Green synthesis and characterization of polyhedral shaped amorphous iron oxide nanoparticles from incense sticks ash waste

Abstract Incense sticks ash (ISA) is one of the most common household waste products, and comprised of 5%–8% ferrous. ISA may prove to be a future alternative source of ferrous materials for iron and iron-based industries (steel) in the future and may be used for different applications like adsorbents, in ceramics and composite materials. The synthesis of iron oxide nanoparticles from waste material like incense sticks ash, is a “green” chemistry method which not only reduces pollution but also provides an alternative material for the synthesis of iron oxide nanoparticles. Initially in this study, ferrous was extracted from a wet slurry by a strong neodymium magnet. Further, ferrous was treated with concentrated HCl for the synthesis of iron chlorides by sonication at 60-700C for 1 h. Iron chlorides were then used for the synthesis of pure iron oxide nanoparticles by a co-precipitation method. The synthesized iron oxide nanoparticles were analyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) for phase identification of the synthesized iron oxide particles. FTIR revealed the characteristic peaks for iron oxide nanoparticles at 452 and 565 cm−1. XRD confirmed the amorphous nature of the iron oxide nanoparticles with a broad peak at 2 θ , 36.090. The average particle size measured by Particle Size Analyzer (PSA) was 734.9 nm and Polydispersity index (PDI) is 0.357. The Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM) both revealed the polyhedral morphology, aggregation nature of the iron oxide nanoparticles whose size varied from 60-600 nm. The Fe and O peaks by Electron Diffraction Spectroscopy (EDS) further validated the formation of iron oxide nanoparticles with high and purity.