Red mud accommodated mesoporous black TiO2 framework with enhanced organic pollutant photodegradation

Abstract

In this work, black TiO₂ (BTiO₂) loaded on black red mud (BRM) was successfully prepared with the conversion of Fe₂O₃ into magnetic Fe₃O₄ in red mud and the reduction of partial Ti⁴⁺ to Ti³⁺ in TiO₂ via the facile sol-gel method and H₂ reduction treatment. The obtained low-cost BRM/BTiO₂ composites exhibit remarkable photocatalytic degradation toward rhodamine B (91.2%) and tetracycline (83.6%) under visible light irradiation, much better than pristine TiO₂. 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/BTiO₂ composites realizes the recycle and recovery of photocatalysts, favoring practical applications in environment. This work provides a cost-efficiency way to prepare RM-supported TiO₂ 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 TiO₂.

Keywords: Magnetic separation; Photodegradation; Red mud; TiO2.