FILTRATION, DIFFUSION, AND MOLECULAR SIEVING THROUGH POROUS CELLULOSE MEMBRANES

Abstract

The theory of filtration and diffusion through porous membranes of Pappenheimer et al. (Am. Jour. Physiol. 167: 13. 1951. Physiol. Rev. 33: 387. 1953.) was verified by direct measurement of the diffusion and ultrafiltration of tritium-labeled water, and aqueous solutions of urea, glucose, antipyrine, sucrose, raffinose, and hemoglobin through cellulose membranes. Equations are presented relating restriction to molecular sieving during ultrafiltration to the total cross-sectional area, length and radius of the membrane pores, and to the radii of the diffusing molecules. Pore radii estimated by the membrane calibration method of Elford and Ferry (Brit. Jour. Exp. Path. 16: 1. 1935.) are shown to be too small, and a new method of calibration is proposed in which the total cross-sectional pore area is measured by diffusion of isotope-labeled water.