The aim of the work is to study the effectiveness of a molecular imprinting technique application for the creation of highly selective macromolecular sorbents for selective sorption of light and heavy rare-earth metals (for example, samarium and gadolinium, respectively) with subsequent separation from each other. These sorbents seem to be promising due to the fact that only the target rare-earth metal will be sorbed owing to the fact that complementary cavities are formed during the synthesis of molecularly imprinted polymers. In other words, the advantage of the proposed macromolecules is the absence of accompanying sorption of metals with close chemical properties. Two types of molecularly imprinted polymers (MIP) were synthetized based on methacrylic acid (MAA) and 4-vinylpyridine (4VP) functional monomers. The sorption properties (extraction degree, exchange capacity) of the MIPs were studied. The impact of template removal cycle count (from 20 to 35) on the sorption effectivity was studied. Laboratory experiments on selective sorption and separation of samarium and gadolinium from a model solution were carried out.

This present study is targeted at the complex investigation of the behavior of interpolymer systems based on acidic rarely crosslinked polymeric hydrogels (polyacrylic acid hydrogel (hPAA); polymethacrylic acid hydrogel (hPMAA)) and basic rarely crosslinked polymeric hydrogels (poly-4-vinylpyridine hydrogel (hP4VP), specifically the poly-2-methyl-5-vinylpyridine hydrogel (hP2M5VP)) either in an aqueous medium or lanthanum nitrate solution. We found that the transition of the polymeric hydrogels in the developed interpolymer systems (hPAA-hP4VP, hPMAA-hP4VP, hPAA-hP2M5VP, and hPMAA-hP2M5VP) into highly ionized states leads to significant changes in electrochemical, conformational, and sorption properties of the initial macromolecules. The subsequent mutual activation effect demonstrates strong swelling of both hydrogels in the systems. The sorption efficiency of lanthanum by the interpolymer systems is 94.51% (33%hPAA:67%hP4VP), 90.80% (17%hPMAA-83%hP4VP), 91.55% (67%hPAA:33%hP2M5VP), and 90.10% (50%hPMAA:50%hP2M5VP). An advantage of the interpolymer systems (compared to individual polymeric hydrogels) is the strong growth of their sorption properties (up to 35%) due to high ionization states. Interpolymer systems can be considered new-generation sorbents for further application in the industry for highly effective sorption of rare earth metals.

Molecularly imprinted polymers (MIPs) as well as non-imprinted polymers (NIPs) were synthesized for selective sorption of lead and terbium. The ratio of raw monomers for the terbium–MIPs’ synthesis was optimized based on the results of the synthesis of lead–MIP. It was found that the molar ratio of template/monomer/monomer/cross-linker = 1:5:5:8 was the most accurate for successful synthesis of the target MIP. As a result, the yields of the MIP and NIP on terbium were 59.3% and 61.2%, respectively. The structure of the imprinted samples was determined by FTIR spectroscopy. SEM analysis of the imprinted structures showed that the Tb–MIP contained a large number of pores compared to the NIP. The size of these pores ranged from 0.779 μm to 1.874 μm. The results of sorption experiments showed that the adsorption efficiency of Tb–MIP was seven times higher than that of NIP: the sorption degree was 70.80% for MIP and 9.95% for NIP. The imprinting factor was calculated and was equal to 7.06. The sorption process was described by the Radushkevich and pseudo-second-order kinetic models. It was shown that sorption by NIP occurred with a fast saturation of a lower Tb concentration, and the MIP’s sorption passed slower and more efficiently. The desorption degrees of Tb–MIP and NIP were 90.15% and 52.67%, respectively.

Aromatic hydrocarbons, epichlorohydrin, and polyethyleneimine were used to synthesize polyfunctional anion exchangers. IR spectroscopy and elemental analysis were used to examine their composition...

Polyfunctional anion exchangers based on aniline, epichlorohydrin, and some polyamines were synthesized. The composition and structure of the anion exchangers were studied by IR spectroscopy and elemental analysis. Molybdenum sorption was studied by classical polarography, and dependences of the sorption of molybdenum(VI) ions on the solution acidity, concentration of metal ions, and time of contact of the resins with the Na₂MoO₄ solution were determined in batch experiments. These ion exchangers exhibit high performance in sorption of molybdenum ions. The developed sorbents with increased sorption ability can successfully solve problems of removing molybdenum(VI) ions from process effluents in nonferrous metallurgy.

A comparative sorption dependence was carried out between the Dowex HCR-S/S″ industrial ion-exchange sorbent and the synthesized ion-exchange sorbent based on dibenzylamine, epichlorohydrin and polyethylenimine in relation to copper and silver ions. The sorption of copper and silver was studied by ionometry and the dependences of the sorption of copper and silver ions in the static mode were established depending on the concentration of metal ions and the duration of ionite contact with solutions of copper and silver nitrates. It was found that the maximum sorption capacity of the synthesized ion exchanger is 672.4 mg/g for copper ions and 721.0 mg/g for silver ions, and 626.3 mg/g and 679.7 mg/g for industrial Dowex HCR-S/S″ ionite, respectively. It is shown that the sorption of copper and silver is described by various kinetic models: for copper, the best correspondence is demonstrated by a pseudo second order kinetic model, whereas for silver, the Elovich kinetic model the different nature of the interaction of ions with active centers. It has been revealed that the synthesized ion exchanger is superior to an industrial sorbent in terms of sorption rate and degree of extraction of valuable metals, especially in concentrated solutions, which indicates the prospects of its use in the processes of selective extraction of copper and silver.