Removal of diatom Nitzschia sp. cells via ozonation process catalyzed by martite nanoparticles

Martite nanoparticles (MNPs) catalyzed ozonation process was utilized for rapid and effective degradation of diatom Nitzschia sp. cells. MNPs were produced using high-energy planetary ball milling technique from the natural martite particles (NMPs). Complete examination of the physical and chemical characteristics of NMPs, and MNPs were carried out by investigating the X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) and atomic absorption spectroscopy (AAS) analyses. The role of MNPs was investigated by XPS analysis, calculating the synergistic factor, and monitoring the dissolved concentration of ozone and oxygen. The decreased dissolved ozone concentration and increased oxygen concentration accompanied with the increased synergistic factor confirmed the positive role of Fe²⁺ and Fe³⁺ species in MNPs. The progress of the process through indirect mechanism was determined using simple organic and inorganic compounds acting as ROSs scavengers. Accordingly, the process for the diatom removal was mainly fulfilled by successive attacks hydroxyl radicals (^[rad]OH) and superoxide radicals (O₂ ^−[rad]). For identifying the effectiveness of the MNPs catalyzed ozonation process, the light microscopic along with SEM images, variation of chlorophyll-a concentration, GC–MS and COD analyses were studied. The results confirmed the destruction of complex structure of diatom cells to the simple structures. Also, the results proved the simultaneous degradation of diatom cells and their chlorophyll a content in the reaction media indicating the effectiveness of this process in comparison with other studied processes.