Enhanced solid-phase photocatalytic degradation of polyethylene by TiO2–MWCNTs nanocomposites

Abstract

In this work, a novel acid vapor method was introduced to prepare the water soluble multi-walled carbon nanotubes (MWCNTs) and the titanium dioxide (TiO2)–MWCNTs nanocomposites photocatalyst were successfully synthesized by sol–gel solvothermal method. Products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD), which revealed that the anatase TiO2 particles were uniform deposited on MWCNTs surface. UV–vis diffuse reflectance spectroscopy (UV–vis) showed that composite photocatalyst had an obviously absorption band which covered the whole range of UV–vis region and exhibited a significant enhancement of optical absorption property. Based on above properties, we used the TiO2–MWCNTs composites as photocatalysts to degrade the polyethylene (PE) plastic. Solid-phase PE film photocatalytic degradation experiments were investigated through monitoring TiO2–MWCNTs–PE composite film's weight loss under mercury lamp irradiation. Results showed that the degradation efficiency could be tuned by changing the concentration of MWCNTs in photocatalyst. The photo-induced degradation of composite film was significantly higher than that of the pure PE film and the Degussa P25-PE film under the same UV irradiation. The weight loss of TiO2–MWCNTs (20 wt%)–PE sample reached 35% under 180 h UV-light irradiation. Our work could be extended to synthesize other MWCNTs based composite with the purpose of enhancing TiO2's activity and inspiring for the practical environmental pollution, especially for degradation of plastics.