Grupo de Caracterización Electrocinética y de Transporte en Membranas e Interfases, Departamento de Física Aplicada I, Facultad de Ciencias, Universidad de Málaga, E-29071 Málaga, Spain
Received 3 November 2012, Revised 7 December 2012, Accepted 7 January 2013, Available online 18 January 2013.
Abstract
The effect of charge and pore confinement in the transport of NaCl solutions through a regenerated cellulose nanoporous membrane (pore radius around 1.2±0.3 nm) has been studied. Ionic transport numbers and diffusion coefficients as well as effective membrane fixed charge concentration where determined by analyzing membrane potential values, while salt diffusion coefficient was obtained from diffusion experiments for a wide range of feed NaCl solutions (between 0.005 M and 0.4 M). These results show the significance of electrical interactions at low concentrations (up to 0.05 M) but diffusive effects are predominant at higher NaCl concentrations and as a result of nanopore size and charge, values of diffusive parameter present a reduction of one order of magnitude. Membrane conductivity was obtained from electrical resistance results determined from electrochemical impedance spectroscopy (EIS) plots by using a parallel resistance–capacitance equivalent circuit as a model.
The similarity in the values of different electrochemical parameters (fixed charge concentration, ionic and salt diffusion coefficients) determined from direct measurements or estimated indirectly by various models supports the reliability of the results obtained and the analysis carried out.
Highlights
► Study on electrolyte transport through a regenerated celullose (RC) nanoporous membrane. ► Evaluation of electrical and frictional effects on ions transport through membrane nanopores. ► Hydrophilic character of the RC membrane supported by tritiated water measurements.
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