奈米科技的發展逐漸影響到人類的生活型態，尤其奈米碳管的發現更是一大驚奇，亦對於污染物的去除開發了新的契機。一般在利用奈米碳管做一吸附材時，必須經過純化程序去除合成奈米碳管時所使用金屬觸媒顆粒，以及在高溫合成時產生碳的不純物質，以提高奈米碳管純度。
本研究藉由奈米碳管對於不同極性分子(對-二甲苯與鄰-二甲苯)的吸附能力，探討奈米碳管表面極性在酸純化前後的變化。研究結果發現，經硝酸純化處理後奈米碳管的金屬含量有明顯降低，相對增加了奈米碳管的純度，並伴隨著官能基的存在。此外，表面積與微孔體積亦有顯著的增加。由動力吸附實驗發現，奈米碳管吸附鄰-二甲苯達平衡的時間比活性碳短，並遵循一階動力模式。等溫吸附曲線實驗結果顯示，鄰-二甲苯與對-二甲苯由於甲基團位置之差異，將會造成苯環上π電子轉移程度不同之現象而直接影響吸附行為。再者，純化後之奈米碳管所增加之表面官能基會吸引水分子聚集現象，即而減低了奈米碳管吸附能力。不論純化前後的奈米碳管，對於二甲苯的吸附皆可以Langmuir與Freundlich吸附模式描述之。在競爭吸附實驗顯示，當奈米碳管同時吸附鄰-二甲苯與對-二甲苯時，表現出相同之親和力。若比較奈米碳管與活性碳的吸附能力，因為活性碳擁有巨大的表面積，因此表現出比奈米碳管為高的吸附量；但以單位表面積表現吸附量時，則顯示出純化前之奈米碳管擁有較高的吸附能力，表示有效吸附孔徑的重要性。此外，由純化前後之奈米碳管對於二甲苯之吸附量比較，純化程序是否真的有其必要性是有待思考的。

CNT is considered a good sorbent due to its high specific surface area and large micropore volume. Usually, raw CNTs contain large amount of impurities (e.g., amorphous carbon and catalytic metal) which come from synthetic process, therefore, purification of CNT is usually required.
In this study, o-xylene and p-xylene were used to probe the alternation of surface properties of CNTs by acidic purification. It is found that purification of CNT by nitric acid significantly reduced the amount of metal catalyst, increased surface area as well as micropore volume of the CNTs, and introduced oxygen-containing group. Adsorption of o-xylene by purified-CNT attained adsorption equilibrium faster than that by activated carbon. The adsorption capacity of CNTs for o-xylene and p-xylene are mainly influenced by the positition of methyl groups and the presence of oxygen functional groups. Purified-CNTs have lower adsorption capability because water clusters compete with o-xylene and p-xylene for sorption sites. The competitive adsorption studies showed that there is no different affinity of o-xylene and p-xylene adsorbed by purified-CNT. Compared to both CNTs and purified-CNTs, activated carbons have larger adsorption capacity for its large specific surface area and no oxygen-containing functional group. However, when the adsorption capacity is calculated on the basis of unit surface area, CNTs have large adsorption capability than activated carbon for CNTs have more suitable pore size.

[1] 李元堯，｢21世紀的尖端材料-奈米碳管｣，化工技術，第11卷第2期，第140-159頁，2003。
[2] 洪昭南、徐逸明、王宏達 ，｢奈米碳管結構及特性簡介｣，化工，第49卷第1期，第23-30頁，2002。
[3] S Iijima, “Helical Microtubules of Graphitic Carbon,” Nature, 354, pp.56 (1991).
[4] 王裕祥，｢利用高分子材料及電弧放電法製造奈米碳管｣，碩士論文，中正大學化學工程研究所，嘉義，2002。
[5] 化工產業技術知識網: http://www.chemtech.com.tw
[6] 麥富德，｢碳奈米管專利地圖及分析carbon nanotube eng 麥富德等作｣，行政院國科會科資中心，台北，2002。
[7] 黃建良、黃淑娟，｢奈米碳纖與奈米碳管合成技術簡介｣，化工，第50卷第2期，第18至25頁，2003。
[8] 奈米科學網: http://nano.nchc.org.tw/
[9] J.F. Colomer, J. -M. Benoit, C. Stephan, S. Lefrant, G. Van Tendeloo,and J. B. Nagy, ”Characterization of Single-Walled Carbon Nanotubes Produced by CCVD Method,” Chemical Physics Letters, 345, pp.11-17 (2001).
