Impedance Characteristics and Electrical Double Layer Capacitance of Polystyrene Based Nickel Arsenate Membrane

Polystyrene-based nickel arsenate membranes were prepared by sol-gel method for various electrolytes (KCl and NaCl) at different concentrations and found to be quite stable. The membrane capacitance and resistance obtained values were found to dependent on the concentration of the electrolyte and to depend on the applied oscillator frequency at isothermal temperature (25  0.1°C). The electrical double-layer at the membrane electrolyte interface was influenced and controlled by the transport of ions. An increase in concentration of electrolyte solution causes the counter ions in the form of double-layer to be pushed inside the membrane. Thus, the membrane becomes more conductive to the incoming ions, which in turn, supports the trend in the behaviour of the membrane resistance under discussion. Deviations from the ideal behaviour in the lower frequency range were attributed to the nonhomogeneous nature of the membrane used in the investigation.