UV–Visible Light Driven Photocatalytic Degradation of Ciprofloxacin by N,S Co-doped TiO₂: The Effect of Operational Parameters

Photocatalytic degradation using TiO₂ is one of the most effective techniques for treating residual emerging compounds present in water. However, practical applications are limited since it only absorbs ultraviolet irradiation. Nitrogen and sulfur (N, S) co-doped TiO₂ nanomaterials (N,S-TiO₂) were prepared by a controlled sol–gel method; the characterization and photocatalytic activity have been studied for the removal of ciprofloxacin antibiotic under UV–Visible light. The interstitial doping of nitrogen and sulfur substitute oxygen and titanium into the TiO₂ lattice, which increases the valence band and decreases the conduction band, respectively. The lowest value band-gap of 2.5 eV and the crystallite size of 5.13 nm compared to other available synthesis methods was observed on N,S-TiO₂ which allowed to broaden the light absorption to the visible region. The low level electron and hole recombination was related by the N, S doping. The optimal ciprofloxacin removal was obtained at pH 5.5, a dosage of 0.05 g, initial concentration of 30 mg L⁻¹ with a removal efficiency of 78.7%. A comparison of the effectiveness of antibiotic treatment of N,S-TiO₂ with synthetic TiO₂ and commercial TiO₂ was also made, taking the potential for regeneration into account. The photocatalytic degradation of ciprofloxacin catalyzed by N,S-TiO₂ was described by pseudo-first-order kinetics.