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Journal of Nanomaterials
Volume 2014, Article ID 204172, 6 pages
http://dx.doi.org/10.1155/2014/204172
Research Article

Asymmetric Electrodes Constructed with PAN-Based Activated Carbon Fiber in Capacitive Deionization

Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China

Received 4 December 2013; Accepted 8 February 2014; Published 11 March 2014

Academic Editor: Jian Lin

Copyright © 2014 Mingzhe Li et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Capacitive deionization (CDI) method has drawn much attention for its low energy consumption, low pollution, and convenient manipulation. Activated carbon fibers (ACFs) possess high adsorption ability and can be used as CDI electrode material. Herein, two kinds of PAN-based ACFs with different specific surface area (SSA) were used for the CDI electrodes. The CDI performance was investigated; especially asymmetric electrodes’ effect was evaluated. The results demonstrated that PAN-based ACFs showed a high electrosorption rate (complete electrosorption in less than half an hour) and moderate electrosorption capacity (up to 0.2 mmol/g). CDI experiments with asymmetric electrodes displayed a variation in electrosorption capacity between forward voltage and reverse voltage. It can be attributed to the electrical double layer (EDL) overlap effect and inner pore potential; thus the ions with smaller hydrated ionic radius can be adsorbed more easily.