Nickel-ruthenium alloys with various compositions have been deposited by electrodeposition for the first time. Cyclic voltammetry and linear stripping voltammetry measurements show that codeposition of nickel with ruthenium is possible below the potential value of nickel reduction. High-quality alloys containing nickel and ruthenium can be plated at cathodic potentials ranging from − 0.5 to − 1.0 V vs SCE. Deposited coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The diffractograms obtained show that an increase of nickel concentration in alloy will lead to a change in the phase composition and formation of NiRu (100) and (101) phases which is observed to be 78 mas.% Ni. SEM studies confirm the surface homogeneity and presence of small, regular grains. AFM observation allows the estimation of the real surface area of obtained alloys which increase with more negative electrodeposition potentials. Ni-Ru alloys were found to be highly electroactive in the water splitting process, which can be connected with the presence of the NiRu phase and a well-developed electroactive area.

An attempt is made to achieve a continuous enrichment of rare-earth metal ions from aqueous solutions in a microflow device by applying magnetic forcing. An aqueous solution containing holmium(III) ions is pumped through a small channel which was exposed to a strong inhomogeneous magnetic field. At the outflow, the near- and far-field parts of the flow are separated and analyzed using UV-Vis spectroscopy. The relative change of ion concentration is determined from the measured absorbance. Results are reported for three different types of flow cells at different flow rates and magnetic field strengths and for a cascaded application of cells. The change of concentration is found to be small, and no clear trend can currently be stated due to the error margin of the concentration measurement.

The rare earths elements (REE) belong to the group of critical metals and they are achieving more and more interest due to their special properties. However, there occur some problems connected with their production. The most difficult phase is separation of REE. It includes a necessity to intensify currently applied processes and looking for new solutions. The present work introduces an idea to use differences in physical properties of the REE ions to get them separated. In the experimental part of the work some efforts were undertaken to analyse results presenting changes of holmium ions concentration under an influence of the magnetic field gradient. There was determined the gradient of magnetic field and concentration of Ho³⁺ ions depending on initial concentration of the solution and time. A simulation of changing the concentration of holmium ions in the solution under an influence of the magnetic field gradient was performed to compare the mathematical model with the obtained results.

This paper presents the results work on the electrochemical deposition of Ni₃Se₂ phase from aqueous acidic solutions. The mechanism of electrode reactions in the Ni²⁺ - H₂SeO₃ – H₂O system was investigated with the use of cyclic voltametry and a gold disk electrode. According to the voltametric and hydrodynamic methods, the process of nickel and selenium co-deposition is determined by the rate of selenium ions diffusion to the electrode surface. Ni₃Se₂ coatings were also obtained by the potentiostatic method on copper substrate. The elemental composition was determined with the XRF method. XRD analysis indicated that, in the range of potentials from −0.6 to −1.0 V the dominating phase is Ni₃Se₂. The influence of applied potential and concentration of electroactive species on the composition and the quality of the obtained coatings was determined. The Surface morphology was investigated with the use of scanning electron microscopy.