Red mud as catalyst for the treatment of pharmaceuticals compounds by advanced oxidation processes – A review

The growing concern over environmental contamination by pharmaceutical compounds has drawn the attention of the scientific community and regulatory bodies worldwide. It is estimated that a wide variety of drugs, including analgesics, antibiotics, hormones, and antidepressants, are widely detected in bodies of water, soil, and even in drinking water supply systems. This contamination represents not only a direct threat to human health and the environment but also challenges conventional water and wastewater treatment systems, which are often ineffective in completely removing these compounds. In this context, advanced oxidation processes (AOPs) emerge as a promising approach for degrading persistent organic contaminants such as pharmaceutical compounds. AOPs are highly effective techniques that involve the generation of reactive oxygen species, such as hydroxyl radicals, capable of oxidizing a wide range of organic pollutants, transforming them into less toxic and more easily treatable products. The importance of using red mud (RM) as a catalyst in AOPs for the treatment of pharmaceutical compounds is underscored by its abundance as a by-product of the aluminum industry and its unique ability to catalyze oxidation reactions. RM is the residue resulting from the Bayer process for refining bauxite to obtain aluminum. Its porous structure and chemical composition rich in metallic oxides confer catalytic properties that can be exploited in the degradation of organic contaminants. In this review, we explore the application of RM as a catalyst in AOPs for the treatment of pharmaceutical compounds. We investigate the mechanisms involved, the methods of preparation and modification of RM for optimizing its catalytic efficiency, as well as review case studies and significant results in the scientific literature. By addressing these aspects, we aim to provide important insights for future research and developments in this area of environmental science and process engineering.