† * **
305-764 220
*
305-353 ! 150
** "
305-380 #$ 103-16 (2003% 8& 11' (), 2003% 10& 20' *+)
Electrosorption of Cobalt Ions by Chemically Treated ACF Discs
Han Sang Kim, Seung Kon Ryu†, Chong Hun Jung* and Kwang Kyu Park**
Department of Chemical Engineering, Chungnam National University, 220, Gung-dong, Yuseong-gu, Daejeon 305-764, Korea
*Nuclear Chemical Engineering Research Team, Korea Atomic Energy Research Institute, 150, Duckjin-dong, Yuseong-gu, Daejeon 305-353, Korea
**Nuclear Power Laboratoty, Korea Electric Power Research Institute, 103-16, Munji-dong, Yuseong-gu, Daejeon 305-380, Korea (Received 11 August 2003; accepted 20 October 2003)
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b ! ;c 01234; 56dG Ie fA ! ;c 56dGg8 2h LB[- D HNO3 1/5 H[8. 012 34; %&56ijA 0.2 N NaClke %lm; nG! ?o
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Abstract−ACF discs were surface treated using NaOH, HNO3 and connected to a graphite bar, for the electrosorption of cobalt ions from an aqueous solution. The total acidity of ACF decreased by NaOH treatment which maintaining the same average pore size and specific surface area. The total acidity, specially carboxyl groups, increased by HNO3 treatment, although the specific surface area was reduced by co. 20%. The Point of Zero Charge (PZC) of ACF decreased from pH 3.1 to 2.6 and 2.2 by HNO3 and NaOH treatment, as a result of increases in anode ion density on ACF disc surface. Therefore, the adsorption rate of cabalt ion by NaOH treated ACF disc was twice larger than that of non-treated ACF disc, while that of HNO3 treated ACF disc was only one fifth of the non-treated ACF disc in electrosorption. The electrosorption rate increased with the elec- trolyte concentration, however, it slowly decreased above 0.2 N NaCl because of competition between Co2+ and Na+. Key words: Activated Carbon Fiber, Electrosorption, Acidity, Co(II)
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†To whom correspondence should be addressed.
E-mail: skryu@cnu.ac.kr
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Fig. 1. Photographs of ACF-discs.
Fig. 2. Schematic view of electrosorption apparatus.
41 6 2003 12
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Fig. 3. pH monitoring of ACF-disc contained NaOH and HCl solution at 40oC, 100 rpm.
Fig. 4. Adsorption isotherms of chemically treated ACF-discs.
Table 1. Structural characteristics of chemically treated ACF-discs ACF SBET(m2/g)Vt(cc/g)Vm(cc/g) Aver.pore dia.(Å)
KF-1500 1,614 1.06 0.83 14
KF-1500-HNO3(20oC) 1,315 0.80 0.57 17 KF-1500-HNO3(40oC) 1,560 0.70 0.64 18 KF-1500-HNO3(60oC) 1,576 0.72 0.67 18 KF-1500-NaOH(20oC) 1,460 0.82 0.59 15 KF-1500-NaOH(40oC) 1,557 0.71 0.66 18 KF-1500-NaOH(60oC) 1,568 0.71 0.67 18 Table 2. Surface acidity of chemically treated ACF-discs
ACF Functional group(meq/g) Total acidity (meq/g) Carboxyl Lactone Phenol
KF-1500 0.044 0.487 0.314 0.850
KF-1500-HNO3(20oC) 0.785 0.861 0.633 2.230 KF-1500-HNO3(40oC) 0.668 0.614 0.344 1.626 KF-1500-HNO3(60oC) 0.640 1.164 0.112 1.916 KF-1500-NaOH(20oC) 0.012 0.542 0.125 0.680 KF-1500-NaOH(40oC) 0.086 0.072 0.456 0.610 KF-1500-NaOH(60oC) 0.060 0.128 0.392 0.580
Fig. 5. Zeta potentials of chemically treated ACF-discs.
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Fig. 6. Electrosorption of Co(II) on non-treated ACF-discs at various concentration of electrolyte solution.
