Figure 1. FTIR spectrum of (a) pristine MWNT and (b) amino-functionalised MWNT.

Footnote: MWNT treated with a mixture of concentrated H₂SO₄ and HNO₃ (v/v 3∶1), and refluxed at 120°C. After cooling to room temperature, the mixture was vacuum-filtered on a 0.2 mm pore Polytetrafluoroethylene membrane. The oxidised nanotube was washed in a NaOH solution. Finally, the product was redispersed in HCl solution. The obtained oxidised nanotubes were dried in a vacuum oven and then were dispersed in ethylenediamine to obtain amino-functionalised MWNTs. The coupling agent,O-(7-Azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluroniumhexafluorophosphate was added to increase the yield of reaction and the dispersion was sonicated. The product was diluted with methanol and vacuum-filtered using a 0.2 mm pore PTFE membrane filter, after which the filtrate was washed extensively with methanol following by vacuum drying.