A Green Chemistry and Energy Cost-Effective Approach in Innovative Advanced Oxidation Processes Through Photoactive Microgels for Sustainable Applications

Sustainability challenges faced by the chemical industry today include the increasing prevalence of persistent Contaminants of Emerging Concern in wastewater, which requires the development of advanced treatment technologies. Additionally, transitioning from petroleum-derived raw materials to renewable biomass is essential for achieving more sustainable chemical processes. PNIPAM microgels with covalently integrated Rose Bengal as a photosensitizer has been synthesized and characterized in this study. The micellar-like structure of the colloidal microgels enhances substrate adsorption and overall efficiency. Designed in alignment with Green Chemistry principles, these materials support sustainable applications such as the green synthesis of 5-hydroxy-2(5H)-furanone, a C4 building block intermediate, and the removal of Diclofenac from wastewater. These photoactive microgels act as efficient photocatalysts, capable of generating singlet oxygen (O₂(¹Δg)) under visible light, with full recoverability and reusability over multiple cycles. By employing direct solar-driven photocatalysis, the approach offers a cost-effective, eco-friendly solution to address economic and environmental challenges in water treatment processes, as demonstrated by scale-up economic simulations. Additionally, it allows the synthesis of 5-hydroxy-2(5H)-furanone in aqueous media, a sustainable key-factor enabled by the enhanced adsorption capabilities of the microgels.