Structural, optical and magnetic properties of porous alpha-Fe2O3 nanostructures prepared by rapid combustion method

Effect of Ce3+ Ions Doped NiFe₂O₄ Magnetic Nanoparticles on Photocatalytic Degradation of Rhodamine B and Antibacterial Activities

In this study, spinel NiCe_xFe_2-XO₄ (x = 0.0 - 0.5) nanoparticles (NPs) was synthesized by microwave combustion technique (MCT) utilizing the fuel of Aloe vera plant extract. The establishment of spinel cubic crystal structure was ensured by powder X-ray diffraction (PXRD) technique. The particles like nanostructured morphology were confirmed by high-resolution scanning electron microscope (HRSEM). Energy dispersive X-ray (EDX) studies confirmed the formation of spinel ferrite structure and ensured that no other elements were present. Magnetic parameters such as remanant magnetisation (Mr), coercivity (He) and saturation magnetization (Ms) were calculated from the magnetic hysteresis (M-H) loops, which exhibited ferromagnetic behaviour. The photocatalytic behavior was investigated by visible light treatment for the photocatalytic degradation (PCD) of rhodamine B (Rh-B) dye and the sample NiCe_0.3Fe_1.7O₄ exhibits higher PCD efficiency (93.88%) than other compositions. The antibacterial activities of gram-positive S. aureus, B. subtilis, gramnegative K. pneumonia and E. coli have been investigated using undoped and Ce³⁺ substituted NiFe₂O₄ NPs and observed higher activity, which indicated that, they can be used in the bio-medical applications.

Flash-cooling assisted sol-gel self-ignited synthesis of magnetic carbon dots-based heterostructure with antitumor properties

This work addresses current direction of the nanoparticles-based systems intended for cancer therapy by developing a newly-formulated innovative chemically-engineered anti-tumor composite consisting in a magnetic, fluorescent, lipophilic, and biologically-active carbon heterostructure capable by itself or through coupling with a chemotherapeutic agent to selectively induce tumor cell death. The anti-tumor compound was synthesized through a modified sol-gel method by addition of a low-cost molecule with recently proven anti-tumor properties which was combusted and flash-cooled along with magnetic iron oxides precursors at 250 °C. The synthesized compound consisted in carbon dots, graphene and hematite nanoparticles which endowed the composite with unique simultaneous fluorescence, magnetic and anti-tumor properties. The in-vitro cytotoxicity performed on tumor cells (human osteosarcoma) and normal cells (fibroblasts) showed a selective cytotoxic effect induced after 24 h of treatment by the drug-free composite, leading to a cell death of 37%, for a composite concentration of 0.01 mg/mL per 10⁴ tumor cells, whereas the composite loaded with an antitumor drug (mitoxantrone) boosted the cell death effect to 47% for similar exposure conditions. The method shows high potential as it boosts drug transfer within tumor cells. Different antitumor drugs already in clinical use can be used following their separate or in-cocktail controlled combustion.

New nanosized Gd-Ho-Sm doped M-type strontium hexaferrite for water treatment application: experimental and theoretical investigations

In this paper, rare-earth doped M-type strontium hexaferrite magnetic nanoparticles SrHo_xGd_ySm_zFe_{(12−(x+z+y))}O₁₉ (x = y = z = 0.01) have been prepared by the sol–gel combustion method for the first time. The properties of the material were investigated using XRD, FTIR spectroscopy, Raman spectroscopy, SEM, UV-Vis spectroscopy, and VSM. X-ray analysis revealed that a magnetic single-phase was formed with a crystallite average size of 49 nm. FTIR spectra confirmed the formation of the structure of the hexaferrite phase. Raman analysis confirmed the formation of all crystallographic hexaferrite sites. A shift in the octahedral site frequencies and a significant shift were observed at site 12k and 2a, indicating that the doping elements occupied these sites. The SEM analysis showed that the particles were different in shape and slightly agglomerated. The EDS result confirmed the purity of the sample. The calculated band gap from the UV-Vis NIR spectroscopy spectra of the sample was 1.62 eV. The magnetic analysis of the sample material at room temperature revealed a coercivity of 5257.63 Oe, saturation magnetization of 67.72 emu g⁻¹, remanence ratio of 0.52, a maximum magnetic energy product of 1.06 MGOe and Curie temperature of T_c = 765 K. First-principles calculations were conducted on multiple configurations of SrFe_12−xX_xO₁₉ with x = 0, 0.5 and X = Sm, Gd, Ho. The site preference of each doping element was determined, and the effect of the doping on the structural, electronic, and magnetic properties of the compound was studied. The magnetic properties of this rare earth (Gd, Ho, Sm) doped strontium hexaferrite indicated that this compound could be used in both permanent magnets and water treatment application.

