Abstract
Electrolyte transport depends on the effective charge density of charged dialysis membranes, and hence determination of effective charge density i s needed to determine inorganic phosphate permeability. However, great difficulty i n measurement of membrane potential of hollow-fiber dialysis membranes makes it impossible to quantitatively compare effective charge density with diffusive permeability for inorganic phosphate. We prepared sheet membranes (16μm thick) of the same material as that of hollog-fiber RC (Regenerated Cellulose) and Hemophan membranes to measure membrane potential from which effective charge density was calculated. Zeta potential of each hollow-fiber membrane was determi nened by the streaming potential method. Diffusive permeability of hollow-fiber RC and Hemophan membranes was also measured with inorganic phosphate in purified water and in saline. Hemophan membrane has higher diffusive permeability than Regenerated Cellulose (RC) membrane, and its value i n saline i s higher than that i n purified water when the absolute value of effective charge density of positively charged Hemophan membrane i s comparable to that of negatively charged RC membrane. Zeta potential of each membrane is negative, and the absolute value of zeta potential of Hemophan membrane is smaller than that of RC membrane. Hemophan membrane has the same internal structure as RC membrane. This indicates that electrostatic resistance may control inorganic phosphate permeability. In conclusion, charge density affects inorganic phosphate transport through charged dialysis membranes that is enhanced by positively charged Hemophan membrane. Inorganic phosphate transport through dialysis membranes may be evaluated by the measurement of zeta potential of hollow-fiber membranes.
