Study On Preparation And Capacitive Desalination Performance Of Porous Carbon Materials

With the serious environmental pollution, energy consumption increased, there is an increasing demand of fresh water resources. The global water resource is decreasing year by year, vigorously developing seawater desalination technology is of great significance to alleviate the existing water resources consumption. The traditional desalination technology, such as reverse osmosis, distillation method, electrodialysis desalination method is at the expense of the large energy consumption, high production cost. Researching low energy consumption, and actively develop environment-friendly new desalination method has been imminent. Capacitive desalination (CDI) is an emerging technology for seawater desalination technology, because of its low energy consumption, no pollution, can be recycled two times, these characteristics make it shows good prospects in the seawater desalination technology. American Biosource, Canada’s Enpar and Changzhou’s Chinese EST and other companies have produced capacitance desalination method products. In the core of CDI as electrode material, porous carbon materials with good storage capacity and excellent ion, electron transfer properties make it widely used. For high electrical conductivity, large specific surface area, suit pore size distribution, high capacity, high rate of recycling of electrode materials with excellent properties is a focus of research in CDI technology.This paper prepared some porous carbon materials such as bamboo based activated carbon, its modified materials (manganese dioxide doped, graphene composited) and carbon aerogels, also homemade the CDI experiment device, investigated the effect of different desalting of different electrode materials, at last discussed the factors that influence the device for capacitive deionization. By the BET test, we fond the bamboo based activated carbon with the specific surface area of 1747m2g-1 and pore size distribution of about 2nm. By co-precipitation method to prepare the different proportions (wt1%, wt5%, wt10%, wt20%) of manganese dioxide doped bamboo based activated carbon, the sample of wt1% manganese dioxide doped material of the highest specific capacity, up to 209F·g-1, through the galvanostatical charge/discharge test. In the desalting tests, the desalting efficiency reached 10.30mg·g-1, the removal rate of 19%, has the very good performance of the seawater desalination. Different ratios (wt1%, wt5%, wt10%, wt20%) of graphene composited bamboo based activated carbon electrode materials were made, in the sample of wt5% grapheme composited, has the very good cycle performance in the galvanostatic charge/discharge test, its specific capacity is 121 F·g-1, in the cyclic voltammetry test shows the good performance of the electric double layer capacitor. In capacitive deionization test, the efficiency of salt removal reached 9.70mg·g-1. We also found that in the CDI test, the two different pore sizes of carbon aerogels, the large diameter (19.6nm) sample CRF300-20 has better effect of desalination to the relatively small (9.8nm) one. In capacitive deionization device, through the test, we choose 1.2V voltage, 10mL·min-1 flow rate, lmm space velocity as desalting operation conditions. To the effects of different concentrations of solution, we found that solution initial concentration increase will make desalination effect increased. Finally, by the adsorption and desorption cycle test, disccuss the effects of repeated use of bamboo based activated carbon and carbon aerogels, after three cycles of electrode materials have a good adsorption performance.