Fig. 7. Electrosorption of Co(II) on chemically treated ACF-discs at −−−−0.2 V, 0.05 N NaCl, Co=30 ppm.
Fig. 8. Electrosorption of Co(II) on NaOH treated ACF-discs at 0.05 N NaCl, Co=30 ppm.
41 6 2003 12
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1. Woodard, F. E., McMackins, D. E. and Jansson, R. E. W., “Electrosorp- tion of Organic on Three Dimensional Carbon Fiber Electrode,” J.
Electronal. Chem., 214, 303-330(1986).
2. Ryu, S. K., “Porosity of Activated Carbon Fiber,” High Temperature- High Pressure, 22, 345-354(1990).
3. Kim, J. S., Jung, C. H., Oh, W. Z. and Ryu, S. K., “Electrosorption and Separation of Co2+ and Sr2+ Ions from Decontaminated Liquid Wastes,” Carbon Science, 3(1), 6-12(2002).
4. Xu, Y., Zondlo, J. W., Finklea, H. O. and Brennsteiner, A., “Electrosorp- tion of Uranium on Carbon Fibers as a Means of Environmental Remediation,” Fuel Processing Technology, 68(3), 189-208 (2000).
5. Lee, S. M., Jung, C. H., Moon, J. K., Oh, W. Z. and Ryu, S. K., “The Adsorption of Cu(II), Co(II), Ni(II) from Aqueous Solution onto Activated Carbon Fibers and the effect of Picolinic Acid,” HWAHAK KONGHAK, 37(1), 34-40(1999).
6. Yoon, Y. Y., “A Study on the Treatment of Chromiun(VI) by Acti- vated Carbon and Surface Treated Activated Carbon,” J. Kor. Soc.
Env. Engs., 9(2), 2001-2005(1987).
7. Chang, G. H., “The Adsorption Characteristics of Phenol by Surface -modified Activated Carbon Fibers,” Engineering Reserch, 22, 311- 322(1991).
8. Boehm H. P., “Chemistry of Heteroatoms on the Surface of Carbon (Plenary Lecture),” Carbon, 7(6), 715(1969).
9. Jr Pittman, C. U., He, G. R., Wu, B. and Gardner, S. D., “Chemical Modification of Carbon Fiber Surfaces by Nitric Acid Oxidation Followed by Reaction with Tetraethylenepentamine,” Carbon, 35(3), 317-331(1997).
10. Manocha, L. M., Bahl, O. P. and Singh, Y. K., “Mechanical Behav- iour of Carbon-carbon Composites Made with Surface Treated Car- bon Fibers,” Carbon, 27(3), 381-387(1989).
11. Park, S. J., Kim, Y. M. and Shim, J. S., “Studies on Anodic Oxidation Treatvent of Surface and Heavy Metal Adsorption Properties of Acti- vated Carbon Fibers,” J. Kor. Soc. Env. Engs., 14(1), 41-47(2003).
12. Shim, J. W. and Ryu. S. K., “Effect of Surface Modificatin of Activated Carbon Fiber for Adsorption on Copper and Nickel Ions,” HWAHAK KONGHAK, 36(6), 903-907(1998).
13. Donnet, J. B. and Bansal, R. C., Carbon Fibers, 2nd ed., Marcel Dekker inc, New York, USA(1990).
14. Blum, L. and Henderson, D., “Mixtures of Hard Ions and Dipoles Against a Charged Wall: The Ornstein-Zernike Equation, Some Exact Results, and the Mean Spherical Approximation,” J. Chem. Phys., 74(3), 1902-1910(1981).
15. Lee, S. M. and Jung, C. H., “The Effect of Electric Potential on the Desorption of Co(II) Ions,” Applied Chemistry, 3(1), 237-240(1999).
16. Grahame, D. C., “The Electrical Double Layer and the Theory of Electrocapillarity,” Chemical Rev., 41(3), 441-501(1947).
17. Jung, C. H., Lee, S. M., Oh, W. Z. and Park, H. S., “The Electrical Regeneration of Carbon Based Electrode,” Applied Chemistry, 3(1), 281-284(1999).
Fig. 9. Electrodesorption of Co(II) from NaOH treated ACF-discs at 0.05 N NaCl.
