Optimization of photocatalytic parameters for the photodegradation of hydroxychloroquine sulfate using the Ag/Cu-TNT nanocomposite

Abstract

In this study, titanate nanotubes (TNTs) were synthesized using the alkaline hydrothermal method, and Ag and Cu ions were used to form Ag/Cu-TNT for use in the photodegradation of HCQ. The materials were characterized by X-ray Diffraction (XRD), Raman Spectroscopy (RAMAN), Transmission Electron Microscopy (TEM), Energy Dispersive Spectroscopy (EDS), Brunauer-Emmett-Teller (BET) textural analysis, photoelectron spectroscopy (XPS) and Diffuse Reflectance Spectrometer (DRS). BET revealed a reduction in specific surface area of 139.77 m² g⁻¹ for 109.34 m² g⁻¹, related to the presence of Ag and Cu ions in the interlamellar region of TNT. XPS featured binding energies Ag 3d_5/2 and Ag 3d_3/2 related to Ag⁰ and Ag⁺ in Cu 2p the peaks 2p_3/2 and 2p_1/2 eV are attributed to oxidation states Cu⁺ and Cu²⁺. The best photocatalytic results were presented at pH 3.0, Ag/Cu-TNT loading of 5.0 × 10⁻³ g, and HCQ concentration of 5.0 mg/L, reaching 88.81 % degradation in 120 min. The study also identified the species that influenced photodegradation and its by-products using LC/Q-TOF MS. It is observed that the suppression of the electron species (e⁻) and superoxide radicals (O₂^•-) in the HCQ solution caused a degradation, respectively, of only 47.05 % and 49.91 %, indicating that (e⁻) and (O₂^•-) are the species that most act in the degradation of this pollutant. Finally, the structural stability of the Ag/Cu-TNT after four cycles was confirmed by XRD and TEM. In this way, the research has developed a durable and efficient photocatalyst with potential for application in environmental remediation.