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The change of geochemical properties of ferric hydroxide nanoparticles under the influence of a weak magnetic field was investigated. Ferric hydroxide nanoparticles formed as a result of the interaction of iron-containing minerals with natural aqueous solutions are of importance for geochemical processes, especially hypergenesis, sedimentation, and soil formation. The hydrolysis of ferric chloride in hot water (t = 70-75°С) was used to obtain ferric hydroxide nanoparticles under laboratory conditions. The nanodispersion (colloidal solution) was exposed to a weak pulsed magnetic field. The spectrophotometric properties of the colloidal solution of ferric hydroxide were determined using an SF-46 spectrophotometer in the wavelength range of 320-610 nm. The size of colloidal particles was calculated by a method based on the theory of Rayleigh light scattering. The size of colloidal particles depended on the exposure duration of a pulsed magnetic field on the colloidal solution. The size of colloidal particles was due to a change in the magnitude of the diffuse ionic atmosphere under the influence of a pulsed magnetic field. The kinetic stability of the colloidal solution was evaluated by the coagulation threshold, which was determined visually by the appearance of the turbidity of ferric hydroxide colloid when adding NaCl solution. The kinetic stability of a colloidal system was determined by the size of colloidal particles. These results can be used to better understand certain hypergenesis, sedimentation, and soil formation processes.

The article is devoted to the development of nanosized sorbents for the removal of cesium and strontium, as well as heavy metal ions simultaneously present in a multicomponent two-phase solution containing complexing agents and surfactants. Magnetically sensitive nanosorbents are currently considered promising since the influence of external fields can improve the performance of the developed sorbents. To create magnetically sensitive nanoparticles and composites based on them, we used carbon-coated nanoparticles of metals in a composition with montmorillonite. The scanning electron microscopy revealed that the use of electric hydraulic discharge to increase the efficiency of sorbents had not led to a positive result because the high voltage electric pulse passage through the aqueous dispersion causes the carbon shell disintegration, while the metal nanoparticles form aggregates as a result of the partial melting. The use of the pulsed magnetic field in the synthesis of a nanosized composite based on montmorillonite and magnetite is explained by the influence of the magnetic field on the particle size. It has been ascertained that the size of the nanoparticles changes depending on the duration of the magnetic field interaction with the aqueous dispersion. At the beginning the particle size slightly decreases, and then it increases. The obtained nanosized composite allows to remove cesium-80%, strontium-90%, iron-99%, cobalt-97%, and manganese-98% from a multicomponent two-phase solution containing simultaneously cesium, strontium, cobalt, manganese, iron and organic substances, including surfactants and complexing agents. The results of the research allow us to recommend using nanosized magnetically sensitive composite based on magnetite and montmorillonite for the purification of multicomponent technogenically polluted waters.

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