Evaluation of combined radiation for the treatment of lamivudine and zidovudine via AOP

Abstract

The presence of pharmaceutical contaminants in nature is an environmental problem generating increasing concerns. Due to this, it is necessary to evaluate treatments that are capable of degrading these contaminants, such as the advanced oxidation processes (AOP). In this work, the photoperoxidation and photo-Fenton AOP were applied to degrade a mixture of the drugs lamivudine and zidovudine, in aqueous medium and synthetic effluent (SE). To this end, a bench reactor (UV-C; UV-A and sunlight irradiations) was built. The AOP treatments efficiency was evaluated by ultraviolet/visible spectrophotometry. The tests involved the application of the irradiations individually and combined. The best operational conditions were [H2O2] of 600 mg.L-1 and [Fe] of 0.5 mg.L-1, for both matrices, with degradations of 90.53% and 89.32% for the photoperoxidation and photo-Fenton processes in aqueous media and 88.69% and 85.79% in SE. Kinetic studies showed a good fit for two pseudo-first order models with R2 > 0.93. Toxicity tests involving the application of lettuce, carrot, and tomato seeds showed an inhibition for the three seeds when submitted to solutions after treatment, for both matrices, this fact is corroborated by the HPLC analysis, in which the formation of small peaks was verified, suggestive of the formation of by-products. Thus, it can be affirmed that both photo-Fenton and photoperoxidation processes are efficient to degrade the drug mixture when applying UV-C radiation.