The aim of the work is to provide a comparative study of influence of ionic radii of neodymium and scandium ions on their sorption process from corresponding sulfates by individual ion exchangers Amberlite IR120, AB-17-8 and interpolymer system Amberlite IR120-AB-17-8. Experiments were carried out by using the following physicochemical methods of analysis: conductometry, pH-metry, colorimetry, and atomic-emission spectroscopy. Ion exchangers in the interpolymer system undergo remote interactions with a further transition into highly ionized state. There is the formation of optimal conformation in the structure of the initial ion exchangers. A significant increase of ionization of the ion-exchange resins occurs at molar ratio of Amberlite IR120:AB-17-8 = 5:1. A significant increase of sorption properties is observed at this ratio due to the mutual activation of ion exchangers. The average growth of sorption properties in interpolymer system Amberlite IR120:AB-17-8 = 5:1 is over 90% comparatively to Amberlite IR120 and almost 170% comparatively to AB-17-8 for neodymium ions sorption; for scandium ions sorption the growth is over 65% comparatively to Amberlite IR120 and almost 90% comparatively to AB-17-8. A possible reason for higher sorption of neodymium ions in comparison with scandium ions is maximum conformity of globes of internode links of Amberlite IR120 and AB-17-8 after activation to sizes of neodymium sulfate in an aqueous medium.

Rare earth elements play an important role in the production, energy, and high technology. Due to the rapid development of industry, the demand for rare earth metals is rising every day. Therefore, it is necessary to improve the extraction of rare earth metals from various sources to meet the demand for these elements. Currently, pyro- and hydrometallurgical technologies are used to extract rare earth metals from an ore and other secondary sources (industrial wastewater, acid drainage mines, etc.). Hydrometallurgical technologies include precipitation, extraction, adsorption, and ion exchange methods. Adsorption is one of the most effective methods for the extraction and separation of rare earth elements. Adsorption methods are highly selectivity to metal ions and have low emissions. However, not all adsorbents are effective in producing the same metal ions. This study provides an overview of the different adsorbents that can be used to extract rare earth elements from aquatic systems. Hydrogels and molecular polymers have been found to be cost-effective methods for high-grade rare earth metals. Further research is needed to ensure the performance of these systems.

The escalating demand for precious metals in high-tech industries and jewelry, combined with the depletion of their reserves, underscores the need for efficient methods of gold recovery from industrial effluents. An interpolymer system comprising industrial ion exchangers KU-2-8 (in H⁺ form) and AV-17-8 (in OH⁻ form) demonstrated strong selective sorption capacity for Au(I) ions from a simulated Au(I)/Fe(II) mixed solution. The optimal KU-2-8:AV-17-8 (3:3) system achieved a sorption efficiency of 97.0% for Au(I) ions after 48 h with a desorption efficiency of 98.0% using a thiourea/sulfuric acid solution. The distribution coefficient (K_d) for Au(I) ions reached a maximum of 3233.3 mL/g at the 3:3 ratio, with a separation coefficient (β) of 40.62, indicating exceptional selectivity over Fe(II) ions. Fourier-transform infrared (FTIR) spectroscopy revealed structural changes post-sorption, including shifts in absorption bands (e.g., from 1273.5 cm⁻¹ to 1292.9 cm⁻¹) and the appearance of new bands (e.g., at 3171.1 cm⁻¹), confirming stable ion interactions. Thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) demonstrated enhanced thermal stability post-sorption, with reduced mass loss up to 100 °C. These findings highlight the KU-2-8:AV-17-8 (3:3) interpolymer system’s high selectivity, robust sorption capacity, and efficient desorption, presenting a sustainable solution for gold recovery in hydrometallurgical applications.

This paper presents a study of the kinetics of neodymium and praseodymium ions sorption using interpolymer systems based on KU-2-8 and AB-17-8 in salt forms. Sorption of target ions was carried out in a dynamic mode (with constant stirring) in interpolymer systems in molar ratios of 4:2 and 3:3 (cation exchanger to anion exchanger). Aliquots were collected during certain time intervals, then widely known kinetic models of sorption were used to construct linear graphs. According to the obtained results, the best model for describing sorption was pseudo-first order (the highest value for the 4:2 system = 0.97885 and 0.98112; for the 3:3 system = 0.9647 and 0.98779). Such results are important for understanding the mechanisms of the sorption process and establishing the limiting factor that can slow down this process. The kinetic model of pseudo-first order may indicate the need to improve the washing out of counterions from the polyelectrolyte matrix for their high ionization and accessibility of functional groups for metal ions. This assumption can be used in the future to optimize industrial schemes of ion-exchange sorption of REE.

The extraction of yttrium ions by interpolymer systems based on industrial ionites: KU 2-8 cationite and AB-17 anionite was studied. The dependences of the yttrium content in the aqueous medium after sorption by the interpolymer system were studied KU 2-8:AB17-8 depending on the time, the degree of binding of the polymer chain (with respect to yttrium ions) by the initial ionites and interpolymer systems KU 2-8: AB-17-8. The maximum content of yttrium ions in the aqueous medium after sorption is observed at ratios of 3:3 and 4: 2 and the duration of remote interaction is 88 hours. At the same time, the content of yttrium in the aqueous medium after sorption is 60 mol.% and 56.4 mol.%, respectively. High values of the degree of binding of the polymer chain with respect to yttrium are observed at the ratios KU 2-8: AB-17-8=3:3

The effect of the solvent/monomer (S/M) ratio on the structure and adsorption properties of microporous polymer particles imprinted with lanthanum and scandium ions is studied. Microporous particles imprinted with lanthanum and scandium ions were obtained from two functional monomers-methacrylic acid (MAC) and vinylpyridine (4-VP) - by forming a complex with the template ion of lanthanum and scandium by ion interactions. The selfassembled lanthanum/monomer complex was polymerized in the presence of an ethylene glycol dimethacrylate (EGDMA) crosslayer by suspension polymerization. The chemical structure, morphology, and adsorption capacity of microporous particles imprinted with lanthanum and scandium ions were analyzed by infrared spectroscopy. Molecular polymers showed high selectivity with respect to lanthanum and scandium ions.