ELECTROCHEMICAL DESALINATION OF NaCl SOLUTIONS BY ELECTROSORPTION ON NANO-POROUS CARBON AEROGEL ELECTRODES

The objective of this study is to elucidate the efficiency of electrosorption on desalination of aqueous NaClsolution using nano-structured carbon aerogel electrodes. The experiments were performed in an electrosorption cell consisting of a pair of carbon aerogel sheets separated by a 0.5cm spacer. The electrosorption performance is investigated with different applied voltages and solution concentrations. It increases with increasing applied voltage, higher concentration gradient and less double-layer overlapping effect. Under the experimental conditions at the optimum applied voltage of 1.2 Volt and initial NaCl concentration 100 - 1000 mg l(-1), the electrosorption capacity was found to be 5.20 - 14.22 mg NaCl/g carbon aerogel.Na+ and Cl- ions are electro-absorbed at the electrical double layer without electron transfer redox reactions at anode and cathode. The good electrosorption performance of carbon aerogel electrodes might be attributed to their high specific area, high electrical conductivity, chemical inertness and optimal pore size distribution for the passage and easy movement of ions during electrosorption and electrodesorption. The process is reversible, as the electrode charge/discharge procedure can be repeated innumerable times without any significant loss of salt sorption capacity in all cycles.