5 NW placed in a series combination.

Flow and fouling in membrane filters: effects of membrane morphology

Membrane filters are used extensively in microfiltration applications. The type of membrane used can vary widely depending on the particular application, but broadly speaking the requirements are to achieve fine control of separation, with low power consumption. The solution to this challenge might seem obvious: select the membrane with the largest pore size and void fraction consistent with the separation requirements. However, membrane fouling (an inevitable consequence of successful filtration) is a complicated process, which depends on many parameters other than membrane-pore size and void fraction; and which itself greatly affects the filtration process and membrane functionality. In this work we formulate mathematical models that can (i) account for the membrane internal morphology (internal structure, pore size and shape, etc.); (ii) describe fouling of membranes with specific morphology; and (iii) make some predictions as to what type of membrane morphology might offer optimum filtration performance.