Magnetic photocatalysts from industrial residues and TiO2 for the degradation of organic contaminants

Abstract

In this study, magnetic photocatalysts were prepared with different levels of TiO2 supported on tar pitch and red mud (RM) (40, 60, 80Ti/C/RM), which were used as carbon (C) and iron sources, respectively. The characterization by TEM, SEM and energy dispersive X-ray spectrometry showed that the RM particles are distributed in the bulk and on the surface of the carbonaceous matrix, forming the C/RM composite. These characterizations also confirmed the presence of TiO2 particles agglomerated on the photocatalysts surface. XDR results showed that the goethite and hematite in the RM was reduced to Fe3O4 and elemental analysis and Raman spectroscopy confirmed the carbon matrix. The obtained photocatalysts showed high efficiency to discolor the remazol black B dye (RB5). The 60 and 80Ti/C/RM photocatalysts decolorized 99% of the RB5 dye in reaction with solar radiation, while sample 40Ti/C/RM discolored 83%. The reactions performed with UV light showed that the 40, 60 and 80Ti/C/RM photocatalysts, decolorized 36, 60, and 71% of the RB5 and reduce 13, 34 and 52% of total organic carbon (TOC), respectively. Magnetic separation was preceded and the characterizations of the magnetic (MF) and non-magnetic fraction (NMF) confirmed that about 25% of TiO2 did not fix in the 60Ti/C/RM photocatalyst. MF and NMF decolorized 70 and 80% of the RB5, respectively, at the photocatalytic reaction (UV light). Sedimentation kinetics showed that photocatalysts are separated faster from aqueous environment than pure TiO2.