PROPERTIES OF CHARGED DYNAMICALLY-FORMED NANOFILTRATION MEMBRANES ESTIMATED FROM PRACTICAL TRANSPORT-COEFFICIENTS

A method for estimating characteristics of a charged membrane has been applied to a dynamically-formed zirconium hydrous oxide-polyacrylate nanofiltration membrane. The membrane is model ed as a collection of p arallel capillary pores described by a radius and a radial potential. Practical trans port coefficients are used to estimate a characteristi c flux that is related to the para meters of the model. The pore radiu s and potential at the pore wall were estimated using data for the nan ofiltration of dilute NaCl solutions with the membrane. The pore radiu s parameter has a weak dependence on the pH, while the pore wall poten tial parameter increases significantly with increasing pH for this mem brane in which most of the fixed charge is generated by ionization of a weak polyacid.