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

Abstract

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.