Effect of Structurally Different Magnetic Alginate Nanocomposite Beads on Fenton-Like Oxidation of Direct Dyes

In this study, the magnetic nanoparticles Fe₃O₄ embedded into the alginate matrix by two ways. In the first approach, the ionic gelation capability of the alginate polymer was utilized for the endo-synthesis of magnetic nanoparticles (Fe₃O₄). This was achieved through the adsorption of divalent (Fe²⁺) and trivalent (Fe³⁺) iron ions, followed by an in situ co-precipitation process, resulting in the formation of magnetic alginate beads, referred to as MABI. The second approach, magnetite exo-synthesized through co-precipitation of iron salts and subsequently dispersed into the alginate polymer matrix via physical embedding. This process involved mixing the magnetite with the alginate solution to form the magnetic alginate beads, referred to as (MABII). The prepared MABI and MABII characterized by various techniques such as infrared spectroscopy (IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Transmission electron microscopy (TEM). The SEM, XRD, and TEM shows that the MABI exhibited a very good particle distribution with nearly no agglomeration and small particle size than MABII. The effect of preparation conditions on the catalytic activity of magnetic alginate beads (MABs) studied for their ability for Fenton oxidation of reactive dye 19 as example of azo dyes. The MABI exhibited an excellent ability for the oxidation decomposition of reactive blue dye 19 (RBD 19) where the degradation % of RBD 19 applying MABI/H₂O₂ oxidation binary system reached 97% after only 40 min while MABII shows a degradation percentage of 86% after 90 min. The Fenton oxidation process conducted under various factors such as amount of catalyst, percentage of H₂O₂ and temperature. The results proved that increasing the amount of catalyst (MABI) and the percentage of H₂O₂ enhances the efficiency of Fenton oxidation for the direct dye.