Plasma-assisted Synthesis of Supported Superparamagnetic Oxides for Enhanced Fenton Reactions

Hybrid composites based on ferrite nanoparticles have shown their effectiveness in the heterogeneous Fenton process due to the multiple properties such as ferromagnetism and biocompatibility. In this work, Magnetite (Fe3O4) nanoparticles are synthesized and dispersed thanks to the anchoring plasma-created sites onto water hyacinth fibers used as the catalytic support. The obtained composites were characterized by XRD, FTIR, SEM/EDX, and the magnetization properties were assessed at different temperatures (20 K, 150 K, and 300 K). The results reveal uniform dispersed nanorod-shaped particles covering the entire surface of the biomass with the saturation magnetization at 15 emu.g-1. The Fenton degradation process was optimized in terms of pH, mass, contact time and pollutant concentration, thus the catalytic performance achieved on two organometallic model pollutants, namely merbromine (MB) and the green complex of naphthol B (NGB) give degradation efficiencies of 97.01 and 99.70% respectively. The Langmuir-Hinshelwood kinetic model better describes the phenomenon where adsorption is the rate-limiting step given the high reactivity of generated species. The trapping species experiments show that besides hydroxyl radicals that contribute mainly to the degradation, other species such as superoxide and hydroperoxyl radicals are involved in the overall degradation mechanism. The obtained material is effective in the plasma-Fenton coupling process and the leaching test confirms their stability after four reuse cycles with the degradation rate greater than 85.10%.