Photo-removal of 3,4,4',5-Tetrabromodiphenyl ether (C₁₂H₆Br₄O) and 2,2',3,3',4-Pentabromodiphenyl ether (C₁₂H₅Br₅O) with Graphene oxide-Ag@Ag₃PO₄/g-C₃N₄ Nanocomposite

Abstract: Polybrominated diphenyl ethers (PBDEs) are a class of organo-bromine compounds that are used as flame retardants. Like other brominated flame retardants, PBDEs have been used in a wide array of products, including building materials, electronics, furnishings, motor vehicles, airplanes, plastics, polyurethane foams, and textiles. They are structurally to polychlorinated diphenyl ethers (PCDEs), polychlorinated biphenyls (PCBs) and other polyhalogenated compounds, consisting of two halogenated aromatic rings. In this study, 3,4,4',5-Tetrabromodiphenyl ether (C₁₂H₆Br₄O) (PBDE-81) and 2,2',3,3',4-Pentabromodiphenyl ether (C₁₂H₅Br₅O) (PBDE-82) photo-removal process was investigated with graphene oxide-silver loaded silver phosphate doped graphitic carbon nitride (GO-Ag@Ag₃PO₄/g-C₃N₄) nanocomposites under different experimental conditions. The effect of increasing pH values (3.0, 4.0, 6.0, 7.0, 8.0 and 11.0), increasing photodegradation times (30, 60, 90, 120 and 150 min), increasing GO-Ag@Ag₃PO₄/g-C₃N₄ nanocomposites concentrations on photodegradation yields of PBDE-81 and PBDE-82 were investigated with GO-Ag@Ag₃PO₄/g-C₃N₄ nanocomposites. The characteristics of the synthesized NCs were assessed using XRD, SEM, TEM, DRS, XPS, ESR and EIS analyses, respectively. Maximum 99.64% photo-removal yield was obtained for 20 mg/l PBDE-81 and PBDE-82 with 4 mg/l GO-Ag@Ag₃PO₄/g-C₃N₄ nanocomposites, after 120 min photodegradation time, at pH=7.0, at 400 W UV-vis light power, and at 25°C. Langmuir-Hinshelwood kinetic can be presented as a first-order equation for the photo-removals of two PBDEs. k_app values for PBDE-81 and PBDE-82 were found as 0.019 min^-1 and 0.017 min^-1, respectively. The μ values was found as 1.234 cm^-1 and 0.987 m^-1 for 4 and 20 mg/l Ag@Ag₃PO₄/g-C₃N₄ nanocomposite concentrations, respectively.