Degradation of textile dyes from synthetic and wastewater samples using TiO₂/C/Fe magnetic photocatalyst and TiO₂

A magnetic photocatalyst containing TiO₂ supported on the composite surface (C/Fe) was prepared from red mud, tar and TiO₂ (herein identified as TiO₂/C/Fe). Characterization by elementary analysis, X-ray diffraction and scanning electron microscopy confirmed the presence of TiO₂, Fe₃O₄ and carbon in TiO₂/C/Fe. TiO₂ P25 was used to determine the best conditions (catalyst weight, pH, dissolved oxygen—DO, radiation intensity—I and radiation incidence area—A) in photocatalysis reactions for discoloration of the textile dye Remazol Black (RB, 40 mg L⁻¹). The best observed condition (240 mg TiO₂, pH 10, DO 7.6 mg L⁻¹, I = 1.20 mW cm⁻² and A = 143 cm²) was applied in order to degrade organic matter in both an actual textile wastewater and a synthetic solution of 40 mg L⁻¹ RB using TiO₂/C/Fe. The magnetic photocatalyst showed that the reaction rate constant increased seven times when the best conditions were used for the RB discoloration. In the tests with the textile wastewater, TiO₂ and TiO₂/C/Fe showed 99 and 46% of discoloration, respectively. Moreover, there was reduction in the chemical oxygen demand, soluble solids and turbidity, which was more efficient than common physicochemical industrial treatments. Thus, TiO₂/C/Fe was photoactive and presented magnetic properties. Graphical abstract:

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