Purification of Single Wall Carbon Nanotubes

0.3选择由聚醚砜制成的μ m孔径的膜过滤器作为将单壁碳纳米管（SWNT）与含SWNT的电弧或激光汽化碳烟灰分离的过滤器。在微滤之前，使用常规的超声振动浴将烟灰分散在0.1%阳离子表面活性剂（苯扎氯铵）的水溶液中。如果起始烟灰含有大量的无定形碳纳米球和其他纳米颗粒，则有必要进行预处理以使用离心分离来增加烟灰中的SWNT含量。因为，纳米球容易粘附在膜过滤器的表面上/或孔中。用于离心分离的样品溶液与用于微滤的样品溶液相同。对于多壁碳纳米管（MWNTs）和单壁碳纳米管（SWNTs），具有8 cm转子半径的离心机的旋转速度分别选择为5000 rpm和12000-15000 rpm，以分离管和碳 关于我们 纳米球通过该离心过程，MWNT和SWNT的含量可以分别增加到超过85%和40%，从电弧衍生的原样制备的烟灰（来自Fe/Ni或Co/Ni催化剂）中的微管含量的几十（MWNT）%到几（SWNT）%。在增加微管含量后，我们采用微滤分离，成功地将微管含量提高到70- 80%。通过在干燥空气中在420-450 ℃下燃烧20-40分钟，然后在浓HCl溶液中浸泡以去除无定形碳和金属残留物，对单壁碳纳米管进行进一步纯化。在这里，重要的是在干燥空气中进行燃烧，因为空气中的水分在低得多的温度下容易攻击小管的碳网络。最终SWNT产物的纯度超过90%。现在，每一个上述纯化步骤可制备约10至30 mg纯化的SWNT。电子自旋共振、拉曼散射和碱金属掺杂研究正在进行中。将安排研究氢吸附到单壁碳纳米管束的研究计划。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