The Optimization Of Carbon Electrode Component Based On Extreme Vertex Method For High Performance Capacitive Deionization

The improvement of human living standards and rapid development of agriculture and industries have been raised a substantially global demand for freshwater. On the other hand, the distribution of water resources in the world is unbalance, in addition to the serious damage to water resources in some areas. Therefore, it requires a cheap and effective water treatment technology to resolve the water resources crisis. Specifically, new and energy-efficient water desalination technologies are urgently desired to obtain fresh water from seawater, as well as to treat the increased sewage generated from industry and human activities.Capacitive deionization(CDI) operates by applying a relatively low potential(ca. 1.0-1.5V)to drive the charged species in salty water to electrodes. Due to the low operating voltage, no electrolysis reaction occurs at the electrodes. Moreover, the electrodes are easily regenerated either by shortened or by reversing the polarity of the applied potential. Comparing with other traditional desalination techniques, CDI represents an attractive water treatment technology including the advantages of lower operating costs and energy consumption, lack of secondary pollution and easy regeneration and maintenance. In this thesis, we report the use of extreme vertices method to optimize the component of carbon electrodes using for CDI and investigated their CDI performance. Extreme vertices method paves a way to optimize the componential ratios of the precursors in the mixture to achieve the best performance of the resulted electrodes. We described the principle of the extreme vertices method and its application in optimizing the preparation of carbon electrodes for CDI.We investigated the effect of acidic electrolyte, alkaline electrolyte and neutral electrolyte on the specific capacitance of the carbon electrodes which were prepared with optimized compositional ratios by using extreme vertex method. According to the results, different ratios of the pore forming agent, binder and conductive agent that used in the precursors mixture for preparing carbon electrodes were determined. CVs(Cyclic Voltammograms) and EIS(Electrochemical Impedance Spectroscopy) were used to characterize the as-prepared carbon electrodes. We demonstrate the extreme vertex method can effectively optimized the component of the carbon electrodes. Furthermore, the effects of metal ions valences on the capacitive properties of the carbon electrodes were also studied. The results prove that the extreme apical point method is efficiently practicable in CDI applications.Finally, we selected a unknown salty water sample as electrolyte and examined the performance of carbon electrodes for their specific capacitance based on the optimized results with extreme vertices method. The results show that the optimized performance of the carbon electrodes can be easily obtained. Therefore, we demonstrate that extreme vertices method can be adopted to prepare optimized carbon electrodes towards practical CDI applications.