This research work describes the cost-effective synthesis and purification of multiwall carbon nanotubes (MWCNTs). Synthesis of CNTs was carried out in distilled water between two electrodes using the electric arc discharge (EAD) method. EAD is a simple and straightforward route in which an electric arc is generated between graphite electrodes through DC power source to produce soot which contains MWCNTs along with impurities. The deposited soot containing MWCNTs was then chipped off and purified. In this case, multistep purification scheme was opted to remove unwanted impurities from produced MWCNTs. Purification route comprised thermal treatment, chemical treatment and a combination of both to yield pure MWCNTs. Thermal treatments were carried out in normal air and under controlled flow of oxygen at different temperatures whereas chemical treatment was performed using acidic solution. Thermo gravimetric analysis (TGA), field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) were carried out before and after purification treatments to investigate the outcome of employed treatments. Results showed that the thermal or chemical treatment alone is not sufficient to remove impurities from soot. Moreover, the introduction of an oxide group through chemical treatment reduces the oxidization temperature of graphitic particles. It was found that the chemical treatment followed by thermal annealing under the controlled flow of oxygen is the most appropriate method for successful purification of MWCNTs synthesized via EAD method.

这项研究工作描述了多壁碳纳米管（MWCNT）的经济高效的合成和纯化。使用电弧放电（EAD）方法在两个电极之间的蒸馏水中进行碳纳米管的合成。 EAD 是一种简单直接的途径，通过直流电源在石墨电极之间产生电弧，产生含有多壁碳纳米管和杂质的烟灰。然后将沉积的含有多壁碳纳米管的烟灰切掉并纯化。在这种情况下，选择多步纯化方案从生产的多壁碳纳米管中去除不需要的杂质。纯化途径包括热处理、化学处理以及两者的结合，以产生纯的多壁碳纳米管。热处理是在正常空气和不同温度下的受控氧气流下进行的，而化学处理是使用酸性溶液进行的。在纯化处理之前和之后进行热重分析 (TGA)、场发射扫描电子显微镜 (FE-SEM) 和 X 射线衍射 (XRD)，以研究所用处理的结果。结果表明，单独的热处理或化学处理不足以去除烟灰中的杂质。此外，通过化学处理引入氧化物基团降低了石墨颗粒的氧化温度。结果发现，化学处理后在受控氧气流下进行热退火是成功纯化 EAD 法合成的多壁碳纳米管的最合适方法。