Low-Temperature Preparation and SnO ₂ Modification of P25 Millimeter Spheres as Recyclable Catalytic Materials for Water Treatment

To address two keys’ drawbacks of secondary calcination and poor conductivity in curing photocatalyst powders with inorganic binders, we developed a low-temperature technology for curing catalyst powders. Silica sol was used as a low-temperature curing binder to prepare P25/SiO 2 (PS) recyclable photocatalytic materials (RPMs) for water treatment, by binding P25 powder onto the surface of millimeter-scale spherical fillers. Furthermore, after the PS RPMs were modified by incorporating SnO 2 conductive agents, P25/SiO 2 /SnO 2 (PS-SnO 2 ) RPMs with millimeter-sized spheres were attained, which are stable and have high catalytic activity for water treatment. The results indicate that P25 powder can be tightly bonded onto the surface of millimeter-sized spherical water treatment fillers at low temperatures through a silica sol binder, and SnO 2 modification further enhances the catalytic property of PS photocatalytic materials. When the SnO 2 modification amount is 12%, the PS-SnO 2 material exhibited good degradation performance in complex aqueous environments, and the photocatalytic efficiency increased by 0.8 times under UV light and by 0.82 times under natural sunlight, respectively. This study successfully achieved the low-temperature curing of catalyst powder and fabricated millimeter-scale spherical RPMs. The as-prepared materials exhibit outstanding long-term stability and superior photocatalytic performance in water treatment, displaying a significant application in wastewater remediation.