Sulfate Radical-Based Oxidation Processes for Emerging Contaminants: Advances and Perspectives on Degradation of Hormones

The increasing presence of emerging contaminants in aquatic environments, particularly endocrine disruptors (EDs), has raised significant environmental and public health concerns due to their toxicity, persistence, and ability to interfere with the endocrine systems of both aquatic organisms and humans. Among these compounds, the steroid hormones 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) stand out, as they are frequently detected in wastewater even after conventional treatment processes, which often exhibit limited removal efficiency. In this context, Advanced Oxidation Processes (AOPs), especially those based on the generation of sulfate radicals (SO₄•⁻), have emerged as promising alternatives due to their high redox potential, extended half-life, and broad effectiveness across various pH levels. This work reviews recent advances in AOPs for the degradation of E2 and EE2, focusing on sulfate radical-based processes. The main degradation mechanisms, operational parameters, removal efficiency, challenges for large-scale application, and gaps in the current literature were discussed. The analysis indicates that, despite their high effectiveness, sulfate radical-based processes still require further investigation in real wastewater matrices, assessment of the toxicity of byproducts, and optimization of operational variables to be established as viable and sustainable technologies for wastewater treatment.