Sustainable Recycling of TiO 2 Nanoparticles with High Photocatalytic Performance from Spent Selective Catalytic Reduction Catalysts

In this work, a sustainable approach to reclaiming high-value anatase/rutile TiO 2 nanoparticles from deactivated or used selective catalytic reduction (SCR) catalysts is demonstrated using a composite flux (NaOH/Na 2 CO 3 ) through an efficient sintering and subsequent leaching methodology. This method directly addresses the urgent need for circular economy strategies in industrial waste management. Sintering experiments revealed that while NaOH enhanced the separation efficiency of V 2 O 5 and SiO 2 , it led to agglomerated products, hindering TiO 2 recovery. In contrast, Na 2 CO 3 enabled the production of powdery sintered residues, facilitating the complete separation of anatase/rutile TiO 2 nanoparticles, as confirmed by XRD. By optimizing the sintering-leaching conditions, this method achieves near-total recovery of TiO 2 with retained photocatalytic performance, ensuring its suitability for reuse in applications such as air/water purification or renewable energy systems. This study advances sustainability by repurposing industrial waste into high-performance materials, reducing the energy and resource demands associated with conventional TiO 2 synthesis, and preventing hazardous material leakage into ecosystems. The scalable, low-complexity process aligns with global sustainability goals, including responsible consumption (SDG 12), climate action (SDG 13), and industrial innovation (SDG 9), offering a blueprint for transforming waste streams into valuable resources for a greener economy.