Composite nanostructures containing iron in different forms exhibit a high adsorption capacity with respect to arsenic. The aim of our study was to investigate the adsorption activity of an adsorbent composite prepared by the oxidation of bimetallic Al/Fe nanoparticles under different conditions. Depending on the oxidation conditions, nanostructures with different morphologies in the form of nanosheets, nanoplates and nanorods with different compositions and textural characteristics could be obtained. The nanostructures obtained had a positive zeta potential and were characterized by a high specific surface area: 330 m²/g for the AlOOH/FeAl₂ nanosheets; 75 m²/g for the AlOOH/Fe₂O₃/FeAl₂ nanoplates; and 43 m²/g for the Al(OH)₃/FeAl₂ nanorods. The distribution of an FeAl₂ intermetallide over the surface of the AlOOH nanostructures led to an increase in arsenic adsorption of 25% for the AlOOH/FeAl₂ nanosheets and of 34% for the AlOOH/Fe₂O₃/FeAl₂ nanoplates and Al(OH)₃/FeAl₂ nanorods. The adsorption isotherms matched most preciously to the Freundlich model. This fact indicated the energy heterogeneity of the adsorbent surface and multilayer adsorption. The nanostructures studied can be used to purify water contaminated with arsenic.

The water oxidation of bimetallic Al/Ag nanoparticles has been shown to yield nanoscale structures whose morphology, phase composition and textural characteristics are determined by the synthesis conditions. Flower-like nanoscale structures with silver nanoparticles, with an average size of 17 nm, are formed in water at 60 °C. Under hydrothermal conditions at temperatures of 200 °C and a pressure of 16 MPa, boehmite nanoplatelets with silver nanoparticles, with an average size of 22 nm, are formed. The oxidation of Al/Ag nanoparticles using humid air at 60 °C and 80% relative humidity results in the formation of rod-shaped bayerite nanoparticles and Ag nanoparticles with an average size of 19 nm. The thermal treatment of nanoscale structures obtained at a temperature of 500 °C has been shown to lead to a phase transition into γ-Al₂O₃, while maintaining the original morphology, and to a decrease in the average size of the silver nanoparticles to 12 nm and their migration to the surface of nanoscale structures. The migration of silver to the nanoparticle surface influences the formation of a double electric layer of particles, and leads to a shift in the pH of the zero-charge point by approximately one, with the nanostructures acquiring pronounced antimicrobial properties.

The treatment of wastewater from arsenic compounds is an important and urgent problem. Composite nanostructures consisting of boehmite and iron compounds have a high adsorption capacity towards As(V) specie. In this work, the adsorption properties of nanostructured composites prepared by the oxidation of bimetallic Al/Fe nanoparticles with different iron contents were investigated. As a result of oxidation, boehmite AlOOH nanosheets are formed, with the resultant FeAl₂ nanoparticles being distributed on the surface of boehmite nanosheets. The nanostructured composites prepared from Al/Fe nanoparticles containing 20 wt% Fe have been found to show the highest adsorption capacity towards As(V) specie, being 248 mg/g. The adsorption isotherms are most accurately described by the Freundlich model, with the arsenic adsorption process obeying pseudo second order kinetics. As a result of the study, the optimal ratio of Al and Fe in Al/Fe nanoparticles has been determined to obtain an AlOOH/FeAl₂ composite adsorbent with a developed and accessible surface and a high sorption capacity towards As(V). This allows us to consider this material as a promising adsorbent for the removal of arsenic compounds from water.

In this work, the samples of the WC-Fe-Ni-Co composition were obtained and studied. Alloy NiCo 29-18 is used as a binder (Fe-Ni-Co). In this paper, a comparative analysis of the samples obtained using commercial micron-sized WC powder and the samples obtained is carried out using nano-WC synthesized via the electric explosion of wire (EEW) method. The samples were subjected to vacuum sintering, then their structure, density, and porosity, as well as microhardness and oxidation resistance, were studied. Five different additives were used to stabilize sintering: VC, Cr₃C₂, NbC, Y₂O₃, and Nd₂O₃. All these additives are described in the literature as additives that are used in the sintering of materials of the WC-Co system. Also, the samples from the WC-Fe-Ni-Co material were obtained using additive manufacturing technology with material extrusion. Bending strength and hardness of the additively fabricated samples were determined.