[10] 工業污染防治技術手冊-有機溶劑污染控制，1995。
[11] Paul C. Hiemenz and Raj Rajagopalan, Principles of Colloid and Surface Chemistry, 3nd ED, Marcel Dekker, Inc. , New York, pp.405-407, pp.411-412 (1997).
[12] 吳錦昆，｢氧化鋁吸附地下水中砷之研究｣，碩士論文，成功大學環境工程學系，台南，1999。
[13] 邱誌忠，｢半導體產業高濃度含砷廢水之處理-化學沈降法與活性碳吸附法之評估｣，碩士論文，中興大學環境工程學系，台中，2004。
[14] Faust and Samuel Denton, Adsorption Process for Water Treatment Samuel D. Faust and Osman M. Aly, Boston Butterworth, pp.16-22, pp.185-191 (1987).
[15] 劉明翰，｢粉狀活性碳吸附氯化汞之研究:操作參數之影響及恆溫吸附模式之建立｣，國立中山大學環境工程研究所論文，2001。
[16] 林哲仁，｢活性碳之評估與選擇｣，環境工程會刊，第六卷第一期，第23-24頁，1995。
[17] 劉曾旭，｢活性碳製造技術及應用｣，產業調查與技術 第一二七期，第84-88頁，1999。
[18] J. Paul Chen, and Shunnian Wu, “Acid/Base-Treated Activated Carbons: Characterization of Functional Groups and Metal Adsorptive Properties,“ Langmuir, 20, pp.2233-2242 (2004).
[19] F. Julien, M. Baudu, and M. Mazet, “Relationship Between Chemical and Physical Surface Properties of Activated Carbon,” Water Research, 32, pp. 3414-3424 (1998).
[20] Marcus Franz, Hassan A. Arafat, and Neville G. Pinto, ”Effect of Chemical Surface Heterogeneity on the Adsorption Mechanism of Dissolved Aromatics on Activated Carbon,” Carbon, 38, pp.1807-1819 (2000).
[21] J.L. Figueiredo, M.F.R Pereira, M.M.A. Freitas, and J.J.M. Orfao, ”Modification of the Surface Chemistry of Activated Carbon,” Carbon, 37, pp.1379-1389 (1999).
[22] Lei Li, Patricia A. Quinlivan, and Detlef R.U. Knppe, “Effect of Activated Carbon Surface Chemistry and Pore Structure on the Adsorption of Organic Contaminants from Aqueous Solution,“ Carbon, 40, pp.2085-2100 (2002).
[23] 林哲仁，｢淺談活性碳吸附現象之影響因素｣，環境工程會刊，第六卷第二期，第14頁，1995。
[24] Jing Kong, Nathan R. Franklin, Chongwu Zhou, Michael G. Chapline, Shu Peng, Kyeongiae Cho, and Hongjie Dai, “Nanotube Molecular Wires as Chemical Sensors,” Science, 287, pp. 622-625 (2000).
[25] Sander J. Tans, Alwin R. M. Verschueren, and Cees Dekker, “Room-Temperature Transistor Based on a Single Carbon Nanotube,” Nature, 393, pp.49-51 (1998).
[26] E. S. Snow, F. K. Perkins, E. J. Houser, S. C. Badescu, and T. L. Reinecke, “Chemical Detection with a Single-Walled Carbon Nanotube Capacitor,” Science, 307, pp.1942-1945 (2005).
[27] L. Vaccarini, C. Goze, R. Aznar, V. Micholet, C. Journet, and P. Bernier, “Purification Procedure of Carbon Nanotubes,” Synthetic Metals, 103, pp. 2492-2493 (1999).
[28] Erik Dujardin, Thomas W. Ebbesen, Ajit Krishnan, and Michael M. J. Treacy, “Purification of Single-Shell Nanotubes,” Advanced Materials, 10 (8), pp.611-613 (1998).
[29] Fu-Hsiang Ko, Chung-Yang Lee, Chu-Jung Ko, and Tieh-Chi Chu, “Purification of Multi-Walled Nanotubes Through Microwave Heating of Nitric Acid in a Closed Vessel,” Carbon, 43, pp.727-733 (2005).
[30] Avetik R. Harutyunyan, Bhabendra K. Pradhan, Jiping Chang, Gugang Chen, and Peter C. Eklund, ”Purification of Single-Walled Carbon Nanotubes by Selective Microwave Heating of Catalyst Particles,” Carbon, 106, pp.8671-8675 (2002).
[31] Konstantin B. Shelimov, Rinat O. Esenaliev, Andrew G. Rinzler, and Chad B. Huffman, “Purification of Single-Walled Carbon Nanotubes by Ultrasonically Assisted Filtration,” Chemical Physics Letters, 282, pp.429-434 (1998).
