The focal point of this work is the design and comparison of two types of iron doped TiO₂ prepared by a simple sol–gel method and then encapsulated in an alginate matrix. The as-prepared recyclable bio-nanocomposite photocatalysts were made of different amounts of TiO₂-Fe₂O₃ and TiO₂-Fe₃O₄ (1%, 2.5%, 5%, and 10%) and were developed to improve the photocatalytic efficiency of TiO₂ and simultaneously to achieve an expanded visible-light response range with high visible-light absorption potential in order to degrade organic pollutants from aqueous solutions, as a potential application. As it is essential to characterize a material to better understand it, accurate characterization of the resulting bio-nanocomposites was carried out using X-ray diffraction (XRD), scanning electron microscopy coupled to energy dispersive X-ray spectroscopy (SEM-EDX), Fourier transform infrared spectroscopy (FTIR) and UV-diffuse reflectance spectroscopy (UV-DRS). In this study, the emphasis on blending the alginate and the iron doped-TiO₂ photocatalyst nanoparticles results in a multicomponent particular shaped system that exhibits a porous structure, an exceptional surface area and a smaller band gap due to the presence of iron nanoparticles that could also maintain e⁻/hole separation for better photocatalytic activity under visible light.