Zeolite-based CuO nanotubes catalysts: investigating the characterization, mechanism, and decolouration process of methylene blue

Novel zeolite-based CuO nanotubes composites were prepared from zeolite-based Cu nanowires by simple thermal oxidation process. The Cu nanowires/zeolite was prepared by reducing a copper–TMEDA complex in an aqueous-cyclohexane bilayer system and using CTAB as a soft template via hydrothermal chemical conversion method. The diameters of the nanowires in the composites are about 300–450 nm with rather smooth surfaces and the diameters of CuO nanotubes in the composites are about 600 nm and their surfaces are rough. It was found that such composites could be used in the photocatalytic decolouration of methylene blue because zeolite bed and CuO form new bands of Cu–O–Si or Cu–O–Al, which act as an electron trapper instead of traditional H2O2 method. Under visible light irradiation, the CuO nanotubes/zeolite showed photocatalytic activities higher than those of pure CuO powder and zeolite. Its decolouration rate has reached 91.5 % within 15 min and the whole decoloration process has completed within 60 min. The as-prepared composites were relatively stable and could be recycled without considering loss of activity.