Electrode separation effects in capacitive deionization desalination systems
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A more energy efficient and sustainable method of desalinating water is needed due to increasing water shortages and contamination of current freshwater sources. Capacitive deionization (CDI), a new emerging technology, is a type of electric desalination that uses an applied voltage to pull the salt ions out of the salty solution and store the ions in porous carbon electrodes. CDI uses less applied energy than more commonly used methods of desalination like reverse osmosis and multi-flash distillation and has the added advantage of energy recovery. This report details experiments conducted to analyze the effect of different separation distances between the electrodes on salt ion adsorption for a high concentration solution under various flow rates and a 1 V voltage potential difference. The testing was performed in the Multiscale Thermal-Fluids Laboratory at The University of Texas at Austin using a uniquely fabricated CDI cell. Voltage, elapsed time, and electrical conductivity measurements were taken during the testing. Electrical conductivity was used to signify salinity of the solution. Two different separation distances were created by placing either one 2mm mesh between the electrodes or by using two 2 mm meshes between the electrodes. The results did not agree with the expectation that the one-mesh tests would adsorb twice the amount of salt ions as the two-mesh tests because of the differences in the electric field between the two types of tests. This is believed to be due to the high concentration tested. Future testing should include repeating these tests to verify the results and performing the tests for lower concentrations to see if they followed the expectation.