Degradation of cytostatics methotrexate and cytarabine through physico-chemical and advanced oxidative processes: influence of pH and combined processes on the treatment efficiency

ABSTRACT

Environmental release of wastewater that contains cytostatic drugs can cause genotoxic impact, since these drugs act directly on the genetic material of aquatic organisms. Thus, the aim of this study was to evaluate the removal of the cytostatic drugs cytarabine (CTR) and methotrexate (MTX) using different physico-chemical methods individually (i.e. US, O₃, H₂O₂ and UV) and combined (i.e. O₃/US, US/H₂O₂, O₃/H₂O₂ and O₃/US/H₂O₂) under different pH conditions (4, 7 and 10). In the degradation tests, the efficiency of the methods applied was found to be dependent on the pH of the solution, with the degradation of CTR being better at pH 4 and MTX at pH 7 and pH 10. The US, H₂O₂ and US + H₂O₂ methods were the least efficient in degrading CTR and MTX under the pH conditions tested. The highest MTX degradation rate after 16 min of treatment at pH 7 was achieved by the O₃+ H₂O₂ method (97.05% – C/C₀ = 0.0295). For CTR, the highest degradation rate after 16 min of treatment was achieved by the O₃ process (99.70% – C/C₀=  0.0030) at pH 4. In conclusion, most of the treatment methods tested for the degradation of CTR and MTX are effective. Notably, ozonolysis is an efficient process applied alone. Also, in combination with other methods (US + O₃, O₃+ H₂O₂ and O₃+ H₂O₂+ US) it increases the degradation performance, showing a rapid removal rate of 70–94% in less than 4 min of treatment.

GRAPHICAL ABSTRACT

KEYWORDS:

• Cytarabine
• methotrexate
• advanced oxidation process
• hospital wastewater
• water pollution

Acknowledgements

W. Pimentel-Almeida, R.C. Testolin, P. Gaspareto, O.M.S. Gerlach, E. Sanches-Simões: Investigation. J. Pereira-Filho, A.X.R. Corrêa, G.I. Almerindo, C.A. Somensi: Formal analysis, Resources, Funding acquisition. W. Pimentel-Almeida, S.Y.G. González, C.M. Radetski: Writing – review & editing, Supervision.

Ethical approval

This article does not contain any studies with human participants or superior animals performed by any of the authors.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Additional information

Funding

C.M. Radetski gratefully acknowledges a grant from Fundação de Amparo à Pesquisa e Inovação do Estado de Santa Catarina, Brazil (FAPESC – Universal project 2021TR000549). Sanches-Simões, O.M.S. Gerlach and W. Pimentel-Almeida acknowledge fellowships from CAPES – Brazil.