In the present work the results of the research on the sol-gel synthesis and structure of cordierite (2MgO?2Al2O3?5SiO2), tialite (Al2O3?TiO2) and cordierite/tialite glass-ceramics as well cordierite containing 2 wt.% of Co and Co+Cu have been described and discussed. The sol-gel synthesis was carried out using different kind of precursors as follows: Al(NO3)?9H2O, Si(OC2H5)4, Ti(OC4H9)4, Mg(NO3)2?6H2O, chlorides or nitrates of corresponding metals, H2O, C2H5OH, Aqua Regia, NH4F and PEG. The synthesized gels were dried and thermally treated in the temperature range from 800?C to 1200?C. The sol-gel processes and structure of the cordierite, tialite and cordierite/tialite glass-ceramics have been investigated by means of XRD, FTIR, TEM, SEM and EPMA. .

Two calcium–cobalt silicates were synthesized in which cobalt occupies different structural positions. The crystal phases belong to two main structural silicate types. In the Co-åkermanite structure (Ca₂CoSi₂O₇), cobalt cations take tetrahedral coordination toward oxygen atoms. In the Co-pyroxene structure of CaCoSi₂O₆, cobalt displays octahedral coordination. Ca₂CoSi₂O₇ was prepared by solid-phase synthesis and CaCoSi₂O₆ was prepared by sol–gel method. The synthesis of the phases was confirmed by XRD, FTIR, and EPR data. On the basis of the XPS analysis, it can be concluded that Co²⁺ cations exist in the studied silicates. Thus, it is possible to study the catalytic activity of two silicate phases containing Co²⁺ cations in different coordinations: tetrahedral and octahedral. It was found that cobalt silicates with crystal structures corresponding to pyroxene and åkermanite possess catalytic activity in the reactions of complete oxidation of CO and toluene. Co-pyroxene exhibits higher catalytic activity than Co-åkermanite, but the higher cobalt content on the surface of Co-pyroxene should also be taken into account. Then, it turns out that catalytically active complexes with Со²⁺ ions in tetrahedral coordination are more efficient than those with such ions in octahedral coordination when equal concentrations of cobalt were used on the surface of the catalysts.

The present research focuses on the application of peanut and walnut shells, in their natural state, for the removal of methylene blue (MB) from water solutions in batch and dynamic (flow-through) conditions. Under batch conditions, at a 100 mg/L MB concentration of aqueous solution, the optimum dose of the studied biosorbents was determined to be 2.5 g/L, reaching about 95–97% efficiency of MB removal for both materials. Langmuir and Freundlich isotherms were used to model and evaluate the experimental data under different initial concentrations of MB (25 to 100 mg/L). The determined maximum adsorption capacities are 41.50 mg/g for walnut shells and 46.80 mg/g for peanut shells. Under flow-through conditions, breakthrough curves are determined for three sizes of fractions (<0.25 mm, 0.315–0.5 mm, and 0.8–1.6 mm). For peanut shells, the smaller the particle size, the higher the adsorption capacity and the column breakthrough time. For walnut shells, however, the particle size seems to have a more complex influence on the adsorption process parameters, and this phenomenon deserves future investigation. The adsorption capacity for one and the same fraction size of 0.315–0.5 mm and initial MB concentration of 50 mg/L is higher under dynamic flow conditions, i.e., 51 mg/g compared to 20 mg/g for walnut shells and 46 mg/g compared to 17.5 mg/g for peanut shells.

Zirconium belongs to the group of critical rare metals and is primarily used in industry. Its most important application, as the basis for specialized alloys, is in nuclear reactors, owing to its exceptionally very low thermal neutron absorption cross-section. Based on theoretical and experimental investigation, the potential for removing metallic (Al, Ti, Hf, V, Fe, Cr, Cu, Ni) and non-metallic (O, C) impurities from technogenic zirconium during electron beam melting (EBM) was assessed. The influence of temperature (ranging from 2350 K to 2750 K) and refining duration (10, 15, and 20 min) under vacuum conditions (1 × 10⁻³ Pa) was investigated concerning the degree of impurity removal, the microstructure, and the micro-hardness of the resulting ingots. It was established that under optimal EBM conditions for technogenic zirconium (T = 2750 K, τ = 20 min), the total refining efficiency reached approximately 87%, and the achieved Zr purity was 99.756%. Among the impurities present in the technogenic zirconium, the lowest removal efficiencies were recorded for Al (54.90%) and Cr (88.89%), with the lower refining efficiency for Al influencing the microstructure and micro-hardness of the ingots produced after EBM.