ZnO–C3N4 solar light -driven nanophotocatalysts on floating recycled PET bottle as support for degradation of oil spill

Abstract

Oil spill from explosion of oil wells and tankers threatens the life of sea creatures. Photocatalytic oxidation of oil spill is a promising way due to its low cost, complete conversion and the capability of using free and abundant sunlight. For better interaction between oil, photocatalyst and the light, it is recommended to use floating photocatalysts. In this research, recycled drinking bottles made of polyethylene terephthalate (PET) were used as a floating support for C3N4 and ZnO photocatalysts. ZnO–C3N4/r-PET composite with various amounts of ZnO (0, 5, 10 and 15 wt.%) were synthesized and characterized by means of X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM-EDX), N2-sorption isotherm (BET-BJH), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR) and UV–vis diffuse reflectance spectroscopy (UV–Vis DRS). The as-prepared ZnO–C3N4/r-PET nanocomposites were tested for the photocatalytic degradation of benzene. The results show that by increasing the amount of ZnO, the particle size decreased, size distribution narrowed and a more homogenous morphology was observed. Moreover, pore volume, pore diameter and BET surface area increased. In details, ZnO crystallite size reduced from 32 nm in ZnO–C3N4/r-PET nanocomposite with 5 wt.% of ZnO to 18 nm in similar nanocomposite with 15 wt.% of ZnO. Increasing the ZnO amount, broadened the band gap but enhanced the light absorption in visible and UV regions. Good interaction between C3N4 and ZnO was confirmed in TEM image. The highest degradation performance was obtained in the presence of 15 wt.% of ZnO. In fact by decreasing the amount of ZnO in the ZnO–C3N4/r-PET composite, the photodegradation rate decreased significantly. Influence of operating parameters like pH, catalyst loading, benzene volume percent and simulated sea conditions on photodegradation of floating benzene were also studied in details.