No abstract

No abstract

Little is knownof the structure of hollow-fiber dialysis membranesfor clinical use or of the effects of structure on solute and pure water permeability. Knowledgeof such aspects of membranestructure as pore radius, surface porosity, tortuosity and water content is required if the desired membranes are to be designed. The objective of the present study, therefore, is to obtain data on the pore radius, surface porosity and tortuosity of hollow-fiber dialysis membranesthrough an analysis of measured water content, and of solute and pure water permeability on the basis of a newly introduced tortuous pore model. In regenerated cellulose membranes, pore radius ranges from 21 to 34 x 10~10 m, and huge pores ranging in radius from 47 to 64 x 10"10 m are identified for EVAmembranes which are permeable to small amounts of serum protein. Values for surface porosity of the regenerated cellulose and EVAmembranes are approximately 33 and 22 %, and tortuosity is approximately 1.9 and 2.2, respectively. The tortuous pore model combined with the Lp and Pmmethod is well suited for elucidating the relationship between membranestructure and solute and pure water permeability.

No abstract

Plasmaseparation experiments with a hollow fibrous filter were madeto clarify the effects of hematocrit, protein concentration and wall shear rate on filtrate flux. The resistance of the polarization layer caused by red blood cells is the dominant factor in filtration and accounts for 50 to 80 % of total filtration resistance. Factors governing the filtrate flux in plasma separation are plasma viscosity, hematocrit and wall shear rate. Anestimation equation for filtrate flux is proposed. Membranestructural changes after plasma separation were evaluated to clarify fouling characteristics in plasma separation by using radioisotope-labeled solute and scanning electron microscopy. The decrease in pore diameter and surface porosity is attributed to both protein adsorption onto pore walls and plugging by red blood cells.