Competitive Electrosorption of Metal Ions by Carbon Aerogel

• Main Authors: Ming-han Lee, 李明翰
• Other Authors: Ching-ju Chin
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/97466686082747886482

碩士 === 國立中央大學 === 環境工程研究所 === 97 === The objective of this work was to understand the competitive electrosorption of heavy metal by capatative deionization (CDI) equipped with carbon aerogel. Single-metal-ion system was studied to understand the effects of ionic radius and valence on the removal of heavy metal ions by CDI. Electrosorption of multi-metal-ion was conducted to investigate the effects of the applied voltage and competitive electrosorption of Pb2+/Cu2+, Cu2+/Cr3+, and Pb2+/Cu2+/Cr3+. The initial concentrations of all three heavy metals used in this work (i.e., CrCl3, CuCl2, and PbCl2) were 0.5 mM in either single-metal-ion or multi-metal-ion systems. The adsorption of Cu2+ was better than that of Pb2+ because the electrosorption efficiency increased with decreasing ionic radius when metal ions have the same valence. The adsorption of Cr3+ was less than that of Cu2+ because Cr3+ had higher charge and the capacitor could hold less Cr3+. For Pb2+ / Cu2+ adsorption, the adsorption of Pb2+ was better than that of Cu2+. For electrosorption of Cu2+ / Cr3+, the adsorption of Cu2+ was better than that of Cr3+. For electrosorption of Pb2+ / Cu2+ / Cr3+, the order of the adsorption amount and rate from the largest and fastest was Cu2+, Cr3+, and Pb2+. The adsorption of Cr3+ was the most competitive, followed by the adsorption of Pb2+ and, then Cu2+. The applied voltage showed effects on the electrosorption Pb2+ / Cu2+, however, showed no effects on the experiments with Cr3+. When Cr3+ was in the system, Cr3+ helped metal ions be fixed on the carbon aerogel after the removal of the applied voltage.