چكيده به لاتين
Membrane capacitive deionization by flow-electrodes is a novel process for deionization of water, where the cell which incorporates the cation and anion exchange membranes, plays an essential role in the process. By applying electrical potential to both sides of the cell, positive and negative ions pass through the cation and anion exchange membranes, respectively, to be adsorbed on the activated carbon electrodes. This process has been studied for the first time in Iran by means of a lab-scale cell. Basic studies have been carried out to provide a better insight into the process and define the effective parameters. Among the effective parameters, the amount of 4% activated carbon was initially found suitable for flow electrodes as optimum value, and the other parameters, such as the optimal voltage of 1.2 volts, were obtained at this level of carbon. Initial concentrations and flow rates for a dilute solution, as well as the process of single pass and circulation, at the mentioned amount of activated carbon and voltage were identified. At the higher concentrations of dilute solution in both of single pass and circulation processes, the dynamic charge efficiency and the amount of salt adsorbed per gram of carbon were increased, while the energy consumption per unit mole of the salt decreased. The higher the flow rate in the circulation mode, the desalination efficiency was greater than that of single-pass mode at the optimum conditions. However, the dynamic charge efficiency decreased and the energy consumption increased, simultaneously. Desalination of 250 mL of a solution of 700 mg/L for 50 min with a flow rate of 5 mL/min for the single pass, and flow rates of 5 and 20 mL/min for circulating mode was conducted. The dynamic charge efficiency for single pass and circulation modes was 94.72%, 92.45% and 73.67%, respectively. Meanwhile, the energy consumption per unit mole of ion was obtained about 61.12, 62.62 and 78.58 (J/mmol ion) for the latter experiments, respectively.
Keywords: Flow-electrode Capacitive Deionization, Desalination, Suspension Electrodes, Water Sweetening
