Highly effective photocatalytic degradation of plastic film (LDPE) using Ruthenium-incorporated g-C3N4 via the Norrish mechanism

Abstract

Microplastics (MPs) are pollutants generated by plastic debris of diameters ≤ 5 mm and are a global concern that can pose severe threats to human and environmental health in both aquatic and terrestrial areas. In this study, low-density polyethylene (LDPE, MW = ∼35000) blended with Ru-incorporated g-C3N4 (Ru-gCN) was fabricated to examine its degradation efficiency. Plastic film (Ru-gCN@PE) degradation was performed by adding an aqueous medium with pH values ranging from 1 to 6 and at different temperatures (0, 35, 50, and 70 °C). The Ru-gCN@PE showed a significant weight loss of approximately 66.04, 74.51, and 69.64 wt% in pH 3 at 0, 50, and 70 °C, respectively, upon light irradiation for 24 h. The high activity of Ru-gCN can result from the formation of a heterojunction of Ru and g-C3N4 (Ru-gCN), which facilitates the transfer of the photoinduced π electrons of g-C3N4. Moreover, H+ is produced at an appropriate pH and temperature to further convert into hydroperoxides and accelerate the formation of macroradicals (∙ROO, ∙RO, and ∙OH) for plastic degradation, which follows the Norrish Type I and II mechanisms. Our study demonstrated the outstanding efficacy of the photocatalytic degradation of LDPE.