The use of natural organic extracts in nanoparticle synthesis can reduce environmental impacts and reagent costs. With that purpose in mind, a novel biosynthesis procedure for the formation of magnetic iron-oxide nanoparticles (IONPs) using Eucalyptus globulus extract in an aqueous medium has been systematically carried out. First, the biosynthesis was optimized for various extract concentrations, prepared by decoction and infusion methods, and yielded IONPs with sizes from 4 to 9 nm. The optimum concentration was found at 5% w/v, where the biosynthesis reaction time and ammonium hydroxide amount were the lowest of all samples. This extract concentration was tested, including in replicated samples, for a scale-up process, yielded a total mass of 70 g. It was found by Rietveld and electron microscopy analyses that the structural and morphological properties, such as crystalline and particle sizes (9 nm), are equivalent when scaling the synthesis process. ⁵⁷Fe Mössbauer spectroscopy results indicated that Fe ions are atomically ordered and in a trivalent state in all samples, corroborating with structural results found by X-ray diffraction. Magnetic analysis showed that the scale-up sample exhibited ferrimagnetic-like behavior suitable for magnetic remediation performance (55 emu g⁻¹). The eucalyptus functionalization was demonstrated by thermogravimetric measurements, whereas the colloidal analysis supported the stability of the magnetic suspensions at pH = 7 (zeta potential > −20 mV). The kinetic adsorption performance indicated a fast kinetic adsorption time of 40 min and remarkable removal efficiency of 96% for lubricant removal from water (emulsion systems). The infrared analysis confirmed the presence of the eucalyptus chemical groups even after the removal experiments. These results suggest that the scale-up sample can be recovered for future and sustainable magnetic remediation processes.

A novel magnetic composite made of Peruvian pyroclastic dust material decorated with maghemite nanoparticles was synthesized and characterized using a variety of analytic techniques. The 13 nm maghemite nanoparticles were grown on the pyroclastic dust using the conventional coprecipitation chemical route. A short-term acute assay was developed to study the ecotoxicological behavior of the water flea, Daphnia magna. A 24 h-lethal concentration (LC₅₀) value equal to 123.6 mg L⁻¹ was determined only for the magnetic composite. While the pyroclastic dust material did not exhibit a lethal concentration, it caused morphologically significant changes (p < 0.05) for heart and tail parameters at high concentrations. Morphologies exposed to the magnetic composite above the 24 h-LC₅₀ revealed less tolerance and significant changes in the body, heart, antenna, and eye. Hence, it affects biomarker growth and swimming. The reproduction rate was not affected by the raw pyroclastic dust material. However, the number of individuals showed a decrease with increasing composite concentrations. The present study indicates the LC₅₀ value, which can be used as a reference concentration for in-situ water cleaning with this material without damaging or changing the Daphnia magna ecosystem.

The Rietveld refinement method has taken high relevance since its creation. Nowadays, it is an useful tool in many fields of industry, materials science, and technology. For these reasons, it becomes a need for scientists and engineers whom pretend to use it for proper analysis of their materials. However, the initiation in the method can be slow, taking into account the accelerated rhythm of the research and economic demands. Thus, this work is an intend to fulfill this hole, providing the basic foundations and methodology of the Rietveld refinement in a brief way, this along with the results of its application in superconducting samples of Yttrium Barium Copper Oxide and magnesium diboride, and functional magnetic nanoadsorbents of maghemite and a multiphasic composite (iron oxide, hydroxyapatite and secondary phases). In the process, an in-detail protocol was designed and provided. It was concluded that the samples were successfully refined and that this work represents a fast introduction to the Rietveld method for which beginners can obtain good results while making correct interpretations ofthe whole refinement process.

By varying salt precursors and precipitating agents, polyphenol‐functionalized γ‐Fe₂O₃ nanoparticles (NPs) were systematically biosynthesized with controlled particle sizes and varying polyphenol layer thicknesses via two distinct approaches. In the in situ process (ISP), green tea (GT) extract influenced the formation of particles with different sizes during the synthesis, while in the after synthesis process (ASP), it enabled the functionalization of preformed γ‐Fe₂O₃ NPs. The use of GT extract significantly reduced the amount of precipitating agent (NH₄OH or NaOH) commonly used in the coprecipitation method. However, even in a polyphenol‐rich environment, the Fe₃O₄ phase is detected only a few hours after the ISP. Results from various characterization techniques revealed that altering the GT extract content—expressed as percent weight‐to‐volume (x = %w/v)—affects the nanocrystallite size, magnetic behavior, and hyperfine properties, particularly in samples biosynthesized via ISP. Functionalization with GT extract enhanced the effective magnetic anisotropy of the γ‐Fe₂O₃ NPs compared to bare γ‐Fe₂O₃ NPs; however, this anisotropy decreased progressively as the x‐value increases. This trend suggests that the thicker organic layer reduced interparticle dipolar interactions by improving the dispersion of the magnetic NPs.

Green‐assisted iron oxide nanoparticles (NPs) were synthesized using Camellia sinensis extract (green tea, GT) at concentrations of 1%, 2%, 3%, 5%, and 10% w/v via three chemical routes: after‐synthesis (ASR), subsequent synthesis (SSR), and in situ synthesis (ISSR). Rietveld refined X ray diffractograms and transmission electron microcopy results confirmed mostly γ–Fe ₂ O ₃ NPs with mean sizes ranging from 8 to 25 nm depending on the synthesis route (Fe3O4 core was also observed in some of the ISSR samples). ⁵⁷ Fe Mössbauer and magnetization data showed superparamagnetic behavior at 300 K for all NP ensembles. The saturation magnetization ( M _S ) value roughly scaled with GT concentrations and, for the 1% of GT sample synthesized by the ISSR‐route, a 16% higher magnetization value (86 emu g ⁻¹ ) was found when compared to the one measured for the control sample (74 emu g ⁻¹ ), an effect attributed to the Fe ₃ O ₄ phase initially stabilized. Fourier transform infrared and UV–vis spectroscopies showed polyphenols from the GT on the NP surface, a result that agrees with the thermogravimetric data. The 15 K ⁵⁷ Fe Mössbauer data indicated that these polyphenols bind to surface iron ions, favoring spin canting and the formation of a “magnetically dead layer” on the NP surface, an effect associated with the functional (─OH) groups of GT polyphenols. Our findings demonstrate that the different routes produce functionalized Fe‐oxide NPs with different crystallite sizes and polyphenol‐layer thicknesses by simply using Camellia sinensis extract.