A novel purification method of carbon nanotubes by high-temperature treatment with tetrachloromethane

The aim of this work was to address the problems associated with the synthesis and purification of carbon nanotubes, which are essential for the use of this material in various modern technologies. Carbon nanotubes and different nano-structured carbon phases were synthesized using the thermal decomposition of methane and o-xylene mixture and the ferrocene catalyst. The morphology of the samples (which were obtained in the form of powder and coatings) was examined by SEM. With an aim to remove the residual Fe catalyst, the batches of carbon nanotubes were treated with CCl4 at 700 °C, and analysed using gravimetric procedures, magnetic balance, EDX and contact angle measurements. It was found that treatment with CCl4 significantly affects on the surface state of carbon nanotubes and different carbon nanostructures. Elemental analysis results showed that CCl4 is an efficient reagent for removing of iron from the carbon phase (from ∼3 up to 1%). Concurrently, treatment with tetrachloromethane increases the amount of chlorine (up to 6.8%).