1 Phenomenon of the long-range effect of poly(methacrylic acid) hydrogelpoly(4-vinylpyridine) hydrogel (gPMAA-gP4VP intergel system) оn erbium ions sorption was studied. It was established that the structure of the basic hydrogel had a significant impact on the self-organization of the PMAA hydrogel. The mutual activation of hydrogels was investigated in an aqueous medium. Dependencies of swelling coefficient, specific electric conductivity and pH of aqueous solutions were determined. Individual PMAA and P4VP hydrogels showed the erbium ions extraction degree of about 44 % and 17 %, respectively. At the ratios 5:1 (83 % of gPMAA-17 % gP4VP) and 4:2 (67 % gMPAA-33 % gP4VP), 56 % and 53 % of erbium ions were recovered, respectively. After 48 h the PMAA and P4VP hydrogels had the polymer chain binding degree of 70 %. The obtained results point to the evidence that at these ratios there are significant changes in electrochemical and conformational degrees of initial macromolecules in gPMAA-gP4VP intergel system.
Some technological solutions contain valuable components and can become an additional source of rare-earth elements to satisfy the current production demands. This research provides the study on using a combination of polyacrylic acid hydrogel (hPAA) and hydrogel of poly-4-vinylpyridine (hP4VP) in different molar ratios for praseodymium ions sorption from its nitrate solution. The mutual activation of the hydrogels in an aqueous medium provides their transformation into a highly ionized state by the conformational and electrochemical changes in properties during their remote interaction. The electrochemical properties of solutions were studied by the methods of electrical conductivity, and pH measurements of the solutions. The research showed that the maximum activation of hydrogels was revealed within the molar ratio of hPAA:hP4VP equal to 1:5. Moreover, the total praseodymium ions sorption degree after 24 hours of sorption by individual hPAA and hP4VP was 54 % and 47 %, respectively, whereas the praseodymium ions sorption degree by the hPAA–hP4VP intergel system in the molar ratio 1:5 became 62 %. A slight increase in the sorption degree of praseodymium ions by the intergel system in comparison with individual hydrogels can be explained by the achievement of a higher ionization degree of hydrogels being activated in the hPAA–hP4VP interpolymer system by the remote interaction effect.
Features of the extraction of yttrium and lanthanum with an intergel system based on hydrogels of polyacrylic acid and poly-4-vinylpyridine To predict the sorption activity and selectivity of hydrogels, the effect of mutual activation of polymer networks in the intergel system was studied. The intergel system of the hydrogel of polyacrylic acid ((hPAA)) and the hydrogel of poly-4-vinylpyridine (hP4VP), which was studied at a distance through the volume of the solvent in the absence of direct contact between the polymer networks, were chosen as the object of study. Intergel systems have been investigated using methods for measuring electrical conductivity, pH, and gravimetry. The mutual activation of La 3+ and Y 3+ ions with the intergel system in an aqueous medium was also studied. It has been established that as a result of the remote interaction of the studied hydrogels, their mutual activation occurs, leading to a significant change in their electrochemical and conformational properties. At certain ratios of acidic and basic hydrogels, a significant increase in the sorption of lanthanum and yttrium ions is observed in comparison with the initial hydrogels. These results indicate the appearance of ionized structures with optimal conformation, providing an optimal ligand environment around lanthanum and yttrium ions.
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