To overcome the titanium oxide limitations, Fe₂O₃- and Fe₃O₄-modified TiO₂ (3:1) nanoparticles were synthesized by a humid and solid path, respectively. These nanoparticles were embedded in sodium alginate biopolymer to prepare beads with efficient adsorption and photocatalytic behaviors in cationic dye degradation under both UV and visible irradiations. Operating conditions were investigated such as initial methylene blue (MB) concentration and contact time to evaluate their impact on the process. The bead recycling was also scrutinized. We have come to the conclusion that Fe₂O₃-modified TiO₂-Alg displayed superiorities, including expanded responsive wavelength range in the visible region (up to 700 nm), narrower band gap (1.79 eV), and better efficiency for MB removal in terms of adsorption capacities and photocatalytic effectiveness under both UV and visible irradiations. Furthermore, these beads can be effortlessly recovered from the reaction medium after the photocatalytic process and reused up to 5 cycles without any noteworthy decline in their initial properties.

Keywords: Alginate; Biopolymer; Iron oxides; Photodegradation; Titanium dioxide; Visible response.