This work presents a detailed study of the coordination of Eu(III) with tartrate and oxalate ligands in aqueous solutions. The following techniques were employed: potentiometric titrations, 1D ¹H, ¹³C multinuclear NMR spectroscopy, 2D NMR experiments (COSY, HMQC, HMBC), and UV-Vis spectroscopy. Overall (cumulative) formation constants (logβ) were determined at ionic strengths of 0.1, 0.5, and 1.0, M KNO₃ over the temperature range 298–318 K. At 298 K, the oxalate complexes are significantly more stable (logβ = 7.63→15.70 as the ionic strength increases from 0.1 to 1.0 M) than the corresponding tartrate species (logβ = 5.11→8.87). Analysis of the temperature dependence of logβ shows that the Gibbs free energy change comprises both temperature-dependent terms and an approximately temperature-independent covalent contribution, the latter becoming strongly negative values in the tartrate system. The NMR data support a bidentate coordination mode involving deprotonated hydroxyl and carboxylate groups, whereas ¹⁷O NMR monitors the mechanism of water exchange within the Eu(III) hydration sphere. In the UV-Vis domain, a distinct blue shift in the absorption band is observed at 0.1 M KNO₃, while at 1.0 M KNO₃, the band shows a pronounced decrease in intensity, a hypochromic effect. This behavior can be attributed to increased structural distortion and a partial loss of coplanarity within the tartrate coordination environment. By contrast, the oxalate system behaves differently: the spectra, together with the thermodynamic data, support a more covalent Eu–O interaction, consistent with stabilization of Eu(III) by two dicarboxylate ligands adopting distinct coordination modes.

This paper is devoted to obtaining a zeolite-containing sorbent based on metallurgical waste — slag. The synthesis of zeolite adsorbent from ash and slag was carried out by hydrochemical and thermal treatment. The initial object and the obtained material were characterized using following methods: Fourier-transform infrared spectroscopy, scanning electron microscopy, energy dispersive analysis, X-ray phase analysis, titrimetry. The way of converting solid-phase waste into a beneficial product has been demonstrated. The study results showed that the surface of the obtained material is saturated with functional groups (hydroxy-, carboxy-, lactone), which predetermine the ability to bind metal ions during adsorption. The adsorption capacity of the product has been estimated for iodine and methylene blue. A thermodynamic analysis of the process of sorption of copper (II) ions from an aqueous solution has been conducted. It has identified that the sorbent can also be used for the adsorptive concentration of ions of rare-earth elements by the example of lanthanum and erbium. Laboratory testing of the possible use of the sorbent to purify industrial water was carried out using the example of wastewater from a chromium plating shop

This study experimentally demonstrates that a bentonite–vermiculite composite (1:2 mass ratio) is the most effective formulation for the treatment of crude oil–contaminated wastewater. The sorbents were characterized using XRD, SEM/EDS, ζ-potential, DLS, and TGA/DSC to evaluate their structural, surface, and adsorption-related properties. Kinetic analysis showed that the adsorption process followed the pseudo-second-order (PSO) model (R² = 0.96–0.99), suggesting that surface interactions and intraparticle diffusion within the layered composite governed the overall adsorption rate. Thermodynamic analysis revealed negative Gibbs free energy values (ΔG < 0) and a moderately positive enthalpy change (ΔH ≈ 26 kJ·mol⁻¹), confirming that adsorption is spontaneous and endothermic, with contributions from physical interactions, ion exchange, and hydrophobic effects. After adsorption, the ζ-potential shifted toward less negative values, indicating partial surface charge neutralization by hydrocarbon species. TGA/DSC data further confirmed strong oil retention and preserved structural stability of the sorbents, while the DSC-derived enthalpy increased from 2.0 kJ·g⁻¹ to 141.6 kJ·g⁻¹ after hydrocarbon uptake, indicating pronounced energetic effects associated with sorbate incorporation. Techno-economic evaluation under industrially relevant conditions (Q = 120,000 L·h⁻¹; C₀ = 392 mg·L⁻¹) showed effective oil removal to residual concentrations below regulatory discharge limits at a low treatment cost.

One of the most critical tasks of modern energy is accumulating thermal energy due to the inefficient use of thermal energy during the underloading of power systems in which heat-accumulating materials are used. Therefore the paper studies the effect of alternating electric current on the heat-accumulating properties in a mixture based on Na₂SO₄·10H₂O. It is established that the AC effect leads to an increase in the melt crystallization temperature of Na₂SO₄·10H₂O and Na₂S₂O₃·5H₂O and also contributes to the return of heat. The selection of the treatment mode of the Na₂SO₄·10H₂O–Na₂S₂O₃·5H₂O (50: 1 wt.) mixture by the AC was carried out. It was shown that the latent heat of melting of 329 kJ/kg is achieved at 500000 Hz frequency.

Developing environmentally friendly and highly effective adhesive compositions is a pressing challenge in modern materials science. This study synthesized and comprehensively characterized a new adhesive based on oxalic acid, formaldehyde, and phthalimide. These compounds were chosen as starting materials due to their expected adhesive properties and relative environmental friendliness. The resulting sample was analyzed using infrared (IR) and ultraviolet-visible (UV-Vis) spectroscopy to identify characteristic functional groups and intermolecular interactions. Additionally, a quantum-chemical analysis using density functional theory (DFT) was performed to evaluate the electronic structure, chemical bonding characteristics, and molecular stability. IR spectroscopy confirmed the presence of absorption bands corresponding to esterification and amide bonds, while UV-Vis spectroscopy data indicated the formation of conjugated systems that provide structural strength. Theoretical calculations are consistent with experimental observations and confirm the favorable electronic properties of the molecule. A combined experimental and theoretical approach provided a comprehensive understanding of the molecular architecture and potential adhesive properties. Thus, the adhesive based on oxalic acid, formaldehyde, and phthalimide exhibits good adhesion strength and is environmentally friendly to synthesize, making it promising for a wide range of industrial and sustainable applications.