TiO₂ and ZnO nanomaterials: Fundamentals and applications in antibiotic degradation

Introduction: The increasing environmental concern regarding water pollution has necessitated the development of effective remediation strategies, particularly for pharmaceutical contaminants such as cefoperazone. One promising approach involves heterogeneous photocatalysis, a process in which semiconductor materials such as TiO₂ and ZnO are used to promote the degradation of organic pollutants under UV or visible light irradiation. TiO₂ and ZnO exhibit significant photocatalytic activity due to the generation of reactive oxidative species under irradiation. Therefore, the purpose of this study was to examine the effectiveness of TiO₂ and ZnO in the photodegradation of cefoperazone under various operational conditions, in order to remove cefoperazone from aquatic systems and promote the development of sustainable water purification systems.

Methods: Direct photolysis and photocatalysis treatments, under different irradiation types, were performed using 20 cm³ of 0.05 mmol/dm³ of cefoperazone, which was irradiated for 60 min. All experiments were carried out at natural pH. Aliquots of 20 μL were injected and analyzed using Ultra Fast Liquid Chromatography with Photodiode Array Detection (UFLC–PDA, Shimadzu), equipped with an Eclipse XDB‒C18 column (150 mm × 4.6 mm i.d., particle size 5 μm) maintained at 30 °C.

Results: The photolytic and photocatalytic degradation of cefoperazone was investigated under different irradiation sources (simulated solar, UV-LED, and UV). The applied nanomaterials showed significantly higher efficiency in the removal of cefoperazone compared to direct photolysis. Among the tested irradiation types, UV irradiation resulted in the most effective degradation of cefoperazone. ZnO proved to be more efficient than TiO₂ in the degradation of cefoperazone. Furthermore, the addition of H₂O₂ enhanced the degradation efficiency of cefoperazone and reduced the overall degradation time due to the increased formation of ^•OH radicals in the suspension.

Conclusions: Results demonstrate the potential of ZnO and TiO₂-based photocatalysts for efficient antibiotic removal from water under different irradiation conditions.