Silica Coated Iron Oxide Nanoparticles for Environment Remediation and Nuclear Waste Management

Environmental contamination, specially water pollution by toxic heavy metals and radionuclides from both natural and artificial sources is a big concern all over the world. Groundwater, Irrigation water and river water pollution by heavy metals mainly coming from industrial sources is also a big problem for Bangladesh. Nanomaterials specially magnetite iron oxide nanoparticles (MNP) are recently gained much interest in biomedical, environmental and nuclear application for its high surface area, adsorption capacity and excellent superparamagnetic properties. To prevent agglomeration, dissolution and leaching of magnetite in aqueous and highly acidic conditions, surface modification of magnetite nanoparticles by silica coating or formation of magnetite - silica core shell structure gained much popularity among the researchers. Silica coating, not only protects the magnetite core but also provides easy conjugation with different application specific functional groups and higher adsorption capacit y. In this work, Silica coated magnetic nanoparticles (SMNP) were prepared by optimized and simplified method s using the available lab facilities. Chemical, S tructural and M agnetic properties of uncoated and coated samples were characterized and measured b y Fourier Transforms Infrared Spectroscopy (FTIR), X - ray Diffractometry (XRD), Transmission Electron Microscopy (TEM), Energy Dispersive X - ray (EDS), Raman Spectroscopy, Differential scanning calorimetry (DSC), Thermogravimetric Analysis (TGA) and Physical properties measurement system (PPMS)/Vibrating sample Magnetometer (VSM). The results confirmed the successful synthesis of uncoated and silica coated iron oxide nanoparticles with average size of 12.19±3.11nm, 14.23±2.79nm and 12.22±2.97nm for uncoated, coated1 and coated2 samples respectively with high purity single phase Fe 3 O 4 inverse spinel cubic structure. The average coating thickness of coated1 and coated2 samples were found approximately 1.76±0.48nm and 1.34±0.39nm respectively. DSC and TGA, confirmed the good thermal stability of SMNP up to 900 0 C and revealed that, the silica coating most probably protects the MNP core from phase transition near 590 0 C. The saturation magnetization and coercivity decreased continuously with increa sing temperature except the Verwey transition point which was observed at 120K in MNP, although the effect was not so prominent due to the small particle size effect, which is an important characteristic for low temperature applications. Near room temperature (300K), The particles obtained better superparamagnetic properties. The saturation magnetization of SMNP (54.5 emu/g) was found lower than the MNP (62.9 emu/g) due to the coating effect but still retained the superparamagnetic properties. Smaller and Uniform particle size distributions, possibility to be further modified by functional groups (presence of Hydroxyl groups) required for specific heavy metal or radionuclides separation and excellent superparamagnetic properties support the potentiality of these synthesized SMNPs to be used in future environmental remediation and waste management applications.OutgoingObjectius de Desenvolupament Sostenible::6 - Aigua Neta i Sanejament::6.3 - Per a 2030, millorar la qualitat de l’aigua mitjançant la reducció de la contaminació, l’eliminació dels abocaments i la reducció al mínim de la descàrrega de materials i productes químics perillosos, la reducció a la meitat del percentatge d’aigües residuals sense tractar, i un augment substancial a escala mundial del reciclat i de la reutilització en condicions de seguretatObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura::9.a - Facilitar el desenvolupament d’infraestructures sostenibles i resilients als països en desenvolupament per mitjà de més suport financer, tecnològic i tècnic als països africans, països menys avançats, països en desenvolu­pament sense litoral i petits estats insulars en desenvolupamen