Purification of Single Wall Carbon Nanotubes

选用0.3 μ m孔径聚醚砜薄膜过滤器，将单壁碳纳米管与含有单壁碳纳米管的电弧或激光汽化碳烟分离。在微滤之前，使用常规超声振动浴将烟尘分散在0.1%阳离子表面活性剂（苯扎氯铵）的水溶液中。如果起始煤烟中含有大量的非晶碳纳米球和其他纳米颗粒，则需要进行预处理，使用离心分离来增加煤烟中的SWNT含量。因为，纳米球很容易粘在膜过滤器的表面或孔中。离心分离的样品溶液与微滤的样品溶液相同。对多壁碳纳米管（MWNTs）和单壁碳纳米管（SWNTs）分别选择转速为5000rpm和12000 ~ 15000rpm的离心转速，转子半径为8cm，用于分离微管和碳纳米球。通过这种离心过程，制备的电弧烟尘（由Fe/Ni或Co/Ni双金属催化剂制成）中纳米碳管和单壁碳管的含量可以分别从几十个纳米碳管增加到几个纳米碳管%，分别增加到85%和40%以上。在提高微管含量后，应用微滤分离，成功地将微管含量提高到70- 80%。进一步提纯swcnts的方法是：在420-450ºC的干燥空气中燃烧20-40分钟，然后在浓HCl溶液中浸泡，去除无定形碳和金属残留物。在这里，重要的是在干燥的空气中进行燃烧，因为空气中的水分很容易在低得多的温度下攻击管的碳网。最终的SWNT产品纯度超过90%。目前，每一种上述纯化程序可制备约10至30毫克纯化的单壁碳纳米管。电子自旋共振、拉曼散射和碱金属掺杂的研究正在取得进展。将制定一个研究计划，研究氢在SWNT束中的吸附。少

0.3 mum pore sized membrane filter made by poly-ether sulfone was selected for a filter separating the single wall carbon nanotubes (SWNTs) from the arc or laser vaporized carbon soot containing SWNTs. In prior to the microfiltration, the soot was dispersed in an aqueous solution of 0.1% cationic surfactant (benzalkonium chloride) using a conventional ultrasonic vibration bath.If a starting soot contains numerous number of amorphous carbon nanospheres and other nanoparticles, it was necessary to carry out a pre-treatment to increase the SWNT content in the soot using a centrifugal separation. Because, the nanospheres easily stick on the surface /or in the pore of the membrane filter. The sample solution for the centrifugal separation is the same as that for the microfiltration. The spinning speeds of centrifuge with a 8 cm of rotor radius were selected at 5000 rpm and 12000-15000 rpm, respectively, for multiwall carbon nanotubes (MWNTs) and SWNTs to separate the tubules and the carbon … More nanospheres. By this centrifugal process, the contents of MWNTs and SWNTs could be increased, respectively, to in excess of 85 % and 40 % from a few tens (MWNTs) to a few (SWNTs) % of tubule content in the arc derived as-prepared soot (from an Fe/Ni or Co/Ni bimetallic catalyst). After increasing the tubule content, we applied the mictofiltration separation and succeed to increase the tubule content up to 70-80 %.Futher purification for SWNTs was carried out by using a combustion at 420-450ﾟC in dry air for 20-40 min. followed by a soaking in concentrated HCl solution to remove amorphous carbons and metal residua. Here, it is important to carry out the combustion in dry air, since the moisture in air easily attack the carbon network of the tubule at much lower temperature. Purity of the final SWNT product was in excess of 90 %. About 10 to 30 mg of purified SWNTs are now available to prepare per one purification procedure stated above.The electron spin resonance, Raman scattering and alkaline metal doping studies are now progressing. A researching plan for the study of hydrogen adsorption into the SWNT bundles will be scheduled. Less