Development of the new nanohexaferrite SrHo_0.01Gd_0.01Sm_0.01Fe_11.97O₁₉ for important applications in industry, which could be very beneficial for applications in magnetic water treatment.

Effect of solvents on morphology, magnetic and dielectric properties of (α-Fe2O3@SiO2) core-shell nanoparticles

Present work describes the formation of α-Fe₂O₃@SiO₂ core shell structure by systematic layer by layer deposition of silica shell on core iron oxide nanoparticles prepared via various solvents. Sol-gel method has been used to synthesize magnetic core and the dielectric shell. The average crystallite size of iron oxide nanoparticles was calculated ∼20 nm by X-ray diffraction pattern. Morphological study by scanning electron microscopy revealed that the core-shell nanoparticles were spherical in shape and the average size of nanoparticles increased by varying solvent from methanol to ethanol to isopropanol due to different chemical structure and nature of the solvents. It was also observed that the particles prepared by solvent ethanol were more regular and homogeneous as compared to other solvents. Magnetic measurements showed the weak ferromagnetic behaviour of both core α-Fe₂O₃ and silica-coated iron oxide nanoparticles which remained same irrespective of the solvent chosen. However, magnetization showed dependency on the types of solvent chosen due to the variation in shell thickness. At room temperature, dielectric constant and dielectric loss of silica nanoparticles for all the solvents showed decrement with the increment in frequency. Decrement in the value of dielectric constant and increment in dielectric loss was observed for silica coated iron oxide nanoparticles in comparison of pure silica, due to the presence of metallic core. Homogeneous and regular silica layer prepared by using ethanol as a solvent could serve as protecting layer to shield the magnetic behaviour of iron oxide nanoparticles as well as to provide better thermal insulation over pure α-Fe₂O₃ nanoparticles.

Hematite nanoparticle clusters with remarkably high magnetization synthesized from water-treatment waste by one-step “sharp high-temperature dehydration”

Hematite (α-Fe₂O₃) nanoparticle clusters with an exceptionally high magnetization of 51 emu g⁻¹ were synthesized for the first time. This material was prepared from water-treatment waste by a new “sharp high-temperature dehydration” process.

Fenton-like degradation of Methylene Blue using paper mill sludge-derived magnetically separable heterogeneous catalyst: Characterization and mechanism

For the paper industry, the disposal and management of the yielded sludge are a considerable challenge. In our work, the paper mill sludge-derived magnetically separable heterogeneous catalyst (PMS-Fe-380) was prepared easily through a facile synthesis method. The morphology and structure of PMS-Fe-380 were fully characterized by means of X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and Brunauer-Emmet-Teller analysis. The catalytic activity of PMS-Fe-380 was evaluated by degradation of Methylene Blue (MB). The reusability and stability of PMS-Fe-380 were evaluated in five repeated runs, which suggested that PMS-Fe-380 manifested excellent stability of catalytic activity. Moreover, leaching tests indicated that the leached iron is negligible (<0.5mg/L). This study provides an alternative environmentally friendly reuse method for paper mill sludge and a novel catalyst PMS-Fe-380 that can be considered as a promising heterogeneous Fenton-like catalyst.

Synthesis of magnetic activated carbon/α-Fe2O3 nanocomposite and its application in the removal of acid yellow 17 dye from water

The adsorption of acid yellow 17 dye on activated carbon/α-Fe2O3 nanocomposite prepared by simple pyrolytic method using iron(II) gluconate was investigated by batch technique. The composite was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). The size of iron oxide nanoparticles formed from iron(II) gluconate precursor is in the range 5-17nm. The saturation magnetization (Ms), remanence (Mr) and coercivity (Hc) of the magnetic carbon nanocomposite is 5.6emu/g, 1.14emu/g and 448Oe, respectively. The adsorption data are found to fit well with Langmuir and, fairly well with Freundlich and Tempkin isotherms at higher concentration of dye (40-100mg/L). Kinetics data indicate that the adsorption of dye follows pseudo-second order kinetics model.