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Microstructure and thermomagnetic characteristics of the amorphous Fe51Co12Si16B8Mo5P8 alloy in the as-quenched state and after 1 h of annealing at 573 K and 773 K are studied. The structural investigations performed by Mössbauer spectroscopy and X-ray diffractometry confirmed the amorphous structure of the analysed materials. An increase in the annealing temperature up to 773 K does not lead to crystallization of the amorphous alloy. Only structural rearrangement that causes changes in the topological short-range order and annealing out of free volume is observed. This behaviour was confirmed by modifications of the shapes of hyperfine field distributions derived from the corresponding Mössbauer spectra of the investigated alloys. The Curie temperatures of the as-quenched and annealed Fe51Co12Si16B8Mo5P8 alloy at 573 and 773 K are 400, 405 and 421 K, respectively.

Microstructure and thermomagnetic characteristics of the amorphous Fe51Co12Si16B8Mo5P8 alloy in the as-quenched state and after 1 h of annealing at 573 K and 773 K are studied. The structural investigations performed by Mössbauer spectroscopy and X-ray diffractometry confirmed the amorphous structure of the analysed materials. An increase in the annealing temperature up to 773 K does not lead to crystallization of the amorphous alloy. Only structural rearrangement that causes changes in the topological short-range order and annealing out of free volume is observed. This behaviour was confirmed by modifications of the shapes of hyperfine field distributions derived from the corresponding Mössbauer spectra of the investigated alloys. The Curie temperatures of the as-quenched and annealed Fe51Co12Si16B8Mo5P8 alloy at 573 and 773 K are 400, 405 and 421 K, respectively. [ABSTRACT FROM AUTHOR]

Iron-based nanomaterials have high technological impacts on various pro-environmental applications, including wastewater treatment using the co-precipitation method. The purpose of this research was to identify the changes of iron nanomaterial's structure caused by the presence of selenium, a typical water contaminant, which might affect the removal when the iron co-precipitation method is used. Therefore, we have investigated the maturation of co-precipitated nanosized ferric oxyhydroxides under alkaline conditions and their thermal transformation into hematite in the presence of selenite and selenate with high concentrations. Since the association of selenium with precipitates surfaces has been proven to be weak, the mineralogy of the system was affected insignificantly, and the goethite was identified as an only ferric phase in all treatments. However, the morphology and the crystallinity of ferric oxyhydroxides was slightly altered. Selenium affected the structural order of precipitates, especially at the initial phase of co-precipitation. Still, the crystal integrity and homogeneity increased with time almost constantly, regardless of the treatment. The thermal transformation into well crystalized hematite was more pronounced in the presence of selenite, while selenate-treated and selenium-free samples indicated the presence of highly disordered fraction. This highlights that the aftermath of selenium release does not result in destabilization of ferric phases; however, since weak interactions of selenium are dominant at alkaline conditions with goethite's surfaces, it still poses a high risk for the environment. The findings of this study should be applicable in waters affected by mining and metallurgical operations. [ABSTRACT FROM AUTHOR]

[Display omitted] • A fungal biomass-based sorbent with encapsulated magnetite nanopowder was introduced. • Fungus-induced changes in magnetite structure were revealed by Mössbauer spectroscopy. • A. niger exhibited significant bioleaching activity unaffecting nanopowder mineralogy. • A. clavatus induced lattice distortions despite its limited bioleaching capacity. • The composite sorbent's performance in arsenic and antimony removal was tested. Fungal biomasses have emerged as cost-effective biosorbents. To augment their sorptive capabilities, in this study, a novel approach was explored - culturing Aspergillus fungi with magnetite nanopowder, yielding pellet-like biomass structures enclosing the nanoparticles. However, this interaction might induce undesired structural and mineralogical changes in the magnetite nanopowder. Therefore, we investigated the fungal impact on magnetite's structural and chemical stability using powder XRD and Mössbauer spectroscopy. Our findings revealed that the mineralogical alterations induced by A. niger in magnetite nanopowder remained subtle. Intriguingly, despite minimal structural changes in both magnetite (90%) and maghemite (9%), major components revealed by Mössbauer spectroscopy in commercially available magnetite nanopowder, A. niger exhibited remarkable iron extraction (approximately 40%). This highlights its capacity to dissolve magnetite nanopowder while preserving its mineralogical integrity. Conversely, A. clavatus , despite insignificant iron extraction, induced notable crystal lattice distortions in both magnetite and maghemite. This suggests its capacity to trigger structural changes even with limited bioleaching activity. Moreover, we assessed the sorptive performance of the biomass-based composite for arsenic and antimony removal, contributing to a comprehensive understanding of the intricate interaction between fungal biomass and magnetite nanopowder. These findings offer valuable insights into the mineralogical and structural modifications of magnetite induced by fungi and lay the groundwork for designing effective biomass-based sorbents for environmental applications. [ABSTRACT FROM AUTHOR]