Influence of the different oxidation treatment on the performance of multi-walled carbon nanotubes in the catalytic wet air oxidation of phenol

► Carbon nanotubes were used as catalysts in the catalytic wet air oxidation of phenol. ► Four chemical oxidants (HNO3/H2SO4, H2O2, O3 and air) were used to modify the CNTs. ► The O3-functionalized CNTs exhibit the highest activity and the perfect stability.