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

•Photocatalysts, TiO2/C/RM, were prepared from TiO2, tar pitch and red mud (RM).•RM and Fe3O4 are in the bulk and on the surface of the carbonaceous matrix.•TiO2 particles were agglomerated on the photocatalysts surface.•The photocatalysts showed high efficiency to discolor the remazol black dye.•The photocatalysts can be separated from the reaction by a magnetic field.