Essay on The Chemical Inertness Of Mwcnts

1600 Words Jan 28th, 2016 null Page
Because of the chemical inertness of MWCNTs, it is essential to create reactive groups on the surface for further modification [15]. The carboylic groups on the MWCNTs provide ideal anchoring point for the covalent immobilization of enzyme using EDC/NHS [15]. It has been demonstrated that sonicating MWCNTs in a mixture of acid solution opens the tube caps and forms carboxylic groups at the defect sites along the side walls [36].
Fig. 1 shows the FTIR spectra of MWCNTs and acid-treated MWCNTs. The appearance of sharp peaks at 1642 cm-1 indicates the presence of carbonyl groups (C=O) of the quinine type units along the side walls of the nanotubes [37], and its intensity decreased after acidification. Two noticeable peaks appeared at 1737 and 3409 cm-1 on the acid-treated MWCNTs, corresponding to the carbonyl (C=O) and hydroxyl (OH) stretching bands of carboxylic groups [8,37,38,39], respectively. This clearly indicates that carboxylic groups were successfully formed on the surface of MWCNTs by the acid treatment.
Because the efficiency of covalent immobilization of GOx depends on the degree of MWCNT carboxylation, TGA analysis was performed to determine the amount of carboxylic groups on the surface of carboxylated MWCNTs. Fig. 2 shows the TGA curves of MWCNTs and carboxylated MWCNTs. If a high amount of amorphous carbon is present, appreciable weight loss should occur below 400 °C. However, no detectable weight loss of (air-oxidized) MWCNTs was observed, indicating only a few…

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