Structure and permeability of dialysis membranes sterilized by various methods.

Appropriate design of dialysis membranes requires correct values of structural parameters such as pore radius, surface porosity, water content and tortuosity. It is impossible, however, to find the pore radius of dialysis membranes using a mercury porosimeter or an electron microscope because the pores are only several tens of angstroms in radius. Consequently, diffusional and convectional procedures such as the Lw method that uses both pure water permeability and water content, the Lw and Pm method which uses both solute and pure water permeability, and the sigma method which uses the reflection coefficient, have been employed extensively to determine the pore radius of dialysis membranes. The structural parameters of symmetric membranes are determined from water content, solute and pure water permeability data based on the Lw and Pm method combined with the tortuous pore model we have proposed. Determination of the structural parameters of microfiltration membranes for plasma separation having huge pores by various methods is required to verify the method of characterizing dialysis membranes based on the tortuous pore model. A dyeing method is also suitable for characterizing dialysis membranes of regenerated cellulose. Pore model studies using permeability and water content data for sterilized and treated membranes facilitate optimal design of dialysis membranes for clinical applications.