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Multimetal oxides nanocomposite photocatalysts based on Gd 2 O 2 CO 3 •ZnO•CuO were prepared by a co-precipitation method and carefully characterized using a range of analytical techniques. More specifically, analysis by X-ray diffraction and electron microscopies confirmed the identity and quality of the as-synthesized powders. The photocatalytic degradation activities of these nanocomposites towards phenanthrene were then investigated by measuring the effects of catalyst dosage, irradiation time, and oxidant addition. In addition, the pseudo first-order kinetic model was used to determine the rate constant of the degradation reaction. Optimum dosages of 0.6, 0.6, and 0.4 gL −1 were recorded when using CuO, Cu-CuO/ZnO, and Gd 2 O 2 CO 3 •ZnO•CuO, respectively. In addition, the Gd 2 O 2 CO 3 •ZnO•CuO composite exhibited a higher removal efficiency than both Cu-CuO/ZnO and the pure CuO nanoparticles. Furthermore, the addition of oxidants influenced the removal of phenanthrene from solution. Finally, the photocatalytic degradation data followed pseudo first-order kinetics as defined by the Langmuir-Hinshelwood model, which allowed prediction of the faster degradation rate by the Gd 2 O 2 CO 3 •ZnO•CuO nanocomposite. The newly synthesized nanocomposite could therefore be considered for the removal of phenanthrene and related polycyclic aromatic hydrocarbons from contaminated water.

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Wastewater treatment challenges faced by conventional methods have necessitated the need for alternative/complementary methods that are environmentally benign and efficient especially toward recalcitrant organic pollutants. In this regard, ZnO/SnO 2 composite photocatalysts were synthesized using sol-gel method and employed in the photocatalytic degradation of Phenanthrene, benzo(a)pyrene and naphthalene, typical PAH's in water solution. The photocatalyst material was characterized with scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) to confirm the properties of the nanocomposite. The photocatalytic degradation activities of these nanocomposites towards phenanthrene, naphthalene and Benzo(a)pyrene were then investigated by measuring the effects irradiation time. In addition, the first-order kinetic model was used to determine the rate constant for the degradation reaction. The photocatalytic degradation data exhibited a trend fitting the pseudo first-order kinetics as defined by the Langmuir-Hinshelwood model, which allowed prediction of the faster degradation rate by the ZnO/SnO 2 nanohybrid (NH).