Comparison effects of gelation on sodium alginate–iron oxide nanocomposites for efficient catalytic degradation of organic dyes

This research investigates the synthesis of sodium alginate–iron oxide nanocomposites (SAL-Fe₃O₄) through the co-precipitation method, with a focus on the impact of gelation time. SAL-Fe₃O₄ nanocomposites were precipitated from Fe₂(SO₄)₃ and FeSO₄ under an alkaline medium in the presence of sodium alginate, maintaining a stoichiometric balance using a molar ratio of 1:2 for iron (III) Fe³⁺ to iron (II) Fe²⁺ ions precursors. Two types of SAL-Fe₃O₄ nanocomposites were prepared by varying the gelation time of sodium alginate to 3 and 24 h. Extensive characterization was performed using UV, FTIR, XRD and SEM with EDX analysis techniques to evaluate the properties of the nanocomposites. Fourier-Transformed infrared Spectroscopy (FTIR) analysis provided insights into the presence of sodium alginate on the SAL-Fe₃O₄ nanocomposite surface and the bonding characteristics within the polymer. X-ray diffraction (XRD) analysis was employed to determine lattices, phases, and preferred crystal orientations (texture) of the nanocomposites. Scanning Electron Microscope (SEM) was utilized to examine morphology, microstructures, dimensions, and size of the prepared nanocomposites. Energy-Dispersive X-ray (EDX) was used for the analysis of the elemental composition of the nanocomposites. Additionally, the catalytic efficiency of SAL-Fe₃O₄ nanocomposites was evaluated through the catalytic degradation of organic dyes using hydrogen peroxide (H₂O₂) as the oxidizing agent. The degradation processes were monitored by UV-visible spectrophotometry and the apparent rate constant (k_app), degradation time, percentage (%) degradation, degradation concentration and half-life values of different organic dyes were studied and compared, highlighting the influence of gelation time on the degradation efficiency.