[32] L. S. K. Pang, J. D. Saxby, S.P. Chatfield, “Thermogravimetric Analysis of Carbon Nanotubes and Nanoparticles,“ Journal of Physical Chemistry, 97, pp.6941-6942 (1993).
[33] S. C. Tsang, P. J. Harris,and M. L. Green, “Thinning and Opening of Carbon Nanotubes by Oxidation Using Carbon Dioxide,” Nature, 362, 520 (1993).
[34] G. S. Duesberg, M. Burghard, J. Muster, G. Philipp, and S. Roth, “Seperation of Carbon Nanotubes by Size Exclusion Chromatograpgy,” Chemical Communications, 3, 436 (1998).
[35] Hui Hu, Bin Zhao, Mikhail E. Itkis and Robert C. Haddon, “Nitric Acid Purification of Single-Walled Carbon Nanotubes,” Journal of Physical Chemistry B, 107, pp.13838-13842 (2003).
[36] Avetik R. Harutyunyan, Bhabendra K. Pradhan, Jiping Chang, Gugang Chen, and Peter C. Eklund, “Purification of Single-Wall Carbon Nanotubes by Selective Microwave Heating of Catalyst Particles,“ Journal of Physical Chemistry B, 106, pp.8671-8675 (2002).
[37] K. Hernadi, A. Siska, L. Thie-Nga, L. Forro, and Kiricsi, ”Reactivity of Different Kinds of Carbon during Oxidative Purification of Catalytically Prepared Carbon Nanotubes,” Solid State Ionics, 141-142, pp.203-209 (2001).
[38] Yan-hui Li, Shuguang Wang, Zhaokun Luan, Jun Ding,and Cailu Xu, “Adsorption of Cadmium(Ⅱ) from Aqueous Solution by Surface Oxidized Carbon Nanotubes,” Carbon, 41, pp.1057-1062 (2003).
[39] Yan-hui Li, Shuguang Wang, Jinquan Wei, Xianfeng Zhang, Cailu Xu, Zhaokun Luan, Dehai Wu, and Bingqing Wei, “Lead Adsorption on Carbon Nanotubes,” Chemical Physics Letters, 357, pp.263-266 (2002).
[40] Richard Q. Long, and Ralph T. Yang, “Carbon Nanotube as Superior Sorbent for Dioxin Removal,” Journal of the American Chemical Society, 123, pp.2058-2059 (2001).
[41] Yan-hui Li, Shuguang Wang, Anyuan Cao, Dan Zhao, Xianfeng Zhang, Cailu Xu, Zhaokun Luan, Dianbo Ruan, Ji Liang, Dehai Wu, and Bingqing Wei, “Adsorption of Fluoride from Water by Amorphous Alumina Supported on Carbon Nanotubes, ”Chemical Physics Letters, 350, pp.412-416 (2001).
[42] Akihiko Fujiwara, Kenji Ishii, Hiroyoshi Suematsu, Hiromichi Kataura, Yutaka Maniwa, Shinzou Suzuki, and Yohji Achiba, ”Gas Adsorption in the Inside and Outside of Single-Walled Carbon Nanotubes,” Chemical Physics Letters, 336, pp.205-211 (2001).
[43] Xianjia Peng, Yanhui Li, Zhaokun Luan, Zechao Di, Hongyu Wang, Binghui Tian, and Zhiping Jia, “Adsorption of 1,2-dichlorobenzene from Water to Carbon Nanotubes,” Chemical Physics Letters, 376, pp.154-158 (2003).
[44] Yan-hui Li, Jun Ding, Zhaokun Luan, Zechao Di, Yuefeng Zhu, Cailu Xu, Dehai Wu, and Bingqing Wei, “Competitive Adsorption of Pb2+, Cu2+and Cd2+ Ions from Aqueous Solutions by Multiwalled Carbon Nanotubes,” Carbon, 41, pp.2787-2792 (2003).
[45] Chungsying Lu, Yao-Lei Chung, and Kuan-Foo Chang, “Adsorption of Trihalomethanes from Water with Carbon Nanotubes,” Water Research, 39, pp.1183-1189 (2005).
[46] 劉旭娟、詹舒斐、鄧宗禹、金光祖、黃志彬，｢改良式固相萃取技術應用於超純水中鄰苯二甲酸酯類之微量分析｣，第二屆環境保護與奈米科技學術研討會論文集，第224-231頁，新竹(2005)。
[47] Robert C. Weast, CRC Handbook of Chemistry and Physics 68th, Boca Raton, Florida, E71.