(Digital Presentation) Degradation of Metronidazole in a Semi-Batch Reactor Employing BDD Electrodes
Authors: Maldonado Sandra María , Morales Gabriela Roa , Balderas Patricia , Barrera Carlos Eduardo 
Published: July 2022

In recent decades, the consumption of pharmaceutical products has risen considerably on a global level, and as such large concentrations of such products have been detected in municipal waters, surface waters, groundwater reserves, drinking water, water treated in wastewater plants, and even in the ground [1]. Considering that the health of many living beings has become affected by the introduction of these compounds into the environment, their removal or degradation has become a topic of great importance on an international level [2].

Antibiotics that are highly soluble in water such as metronidazole are frequently used for the treatment of some parasitic infections. Metronidazole has high effective activity against a number of anaerobic bacteria, bacteroides, and protozoa [3] that cause serious health problems for both human beings and animals. Unfortunately, despite the significant advantages that they offer, it has been shown that prolonged exposure at high concentrations makes metronidazole carcinogenic. Furthermore, it can cause mutagenicity, or lead to problems in the central nervous system [4].

The waste from these antibiotics go to treatment plants through discharges from the home, hospitals, farms, and even illegal dumping through the pharmaceutical industry, and as such they do not receive the optimum treatment [5]. Due to being complex molecules of a large size, they are not degraded at 100% in wastewater treatment plants through conventional methods. Thus, treatments through advanced oxidation such as fenton, photo-fenton, ozonolysis, and electrochemical methods, have become an excellent alternative in recent years [6] .

This investigation intends to degrade the metronidazole molecule through an electrochemical process through aqueous means, using a semi-batch reactor, determining the most efficient conditions for the degradation of the compound (initial concentration, current density, flux, and concentrations of the supporting electrolyte) through various analytical techniques [7], in addition to the kinetic order.

It is relevant to highlight that with the purpose of achieving mineralisation, a Diacelll cell will be adapted, employing an inoxidable steel electrode as a cathode and a boron doped diamond (BDD) electrode as an anode due to the electrochemical advantages, including a low undercurrent, an ample operation potential, and a frequently low adsorption compared with conventional carbon materials [8].

References

[1] Xu, L., Li, W., Désesquelles, P., Van-Oanh, N. T., Thomas, S., & Yang, J. (2019). A Statistical Model and DFT Study of the Fragmentation Mechanisms of Metronidazole by Advanced Oxidation Processes. Journal of Physical Chemistry A, 123(4), 933–942.

[2] Sousa, C. P., Ribeiro, F. W. P., Oliveira, T. M. B. F., Salazar-Banda, G. R., de Lima-Neto, P., Morais, S., & Correia, A. N. (2019). Electroanalysis of Pharmaceuticals on Boron-Doped Diamond Electrodes: A Review. ChemElectroChem, 6(9), 2350–2378.

[3] Luo, T., Wang, M., Tian, X., Nie, Y., Yang, C., Lin, H. M., Luo, W., & Wang, Y. (2019). Safe and efficient degradation of metronidazole using highly dispersed Β-FeOOH on palygorskite as heterogeneous Fenton-like activator of hydrogen peroxide. Chemosphere, 236, 124367.

[4] Vicente, D., & Pérez-Trallero, E. (2010). Tetraciclinas, sulfamidas y metronidazol. Enfermedades Infecciosas y Microbiologia Clinica, 28(2), 122–130. https://doi.org/10.1016/j.eimc.2009.10.002

[5] Wang, L., Wang, J., Lin, J., Zhang, S., & Liu, Y. (2018). Degradation of metronidazole by radio frequency discharge in an aqueous solution. Plasma Processes and Polymers, 15(4).

[6] Chianeh, F. N., & Parsa, J. B. (2016). Electrochemical degradation of metronidazole from aqueous solutions using stainless steel anode coated with SnO2 nanoparticles: Experimental design. Revista Mexicana de Urologia, 76(1), 424–432.

[7] Ammar, H. B., Brahim, M. Ben, Abdelhédi, R., & Samet, Y. (2016). Green electrochemical process for metronidazole degradation at BDD anode in aqueous solutions via direct and indirect oxidation. Separation and Purification Technology, 157, 9–16.

[8] Abou Dalle, A., Domergue, L., Fourcade, F., Assadi, A. A., Djelal, H., Lendormi, T., Soutrel, I., Taha, S., & Amrane, A. (2017). Efficiency of DMSO as hydroxyl radical probe in an Electrochemical Advanced Oxidation Process − Reactive oxygen species monitoring and impact of the current density. Electrochimica Acta, 246, 1–8.