Red mud accommodated mesoporous black TiO 2 framework with enhanced organic pollutant photodegradation

In this work, black TiO 2 (BTiO 2 ) loaded on black red mud (BRM) was successfully prepared with the conversion of Fe 2 O 3 into magnetic Fe 3 O 4 in red mud and the reduction of partial Ti 4+ to Ti 3+ in TiO 2 via the facile sol–gel method and H 2 reduction treatment. The obtained low-cost BRM/BTiO 2 composites exhibit remarkable photocatalytic degradation toward rhodamine B (91.2%) and tetracycline (83.6%) under visible light irradiation, much better than pristine TiO 2 . This enhancement is attributed to the narrow bandgap with the desired solar-light excitation, the black color with good solar-light absorption, and the heterojunctions with the efficient separation of photogenerated electron–hole pairs. Moreover, the desired magnetic separation of BRM/BTiO 2 composites realizes the recycle and recovery of photocatalysts, favoring practical applications in environment. This work provides a cost-efficiency way to prepare RM-supported TiO 2 composites for treating organic pollutants in the wastewater, which is of great significance to the comprehensive utilization of RM waste, the cost saving of the photocatalyst, and the visible-light active enhancement of TiO 2 .