The sorption, structural, and thermal properties of the interpolymer system based on polymethacrylic acid (PMAA) and poly-4-vinylpyridine (P4VP) were studied at different component ratios for the extraction of rhenium (ReO₄⁻) and molybdenum (${\mathrm{M}\mathrm{o}\mathrm{O}}_4^{2-}$) ions from model solutions. The results showed that sorption efficiency depends on both composition and contact time. Systems with molar ratios of 3:3 and 2:4 exhibited the highest activity, reaching more than 90% extraction for rhenium and up to 94% for molybdenum after 48 h. FTIR spectra indicated the involvement of carboxyl and pyridine groups in complex formation with the metal ions, as evidenced by band shifts and the appearance of new absorption features. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) demonstrated that modification of PMAA with P4VP enhances the thermal stability of the system, which is maintained even after desorption. The system with the optimal composition showed structural stability and the ability to regenerate without a notable decrease in sorption capacity. Sorption performance was preserved across a wide pH interval, with maximum values at pH 2–4, which makes the system suitable for hydrometallurgical applications. Comparison with literature data indicates agreement with current approaches to rare-metal recovery, while the PMAA–P4VP system is distinguished by improved stability and potential for further development. These findings provide a basis for the design of selective and environmentally safe processes for rhenium and molybdenum recovery, relevant to the conditions of the Republic of Kazakhstan, where technogenic solutions rich in these metals are available.

In this work, the processes of sorption and desorption of chromate ions from the solution obtained as a result of the processing of high-chromium ilmenite concentrate were studied using sorbents: Amberlite IR120 (Na), Amberlite IRA-35, PuroliteA-100, LewatitMono Plus M-500. The influence of pH factor and sorption system composition on the sorption process of chromate ions (VI) was investigated. Different polymers were tested to evaluate their combined effect on the recovery of chromate ions. A correlation was found between the increase in the efficiency of the sorption process of chromate ions (98%) and a decrease in pH from pH 13.5 to pH 2.5. In addition, the sorption process was improved at higher sorbent concentrations and the desorption efficiency increased at higher molar concentrations of sodium hydroxide (NaOH). The study's results will serve for the optimization of sorption processes for the extraction of chromate ions (VI) with the participation of various polymeric sorbents in the industry.

Isolating rhenium and molybdenum selectively from multicomponent acidic hydrometallurgical solutions remains problematic because of the abundance of competing cations and the low concentration of target oxoanions. This study investigates the sorption of Re(VII) and Mo(VI) oxoanions by an interpolymer system (IPS) comprising a cellulose–polyethyleneimine–glutaraldehyde (Cellulose-PEI-GA) weak-base anion exchanger and a sulfonated styrene–divinylbenzene cation-exchange resin (Lewatit MonoPlus SP112H), operating as spatially separated but solution-coupled phases. The industrial feed, a sulfuric acid leach liquor from electrostatic precipitator dust at the Zhezkazgan copper smelter, Kazakhstan (pH 1.25), was pretreated by liquid–liquid extraction with a trialkylamine-2-ethylhexanol–kerosene system followed by ammonia stripping to give an alkaline re-extract (pH 11.98) used for sorption. At the optimal 1:1 mass ratio of the two components (3:3), the IPS achieved a rhenium recovery of 77.7% (Kd = 3678 mL g⁻¹, q = 4.51 mg g⁻¹) against a markedly lower molybdenum recovery of 24.0% (Kd = 333 mL g⁻¹), giving a Re/Mo separation factor β of 8.8–15.5 across the studied compositions; this uptake exceeded the value predicted from the individual sorbents by a factor of ~2.6, indicating a cooperative rather than purely additive effect. Sorption kinetics (pseudo-first-order, pseudo-second-order and Elovich models) and diffusion mechanisms (Weber–Morris and Boyd models) were consistent with mixed film- and intraparticle-diffusion control. Desorption with hydrochloric acid recovered 91.4% of the sorbed rhenium and 89.1% of the molybdenum, and FTIR, TGA, and BET analyses (surface area increasing from 1.93 to 8.62 m² g⁻¹ for the cellulose component and from 7.21 to 8.46 m² g⁻¹ for the resin) confirmed sorbate-induced textural and compositional changes consistent with the proposed complementary anion-/cation-exchange mechanism.

Rhenium and some trace elements are different from other metals. Their importance comes from the fact that they are used in high-temperature alloys, optoelectronic devices, catalytic systems, and energy technologies. Because they are rare in nature and are often found in small amounts in copper, molybdenum, zinc, and aluminum ores, it is hard to extract them. This depends on how the metallurgical industry works and how much money it makes. This, along with the fact that the quality of the ore is getting worse, has brought to light a wider range of raw materials, such as off-gases, metallurgical dust, coal waste, and spent catalysts. Hydrometallurgical methods are the main ways to extract minerals. They include different combinations of leaching, ion exchange, solvent extraction, and sorption. Polymeric materials, particularly interpolymer hydrogel systems made of polymethacrylic acid and poly-4-vinylpyridine, have become useful for binding perrhenates and trivalent lanthanide ions in the last few years. This is because the interactions between the polymers are controlled and work together in the polymer matrix. These improvements make it possible to extract a wider range of raw materials and open up new ways to selectively extract metals at very low concentrations. This review summarizes information about the geological and anthropogenic resource base, the most common ways to get rhenium and trace elements, and the latest technological advances in processing these materials.