Preparation of activated carbon sheet electrode assisted electrosorption process

Electrosorption, defined as potential-induced sorption on the surface of charged electrode, is a promising method for water purification and desalination. To prepare carbon electrodes assisted electrosorption process at the point of economical view, activated carbon powder was coated with polyvinylidene fluoride (PVDF) binder in a thin sheet-like formulation. Electrochemical properties of the fabricated carbon electrodes were analyzed via cyclic voltammetry and galvanostatic charge/discharge experiments. From the results, the electrosorption characteristics of the fabricated electrodes can be improved in KOH solution. Increasing the PVDF content diminishes the specific capacitance and increases electrical resistance in electrosorption. The carbon electrode prepared with 10 wt% PVDF has enough mechanical strength, good electrochemical stability, and favorable capacitive characteristics for electrosorption of ions. From the electrosorption experiments of capacitive deionization, the electrosorption efficiency and electrosorption capacity for 0.002 M NaCl solution with an applied potential of 1.2 V are 96.7% and 44.5 mu mol/g, respectively. The regeneration of the polymer-binder carbon electrode can be achieved by depolarizing the electrode at 0.0 V. It indicates that electrosorption-desorption of ions is a reversible process, with respect to electrical double layer formation on the charged surfaces of carbon electrode. Therefore, the PVDF-bonded activated carbon sheet electrode would be a desirable electrode for capacitive deionization. (C) 2011 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.