Characterisation of ultrafiltration membranes by impedance spectroscopy. I. Determination of the separate electrical parameters and porosity of the skin and sublayers

Characterization of ion transport in thin films using electrochemical impedance spectroscopyI. Principles and theory

“…The film is then expected to behave as a "leaky" capacitor C m connected in parallel with a resistor R m and in series with the double layer capacitance C dl . This or similar electric representations have been used in impedance analysis of paints and coatings [23], lipid bilayers containing ion channels [29,30], self-assembled monolayers [26], as well as synthetic separation membranes [43][44][45].…”

Modification of polysulfone membranes with polyethylene glycol and lignosulfate: electrical characterization by impedance spectroscopy measurements

“…Impedance spectroscopy data allow the determination of the membrane electrical resistance and capacitance, and from these results membrane geometrical parameters can also be determined [20,28,29]. Symmetric dense membranes (or the dense active sublayers of composite membranes) can be considered as plane capacitors [20,30],…”

“…Symmetric dense membranes (or the dense active sublayers of composite membranes) can be considered as plane capacitors [20,30],…”

“…Membrane electrical resistance was determined from impedance spectroscopy (IS) measurements, which were carried out with the membranes in contact with NaCl solutions at different concentrations. IS measurements enable us to obtain information about the different sublayers of heterogeneous systems (such as those formed by membrane/electrolyte solutions) by means of the impedance plots, using equivalent circuits as models, in order to correlate the different circuit elements with the structural/transport properties of the system [19][20][21][22].…”

Electrical and surface chemical characterizations of the active layer of composite polyamide/polysulphone nanofiltration commercial membranes

“…From the hC a i values, assuming that the active layer behaves as a plate capacitor, the thickness of this sublayer (x a ) can be estimated 6 by taking into account that hC a i D ε o ε a S m /x a , where ε a is the active layer dielectric constant and S m is the membrane cross-area. Estimated thicknesses for the active layer of the NF70 and NF45 membranes, which were obtained by taking the value 7 ε a D 5, are shown in Table 1.…”