CHARACTERIZATION OF A MEMBRANE SYSTEM - COMPLEX CHARACTER OF THE PERMEABILITY FROM AN ELECTRICAL MODEL

In the present article a dynamic system formed by a microporous membra ne-type Nuclepore (track-etched hydrophilic policarbonate film) is cha racterized. The pore size of the membranes ranges from 0.6 to 8 mu m. The membranes are put between two phases of bidistilled, degassed, and deionized water, and their response to a flow step is studied in orde r to know the transfer function for the membranes. Nevertheless, an in determination between two possibilities is observed (a first- or secon d-order system characterization). To resolve it, a wave input is used, and from the results obtained it can be concluded that ic is a first- order system. As a consequence, the hydrodynamic permeability asa comp lex function of the frequency is obtained from a proposed electrical m odel whose equivalent resistance and capacitance are found.