Degradation of Polyethylene Plastic by Non-Embedded Visible-Light Iron-Doped Zinc Oxide Nanophotocatalyst

Abstract

This study investigated the photocatalytic degradation of pure low-density polyethylene (LDPE) and commercial-grade polyethylene (PE) films with iron-doped zinc oxide (Fe-ZnO) nanoparticles under visible light. The study was particularly focused on the role of reactive oxygen species (ROS) and the types of plastic degradation. The Fe-ZnO were synthesized using the co-precipitation method and characterized by TEM and XRD. Degradation of 6.35 cm 2 films of LDPE and commercial grade PE was tested under artificial LED light (84 lm/W) and dark in Fe-ZnO suspensions of 10 ml having concentrations ranging from 10 to 1000 𝜇g/ml. The results showed a maximum weight reduction of 13.8 % for pure LDPE films at 200 𝜇g/ml and 15 % for commercial grade PE at 1000 𝜇g/ml in 14 days. In comparison, no weight reduction was observed in the dark, which confirmed that the degradation was induced by the production of ROS moieties in visible light i.e., singlet oxygen (30.11 %), hydroxyl ions (30.45 %), and hydroxyl radicals (39.34 %). The degradation was further confirmed by FTIR with the formation of alcohols and alkenes and SEM analysis that showed visible cracks in both LDPE and PE. The study unveiled Fe-ZnO nanoparticles as an efficient substitute to degrade polyethylene under visible light.