Purification of Single-Wall carbon nanotubes by heat treatment and supercritical extraction

Abstract

Arc discharge is the most practical method for the synthesis of single wall carbon nanotubes (SWCNT). However, the production of SWCNT by this technique has low selectivity and yield, requiring further purification steps. This work is a study of purification of SWCNT by heat treatment in an inert atmosphere followed by supercritical fluid extraction. The raw arc discharge material was first heat-treated at 1250 °C under argon. The nanotubes were further submitted to an extraction process using supercritical CO 2 as solvent. A surfactant (tributylphosphate, TBP) and a chelating agent (hexafluoroacetylacetone, HFA) were used together to eliminate metallic impurities from the remaining arc discharge catalysts. Analysis of Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) showed an efficient removal of iron and cobalt (>80%). The purified nanotubes were further analyzed by TGA and Raman spectroscopy.

Modifications of mechanical, thermal, and electrical characteristics of epoxy through dispersion of multi-walled carbon nanotubes in supercritical carbon dioxide

“…The advantages of using SCC over conventional methods for processing of carbon nanomaterials are not only environmental but also chemical and economical. Due to its unique inexpensive, non-toxic, and non-flammable properties and excellent recyclability without energy expenditures, SCC has been used for processing of one dimensional carbon nanostructures [1], synthesis of carbon nanotubes (CNTs) [2,3], patterning of carbon nanomaterials [4], growth of CNTs [5] and carbon nanocages [6], purification of sing-walled CNTs (SWCNTs) [7,8], coating of inorganic nanoparticles [9] and polymers over carbon nanostructured surfaces [10], non-covalent functionalization of CNTs with molecular anchors [11], and preparation of endohedral derivatives of CNTs [12] and CNT/polymer composites [13][14][15].…”

Fracture toughness and toughening mechanisms in a (ZrB2–SiC) composite reinforced with boron nitride nanotubes and boron nitride nanoplatelets

“…Tian et al [11] reported that the fracture toughness of a (ZrB 2 -SiC) composite increases by up to $15% at 2.0 wt.% CNTs. However, it is worth noting that the low starting oxidation temperature of CNTs ($400°C) [13] might degrade the mechanical properties of CNT/(ZrB 2 -SiC) composites at elevated temperatures.…”

Applications of Supercritical Fluids in Latin America: Past, Present and Future Trends

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