Heterogeneous Photocatalysis for Efficient Degradation of Lamivudine and Zidovudine Antiretroviral Drugs: Assessment Toxicological in Carrot and Tomato Seeds

The release without proper treatment of pharmaceutical contaminants into the environment, such as the antiretrovirals lamivudine and zidovudine, can lead to serious changes in ecosystems, causing different types of environmental problems. In this scenario, it is necessary to study and apply treatments capable of degrading these types of contaminants, such as the application of advanced oxidation processes (AOP). In this work, the heterogeneous photocatalysis AOP was applied for the degradation of a mixture of the drugs lamivudine and zidovudine (15 mg‧L⁻¹ each) in aqueous medium (AM) and synthetic effluent (SE). For this, a benchtop photolytic reactor equipped with UV-C, UV-A and sunlight irradiations was used. Assays for heterogeneous photocatalysis were carried out with brass plates calcined at 500 °C and coated with 2 types of TiO₂ ((A) and (B)), with the efficiency of the treatment being evaluated via ultraviolet/visible spectrophotometry. The optimized operational conditions were obtained using a coating ratio of 0.6 mg.cm⁻², and under UV-C irradiation for the two matrices, reaching a respective degradation of 70.83% and 60.40% in AM and 37.81% and 37.29% in SE after 300 min. The kinetic evaluation showed a good fit to the pseudo-first order model with (R²) ≥ 0.96. Toxicity tests involving the application of lettuce, carrot and tomato seeds were carried out. These showed an inhibition of the growth of the three seeds for the solutions submitted to the AOP, for the AM and the SE. Such behavior was not verified for the initial solutions, indicating that the intermediates formed during the AOP can be more toxic even after application of the treatment.