Removal of ethidium bromide from aqueous waste using advanced oxidation processes via heterogeneous photocatalysis

Ethidium bromide (EB) is a compound used as an intercalating agent in molecular biology for the visualization of nucleic acids in agarose gels. Its high mutagenic and carcinogenic properties, along with its potential for bioaccumulation, raise concerns regarding its release into aqueous effluents from research, diagnostic, and teaching laboratories. In this context, advanced oxidation processes (AOPs), particularly heterogeneous photocatalysis, are presented as an alternative for the complete degradation or mineralization of recalcitrant organic contaminants. In these processes, a radiation-activated semiconductor generates highly reactive radicals (•OH, •O₂⁻, h⁺) capable of breaking aromatic bonds and removing contaminants that escape conventional treatments. The objective of this protocol is to propose an experimental methodology for the removal of EB from laboratory wastewater using heterogeneous photocatalysis and to optimize operating parameters.

Based on the preliminary results obtained, the use of advanced oxidation processes, specifically heterogeneous photocatalysis with TiO₂, is a viable method for removing ethidium bromide (EB) from laboratory wastewater. It is expected that, under optimized conditions (pH, catalyst dosage, irradiation, aeration), removal rates greater than 80% can be achieved within reasonable operating times, with kinetic constants on the scale of 10⁻³ min⁻¹. Furthermore, it is essential to consider minimizing byproducts, evaluating mineralization (TOC/COD), and transitioning to continuous or scalable systems. In this regard, the findings support the integration of this technology into biotechnological effluent treatment flows, promoting environmentally responsible management and reducing the risk associated with EB release into aquatic environments.

Keywords: Advanced oxidation processes; ethidium bromide; heterogeneous photocatalysis; contaminant degradation