Amphiphilic carbon nanotubes for catalytic wet peroxide oxidation of 4-nitrophenol
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Carbon nanotubes (CNTs) were synthesized via chemical vapor deposition (CVD) over an AlCoFeO4 catalyst by a
sequential feed of ethylene (E, as carbon source) and acetonitrile (A, as nitrogen source). The resulting samples
were noted E20 (hydrophobic), E10A10 (amphiphilic), and A20 (hydrophilic), the number referring to the feed time
(minutes) of each precursor, as reported elsewhere1. These materials were tested in the catalytic wet peroxide
oxidation (CWPO) of 4-nitrophenol (4-NP). The reaction was monitored by HPLC (to determine the concentration of
4-NP and respective intermediates), TOC analyzer, and UV-vis spectrophotometry (to quantify H2O2) (Figure 1). After
8 h of reaction, A20 led to the highest consumption of H2O2 (90%), followed by E10A10 (61%) and E20 (52%). On the
other hand, the highest degradation of 4-NP was observed with the amphiphilic E10A10 material (98%) followed by
E20 (95%), whereas A20 only led to a removal of 69%. Similar behavior was found when analyzing the formation of
reaction intermediates (data not shown), i.e., while A20 resulted in the accumulation of 4-nitrocatechol (4-NTC) and
hydroquinone (HQ) E10A10 and E20 led to the total conversion of formed 4-NTC and HQ. This resulted in a lower
TOC removal for A20 (37%) than to E10A10 and E20 (53%). Therefore, the amphiphilic E10A10 material is a
promising catalyst for the CWPO of 4-NP.
