Macroporous Hollow-Fibrous and Magnetically Recoverable TiO2 Catalysts for Converting Dye Wastewater to Valuable Resources

Abstract

The photocatalytic TiO₂ has been regarded as a promising catalyst of nonbiodegradable organic pollutants in wastewater. Resolving some issues of agglomeration, recoverability, and poor efficiency, an inorganic TiO₂-based catalyst has been constructed by a template method, which picks out bamboo fibers originating from processing waste. Characterization of the hollow fibrous TiO₂/Fe₃O₄ catalyst confirms the successful loading of Fe₃O₄ and TiO₂, along with a well-developed macroporous structure and high porosity (67.46%). At a solar intensity of 1 kW/m², when the amount of TiO₂/Fe₃O₄ is 0.3 g and the amount of H₂O₂ added is 3 mL, its degradation effect of 88.36% on industrial dye wastewater is optimal. The high magnetic saturation strength (5.78 emu/g) endows TiO₂/Fe₃O₄ with ultra-high magnetic properties. As expected, after 10 catalytic cycles, the average degradation rate of TiO₂/Fe₃O₄ toward methylene blue (MB) (0.2 L, 10 mg/L) remains above 96.2%, indicating that TiO₂/Fe₃O₄ has ultra-high recyclability and repeatability. Furthermore, the degradation kinetics analysis shows that TiO₂/Fe₃O₄ exhibits complete degradation of MB within 1 h and the degradation follows quasi-primary kinetics (k = 06062 min⁻¹, R² = 0.99747). Free radical burst experiments also indicate that hydroxyl radicals are active species that may play a major role in the solar-photo-Fenton system.