Magnetic Fe3O4-natural iron ore/calcium alginate beads as heterogeneous catalyst for Novacron blue dye degradation in water by (photo)Fenton process

Purposely prepared magnetic nanocomposite beads were investigated as catalysts for the degradation of Novacron blue (NB) dye (a reactive azo dye widely used in textile industries) by Fenton and photo-Fenton processes. Specifically, magnetic Fe3O4 nanoparticles and natural iron ore (NIO) were incorporated into sodium calcium alginate material to form Fe3O4-NIO calcium alginate beads using an inexpensive protocol. While Fe3O4/calcium alginate beads might be a good catalyst for Fenton and photo-Fenton processes, adding NIO could be beneficial to enhance the stability of the magnetic beads. The as-prepared catalyst was characterized by several techniques such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Brunauer, Emmett and Teller (BET) and Barret-Joyner-Halender (BJH), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and UV–vis diffuse reflectance analyses. Such characterizations showed that the (photo)catalyst was successfully synthesized, as well as its porous nature with a specific surface area of 26 m2/g. Magnetic nanocomposite alginate beads showed adsorptive properties by removing 22 % of NB dye under optimum conditions (pH 2, [NB]0 = 40 mg/L, and 0.2 g dose of beads). This magnetic catalyst proved a great photocatalytic behavior according to its optical properties and contributed as a photo-Fenton catalyst to the degradation of 80 % of NB dye after 120 min treatment compared to only 50 % after 120 min of Fenton process. This cheap, eco-friendly, non-toxic, magnetically separable and stable catalyst was reused for six subsequent photo-Fenton tests. All these advantages show its potential to be used as heterogeneous catalyst in wastewater treatment applications making it worthy of further investigation under more realistic conditions.