Enhanced Salt-removal Percentage in Capacitive Deionization of NaCl Solutions with Modified Activated Carbon Electrodes by HNO₃

Carbon electrodes for desalination system have successfully been synthesized with and/or without modified activated carbon by chemically activated using HNO₃. The freezing-thawing method was used to synthesize the carbon electrodes. In this study, 5 cycles of freezing-thawing were applied in the synthesized carbon electrodes (1 cycle is 12 hours for freezing and 6 hours for thawing). Electrochemical properties of the synthesized carbon electrodes with and/or without modified activated carbon were characterized and observed by cyclic voltammetry (CV) and Electrical impedance spectroscopy (EIS). The salt-removal percentage experiments were conducted to evaluate the performance of capacitive deionization (CDI) cell using the two pairs of carbon electrodes with each pair consisting of two parallel electrodes that separated by a spacer. The result showed that the salt removal percentage of the carbon electrodes with modified activated carbon has greater than the carbon electrodes without modified activated carbon, with reduction level at 55.7 and 24.8%, respectively.