Recycling of Heavy Metal Ions from Wastewater by TiO₂ Photocatalysis

Heavy metals pose a significant concern in environmental science due to their potential threats to human health. Effective recycling of these metals is essential for achieving sustainable development, as they are vital resources widely utilized in daily life. Photocatalytically active TiO₂ has been extensively employed for the removal and recycling of heavy metals because of its excellent chemical stability, low cost, and unique structural properties. This chapter summarizes the mechanisms of TiO₂ photocatalytic treatment for heavy metal recovery, focusing on the reduction of copper (Cu), chromium (Cr), and uranium (U), as well as the oxidative recovery of arsenic (As). We systematically analyze the advantages of constructing heterojunctions, introducing photoelectric catalytic processes, doping with elemental substances, and incorporating functional additives to enhance photocatalytic efficiency. Finally, we explore the future prospects of using TiO₂ for heavy metal photocatalysis.