Adsorption applied to the removal of pharmaceuticals from industrial wastewater: Advances in the use of hydrogels as adsorbent materials

The presence of pharmaceutical compounds in industrial wastewater has become an increasing environmental concern due to their persistence, biological activity, and the limited efficiency of conventional treatment processes for their removal. In this context, adsorption has been widely investigated as a promising alternative for the removal of pharmaceutical contaminants from aqueous media, owing to its operational simplicity, high efficiency, and versatility. This review discusses recent advances in the application of hydrogels as adsorbent materials for the treatment of wastewater containing pharmaceutical compounds. Initially, the main factors influencing adsorption processes are addressed, including solution pH, its relationship with the pKa of pharmaceuticals, adsorbent concentration, and the role of functional groups on the adsorbent surface. Subsequently, adsorption mechanisms and models commonly used to interpret the behavior of adsorptive systems in aqueous environments are discussed. The review also examines hydrogels as adsorbents and highlights the development of sustainable hydrogels modified with functional materials such as carbon-based nanomaterials, metal oxides, clays, and biomass-derived residues. These hybrid systems demonstrate significant potential for removing pharmaceutical contaminants, expanding the prospects for developing more efficient and sustainable technologies for industrial wastewater treatment.