Visible-light-driven Degradation of Phenanthrene in the Presence of metal-doped lithium Titanate Photocatalysts in Water Matrixes

Abstract Polycyclic aromatic hydrocarbons (PAHs) are organic pollutants known for their toxicity and resistance to degradation by conventional water treatment methods, which implies significant environmental and public health risks. To develop more effective removal strategies, this study assesses the degradation of phenanthrene (a model PAH) under visible light photocatalysis using lithium titanates modified with nickel, cobalt, and copper. The photocatalysts were synthesized via solvothermal method and thoroughly characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), infrared spectroscopy (IR), UV–Vis and diffuse reflectance (DRS) spectroscopy. The photocatalytic phenanthrene degradation using metal-doped lithium titanates was followed by UV–Vis spectroscopy and the photocatalytic activity was discussed in terms of the phenanthrene conversion, the pseudo-first-order kinetic constants and the bandgap values of the materials. The photocatalytic performance of metal-doped lithium titanates was notably superior to that of conventional TiO 2 . Maximal phenanthrene degradation (up to 82%) was reached with Ni- and Co-lithium titanates due to the greatest conversion values, high pseudo-first order kinetic constants achieved in 120 min under visible light irradiation and due to the lower bandgap values. In this sense, metal-doped lithium titanates have proven to be a potential and energy-efficient alternative for treating PAH-contaminated wastewater. Graphical Abstract